C6 Corvette E85 Conversion - Corn-vette

D6C Goes Green, Thanks To An E85 Conversion

Chris Endres Jan 19, 2008 0 Comment(s)
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E85: A Primer
Okay, here's a hot button topic for you: Alternative fuels and, in particular, E85. While it might not be as controversial as, say, a Bose sound system, it is (or should be) far more important to the hardcore performance enthusiast. Why? Three words: cheap race gas.

There are a myriad of issues that can be argued regarding the pros and cons of E85. Because the ethanol used to produce it is largely derived from corn, E85 production has been blamed for everything from the rising cost of T-bone steaks to the skyrocketing price of tortilla shells in Mexico. E85 is currently all the rage among domestic auto manufacturers (mainly due to CAFE credits offered for producing flex-fuel vehicles), but it is often looked upon negatively by the high-performance crowd. I think that's a mistake, and I'll tell you why.

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As nimble on the keyboard as he is handy with a wrench, HiTech Motorsport's Casey Wittmer is a huge fan of E85, having converted his own vehicles as well.

The U.S. Department of Energy classifies E85 as an alternative fuel that "burns cleaner than gasoline and is a completely renewable, domestic, environmentally friendly fuel that enhances the nation's economy and energy independence." As the name implies, E85 is a blend of 85 percent ethanol and 15 percent gasoline. Many believe the "85" is an indication of the fuel's octane rating. Not true, as the appellation bears no reflection on this number, which is actually 105.

So what's ethanol? It is a form of alcohol that happens to be a renewable fuel produced by the fermentation of plant sugars. In the U.S., ethanol is typically produced from corn and other grain products. Other sources, such as agricultural and forestry wastes or purpose-grown "energy crops," can also be utilized. One such alternative source is switch grass, which is easily renewable and produces far more ethanol per acre than corn. Brazil, which has been largely E85-powered for decades, economically produces ethanol from sugar cane.

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Wittmer's weapon of choice for tuning the C6 PCM is EFI Live. This tuning software offers unparalleled access to all of the tables that need to be manipulated in order to maximize the effectiveness of the conversion.

There's no question that petroleum consumption in the United States is constantly on the rise and that we currently import more than half of the oil we consume. E85 has the potential to reduce our use of foreign oil, but it is really too soon to say by how much. It also has the potential to reduce pollution caused by motor vehicles. Uncle Sam says that E85-powered vehicles produce lower hydrocarbon and benzene emissions compared with gasoline-powered ones. They also generate fewer carbon dioxide (CO2) emissions. Widely acknowledged as a harmful greenhouse gas, CO2 is considered to be a major contributor to global warming.

But for performance addicts, E85's biggest selling point-and the one the political wonks completely overlook-is its stratospheric octane rating. In forced-induction applications, the added octane makes it possible to run more boost without harmful detonation. Those of us running naturally aspirated engines ought to give E85 consideration as well. To me, the ability to utilize more ignition timing and eventually increase the compression ratio makes it a no-brainer. With E85 in the tank, running a street engine with a compression ratio as high as 13:1 is no problem.

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MSD's new Jammer fuel injectors will happily integrate into either low- or high-impedance EFI systems. They exhibit extremely linear flow, which makes for a nice, smooth idle and outstanding throttle response. MSD rates them at 60 lb/hr.

Things to Consider
Availability is a key consideration when contemplating an E85 conversion. My home state of Minnesota just happens to possess the largest concentration of E85 fueling stations in the nation. At the time of this writing, there are more than 320 facilities here in the Great White North. That's more than double the next-most E85-friendly state, Illinois, which has approximately 150 stations.

As with conventional gasoline, E85 prices fluctuate daily (or hourly, it seems, at some stations). In Minnesota, E85 can often be found for $.40 per gallon less than 87-octane gasoline. The last time I filled D6C's tank, E85 was $2.29 per gallon-approximately 25 percent cheaper than 92-octane premium, at $2.89. And what about race gas? My last check found 100-octane unleaded hovering at the $4.50-per-gallon mark.

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Nasty Performance is a relatively fresh face on the LSX engine scene. The company has an entire line of high-performance fuel systems for Corvettes, GTOs, and F-bodies. Here is a look at one of their billet fuel rails, which is capable of supporting 2,000 horsepower!

Many sources proclaim that E85 exacts a 30 percent fuel-mileage penalty the instant it hits your tank. And sure enough, OEM flex-fuel vehicles often do exhibit such a loss. That's enough to completely negate any financial gain of running the fuel, though it may still leave you with a warm, green fuzzy feeling while piloting your Suburban through rush-hour traffic. But while there's no disputing that E85 contains less energy potential per gallon than conventional gasoline, one tuner we spoke with stated that the mileage differential can be reduced to approximately 10 percent with proper tuning.

When it comes to Corvettes, E85 compatibility is largely determined by model year. If your Vette was built within the last 10 years, you should be in good shape. Older cars can be converted too, but will require a little more work. Essentially, anything in the fuel system that is not alcohol-compatible should be replaced. That could include fuel pumps, lines, and carburetor components. You will also need to richen the mixture by whatever means are appropriate, be they larger jets in the carb or bigger injectors. Lastly, you should take advantage of the higher octane by advancing your ignition timing.

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Though they have performed flawlessly to this point, the stock injectors and fuel rail were pulled to make room for the MSD and Nasty parts.

The Internet is littered with "E85 Conversion Kits." Be wary of these, as they generally do not supply the components required to do the conversion correctly. You should also be aware that like so many other performance-enhancing modifications, the EPA has not given approval to any conversion process or kit. That means you shouldn't be driving your clean-burning E85 Cornvette on the street. Got it?

Getting Down to Business
For D6C's conversion, I turned to HiTech Motorsport, in Elk River, Minnesota. As the name implies, HiTech specializes in late-model fuel-injected mills, but the shop also has an extensive racing background ranging from Trans Am to NHRA Super Stock. The folks at HiTech have been performing high-performance E85 conversions for a couple of years now, and that experience taught them everything they needed to know in order to extract maximum power from my little LS2.

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Nasty supplies all the hardware needed to bolt the fuel rail up to the FAST intake manifold. One nice side benefit is that it eliminates the need for the FAST injector spacers, reducing the amount of clutter in the intake area.

If you've been following D6C's progress, you will notice a rather large discrepancy between the dyno numbers recorded in our last installment and this story's baseline figures. After the FAST intake install, the car produced 451 horsepower and 430 lb-ft of torque on the LG Motorsports Dynojet. When strapped down to HiTech Motorsports' Dynojet, D6C made only 420/405. Eyebrows around the room went up. There had been no hint of detonation or knock retard when the car was last dyno-tested at LG, but a look at the data log from the HiTech pull showed 10 to 12 degrees of knock retard, resulting in a super-rich air/fuel ratio of 10:1. Not good.

Before we could diagnose the problem, it was discovered that the car's PCM was locked from the previous tune, meaning we were dead in the water. The PCM had to be sent out for the tuning-software manufacturer to unlock, so I used the downtime to tear into the car. I pulled the plugs and found them to be clean. Off came the valve covers for a visual inspection of the valvesprings and push rods. No issues. Much head-scratching ensued.

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A factory-style quick-release fitting is supplied to mate with the stock supply line. The braided-stainless line is then routed over the back of the manifold and plumbed to the rear of the passenger-side rail.

Upon return of the now unlocked PCM, I returned to HiTech for another try. Just as on the original visit, D6C made 420/405, again with massive knock retard and an obnoxiously rich AFR. This time, however, HiTech's tuning-wiz service manager Casey Wittmer was able to access the tune with his trusty EFI Live. After a little tweaking, the numbers were brought a little closer together, up to 431/412. Further work likely could have netted a few more horses, but that was not the focus of our efforts. It was time to start the conversion process.

As mentioned earlier, converting a late-model Corvette is pretty easy. You'll need larger injectors to deliver the additional fuel volume, along with a recalibrated PCM. In most cases, that's it. The LS2's stock 34-pounders have done an acceptable job thus far, but would quickly fall behind with the increased volume of E85 required to make the same amount of power.

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A crossover is routed just behind the throttle body at the front end of the rails.

MSD Ignition is beginning a big push into the EFI market, and one of the company's newest products is a set of Jammer 60 lb/hr injectors that are compatible with both low- and high-impedance fuel systems. MSD promises excellent throttle response and idle-two traits not often associated with large injectors. The only downside to using them on the LS2 is that they employ a traditional Bosch harness connector. This is easily overcome, however, with a set of injector-adapter harnesses.

Since the top side of the fuel system was coming apart, I also took the opportunity to install a Nasty Performance billet-aluminum fuel-rail kit. Nasty's polished rails are milled from solid aluminum and accept 3/8-inch pipe fittings-enough to support 2,000 hp, according to Nasty proprietor Nate Bonham. These fittings, plus a quick-release adapter for the factory supply line, a length of -10 braided line, and a fuel-pressure gauge are also included in the kit.

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The MSD injectors utilize traditional Bosch harness connectors, while the LS2 uses the more modern EV6 style. Eight of these simple adapters fixed me right up.

These parts from Nasty allowed the MSD injectors to be mounted to the FAST intake without the spacers required when using the stock fuel rail. That cleaned up the install considerably. The red and blue anodized fittings and stainless lines also added a racy look to the engine room, something D6C desperately needed. These parts look so good that I have to have more. Keep an eye out for more finery from Nasty and MSD in a future installment.

On the Dyno
With the hard parts in place, it was time to retune for the MSD injectors. On paper, this should be a simple matter of rescaling the injector sizing in the tune. Sometimes, it doesn't work out quite so smoothly, as some injectors are very non-linear in their fuel delivery across the rpm band. In the case of the MSDs, no such problems existed, so the car was right back to 430 rwhp on just the second pull. There was definitely a noticeable improvement in the idle, with a bit less lope evident.

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Ten gallons of E85 were added to an almost empty tank to keep dilution to a minimum. One other upside of E85 is its pleasant, slightly sweet smell. While it doesn't smell quite as good as race gas, it doesn't reek like the pump stuff.

It was now time for the moment of truth. The fuel gauge was hovering at 1/16 of a tank, so there was no reason to be concerned about significant dilution of the E85 by the existing 92-octane gasoline. Ten gallons of corn juice were added, and EFI Live was once again called to action. Wittmer told me a simple arithmetic equation was all that was required to adjust the tune for the E85 now flowing through D6C's fuel system.

The first dyno pull on E85 showed a gain of 8 rwhp, with a significantly rich AFR of around 11:1. This power gain was the result of the LS2's ability to accept more timing without detonation, thanks to the additional octane provided by the ethanol mixture. A few more tune/pull cycles were completed on the Dynojet to touch up the AFR in a few spots. Interestingly, Wittmer experimented with advanced WOT ignition timing well past 30 degrees with no detonation, but the LS2 made no more power than it did at 29.5 degrees. It had given all it had, producing final numbers of 442/427.

As for the rest of the fuel system, careful observation of the Nasty Performance fuel-pressure gauge showed that the OEM pump was supplying plenty of volume to maintain 58 psi. The AFR confirmed this, hovering at 12.5-12.7 throughout the final pull.

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This dyno sheet shows D6C's output on gas (with the MSD injectors and Nasty fuel rails) vs. final power after the E85 conversion. Check out the massive 20hp gain through the meat of the power band.

In the end, D6C rolled out of HiTech with 22 rwhp more than it had on arrival. What's impossible to quantify is the snappy throttle response the car now has, no doubt attributable to the more aggressive timing curve. It also had a much cleaner idle, thanks to the MSD Jammer injectors and the fresh tune. Is it possible that it would now show something in the neighborhood of 473 rwhp on the LG dyno? Sure, it is. And if such an opportunity were to present itself, you can be sure I'd be all over it.

In the Real World
A few weeks prior to the E85 conversion, I competed with D6C in a unique autocross put on by the Minnesota Austin Healey Club. The course culminated with a flat-out, 3/10-mile straightaway on a rural airport taxiway. Stationed at the end of the taxiway was a course marshal with a radar gun. On 92-octane gasoline, D6C knocked out 131 mph at the top end of the straight. Pretty good, but not enough to match the Ford GT or the built-LS6-powered Porsche 914 on hand, both of which managed 132 mph. Damn.

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HiTech Motorsport's new facility in Elk River, Minnesota, features a state-of-the-art dyno cell with a Dynojet 248 and a massive ventilation system capable of changing the air every 9 seconds. The rest of the shop is just as impressive, with an engine dyno in the adjoining room and full machine-shop and assembly facilities. HiTech also has more than 5,000 square feet of hoist area, making it the largest and most comprehensive shop in the Twin Cities.

Two weeks after completing the E85 conversion, I again competed at this event. Much to my chagrin, the straightaway had been shortened approximately 200 feet, meaning it was essentially a quarter-mile drag strip. While this was a bummer initially, that frown quickly turned upside down when D6C posted a new corn-powered top speed of 133 mph. Yes, I picked up two mph in 200 fewer feet of real estate. That is an impressive gain. The GT was back, though, and with more power as well. This time it threw down a 136. Double damn.

So, is E85 right for everyone? Probably not. Is it worth considering? Absolutely, with a few qualifiers. One, you need to make sure it's available in your area. Two, you need to have access to a knowledgeable tuner or the expertise to do the work yourself. Three, you should have the ability to take advantage of E85's higher octane by running more boost, timing, or compression. And four, you should be prepared to find yourself at the center of many arguments among your gearhead friends.

In the end, there is no question that more power can be made with E85 than with unleaded pump gas. The deal gets even sweeter when you consider that you are doing something positive for the environment and the economy. Alternative fuels do not mean the end of high-performance as we know it. In fact, they can open many doors to even higher performance. That alone should make them worth the price of admission.


HiTech Motorsport
Ramsey, MN 55303
LG Motorsports
Nasty Performance
Lake in the Hills, IL 60156,


How To
Our Project D6C 2005 Chevrolet Corvette goes green, thanks to an E85 conversion
Chris Endres Jan 19, 2008


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