5.0 Mustang & Super Fords
E85 Terminator - Corn Snake
Converting An '04 Cobra To E85 Is Worth Some Power, Thanks To The Ethanol-Imbued Fuel's Higher Octane
Horse Sense: The public at large may be interested in E85 because it's renewable and cheaper by the gallon, but performance junkies want it for its 105-octane rating. If you're looking for it, e85refueling.com is a handy locator for finding a station.
If you've been paying attention to the news or any of the consumer-focused car magazines, you've heard about flex-fuel vehicles that run on E85 or regular gasoline. E85 gets its name from being a blend of 85 percent ethanol and 15 percent gasoline. It has gained mainstream popularity and government support because it burns cleaner and it's a renewable energy source, produced in the USA from crops such as corn. Why are we talking about E85 in 5.0 Mustang & Super Fords? Because it has a 105-octane rating and costs less than regular unleaded.
The performance benefit of E85 for cars is simple. With the higher octane rating, you can dial in a more aggressive tune before reaching the detonation threshold of the fuel. In short, you can run more timing and make more power safely for a given combination of parts. If you've already built an aggressive street or race motor with high compression or boost, you know what a drag it can be to get it to run on pump gas without detonating. Until now, the only alternative may have been to run on expensive race gas. Let's face it-race gas limits how much cruising is done each year.
So, what's the drawback and why doesn't everyone run E85? The rub on E85 is that it contains less energy than pure gasoline by volume-more E85 is needed to make the same horsepower or travel the same distance. That's why you can't run E85 in a vehicle that's only tuned for gasoline. Nearly every manufacturer, Ford included, currently sells FFVs that can burn E85 or unleaded gas. HiTech Motorsport in Elk River, Minnesota, is making a name for itself by-among other things-converting performance cars and trucks to run safely and make more power by burning E85.
Our test subject is Mark Norton's factory supercharged '04 Cobra. His car is equipped with a 2.76-inch Billetflow pulley and idlers, an open-element K&N filter, and a Runnin' With the Devil tune. After swapping in some new NGK plugs, the Cobra put down 444 hp and 469 lb-ft of torque. The intake air temp was 68 degrees, and the air-charge temp after the intercooler was 92 degrees at the beginning of the run. The engine coolant temp was 188 degrees, and the timing advance peaked at 21 degrees.
HiTech's E85 conversion consists of two phases: upping the capacity of the fuel system and altering the tune. As mentioned above, it has about 28 percent less energy by mass, but it isn't as simple as only adding 28 percent more fuel and calling it a day. E85 burns differently than straight gasoline at part throttle and wide-open throttle, necessitating a complete retune and at least 50 percent more fuel flow capacity. For Mark's Cobra, that meant replacing the stock fuel pumps and 39-lb/hr injectors. Casey and Ron at HiTech dropped the tank and swapped in a pair of Ford GT pumps and a set of 60-lb/hr injectors to keep up with the flow.
Back on the dyno, Brian Ebert set up the Cobra with a DiabloSport flip chip so Mark could switch back and forth between E85 and 92-octane gas. This will come in handy, as E85 isn't available everywhere yet.
Before the conversion, we baselined Mark's Cobra. With only a 2.76-inch Billetflow pulley, a K&N open-element filter, and a Runnin' With the Devil tune, the car put down 444 hp and 469 lb-ft of torque.
The first step of HiTech's E85 conversion was to drop the fuel tank to swap out the pumps. Casey and Ron began by using a tranny jack, but decided they could lift it themselves because it was nearly empty.
Pop off a few bolts and the stock Cobra pump assembly comes out. "Assembly" really is the only way to describe this setup.
These are the new Ford GT pumps (PN PFB-81 4G7Z-9A407-CA). They look the same as Cobra versions, but they move more fuel. Ford Racing Performance Parts also offers a GT 500 pump assembly (PN M-9407-GT05); it would drop in without the need to rewire.
As it turns out, the GT pumps weren't a plug-and-play affair. The guys at HiTech swapped some electrical connectors to get the wiring to line up with the rest of the assembly. They also reused the Cobra fuel socks.