Travis Thompson
July 20, 2007

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.

Who says musclecars and the environment can't get along? With all the benefits of E85, including its higher octane, it's a natural fit for aggressively tuned performance cars such as the supercharged '03-'04 Cobras and Shelby GT 500s.

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.

The first thing that HiTech did with Mark Norton's '04 Cobra was swap in new NGK BR7EFS plugs before the baseline run. They feature a non-projected-tip design, which keeps the ground strap from overheating and causing pre-ignition.

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.







  BASELINE E85 DIFFERENCE
RPM POWER TORQUE POWER TORQUE POWER TORQUE
2,400 195.37 427.55 {{{200}}}.69 439.19 5.32 11.64
2,500 208.37 437.75 217.30 456.51 8.93 18.76
2,{{{600}}} 221.05 446.53 229.91 464.43 8.86 17.{{{90}}}
2,700 231.69 450.69 {{{240}}}.93 468.66 9.24 17.97
2,800 241.58 453.15 252.05 472.79 10.47 19.64
2,{{{900}}} 252.07 456.51 261.78 474.10 9.71 17.59
3,000 262.41 459.39 273.84 479.42 11.43 20.03
3,{{{100}}} 273.69 463.70 284.43 481.88 10.74 18.18
3,200 283.22 464.85 294.21 482.88 10.99 18.03
3,{{{300}}} 291.45 463.86 304.65 484.87 13.20 21.01
3,400 302.47 467.23 315.50 487.36 13.03 20.13
3,500 312.33 468.68 326.22 489.52 13.89 20.84
3,600 320.86 468.11 332.86 485.61 12.00 17.50
3,700 329.67 467.96 343.23 487.22 13.56 19.26
3,800 336.31 464.83 350.23 484.06 13.92 19.23
3,900 344.25 463.60 358.37 482.61 14.12 19.01
4,000 351.35 461.33 367.01 481.89 15.66 20.56
4,100 357.74 458.26 376.31 482.06 18.{{{57}}} 23.{{{80}}}
4,200 364.41 455.69 379.87 475.02 15.46 19.33
4,300 373.41 456.10 386.51 472.09 13.10 15.99
4,400 383.19 457.40 400.34 477.88 17.15 20.48
4,500 391.89 457.39 407.97 476.16 16.08 18.77
4,600 398.42 454.90 418.04 477.31 19.{{{62}}} 22.41
4,700 {{{405}}}.27 452.88 424.52 474.39 19.25 21.51
4,800 414.52 453.56 433.77 474.63 19.25 21.07
4,900 421.20 451.47 438.39 469.89 17.19 18.42
5,000 425.72 447.18 445.71 468.18 19.99 21.00
5,100 429.81 442.63 451.36 464.82 21.55 22.19
5,200 437.31 441.69 452.72 457.26 15.41 15.57
5,300 439.03 435.07 456.92 452.79 17.89 17.72
5,400 438.45 426.45 457.36 444.84 18.91 18.39
5,500 442.30 422.37 460.29 439.54 17.99 17.17
5,600 441.89 414.43 462.41 433.69 20.52 19.26
5,700 444.02 409.13 460.23 424.07 16.21 14.94
5,800 443.50 401.61 459.89 416.45 16.39 14.84
5,900 444.97 396.11 461.97 411.24 17.00 15.13
6,000 444.01 388.66 461.03 403.56 17.02 14.90
6,100 438.98 377.96 457.86 394.22 18.88 16.26
6,200 422.93 358.27 451.61 382.57 28.68 24.30
6,300 421.54 351.42 450.26 375.37 28.72 23.95

On The Dyno
The HiTech E85 conversion netted us about 19 hp and 20 lb-ft of torque. Peaks were up to 465.49 hp and 489.52 lb-ft of torque from 446.24 hp and 469.38 on gasoline. The air and coolant temps were near baseline. The intake air was 62 degrees, the air charge was 88 degrees at the beginning of the run, and the engine coolant was 190 degrees. The timing advance peaked at 24 degrees.

The air/fuel ratio was also much flatter than on the baseline run. Interestingly, standard lambda/O2 sensors aren't calibrated to read E85, so the air/fuel numbers on our dyno graph weren't accurate. E85 contains more oxygen than regular gasoline, causing the standard O2 sensor to read much leaner than the Cobra is actually running. Remember, more E85 is needed to make the same power, meaning a richer air/fuel ratio is required. The O2 (lambda) sensor is reading and outputting a signal relative to stoichiometric, which is 14.7:1 for gas, but a richer 9.7:1 for E85. Even though the O2 sensor tells us we're running 11.5:1, it's also telling us that the car is running richer than stoichiometric, in this case around 7.59:1 on E85 (11.5 times 9.7, divided by 14.7).

E85 is cheaper at the pump, but it burns more quickly-so does it save money in the end? Mark reported a drop from 15 to 12.6 mpg with his particular blend of smoky burnouts and highway driving. Results may vary. Given the lower price of E85 per gallon ($1.90 versus $2.60 in this area), Mark will save $270 this year, assuming he drives 12,000 miles. This alone might not make the conversion worthwhile, but with the environmental and economic benefits-and the additional horsepower and torque-it makes perfect sense.

Since E85 has less energy per gallon than regular gas, you need to get more of it into the cylinder to make the same power. To meet the demand, the guys at HiTech replaced the stock 39-lb/hr injectors with 60-lb/hr squirters.





The new injectors required these EV-1 to EV-6 conversion harnesses.








Swapping in new injectors means removing the upper plenum and throttle body. Other than that, the install is straightforward. Make sure the injectors are snapped tightly into place on both ends.





The final step of the conversion was to install the DiabloSport flip switch and LED indicator in the glovebox. Mark can now toggle between E85 (green light) and regular gasoline (red light), giving him the ability to fill up anywhere in the country.