This is not a story on trashing oxygen (O₂) sensors even though the title might appear to make that implication. Instead, we thought we’d share some insight into how O₂ sensors work and how they might conspire – unintentionally – to fool you. So as not be deceived, it’s necessary to learn how O₂ sensors operate.

The most important point is that O₂ sensors do not measure air-fuel ratio. As their name implies, oxygen sensors measure the presence of oxygen in the exhaust. Once measured, the system’s ECU and software compute the relationship of oxygen to fuel based on a given fuel’s stoichiometric ratio. Once that ratio is calculated, the meter displays that information as an air-fuel ratio (AFR).

Because O₂ sensors use free oxygen as their only measurement for calculating AFR, they can be subject to significant error when working at idle on engines equipped with long duration camshafts and/or cams with excessive overlap.

Idle Hands Make the Devil’s Work

Overlap is defined as the amount of time (in crankshaft degrees) that both the intake and exhaust valves are open simultaneously. Overlap is what creates that desirable lumpy idle for street engines. The problem occurs when an excessive amount of oxygen makes its way from the intake port directly into the exhaust at idle and low engine speeds because of overlap. This free oxygen is picked up by the O₂ sensor and determined to be indicative of a lean AFR condition when, in reality, the engine could potentially be running slightly rich.

As an example, we have some experience with a carbureted 4.8L LS engine in a street Chevelle. Even though the engine is equipped with a conservative 219 degrees of duration at 0.050 in its hydraulic roller cam, the tight converter created a sufficient load to pull the idle speed down when in gear to around 750 rpm. Despite the cam’s mild overlap, the on-board wide-band sensor produced readings of between 16:1 and 17:1 AFR on our wideband O₂ sensor.

We knew from experience that this engine would not idle at a true 16:1, so this was clearly an error produced by the overlap in the camshaft. This only occurred at idle. As soon as RPM increased to over 1,000, the AFR readings became increasingly richer and more accurate. This makes relying on the O₂ sensor problematic for engines with long duration and high overlap camshafts at idle. This is also why “self-learning” throttle body EFI systems tend to struggle when used on engines with lower than 10 inches of manifold vacuum. The excess oxygen “fools” the self-learning system into tuning for a rich AFR. Let’s look at why this occurs.

Let’s assume we have an engine that is equipped with self-learning throttle body EFI but is also equipped a long-duration camshaft that idles at 9 inches of manifold vacuum. The owner commands a target idle AFR of 13.5:1. This is one point that the EFI system will use to calculate the amount of fuel to deliver to the engine. Engine displacement, idle speed, and manifold vacuum are also integrated into the equation used to produce an idle fuel number.

With excess free oxygen in the exhaust, the O₂ sensor reads this as a too-lean condition, so the ECU adds fuel. Then when the engine is shut off, most of the self-learning systems add this fuel to the long-term fuel trim number – richening the overall fuel delivered at idle. When the engine is started again, the whole process repeats. After about 15-30 restarts, the engine is now running excessively rich and yet the O₂ sensor still detects free oxygen present in the exhaust. The owner is frustrated because the engine is running way too rich, fouling plugs, and generally runs poorly.

Fooling the Brain

One solution to this issue is to make sure there are no leaks in the system that could contribute to this problem. Even a small exhaust leak will pull fresh air in from the outside and greatly exacerbate this free oxygen problem. The next step is to start over by re-booting the system, establish a decent running AFR where the engine runs cleanly at idle (regardless of what the O₂ sensor reads) and then disable the learning function at idle so further corrections do not continually add fuel to the system. This isn’t as dramatic as it sounds, since a majority of learning with these systems is accomplished within the first hour of driving the engine in various situations.

This problem with high overlap camshafts and O₂ sensors isn’t limited to just EFI engines. Carbureted engines can suffer problems as well. Engine builders and tuners all agree that when evaluating a tuning routine – it’s always recommended to adjust air-fuel ratio and timing for what the engine wants, not necessarily toward a specific number. This means if you change the idle fuel or ignition timing – listen to the engine.

If it sounds better, the vacuum gauge reads a higher and more stable number, and the idle speed increases, all of these are indications the engine liked the change. When these things occur, the engine is telling you that this was a good step – regardless of the number displayed on the AFR device. Another way to put this is to not chase after a magic AFR number that you think the engine should achieve. The engine will tell you what it prefers if you pay attention.

A Computer Isn’t A Substitute For Your Brain

This doesn’t mean we cannot use high-tech devices to help us with the tuning effort. We recently installed a Holley Sniper system on a big-block Chevrolet. With the engine warmed and idling, the default idle AFR was 13.8:1.The engine idled decently and sounded good. We then installed an EMS five-gas exhaust analyzer to evaluate the idle quality. The machine indicated very high HC (unburned hydrocarbons – raw fuel).

A high HC number could mean that the AFR is excessively rich. But it could also indicate a misfire because the engine was running lean. The engine was equipped with a relatively mild hydraulic roller camshaft that did have some overlap. We commanded a 13.2:1 AFR and the HC count dropped, revealing that the engine wanted the extra fuel to idle more efficiently.

This is where a preconceived notion that the engine should run at 13.8:1 would not necessarily be what was best for the engine. Admittedly, the HC difference was minor, but the point is that when we richened the idle AFR, idle vacuum also increased about 0.5 InHg. The bottom line was that the engine wanted more fuel at idle.

Please don’t interpret this to mean that you should not use an O₂ sensor to help tune. Instead, it’s a matter of understanding what is really happening inside the engine. Once an engine reaches a certain engine speed – 2,500 rpm as an example – the issue of overlap isn’t as critical because there’s less time for this to occur. This will make the O₂ sensor readings far more accurate.

Accuracy vs. Precision – The Eternal Struggle

“Accuracy” is a relative term, even here, because of how the O₂ sensors are designed. As we mentioned earlier, O₂ sensors use free oxygen as the basis for a calculation of an AFR. We won’t get into all the details of how this calculation occurs but each manufacturer uses a different smoothing process to record this data and determine the AFR. This is one reason why comparisons of several O₂ sensors from different companies in the same exhaust system will display different results. If an O₂ sensor is used as a comparator on a given engine, then its accuracy isn’t as critical.

As an example, let’s say we have a big-block Chevy on the dyno and the O₂ sensor tells us the AFR is 12.8:1. This may or may not be an ideal ratio for that engine and that number may or may not be 100 percent accurate. What is important is that we’re using it as a reference point from which we can evaluate a change. Assuming we added 2 jet sizes, the AFR changed to 12.4:1, and the power dropped 6 hp, we know we’ve increased fuel and the engine responded by losing power. The indicated AFR number is a reference point.

What we know is that the indicated 12.4:1 is too rich. So we then changed jetting to two jet sizes leaner than the original jetting. This test revealed that the AFR moved to 13.2:1 and power was down from the baseline but only slightly. Some tuners may then say – that engine wants a 12.9:1 AFR. Our version is that with that particular O₂ sensor that might be a correct statement. But what we would suggest is that the engine is now very close to best peak power under the current atmospheric conditions. The tuner could then use 13.0:1 as a point of reference.

All wideband O₂ sensors calculate an AFR based on a known standard, which is called the fuel’s stoichiometric air-fuel ratio. For pure gasoline, this is 14.7:1. But right away it’s important to mention that nearly all pump gasoline sold in this country is laced with 10-percent ethanol. This may not sound like a big deal, but it changes the fuel’s stoichiometric number from 14.7:1 to 14.1:1.

Here’s why this is important. Since nearly all wideband oxygen sensors uses 14.7:1 as the baseline from which to calculate the actual air-fuel ratio, right from the beginning the O₂ sensor’s display is off by roughly half a ratio. Let’s confuse this situation further by adding that any oxygenated race gasoline will likely spec a different stoichiometric AFR.

To underscore this point, VP Racing Fuels‘ Q16 sports a stoichiometric ratio of 13.3:1. That’s a 1.4:1 or a 10-percent shift from 14.7:1. If you think this will create a significant AFR “error” on a wideband O₂ sensor, you would be correct. Racers will tell you “Yeah, Q16 always reads rich.” Now you know why.

We’ve touched on several areas on how to keep track of not only what your O₂ sensor is telling you but how to interpret those numbers so you don’t get lost or confused. Just remember to use that wideband gauge as a comparator. Being a sharp tuner means understanding how all the systems work and then using that information to make intelligent decisions.  Your engine will thank you.

Wiring in any form is more than intimidating; it’s actually pretty scary. Unless you know what you’re doing and what you’re working with, it could prove to be the most stressful and frustrating part of building a racecar.

With so many different colored wires of assorted gauges routing to different components throughout the car, it’s important to do research and prepare materials for the task ahead. It was about time for our drag car, BlownZ, to get a wiring harness update along with some other new components. We called in wiring maven Jeff Jordan to work his magic. If you aren’t familiar with Jordan, he is the owner and founder of Jordan Innovations, which has been involved in the racing industry since 2006.

Jordan has had experience with Global Time Attack builds, Formula Drift machines, SCCA/NASA racecars, and much more. We were happy to work with him and learn about some of his tips and tricks while he was hard at work on BlownZ. Luckily, he was nice enough to sit down with us and go over his five “do’s” and five “don’ts” of automotive wiring. Follow along as we show you some great tips about wiring a racecar!

The Do’s:

1. Diagram Everything, Electrically And Spatially 

The first, and most important do is to diagram everything. Using a navigation system is very similar to wiring because every route needs to be planned out. Without proper planning, the wiring could turn out to be one of the biggest clusters ever experienced. Mapping out where everything goes, how much supplies are needed for each and every system in the car, and where to start are crucial to begin a wiring project.

“The biggest ‘do’ and the biggest thing that I think people should take away is that a lot of people are intimated by the thought of doing a wiring job. And because they haven’t done it before, they don’t understand 100-percent of all the things that they’ll have to do. If the person doesn’t know where to start, they’re just going to start soldering stuff, or, you know, running wires and all that without a plan. That’s when they run into some really difficult decisions, and unless they know what they’re doing, they’ll get in over their head,” Jordan explained.

“You make a list of what all the components need. If you have all the information you need to make the diagram, then you have all the information you need to make the harness. If you can’t get through the diagram, meaning that if you don’t know what you need or if you don’t know where stuff goes, you need to figure that out before you start,” added Jordan.

2. Use Crimps When Vibration Or Strain Is An Issue

We all know that racecars vibrate a lot. whether they’re under load out on the track or sitting and idling, there will be vibration. There are also times when wires route through tighter places than others, causing strain. When vibration is a big issue, it is better to use crimps to make a connection, rather than soldering it. Solder is great for electrical connections, but it isn’t a true fusing of metal like an actual weld. It has the tendency to crack under vibration or strain, causing the connection to short, or disconnect completely. Remember to always plan out where your solder joints will be so that when it comes time to add them in, the area is already relieved of stress.

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“We use crimps when mechanical forces are an issue. I come from the aviation world where crimps are the norm because vibration is always an issue. But in cars, as long as you can strain relieve and isolate the joint from vibration, solder joints work very, very well for a lot of things,” explained Jordan.

“The downside to crimps, most of the time, is that they’re much bigger than a solder joint. If you had a bundle of 50 soldered wires and you staggered the joints, you wouldn’t be able to tell where those splices were. But if you shaped that harness, vibrate it, or put a lot of strain on it, you’re gonna break a few of those solder joints, whereas crimps would not break,” Jordan stated.

3. Stagger Your Solder Joints

Staggering solder joints is a very good tip for basic wiring or even for building something as extensive as a wiring harness. When there is a bundle of wires that need to be spliced, it would be ineffective to splice all of the wires in the same spot because it would create a larger diameter spot in the harness. By staggering the joints, it allows for an even diameter throughout the harness.

“Whenever you have a splice it’s gonna be a little bit thicker in that spot. If you stagger the joints, the bundle diameter stays closer to constant. You don’t want there to be one thick section and one thin section,” Jordan explained.

4. Strain Relief and Abrasion Resistance 

A wiring harness can be routed anywhere throughout the car. It would be in your best interest to strain relieve the harness, should any mechanical forces pull on the harness while the car is idling, under load, or even stationary. This can be done by adding some method of external support for the harness at every splice.

“Everywhere you have a mechanical force on the harness, trying to pull it apart or trying to pull it in one direction, you want to have something like a ziptie  or P-clamp so that the mechanical forces acting on your harness don’t pull it apart or vibrate it out of commission. Think of a half-inch harness that splits off into quarter-inch harnesses; you want to make sure that if you pulled those quarter-inch harnesses apart that it doesn’t rip into your half-inch harness. You’re making sure that you’re not bending and vibrating the harness at the same point over the lifetime of the harness, because the individual copper wire strains can break. That’s what zipties are for in every splice,” Jordan stated.

Another thing that is often overlooked is strain-relieving the wire ends where they enter other components, especially connectors.

“We strain-relieve all of the crimps where the wire enters the pin that goes into the connector. Those all have a wire crimp and insulation crimp. The insulation crimp is the part of the pin on the back that goes over the plastic, and the purpose of that strain-relief is that if you pulled the wire, it’s holding on to the insulation, not just the copper, because the copper will work-harden and break,” said Jordan.

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If the harness is going to be routed anywhere where the loom can be ripped, like sharp corners or edges, or through the frame or firewall, it would be a good thing to prepare the area for abrasion resistance. That can be done by using rubber grommets to protect the harness from the spot where it enters the frame to the spot where it exits the frame.

“Whenever you have a harness that passes over a sharp corner, you want prevent the harness from getting rubbed or cut. Running stuff through the frame is really cool, except everything vibrates, rattles, and gets pulled on. Putting grommets where harnesses pass through bulkheads is key,” Jordan explained.

5. Use Good Materials And Tools

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Left: T&B Ty-Rap zipties are choice for Jordan because they have a stainless steel locking mechanism for maximum strength and longer life, rather than a standard ziptie with a nylon locking mechanism. Right: Jordan’s Metcal soldering station where all of the wiring magic happens.

Knowing your business when it comes to wiring is one thing, but using good tools and good materials is half the battle. Using supplies that are tried-and-true is the way to go when tackling even the easiest of motorsport wiring jobs.

“Having good tools and materials is all relative. There’s definitely another level of materials and tools above what I use that Formula One uses. You’re not going to be doing a motorsport-level wiring job with stuff from Auto Zone. Some of that stuff might work well, but there’s a reason why professionals tend to use better tools and materials. Some people aren’t going to pay $700 for a pair of crimpers if they’re only gonna use them once, but some might pay 50 bucks for the next step down on eBay or Craigslist,” Jordan added.

Often, the step up in price from bargain no-name equipment and raw materials to decent quality stuff is relatively modest, although it can add up when wiring an entire car. Compare that to the cost of making repairs or troubleshooting, though, and it’s worth every penny.

The Don’ts:

1. Don’t Hack Or Get In Over Your Head

The number one rule when it comes to wiring is to have patience. Don’t have the mindset to wire the car up hastily just to get it running and say you will build a nice harness later, because “later” never comes. Just do it right the first time and you will be surprised at how much time and money was saved. You’ll also have a running car!

“Build the harness and then test each part of it before you go invest a ton of money to take your car to the track. That disappointment of ‘I thought the car was working and it’s not’ is such a powerful demotivator to car fans, and that’s how cars get left sitting for the whole season. You know, like ‘ah f@&# it, I’m just going to leave it in the garage,’” explained Jordan.

Frustration leads to mistakes, and when you’re working with electrical systems, mistakes lead to fun stuff like cars not running, or worse yet, cars catching on fire. If you don’t have a good understanding of what you’re doing, stop and fill in the gaps in your knowledge before continuing the job, or bring in an expert if it’s truly beyond your abilities.

2. Don’t Wire Both Ends Then Route The Wires

This is a big one, and it’s something that a lot of people do without knowing that what they’re doing is wrong. By doing this, it’s very easy to end up with a bunch of wires running all over the place. To avoid soldering or crimping both ends before the wires are routed, simply refer back to the diagram of the electrical system you are building and you will see how everything needs to be routed.

“Something that a lot of people do is they’ll run wire run and solder or crimp the ends, and then figure out how it routes through the car. That’s how you end up with stuff that just runs all over the place. This goes back to if you have a diagram of where all your stuff needs to go. With that diagram, you’ll know that the wires that go from A to B will need to pass through there and there to get there using the routing that you designed. All of your wires will have enough length on them and they’ll go where you want them to go,” added Jordan.

3. Don’t Place Solder Joints In Areas With Vibration Or Strain

When a solder joint is made in an area with a lot of vibration or strain, it will easily break and cause a short or open circuit in the system it’s running to. Use crimps in these areas, as they are far more flexible than a soldered joint.

“What’s so bad about solder joints that break is when you go to pin out the harness, It’ll pin out with continuity, you know, if you’re on a continuity test on the multimeter and you’re testing from A to B, it’ll beep and read 1 ohm or 0 ohms because it does have continuity, but its broken. As soon as you try to pass some power through there, it’s going to create a bunch of resistance and your voltage is going drop because the solder joint is broken. That wire’s joint’s ability to pass power through it is now one 1/100th of what it’s supposed to be,” stated Jordan.

4. Don’t Use Regular Pliers For Important Crimps

The reason why it’s not good to use pliers, or any other tool not meant for the job, for important crimps in the system is because they won’t hold. It might look like a good crimp, but there is no way to tell. So, in this case, it is really beneficial to use the proper pair of crimpers for the job.

“A lot of people don’t buy good crimpers or they don’t know where to buy good crimpers, so they end up using pliers. The important thing about a crimp is that a crimp doesn’t have solder to help out with the mechanical connection between the wires. All you have is a mechanical connection that you’re able to put on these wires with the crimp. Also, there’s no way to tell when the crimp fails because it will still be touching, but it won’t be touching all the way around. It’s very hard to diagnose when a crimp fails,” Jordan explained.

5. Don’t Rush

Chances are that if you rush a wiring job, you’re setting yourself up for disappointment. Just take your time to learn what you’re working with, make a diagram, take good measurements, and everything will go together as it’s supposed to. Because it’s usually one of the tasks left to the end of a project, wiring a car often doesn’t get enough time budgeted for its completion, and builders will make the error of speeding through the process as quickly as possible to meet a deadline.

“The only way to guarantee failure is to rush.  You could have done everything else right, but if you rush your chances of having a harness that doesn’t work go way, way, way up and that’s true for anybody. It’s true for somebody that does it 5 days a week, just like its true for somebody that does it once every couple of years.  So, take your time,” Jordan added.

Positive Energy

Hopefully these tips will help a lot when it comes to wiring up your own project car. With wiring, it’s really important that a diagram is made, good materials are used, quality tools are used, and that you have quite a bit of time on your hands, as doing things right can be a very time consuming process. The last thing you’d want is for your wiring to ruin the whole project, so just take your time and understand what you’re working with before you get started.

We want to give a big thanks to Jeff Jordan of Jordan Innovations for taking the time to sit down with us and go over these helpful tips with us. And we also want to thank him for doing an awesome wiring job on our beloved BlownZ!

Over the years we’ve seen all sorts of misinformation floating around the web on various forums and other social media interfaces with respect to E85 and ethanol fuels, so in the interest of education, we’ve taken some of those questions and put them into a Q&A format for you, dear reader. Without further ado, here are 16 things you need to know to maximize your E-xperience.

Q: What is ethanol?
A. Ethanol is a fuel created from the distillation of sugar. This fuel comes from renewable resources, such as corn and sugar cane. This fuel has certain advantageous attributes that make it a popular fuel for performance and racing. Currently NASCAR uses a race gasoline mixed with 15-percent ethanol, and the Indycar Series racers that initially switched from methanol to E98 subsequently converted to E85 in 2012.

Q: What is E85?
A: Anytime you see gasoline with an E prefix, that indicates the fuel contains a given percentage of ethanol. So E10 would contain 10-percent ethanol, E30 is 30-percent ethanol by volume and so on. This makes E85 a fuel with 85-percent ethanol and 15-percent gasoline. Along these same lines, E0 would indicate no ethanol is added to the gasoline.

Q: I’ve heard that ethanol is corrosive.
A: Ethanol by itself is not corrosive. E98 will likely contain an average of 0.5-percent water. This is because it is extremely expensive to remove that last bit of water. When ethanol is mixed with sufficient amounts of water, this can cause corrosion, but the effects can be minimized with easy steps such as keeping the fuel tank full when the vehicle is stored. Oddly, ethanol is also an excellent cleaner and will remove deposits often left by “bad gas.” Ethanol is often mistaken or linked with a fuel called methanol, a wood- or petroleum-based alcohol that is especially corrosive when stored in solution with bare aluminum. Ethanol is not an acid and has little effect on aluminum fuel system components.

Q: What is E85’s octane rating?
A: Gasoline is most often rated on an anti-knock index (AKI) that averages both a research and motor octane number. Premium pump gasoline (E10) is most commonly found with either 91 or 93 AKI. E85 has an octane rating between 100 and 105. You will read claims that can vary by a tremendous amount. This number can vary depending upon some complex ways that octane is measured which do not take into account E85’s ability to cool the inlet air.

Q: Can I pump E85 into the gas tank and run it?
A: If your car is a factory-built Flex-Fuel Vehicle (FFV) the answer is yes. But for a typical late-model car the answer is no without making significant changes to the amount of fuel delivered by the fuel injectors. Older carbureted cars and performance cars can be adapted to take advantage of this fuel’s outstanding octane and cooling benefits.

Q: What is the difference between ethanol and methanol? I’ve heard that methanol is nasty stuff and really corrosive.
A: Ethanol (sometimes referred to as E98) is simply no different than distilled spirits – sippin’ whiskey, if you will. The other 2-percent is gasoline, so it should definitely not be consumed. This fuel offers many of the benefits of using alcohol as a fuel with fewer of the negative side effects. Methanol is often called wood alcohol, or it can be made from natural gas. Methanol is toxic and should not be ingested. Methanol also has a lower heat content. However the BTU (heat) content of methanol is roughly half that of gasoline, which means you have to burn twice as much to make the same heat. Methanol is also more corrosive than ethanol, which is why ethanol is a better choice for street-driven engines. Indy cars prior to 2006 used methanol, converted for a short time to E98 and now run E85. NASCAR recently switched to Green E15 for the Cup cars.

Q: What is denatured alcohol – is that different from ethanol or E85?
A: Both start as ethanol, which is a spirit derived from any number of sources, the common being corn and (or) grains. Denaturing adds a small percentage of a poison like gasoline to the ethanol to render it toxic to ingest. This is done to allow its manufacture for purposes other than for human consumption. Other than the additive, it is usually straight ethanol, although our sources indicate that fuel grade ethanol has impurities like iso-butanol, which will certainly make someone very ill if consumed.

Q: Can I just increase the size of the jets in my carburetor and use E85?
A: The simple answer is that this probably will not work. E85 has roughly 25- to 30-percent less heat per pound of fuel so you need to increase the size of the jetting by roughly that much. So if the stock jetting was 75, it would require as large as 100 to 105 jets. This becomes an issue because the rest of the carburetor is not appropriately sized to meter that much fuel. It’s better to invest in an E85-designed carburetor. There are several companies that offer E85-specific model carburetors.

Q: Why does an engine require more E85 to make power compared to gasoline?
A: This has to do with ethanol’s chemical makeup. Because ethanol contains oxygen, it produces less heat for the same volume of fuel. As an example, a gallon of gasoline typically will produce 114,000 BTUs of heat while ethanol comes in at a lower rating of 76,600 BTUs per gallon. You will read estimates of 15- to 18-percent loss in mileage-per-gallon when using E85 compared to gasoline in flex-fuel vehicles (FFV). But an interesting change occurs with E85. It has a much greater cooling effect on the inlet air than gasoline and also delivers a much higher 98 to 100 octane rating. For any engine that can benefit from a fuel with a higher octane, it’s common to see a significant power improvement when using E85. This is especially true with supercharged or turbocharged engines. For naturally-aspirated, street-driven vehicles, there will be a mileage penalty with E85 compared to gasoline.

Q: I’ve read that all gasoline sold in the U.S. contains 10 percent ethanol. Is that true?
A: Not entirely. However, currently 96- to 97-percent of pump gasoline sold in the U.S. is blended with what averages to 10-percent ethanol. This was part of the EPA’s Reformulated Fuel Standard (RFS) that eliminated or reduced the use of other octane-enhancing additives that were deemed dangerous. In certain portions of the country you can purchase E0 or gasoline that does not contain ethanol. However, these fuels are blended with much higher concentrations of octane improving chemicals called aromatics that increase the emission of exhaust toxins.

Q: I’ve read several magazine stories where supercharged engines really benefit from E85. Is there any advantage to using E85 for a naturally-aspirated engine?
A: Absolutely. First, E85 offers an excellent octane or anti-knock index (AKI) rated between 100 and 105 octane. This can allow increasing the static compression ratio up to as much as 13.0 to 14.5:1 and will certainly improve performance on engines even at 11.0:1. Plus, E85 reduces inlet air temperatures which improves power by cooling the air entering the cylinder. Cooler air is denser, which adds power. There will be significant tuning changes necessary when using E85 instead of gasoline, but high-compression engines can especially benefit from E85.

Q: I hear one of the advantages of E85 is something called heat of vaporization. What does that mean?
A: The term most commonly used is latent heat of vaporization. What this refers to is the amount of heat required to convert a liquid—in this case E85—into a gas or vapor at a constant temperature and pressure. What this means is that when ethanol vaporizes, it pulls heat out of the air in the process, which cools the surrounding air. Ethanol has three times the cooling effect, by volume, than gasoline and four times the cooling based on BTU content. Cooling the inlet air simultaneously reduces the engine’s sensitivity to octane. This is why engines tend to knock or detonate with higher inlet air temperatures. When E85 fuel vaporizes in the intake manifold, it cools the air, making the engine less sensitive to detonation.

Q: I’ve heard that the percentage of ethanol in E85 can vary. Is there an easy way to test the actual percentages of ethanol and gasoline?
A: There are several inexpensive E85 testers on the market. Most of them merely have you add a specific amount of water into a tube and fill the rest with your E85 fuel test sample. The water will separate out the gasoline and you can read the percentage right on the side of the tube. This is a simple test that can have an error factor of up to five-percent. The more precise tools are the hand-held electronic devices that are within one-percent. There are also OE sensors that are designed to be permanently mounted in the vehicle’s fuel line. Percentages of E85 will vary most often during winter when the percentage of gasoline is increased to improve cold weather starting for Flex-fuel vehicles.

Q: I keep reading about E98. Why isn’t it just E100 – pure ethanol?
A: The term E98 is used as a more accurate accounting of the total amount of ethanol. For the practical purposes of using ethanol as a fuel, E98 is essentially just ethyl-alcohol or ethanol plus 2-percent gasoline so that it cannot be consumed.

Q: I’ve been told that if I put E85 in my older muscle car, I will have to use a special and very expensive PTFE fuel line. Is that true?
A: It is a good practice to replace the original fuel system in an older car when building a performance car, with the emphasis on eliminating corroded, bent, or otherwise damaged fuel line with fresh new material. While ethanol has taken the blame for much of the “damage” that has occurred from reformulated gasoline (RFG), it’s important to point out that 25-percent of US fuel contains aromatics that are also detrimental to fuel systems. Over time, it has been shown that it is these aromatics, and not necessarily the ethanol, that can cause fuel system damage. The polytetrafluoroethylene (PTFE) linings now popular for performance fuel systems is similar to what the OE manufacturers use for fuel systems today. It is not mandatory that you use the PTFE style fuel line, but it will offer long-term reliability.

Q: I know that pure alcohol burns almost invisible in daylight. Does E85 also burn invisibly?
A: Pure methanol (wood alcohol) burns with a pale blue light that is nearly invisible in daylight. This may be what you are referring to. Straight ethanol, the alcohol used in E85, burns with a pale yellow flame. Under bright daylight conditions, burning E98 will be very difficult to see. Mixing 15 percent gasoline with ethanol (E85) produces a much more orange hue to the flame, making it very easy to see in daylight and therefore much safer as it relates to seeing the flame.

Q: I hear that E85 is not really E85 anymore. What is it?
A: The American section of the International Society for Testing and Measurements (ASTM) fuel standards and other regulatory rules now call out Ethanol Flex Fuel instead of E85. This allows the fuel regulations to provide the same fuel properties throughout the entire country to be anywhere from E51 to E83. If that sounds confusing—it’s because it is! The point is you will need to be aware of the fuel coming out of that yellow-handled pump—it often will not be true E85.

We hope this has cleared up some of the misconceptions and “So I heard” questions you may have related to the use of E85 and (or) ethanol in your hot rod. Thanks for reading!

It’s the age old debate of which is better, air or water? Both are required for our biological survival as human beings, and both are used as a cooling medium for compressed intake charges in automotive applications. While there are benefits and drawbacks to both air-to-air and air-to-water charge cooling, what is “best” will vary greatly by application and the debate will rage on for a very, very long time.

However, before you can get in on the debate, you really need to understand how each type of charge cooling system works. For that, we turn to Jason Fenske of Engineering Explained. In his latest video, he goes over the basics of each type of system, and their pros and cons in a production application.

Air-To-Air

The air-to-air intercooler system is relatively simple. It uses airflow through the intercooler to remove heat from the compressed charge air. Heat is transferred from the charge (air) to the atmosphere (air) – hence the name “air-to-air”. “You have air coming in through the air intake, through the compressor, then to the front of the vehicle through the heat exchanger and then into the intake manifold,” Fenske explains of the air-to-air system.

Air-To-Water

In an air-to-water system, the heat from the intake charge isn’t removed by external airflow (at least not directly), but rather by a liquid coolant. “The air to water system is a little more complicated. The air again comes in through the intake and through the compressor,” Fenske says. “The compressed air then feeds into the intake manifold with its integrated intercooler.”

While in the production example Fenske is using – a BMW X3 M40i with the B58 engine, which uses a manifold-mounted air-to-water intercooler, much like the venerable lineup of supercharged Ford Four-Valve Modular engines, and aftermarket Kenne Bell and Whipple supercharget kits – the science and design of all air-to-water intercoolers are similar across the board, regardless of charge cooler mounting location.

In addition to the actual charge cooler, air-to-water systems have a secondary cooling system, much like a standard engine cooling system, but dedicated specifically to the intercooler. “You have a coolant which passes through the intercooler core and is then pumped through the system to a radiator in the front of the car to have the heat removed,” Fenske says.

Pros and Cons

Trying to ask which method of charge cooling is better is like asking what the best power-adder is. The answer is simply, “It depends.”

“The air-to-air system is a much simpler system. You don’t have to worry about fluid leaks; you don’t have the additional heat exchanger and the [associated] fluid plumbing. You have less weight with an air to air system as well,” explains Fenske

In an air-to-water system, once the coolant has pulled the heat out of the charge air, the heat must then be pulled out of the coolant itself. “Another big advantage to the air-to-air system is that you are only relying on heat being exchanged once. With the air-to-water, you’re relying on ambient air to get the temperature of the coolant as low as possible.”

Fenske does point out that air-to-air coolers do have drawbacks, saying, “However, you must mount an air-to-air where there is airflow, and ideally that would be in front of the engine, although you can mount it on top of the engine as well. You won’t get as much airflow, and potentially be susceptible to heat soak from the engine.”

Moving to the air-to-water system, Fenske continues, “Air to water intercoolers [in production applications] reduce the volume of space between the compressor and the intake valves, because the air-to-water charge cooler can be mounted anywhere under the hood, and not have to be routed up front into the airstream This reduces the distance the compressed charge has to travel.”

In theory, that reduction in volume and distance traveled by the compressed intake charge will not only increase engine responsiveness (reducing lag) but also reduce the potential of further heat soak by reducing the amount of time the charge is exposed to underhood heat.

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Here you can see aftermarket examples of air-to-water intercoolers. On the left, a Vortech Power Cooler, which does keep the path from the compressor outlet to the intake manifold about as short as you can get with an intercooler, highlights Fenske’s argument. However, on the right, you can see a popular setup for high-power drag racing vehicles, in which the air-to-water intercooler is located in the rear seat, requiring the intake charge to travel quite a distance, and increasing the volume of tubing between the compressor outlet and the intake manifold substantially.

Racing Applications

Up to this point, Fenske has been looking at production applications. However, once you get into aftermarket forced induction and competition settings, not only is it a whole new ballgame, thanks to specific rulebooks, but also the specific form of racing can change what you are asking of the system.

For example, in drag racing, remote-mounted air-to-water intercoolers increase the intake charge system volume significantly – the opposite of what is discussed here – and since the duration of the performance window is so much shorter, the second heat exchanger can be eliminated, and ice water used, to significantly increase the charge cooling capabilities of the system.

Conversely, for a form of motorsport that gives a lot of airflow due to sustained high-speeds, like road racing, the lighter weight and simplicity of an air-to-air system may be preferable. Again, it all comes down to application, rulebook, and ultimately, personal preference. Step one to any of that is understanding how each system works, along with its strengths and weaknesses.

Late-night pitchman Ron Popeil coined the phrase “set it, and forget it” when he was promoting one of his many inventions from the past few decades. While that notion may be just fine for a rotisserie chicken or a roast, it’s not exactly the best advice for your automobile. If you’re truly an enthusiast, you’re going to be under the hood tinkering with something sooner or later – even if it isn’t necessary. For us, there’s a different catchphrase: “forget it, and regret it.”

Most of us know we have to open the hood and do a good visual inspection. However, one area that doesn’t get much attention after the installation is complete, is exhaust headers. They get installed and essentially ignored unless you hear that ticking sound indicating an exhaust leak. If you choose to reduce underhood temperatures, you might even decide to put a thermal wrap on your headers. Like many other controversial topics, you can find many who are for wrapping them up, and just as many who are against it.

Rather than just sharing our opinion on the matter, we decided to reach out to the experts on both sides of this topic to find out what they say about wrapping headers. Our goal is not to start a debate to see who’s right or wrong, but to come to an understanding and give you the best advice from the experts: Moroso Performance Products and Design Engineering (DEI). We also reached out to one of the better known names in exhaust headers: Hooker.

Header wraps aren’t just for looks, they’re functional when installed properly. But it doesn’t stop there. Just like the vital fluids that keep your engine and transmission functioning properly, a header wrap also requires some level of maintenance and monitoring. If you use the same principle mentioned above – set it and forget it – you just might end up with more problems than solutions. First, let’s look at the different types of header coatings and what to expect once you wrap them.

Exhaust Headers And Header Coatings

When it comes to exhaust, Holley’s Hooker brand has been one of the leaders for decades, and is a name synonymous with performance. We spoke with Jeff Teel, sales and client services expert at Hooker, and first asked him to explain the various coatings you can find on headers, and which ones might be a problem for header wraps.

“Industrial chrome or painted mild-steel headers will have the greatest potential for developing corrosion beneath the wrapping,” Jeff said. Most of us have owned a set of chrome or painted headers, While they look great going on, they don’t look so great a couple of years later. The heat cycles of the headers themselves, along with changes in outside temperatures, can wreak havoc on the finish. Jeff recommended the stainless steel, saying, “It is the most robust and durable material from which to build headers, in any case.”

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Whether you’re wrapping painted or stainless steel, underhood temperatures can be reduced considerably. Both Moroso and DEI recommend removing the headers to wrap them, and you can see why just looking at these ‘shorty’ headers. Working on a bench is going to save you a lot of headaches.

While you might think ceramic coated headers would provide the best protection against corrosion, Jeff explained, “Ceramic-coated mild steel and even stainless-steel headers can also be affected by corrosion. However, it will happen to a lesser degree depending on the quality or application method used for the coating, or the specific type of stainless steel used to build the headers.”

We also asked about headers that have had the proper, high-temperature paint applied correctly, such as on clean steel. Jeff told us, “The degree of how well they will hold up depends greatly on environmental and usage factors.” When asked about ceramic-coated headers specifically, in addition to his thoughts on application methods, he said, “The primary tube-to-collector connection points is the area that is usually first to show signs of corrosion if the application is of higher quality.”

It seems no matter what you do, you’re going to see some form of corrosion either on the tubes themselves, or at the welded areas. So what’s the purpose of wrapping them up if it’s just going to cause problems anyway? For that answer, we reached out to Moroso National Sales and Marketing Manager, Thor Schroeder.

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Header wrap can come in various materials, including woven ceramic from Moroso (left). You have a few choices from DEI, including coated fiberglass (center) or a pulverized lava rock (right) in the Titanium series.

Header Wraps And Their Heat Control Properties

Header wraps are nothing new. Some people wrap their headers because they like the way it looks, others wrap their headers because of the tremendous reduction of underhood temperatures. Thor told us that header wraps can reduce the temperature by roughly 50-percent, and the surface temperatures can be reduced by as much as 30-percent.

What this equates to is a 300- to 400-degree drop in temperature, according to Mike Buca, DEI brand manager.

“We offer three basic material types: glass fiber, Titanium, and EXO,” said Mike. “Each has its benefits-to-cost ratio, with the glass fiber being the least expensive.” Those cost ratios increase not only in price, they also increase in heat protection. Mike continued, “Glass fiber is good for up to 1,200 degrees, while our Titanium wrap is good for up to 1,800 degrees. Our EXO wrap, which is designed for off-road use, is a glass fiber base, but it is inside a stainless-steel mesh sleeve.”

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The various materials offered from DEI are also available in a couple of different colors. If you’d rather black out your headers, you can do so with the Titanium or EXO wraps.

DEI’s Titanium wrap is more pliable than the glass fiber wraps, making it easier to install. But, Mike does warn us that you have to be careful and keep the wrap tight, especially with ceramic-coated headers. “Ceramic can be a little more difficult because of the slick surface,” he said. “But, this only comes into play when starting to wrap the pipes, once the wrap is installed, it’s fine.”

“Header wrap benefits can be broken down into two major groups,” Thor said. “The first is protection. Reducing engine compartment heat protects crew members from burns and prevents starter wires and plug wires from coming into contact with hot header pipes.” With that kind of surface reduction, it could be the difference between smelling something burning, to making it back home after a cruise.

“The second group is increased exhaust-cycle efficiency, ” Thor continued. “By retaining the heat in the header, it improves the scavenging of the cylinders by keeping the exhaust-speed high.” This very reason is why many companies offer a ceramic coating. The ceramic coating will help keep external surface temperatures lower than a painted or chrome header.

If you have ever done the burn test – where you reach in and accidentally burn your hand or your arm – then you know that a ceramic-coated header will cool down much quicker than chrome or painted tubes. The insulating properties of header wrap will help the scavenging process even more, because unlike ceramic, the material used in header wraps don’t retain heat on the surface.

Don’t Forget About Your Header Wrap

Once you’ve wrapped your headers however, you’re not done with them. There’s a bit of maintenance needed to ensure you haven’t had any abrasion that could cause the wrap to unravel or come loose. This abrasion could be from a steering linkage or other moving parts in the engine compartment. If this happens, the onset of corrosion can occur even quicker.

Should the header wrap start to unravel, Thor reminds us that a loose piece could get wrapped up in the engine’s pulley system. If that happens, you will get a rude awakening from the engine – and it won’t be pretty. That’s why you should always make sure they stay tightly wrapped. Even if it doesn’t start unraveling. “If it becomes extremely loose it will no longer be as effective as a thermal barrier,” stated Jeff.

Although Thor tells us that header wrap is designed to be installed and left on the headers, Jeff suggested it be inspected for corrosion, specifically on mild-steel headers. Inspecting headers periodically like we do with any other area of our engine is a good idea, up to and including unwrapping them to see the entire surface, and not just the weld joints on stepped headers or at the collector.

Another factor that can adversely affect the header wrap is engine fluids and oils. Thor said, “header wraps can last years, but they are affected by abrasion or being soaked in chemicals.” Those chemicals include typical oils and other fluids, as well as engine cleaners and degreasers.

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After starting the wrap, a couple of ties will keep it in place and keep it snug. That will allow you to move further down each tube without having to worry about the top unwrapping. When you reach the end of the wrap, tie it up and continue with a new piece.

Wrapping It Up

If you’re going to wrap your headers, both gentlemen suggest doing so with the headers removed, or wrapping prior to header installation. Thor said, “It’s always best to wrap them on a bench if that is an option. It allows the installer to get a nice clean wrap with proper coverage around the header or exhaust.”

Another reason wrapping the headers on the bench is best is because it allows you to see the back side of the header without using smoke and mirrors, or trying to cram your noggin down into the engine compartment to see. Additionally, it makes more sense when you think about having to lean over the fender and thread the roll between the primaries.

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Start the wrap at the primaries and wrap each tube indivudually until the tube connects to another tube or the collector, overlapping enough so that there are no gaps in the wrap.

It seems both of our experts agree on the purpose and benefits of wrapping headers. While they both have a different hand in the matter, we can all agree that keeping the heat inside the header will help with performance, and keeping the outside temperature lower can protect other components in the engine compartment – especially an arm or a hand while reaching down to tighten or adjust something.

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Once you have reached the end of a tube, and are at the collector, the stainless-steel ties will secure the wrap to the header. Remember: if it’s slightly loose, then it can unravel, so keep it snug as you wrap the header.

Of course, the decision to wrap or not to wrap ultimately relies on the user’s preference. Thor has some strong points as to why header wraps are significant, but neither he nor Jeff were in favor or against wrapping the headers. If you want to find out more about wrapping headers, reach out to Moroso Performance Products or DEI and let them know how you use your car and what type of header you have installed. If you’re planning on wrapping a new set of headers, check with Hooker Headers.

Since the invention of the metal piston ring at the start of the industrial revolution (which, you could argue, finally made steam power practical), there’s been constant innovation and improvement in cylinder sealing technology for these seemingly simple parts. The ring package has three primary goals: Keep pressure confined to the combustion chamber on both the compression and power strokes, transfer heat from the piston to the cylinder walls where it can be removed via air or liquid cooling, and control lubrication to limit oil consumption and unwanted emissions.

While it’s easy to look at the top ring or the oil ring at the bottom and intuitively understand their contribution to meeting these objectives, the second ring is more of a mystery. What’s it supposed to be doing, and why is it necessary? How do the materials used and the physical properties of the second ring affect performance? To answer these questions, we turned to Wiseco Senior Technical Account Manager Alan Stevenson.

Under Pressure

For our first question, we asked Stevenson whether the second ring had a role in containing compression or combustion gasses. “There was a time when bores were so bad in terms of surface finish, roundness, and so on, and ring materials were a lot worse, so that pistons used to have four rings; two for compression sealing, one for scraping oil, and one for pumping oil,” Stevenson explains. “The terminology hasn’t kept up with the technology. Referring to a contemporary second ring as a compression ring is a misnomer.”

So what’s the contribution of a modern second ring to combustion chamber sealing? Per Stevenson, “Negligible. There have been SAE papers published that prove how enlarged second ring gaps actually increase top ring sealing and power. Combustion sealing is 100-percent the top ring’s job.”

Combined with other piston features, the second ring’s role in this respect is to keep the pressure in the crevice space between it and the top ring as low as possible, giving any blow-by that makes it past the top compression ring a way to quickly escape to the crankcase.

“An accumulator groove works in concert with larger second-ring gaps,” Stevenson explains. “In short, there will always be some combustion pressure leakage past the top ring due to secondary piston motion and cylinder crosshatch. Any pressure that makes it past the top ring tends to get trapped between the top and second ring, which then pressurizes the top ring from underneath which leads to ring flutter (especially at high RPM).”

“The accumulator groove creates additional volume which decreases pressure. This is where Boyle’s law is applicable; volume and pressure have an inverse relationship, so increasing volume of the chamber decreases pressure. Coupling this with larger second-ring gaps provides a smoother transition of the trapped gas out of that space and reduces top ring flutter.”

Because the second ring is specifically intended NOT to be a pressure seal, it’s often constructed quite differently from the top compression ring. “Many top rings have inside diameter bevels that cause them to twist opposite of the forces acting upon it in order to help keep it flat in the groove for better sealing,” Stevenson says. “Second rings have a bevel opposite to that, so they actually twist the wrong way to help sealing.”

The Heat Is On

Having established that the second ring is most definitely not there to provide compression or combustion sealing, let’s look at the second main objective of the ring package: transferring heat out of the piston and out to the cylinder walls, where it can be managed by the cooling system.

It might seem like the relatively tiny amount of contact the rings make between the piston and the bore couldn’t possibly be a significant route for heat conduction, but it turns out to be the major provider. Per Stevenson, “There are many variables here, but the rings transfer about 70-percent of combustion heat from the piston to the cooling system.”

The remaining 30-percent escapes via other routes, like radiation and convection cooling of the underside of the piston to the air inside the crankcase, conduction cooling through contact between the piston skirt and the cylinder bore, and heat carried away via oil splash from crankshaft windage. Some engines even employ oil squirters at the bottom of each cylinder bore that direct a spray of lubricant at the underside of the pistons specifically to aid in cooling.

Other sources of heat transfer notwithstanding, the ring package handles most of the load when it comes to keeping the piston at an acceptable operating temperature. Stevenson further breaks down the previously mentioned 70-percent of total piston heat, “The top ring transfers 45-percent, the second ring 20-percent, and the oil ring 5-percent,” says Stevenson. While the second ring definitely plays its part in this critical task, it’s still not the ring’s primary reason for being there.

Oil Control For The Win

As it turns out, the second ring has a lot more to do with lubrication control than the “oil ring” beneath it. “The second ring is what scrapes the oil,” Stevenson explains. “The oil ring is what gathers it and pumps it away from the cylinder walls via oil return holes in the oil ring groove.”

The second ring’s main function is to continuously remove excess oil from the bore — as the crank rotates, oil escaping from the pressure bearings on the rod big ends is constantly thrown up behind the piston, coating the walls of the bore. On the downstroke, the second ring and the oil ring work in concert to clear all but a tiny amount of oil and return it down the bore to the sump.

“The top rings will always receive latent lubrication by oil trapped in the cross-hatch of the cylinder walls,” Stevenson says. It’s that microscopic texture on the bore that retains just enough oil to keep friction between the ring package and the cylinder wall to a minimum, while the second ring prevents too much oil from making it up past the top ring and into the combustion chamber.

Theory Into Practice

Now that we understand each ring’s purpose in the package, we can see why different specific materials and ring cross sections are often used for the top and second rings. “The demands and intended function of the top and second rings are different, for sure, so the materials often are as well,” Stevenson continues.

“The overall best top ring material is steel. Now, granted, some steels are better than others, but as rings get smaller and specific output increases, the demands on the top ring (which sees the most abuse) are highest.”

Move down a groove on the piston, and the different job being performed places lower demands on the material being used. “Many second rings in racing engines are still cast iron or ductile iron. The second ring is not under enough stress and temperature to necessitate steel,” Stevenson explains.

The shape of the ring profile also has a significant effect on how efficiently it removes oil, as well as how much friction it introduces, and both the interior and exterior diameters have a role to play. “Bevels are on the inside diameter of the ring and dictate the direction the ring twists to aid in scraping,” Stevenson says. “Taper, Napier and steps are all variations of the outside diameter shape.”

Viewed in cross-section, a beveled ring has one edge of the inside diameter cut at an angle, as Stevenson points out, this encourages the ring to dynamically twist in the groove as it moves down the bore and focus additional pressure on the outside corner — in order to more efficiently sweep excess oil away.

The goal with all these profiles is to concentrate contact into a narrow band to increase the efficiency of the scraping action. As the name implies, a tapered outer profile is narrower at the top than at the bottom, while a stepped ring profile has what looks like a notch in the cross-section, oriented toward the direction of travel on the downstroke.

A Napier ring, named for the famed British D. Napier & Son engineering firm that originally developed the profile, is actually undercut at an angle or even hook-shaped on the outside diameter, further decreasing the contact area and providing space for scavenged oil to escape, away from the cylinder bore. “In order, the most efficient scraper is Napier, followed by step, followed by taper. Run a Napier if it’s available in your bore size and suits the groove in the pistons,” Stevenson concludes of second-ring face shapes.

Application Dictates the Details

What kind of a combination you are running will also influence the optimum choice for your ring package, including the second ring. “Thinner second rings are more prevalent in dry sump engines pulling gobs of pan vacuum,” Stevenson advises. “Naturally aspirated with no vacuum help, the ring should usually be 1.5mm or larger, while forced induction should err towards even-larger 1/16-inch rings.” Because crankcase vacuum helps ring seal across the board, it’s possible to get the desired results without working the second ring quite as hard.

“Of course, this is all relative to bore size; you can almost think of it as a ratio of ring size to bore size,” Stevenson cautions. “A big boost four-cylinder engine will control oil just fine with a 1.2mm ring, while a 4.600-inch-bore big-block would be happier with a 1/16-inch ring. There are also substantial variables in crankcase efficiency when it comes to oil control. Modern engines with deep-skirted blocks, segmented oil pans, windage trays, and crank scraping/scavenging all have an effect on how much oil is thrown up into the cylinders. The more oil present, the harder the second ring’s job is.”

As you can see, second ring design and engineering is a complex subject, but fortunately, the experts at Wiseco have the collective experience in all forms of high-performance engine builds to provide you with sound advice for your particular needs. While we can’t cover everything in a single tech article, we hope that what you’ve learned here will help you to better understand the “why” behind a ring package’s specifications, and take full advantage of the knowledge on tap from Wiseco’s staff when putting together your own combination.

ed. note: This article was provided by Wiseco Pistons, and we felt that the editorial merit was worth sharing it with you. 

One of the first and certain most necessary upgrades to any car, truck, or SUV headed for a track event is replacing the OEM brake fluid with one that can tolerate much higher temperatures without boiling. Upgrading fluid and bleeding brakes is an immensely important upgrade because driving at speed around a track adds an enormous amount of heat to the braking system, especially the rotors and calipers.

Why Air Is Bad

And when the brake calipers get hot they transfer that heat to the brake fluid. And when OEM or standard replacement brake fluid gets hot, it’s more likely to boil at a lower temperature, releasing air into the system. This is bad because air compresses very easily (which makes it great for tires, but bad for brakes). In this circumstance, when you squeeze down on the brake pedal, it goes mostly or even all the way to the floor because you’re compressing air rather than transferring braking force through the hydraulic fluid.

You might remember Pascal’s Law from school, whereby when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the system. That’s why we use fluid to actuate the brakes on our cars.

It’s virtually impossible to drive in a consistent manner and improve your skills when the braking system is erratic; especially when a situation or even an accident can be avoided for around $60 in new racing brake fluid and less than an hour’s worth of your time.

How Air Gets Into Your Braking System

According to Anne Marie Helmenstine, Ph.D., a former research scientist for the US Department of Energy, explains where the problem lies. “A hygroscopic substance is able to adsorb water from its surroundings. Typically, this occurs at or near ordinary room temperature. Most hygroscopic materials are salts, but many other materials display the property [which is why table salt and sugar get lumpy on humid days – ed.]

“When water vapor is absorbed, the water molecules are taken into the molecules of the substance, often resulting in physical changes, such as increased volume. Color, boiling point, temperature, and viscosity can also change. When water vapor is adsorbed, the water molecules remain on the surface of the material,” Dr. Helmenstine writes.

So if water and air in the brake fluid are bad things, why is brake fluid formulated to absorb moisture in the first place? Good question. The decision was made many years ago that to reduce the risk of brake lines rusting through from the inside, which is nearly impossible to spot, it’s better to trap any atmospheric moisture that gets into the braking system in the fluid itself. The fluid is much easier to change than steel brake lines and it helps to avoid catastrophic failure. There are pure race fluids that have no hygroscopic (not hydroscopic, BTW) properties, but in order to meet DOT standards for use on the street, a high-performance brake fluid needs to maintain its hygroscopic qualities.

End of Science Class. Please move quietly to your next period class.

Our race trailer has a bucket packed with everything we need to bleed the brakes on our Honda Challenge race car: a 10 mm wrench for loosening the bleed screw, fresh bottles of DOT 4 high-temperature racing brake fluid, a bottle with a cable on it to hang off a wheel stud and catch fluid, and a clear tube to go from the bleed screw to the bottle.

Tip One: Use a Brake Fluid That’s Formulated For Track Use

The type of racing brake fluid required for track day use isn’t something you will find on the shelves of your local auto parts store. You’ll need order ahead of time well before your track day. With Amazon carrying many of these fluids, there’s no longer an excuse for not getting your brakes ready on time. Really good racing brake fluids, like Performance Friction Corporation’s PFC665 or Hawk Performance’s HP520, are readily available online.

I spoke with Chris Dilbeck, who is the NASCAR and Short Track Sales Manager for Performance Friction Corporation (PFC) Brakes, and he stated that the only way to maintain a stiff brake pedal is with a good racing brake fluid. “Our RH 665 racing brake fluid has been tested by Porsche and numerous racing teams,” said Chris. “Our fluid is often compared to Castrol SRF for its similarity in performance, however our fluid is only $29 per bottle, where Castrol SRF goes for about $70 per bottle.”

Racing brake fluid is certainly more expensive than DOT 3 fluid from your local parts store but due to the level of heat a brake system sees during a track session, which can be over 1,000 degrees Fahrenheit, it’s a no-brainer that all of the hydraulic fluid in the braking system for a car driven on race track should be replaced with racing fluid.

Tip Two: Proper Set Up 

Here is how to prepare yourself, your tools and equipment, and your car to remove all of the old brake fluid out of the system using a simple process that doesn’t require any engineering skills or special tools:

PREPARATION STEP 1:

Put your car on four jackstands (the same height) or put the car on a lift (where the chassis is lifted, not the wheels)

PREPARATION STEP 2:

Remove all four wheels/tires and locate the brake bleed screw on each brake caliper.

PREPARATION STEP 3:

Locate the master cylinder (under the hood) and open the cap. Have your new racing brake fluid bottle (or bottles, depending on the volume of your system) ready to go. You will need a razor blade to open the seal on the top of each bottle; the bottles are nitrogen filled.

PREPARATION STEP 4:

Find a friend. This is a two person job. Sorry, your dog can’t help you here.

PREPARATION STEP 5:

Put the friend in the driver seat and tell them their leg is going to get tired, but not to complain, because nobody cares.

Pro Tip 3: Bleeding the Brakes

BLEEDING STEP 1:

Go to the furthest brake caliper away from the master cylinder (usually the right rear). The goal here is to push as much of the old hydraulic fluid out of the system so the further away are from the master cylinder the better. Bring the correct size end wrench or flare nut wrench to loosen the brake bleed screw. Also bring your brake fluid catch bottle and a rag. Rags and a spray bottle of brake cleaner are handy through this oftentimes messy process. If this is the first time you’ve bleed the brakes and you’ve never cracked the bleed screw before, be extra careful as it could be quite stuck. Make sure you’re using the proper size box end wrench for the best distribution of force as you don’t want to strip the bleed screw.

BLEEDING STEP 2:

Place the end wrench or flare nut wrench over the brake bleed screw and then place your clear tubing over the nipple of the brake bleed screw. This should be a tight fit where no air can seep in. Have your friend slowly, gently push on the brake pedal. Do not pump! Give the wrench a quick hit counter clockwise.  You don’t have to turn the bleed screw much, just enough so that fluid begins to travel through the tube into your catch bottle. As this occurs your friend in the driver seat will feel the pedal go to the floor. Once he or she hits the floor, lightly tighten the bleed screw and tell your friend to “release.” You are going to do this process over and over again until you see fresh new fluid coming through the lines.

 

BLEEDING STEP 3:

It is important during Step 2 that you continually fill the master cylinder. You DO NOT want this to go dry while you are bleeding the brakes as you will add air into the system, which we’ve already learned is a bad thing. Neither the person pushing on the brake pedal nor the person at the brake caliper can see the master cylinder draining as you bleed the system. You either need another friend (three-person job) standing over the master cylinder pouring in fluid or you need to take small breaks and check the master cylinder fluid level height and make sure it always has sufficient fluid in it.

BLEEDING STEP 4:

Here is the work flow and commands our team uses as we go through this process:

The person at the brake caliper yells out, “Pressure!”
The person on the brake pedal presses on the brake and says, “Pressure!”
The person at the brake caliper slightly loosens the brake bleed screw and watches the fluid pour through the tube and checks for air bubbles.
When the person at the brake pedal feels the pedal hit the floor they yell out, “Floor!”
The person at the brake caliper then tightens the brake bleed screw. Once it is tight he then yells out, “Release!”
The person at the brake pedal slowly releases their foot from the pedal and it comes up. They yell out, “Released.”

Then the person at the caliper starts the entire process over again when they say, “Pressure!” Repeat, repeat, repeat. Fluid gets pushed through the system and the helper’s leg gets sore.

BLEEDING STEP 5:

Once you see fresh fluid and no air bubbles coming through the line you are about ready to move to one of the other three brake calipers (usually the left rear, whichever next one is farthest from the master cylinder). But before you move, to complete the bleed on the brake caliper you started with, on your last bleed, you are going to try and close the bleed screw and catch the brake pedal as it is coming halfway down, before the person inside the car yells, “Floor.” This way you know for sure no air sucked up into the bleed screw before you get the chance to tighten it. Now it is time to move on to the next caliper.

BLEEDING STEP 6:

Repeat steps 3, 4, and 5 (remembering to check the fluid in the master cylinder constantly) until all four brake calipers are bled and only clean fluid with zero air bubbles is visible in the tube at the bleed screw.

Look at the routing of your brake lines when deciding which brake caliper is the furthest from the master cylinder. On our Honda Challenge race car our left front caliper is directly under the master cylinder (theoretically the closest caliper to the master cylinder), however due to the routing of the brake lines (the lines go from the master cylinder across the bulkhead and through a T and then back across the bulkhead into the left front caliper) the left front caliper is further away (hydraulically speaking) than the right front caliper. We do our right front caliper last (because is has the shortest lines connecting it) while bleeding brakes.

BLEEDING STEP 7:

Ensure all of your brake bleed screws are tight and clean them with brake cleaner and a rag. To check for fluid leaks have your helper press the brake pedal as far down as it will go while you inspect to confirm all the bleed screws remain dry. Ensure the master cylinder is topped off and close the cap on the master cylinder tightly. Replace wheels/tires, torque your lug nuts to the correct specifications and put the car on the ground.

Congratulations, you have just flushed your entire brake system with good performance brake fluid and you are off to the races, literally.

Pro Tip 4:

Most racing teams will bleed just what fluid is in the brake calipers after a track session or a race weekend. The process is exactly as explained above only the entire system isn’t flushed, instead only what small amount of fluid was in each caliper (the location where the fluid receives the the most heat during track duty) is bled out.

Chris Dilbeck of PFC Brakes agrees with that methodology, “After a full flush, we recommend at least one hot bleed after a session to ensure any air is out of the system. If the pedal remains stiff after a race, then the brakes don’t need to be bled. But if there is any alteration in pedal feel then it would be time to bleed them again.”

Pro Tip 5:

Our team keeps all of our tools and fluid in a brake bleed kit bucket to keep messy brake fluid away from other tools in the trailer. You can also use the bucket as a set while opening and closing the bleeder screws, If we come across a master cylinder that has really black old ugly fluid in it, we will use a syringe to take the fluid out of the master cylinder instead of pushing all of that bad fluid through the entire hydraulic system (then we refill the master cylinder with new fluid and start the bleeding process). We use rubber gloves while doing brake bleeds and normally use the three-person method to knock the job out quickly (one person on the caliper, one person on the brake pedal, and one person filling the master cylinder).

WARNING: Brake fluid is highly corrosive to vehicle paint so be careful not to let it touch your finish, even if it is transferred from your gloves. Keep rags handy. Don’t say we didn’t warn you.

Bleeding brakes is part of every professional and amateur race team’s processes and they use only the finest high-temperature brake fluids. The process is simple and inexpensive, which is why anyone thinking of taking their car out to a track day should certainly go through the procedure of upgrading its brake fluid. Have fun and remember the words, “Pressure, Floor, Release” over and over and over again. And the person pressing on the brake pedal, yup, that is going to be one sore leg.