5.0 Mustang & Super FordsNews & Views
Kenne Bell E85 Fuel Testing - Corn Husking
As ready supplies of E85 fuel reach the West Coast, Kenne Bell shows its potential in high-performance applications.
Next, how powerful is the vaunted cooling capacity of evaporating alcohol? Race goers are used to seeing frost forming on alcohol dragster injector hats, for example, and if you believe the loose talk then E85 must be a veritable combustion chamber refrigerator (hard to do that while making more power, but work with us here). Without the ability to directly measure combustion chamber temperatures, KB used exhaust gas temperatures as a reasonable surrogate, and again, there is a chilling effect on exhaust gas temperatures (EGT) from E85—but nowhere near what the Coors Light Silver Bullet train is up to.
At identical air/fuel ratios E85 EGTs are less than 10 degrees cooler than C16’s in Kenne Bell testing. When the E85 air/fuel ratios were richened, E85 averaged 69 degrees cooler per each point of air/fuel ratio increase. So it runs cooler, but not significantly until you richen the mixture past max power. Then again, gasoline does the same thing. Or, as we once heard an old hand describe running rich, "You’re putting the fire out with gasoline."
Because automotive enthusiasts are typically not familiar with EGTs we’ll mention Kenne Bell’s testing accurately reconfirmed that any change in the ambient air temperature carries through to the EGT. For example, on a 60-degree day the EGTs might measure 1,320 degrees. If nothing else changes, but the sun comes out and the air rises to 80 degrees, then the EGTs will measure 1,340 degrees. In KB’s testing, inlet temperature changes as small as a couple of degrees (as measured just before the air filter) were reflected in the EGTs. It’s something for tuners to keep in mind, both weather-wise and from heat-soaking while a car sits on a chassis dyno.
Another mixture-related idea Kenne Bell explored was how much power changed from richening or leaning the E85 mixture. We all know leaning a gasoline mixture from its "safe" (low chance of detonation) setting yields a power increase, at least until detonation stops the party. Not so with E85 it turns out. With ethanol containing nearly 30 percent oxygen, there’s little gain in taking some E85 away from the engine; in fact, you can richen the mixture far more than with gasoline with no detriment to power. That lowers the EGTs but doesn’t hurt power, which may be the source of all those stories about E85 running so cool. It does if you pour it in with a hose and you don’t pay a power penalty for it. These results are summarized by comparing dyno runs 009 and 010 in the chart.
Also on the chart, the variable in runs 004 and 011 was boost. This wasn’t done to check max power, in fact, with the power reading being taken at 6,000 rpm because the fuel system couldn’t quite keep up after that, the power listed in the chart just hints at the max power. No, this boost test was to establish the relationship between EGT and boost. Jim penciled that out as each 2.2 pound of boost gaining 34 hp and raising the EGT 17 degrees. And yes, the power did go up, so that checked out as well.
The chart above is a small sampling of the Kenne Bell E85 tests. Note the fuel system on the test car proved slightly undersized with E85, so to allow comparison, all data was taken at 6,000 rpm. Horsepower is greater at higher rpm (the mechanical combination made power to 7,500 rpm), and Kenne Bell says a rough approximation of maximum power can be achieved by simply adding 41 hp to the peak power reading in the chart.
The Average and Converted Actual air/fuel ratios bear explanation. The Converted Actual Air/Fuel Ration is the actual air/fuel ratio the fuel system delivered during that test. The Average Air/Fuel Ratio is identical for gasoline, but is a calculated number with E85. It represents the air/fuel ratio E85 would be if it were gasoline. This eases comparing air/fuel ratios between gasoline and E85.
Besides fitting a large enough capacity fuel system, it is necessary to accommodate E85’s corrosive nature. Ethanol is not particularly friendly to some rubber, plastic, and composite parts, so everything in the fuel system must be vetted for use with alcohol.
"Everything must be alcohol compatible," says Jim Bell. Hoses, fuel line fittings, and epoxies used as electrical sealants in the fuel pumps all proved vulnerable to chemical attack from E85 in Bell’s experience. "You can’t let the car sit a long time with E85 in it ... it corrodes the injectors."
The issue is fuel injectors have electrical windings in their coils, and it turns out the coils use mild- and not stainless-steel wire. The alcohol corrodes the coils, sticking the injectors fully open or shut. Injectors approved for use with E85 seem to have coils protected by a coating; in any case, only injectors approved for use with E85 can be used. And they are expensive.
Jim Bell went on to note E85 is corrosive to aluminum, "So you don’t want to pour it through a supercharger." The rotors are aluminum and corrode. This isn’t an issue with a fuel-injected Mustang engine because the injectors are downstream from the blower, but draw-through carburetor applications are susceptible.
"The reason to run E85 is power," says Jim Bell, and he’s right. Up to 550 hp on pump gasoline makes more sense. It’s widely available, offers the greatest fuel economy and gives the longest range from a tank of gas. But when the desire is for more than 550 hp, then E85—if you can get it—is the ticket. It’s far less expensive than race fuel, won’t hurt the cats or oxygen sensors and seems to have the octane to support truly large horsepower.
The downside is the considerable expense of setting up the fuel system to both flow the volume needed and ensure against alcohol-based corrosion. But once you’ve got that handled, corn is looking good.