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Tuesday, January 19, 2010

E85 Fueled GT-R Tuning Results


Tim Bailey, the head calibrator with Cobb tuning recently ran an R35 GT-R with E85 fuel on the dyno and obtained some impressive results.  E85 is a blended fuel of ethanol and gasoline. 85% ethanol and 15% gasoline.  E85 is 105 octane, and a renewable fuel. However it does have some downsides,but as this is an enthusiast blog, I won’t go into them much, look it up.  Here in California we only have a few places that you can purchase E85, and the energy contained within the fuel is lower than gasoline, so it takes more ethanol to go the same distance, and to make the same power. E85 fuel requires a retune, as the fuel requirements are about 30% higher than 100% gasoline.

The positives are that it is relatively cheap compared to a race fuel, and that it is available at the pump in a lot of places in the US.   Bailey took a GT-R with a midpipe, cat back exhaust , twin 255 fuel pumps, and 800 cc injectors, and put it on the dyno.

Because our injectors are mathematically ideal for ~30% higher flow it’s clear that the stock fuel pumps simply cannot keep up with higher duty cycle with 800cc injectors.To combat the lack of fuel we installed two walbro 255s in the place of the stock fuel pumps. The installation took about 4 hours total as the stock in tank fuel surge tank needed heavy but straightforward modification. With new fuel pumps installed we went back to the dyno with high hopes of sufficient fuel delivery.



Stock on 92 octane the car did 435 hp / 435 ft/lb . On 92 octane with the exhaust mods at 16.5 psi the car made 513 hp/512 ft/lbs. With the E85 in the tank, 18 psi of boost, the car made 574 hp/585 ft/lbs.  They think they can make over 600 whp on E85 with a few more tweaks.


Source : Cobb Blog (say that 5 times fast)

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