I was workin' on my 90' EFI F150 and got a bright idea of possible redoing the 302ci engine for E85 and more power. I started looking at rebuild and stroker kits along with piggy-back compters and ajustable fuel pressure regulators. I found that E85 has a 115 octane rating and works better for engines with higher compressions (14:1 was "ideal"). I found that with flat top hypretentic pistons in my truck I could get ~ 10.5:1 compression and with just a fuel rail pressure ajuster I could run E85 (with out anyother upgrades). Is this true and could I get this truck started in the winter? Also would a set of 289ci heads fit on the engine to increase the compression?

 

10.5 will still be poor with E-85. Probably a 4+ MPG drop over regular gas. E-85 does however give you the advantage of being able to advanced the timing A LOT without detonation.

If you really want to build an E-85 motor, you'd probably want at least 13:1, but then you have to consider what if you ran out fuel, and you were not near an E-85 station? I doubt even premium would behave well with 13:1.

I'd personally go for a 91/93 engine.

 

FTE has a fuel/ inj/ etc. forum , with lots of smart folks. If you didn't find the answer, try the search function.
I did a lot of research last year when the gas prices went crazy (especially race gas) but mine was more performance, rather than street-related, but this might help: E85Forum.com :: Home

Pro:
PRICE - It is the cheapest race fuel available.
Power and torque improvements - 4.5+% available simply from the change over - more if you build the engine specifically for it.
Acts more like 112 octane due to cooling.
High evaporative cooling - great for hot environments.
Not as sensitive to running rich as gasoline fuels.
Clean burning and smelling.
engine and oil does not carbon up nearly as much as gasoline fuels.


Con:
Some fuel system parts are not compatible for long term use - rubber seals and gaskets, and untreated aluminum tanks and fittings.
Availability in some areas is scarce.
Fuel system needs to be able to flow more than gasoline.
Reduced mileage unless you take advantage of all benefits.
Hygroscopic - absorbs moisture easily in storage.
Occasional flushing required - run on gasoline from time to time.
Does NOT like cold starts in a cold climate.

If you are going to use an AFR/Lambda meter, make sure it can use the wider range Bosch 4.9 sensors that will accurately read much richer (and leaner) mixtures (~9.0:1-36:1) than normal Bosch 4.0/4.2 sensors (~10.2:1-22:1).
Another problem is, blends change according to time of year a bunch, dropping octane accordingly, just like gas (just part of MY learning curve).

If you want more info (race related) feel free to PM me.


Pete