E85 use is becoming more common with racers these days as class rules increasingly permit the fuel’s use. There are several benefits to using it over racing gasoline besides its octane number, which make it a popular choice in a variety of high-performance applications. We spoke with Brett Clow of Aeromotive Inc. to get more information on this topic and give you a brief idea of what you may need to consider when moving to an E85-based fuel system.
Racers are choosing E85, especially in turbocharged and supercharged engine combinations, which benefit greatly from the increased octane over pump gas and the cooling properties associated with using it. The decreased intake air temperatures provided by the vaporization of ethanol are beneficial to both horsepower production and engine longevity. That said, E85 requires more volume per horsepower than gasoline and is a bit more corrosive, and these factors require the user to consider specific fuel system products, implement various compatible engine components, and take care to perform the added maintenance related to a more corrosive fuel.
Our upcoming turbocharged, small-block Ford-powered Ultra Street project (which we’ll get to more in a minute) is set to utilize E85 fuel, and so this topic is very central to our planning as we assemble the car and then get it on the racetrack.
“E85 fuel systems are a common source of questions,” says Clow. “Very few people understand why the engine is going to run cooler, or more specifically, why the air charge is cooler, with E85. Any fuel, to become usable for combustion, must change from liquid to vapor in the intake runner or combustion chamber before it will burn. Changing liquid to vapor consumes heat, which is taken from the air in the intake charge. The heat extracted from the air by the evaporating fuel is a phenomenon called ‘latent heat of vaporization.’ Ethanol has a much higher latent heat of vaporization than gasoline.
“The net effect of a colder intake air charge is an increase in charge-air density, which means more oxygen per cubic foot of intake air in the combustion chamber, which when matched with the additional fuel to maintain a proper AFR (air/fuel ratio), results in more power,” Clow continues.
For reference, we can look at what would be the chemically correct (stochiometric) air/fuel ratio for different fuels, to get some idea of the differences.
“The Stoichiometric ratio of gasoline, the ratio of air to fuel, is 14.7:1, which provides a complete burn,” Clow explains. “When you look at E85, it has a stoichiometric ratio of 9.8:1. What that tells you is that you need a lot more fuel combined with air to burn ethanol effectively. Of course, the challenge becomes, how do you factor that into selection of fuel system components?”
Calculating Fuel Consumption To Determine The Correct Products
Clow uses a horsepower projection, including any power adder specifications, along with the fuel type to be used, to determine a brake specific fuel consumption (BSFC) factor. This allows him to calculate realistic fuel consumption values.
“BSFC factors for various engine combinations and fuel types are the product of decades of dyno testing, and have proven to provide a reliable basis for projecting an engine combinations’ fuel needs,” Clow tells us. From there, looking across the range of Aeromotive pump flow curves, he can accurately choose the correct fuel pump and fuel system components to reliably feed the beast.
“There’s a great Tech Bulletin, TB-501, that covers the topic of BSFC and determining fuel consumption in detail,” Clow says. “With the basic math outlined that anyone can use to get at least a good idea of how much fuel will be required for a given job. ”
Clow tells us that a common customer concern is making sure to account for the additional fuel needed to fuel the power lost to turn a supercharger. For that, Clow says, “The easier way to factor the parasitic lost horsepower from turning a blower, or the exhaust back pressure to spin a turbo, is to increase the BSFC accordingly.”
“If you’re using pounds-per-hour (lb/hr) flow rates for your injectors, it’s easy to calculate injector size and max duty cycle, as well. What happens when we go to ethanol is, naturally aspirated engines have a BSFC of around 0.7 pounds of fuel per horsepower per hour, compared to the gasoline number of 0.5. For forced induction engines we’ll use a BSFC factor of 0.9 on ethanol compared to 0.65 on gasoline.”
E85-Fueled Ultra Street Fuel System
With our Ultra Street project, we are dealing with your normal, track-only fuel system that can support a turbocharged engine combination. The powerplant in question is a 400 cubic-inch small-block Ford spec’d by KBX Performance and built by Bennett Racing. It’s based on a 9.5-inch deck block that is stuffed with a Callies Performance Products crankshaft, GRP connecting rods, and Diamond pistons. The short-block is topped with CNC-ported, Trick Flow Specialties High Port 265RX cylinder heads and a custom Bennett Racing camshaft actuates the valves.
The power adder for this build is a class-spec 76mm turbocharger, and KBX’s John Kolivas said that boost will be turned up to 35-plus psi to produce somewhere in the neighborhood of 1,800-plus horsepower.
“Looking at a projected 1,800-2,200 flywheel horsepower, using 2,200 as a max calculation, we’re looking at 2,200 x 0.9 lb/hr per horsepower, or 1,980 lb/hr into the engine,” Clow explains. “With 320 lb/hr injectors at 43.5 psi base fuel pressure, we would be at 77-percent duty cycle, and fuel pressure would be 78.5 psi with 35 psi boost pressure. E85 at 85 percent ethanol, 15 precent gasoline has a mass of 6.62 pounds per gallon. That translates into 4.98 gallons per minute into the engine.
The selected 10 gpm pump is somewhat overkill for the combination, but leaves plenty of room for growth, providing 9.31 gpm at 80 psi (base plus boost) fuel pressure. We normally don’t want to exceed 6 gpm on the regulator bypass to ensure fuel pressure rises 1:1 with boost, and this combination falls under that limit.
In addition to making the fuel calculation to ensure the fuel pump can deliver the needed volume of fuel, it’s also important to ensure that the pump is compatible with the type of fuel you intend to use. The high ethanol content in E85 does affect certain components and sometimes requires specific materials to be used in compatible components.
“Ethanol conducts electricity about 10 times better than gasoline,” Clow says. “When you run this type of fluid through a brushed motor, electrolysis can occur in the pump assembly, shortening electric motor service life. Where there would normally be a copper winding and carbon brush, the Aeromotive brushless fuel pump, uses electronic pulses to drive the armature, so electrolysis is not a problem, because there are no exposed materials.”
Clow also noted that with E85 use, a micro-glass 10-micron filter element should be employed for EFI applications.“We need to use a micro-glass element, not a paper element,” Clow notes. “There should be a 10-micron filter after the pump to protect the injectors. Some people use a stainless steel filter, but we don’t recommend them because most people don’t have the necessary ultra-sonic cleaner needed to maintain them.”
A Fitting End With Russell
In addition to the fuel pump and regulator, one should look at the parts that connect them when using specific racing fuels.
“Fittings (if anodized) will generally withstand the highly corrosive nature of high-purity methanolfor a brief period of time,” says Russell Performance’s Brian Hosenfeld. “Most methanol racing fuels have a 99-plus-percent purity level and for sure can cause havoc on a fuel system. Hoses, fittings, fuel pumps and regulators and any rubber components that are not rated for alcohol use will suffer over time.”
“Methanol (like ethanol) is hygroscopic, meaning it will attract and absorb water. While methanol is corrosive, it’s the water that kills the aluminum fittings. Most fittings on the market will handle methanol/ethanol fuels, but the length of time in service is the key. They are parts that need to be inspected frequently to ensure they are still serviceable and not showing signs of deterioration. Hose, on the other hand, typically deteriorates much quicker. Special PTFE-lined hose is needed with using methanol and ethanol fuels.”
To deliver the E85 to our hungry Ford engine, we ran a -12 ORB pre-filter from the tank to the fuel pump, which has a standard -16 ORB female inlet. We’ll use a reducer fitting to size that down to -12. The pump is mounted in the trunk near the tank. A -12 outlet and lines carry the fuel to the pump through a pre-filter to a post-filter, and onward to the fuel rails. The regulator, positioned in the engine bay, is in the return feed,, back to the tank.
The fittings are all Russell’s black-anodized aluminum parts, all universal in use. The hose ends, meanwhile, are Russell’s Pro Classic Hose Ends, which are made from 6061-T6 aluminum and have a long-taper design to ease assembly. They have an AN-standard 37-degree flare, and work with all AN fittings. These include 90- and 45-degree swivel ends.
The hose is Russell’s lightweight black nylon braid ProClassic, lined inside with CPE (Chlorinated Polyethylene) rubber. Russell markets ProClassic hose for builders who want a high quality braided hose that is lighter and easier to assemble than traditional braided steel hose. The hose has a maximum pressure rating of 350 psi.
Russell’s products were also utilized to cycle water to and from our cylinder heads to keep the operating temperature in range, as well as in our intercooler and in the engine (water) tank. We’ve used -20 AN fittings and lines for the intercooler tank, 1-1.25 NPT for the inlet and outlet on our engine water tank, and 1/2-inch NPT inlet and 3/8-inch NPT outlet for the cylinder heads.
With the added performance available from E85, it is important to note that there are some tradeoffs. Correctly choosing compatible components to ensure that your fuel system will last as well as perform as intended will keep your racing program running at an optimal level.