I'm planning a sleeper type build in the distant future, I want to maintain the stock look as much as possible and hence want to keep the stock intercooler. I know its safe up to ~10psi on regular gas, what about e85? How much higher could I go? I'm looking at getting to around 250-350rwhp after porting etc as well if possible. s4 engine. Would be primarily for mountain road driving.

 

so the E85 won't change the intake temps, so those will still be high, it just matters less cause you have better/different fuel. 250hp should be no trouble at all, even 300 should be ok.

 

Think this is a loaded question.

Intake temp sensor is right before the throttle body. It would only see the effects from ambient air, turbo compressing, and intercooler.

then you have to factor in specific heat capacity, latent heat of vaporization, the increased multiple of e85 being sprayed vs gasoline, predetonation temp of e85.

here’s the kicker: how would you know the IAT of the air fuel mixture right at the intake port, and really inside the rotor’s intake chamber? Math, a second air temp sensor, experience.

just a quick example is the hoonicorn which sprays methanol (alcohol) and doesn’t need an intercooler. Different thermal properties but e85 has better properties than gasoline.

It’s an interesting problem which probably has surprising results.

just some quick googling: https://www.modularfords.com/threads...th-e85.194918/

edit: the more I think about it, you’d use knock as a derivative of Iat’s in the combustion chamber.

 

Would the post injection air temps be needed?
My train of thought was that I could get away with higher air temps with e85 due to its knock resistance, not particularly because of its cooling effects.

Though in hindsight I think for my objective it would be more practical running water-meth injection.. I could use the washer fluid reservoir, after all washer fluid is essentially water/methanol solution. E85 is also pretty scarce and expensive here too.

 

I have been running 12psi on stock S5 intercooler on 72% E85 according to my Haltech/flex sensor (highest ive seen from my local stations ).

I have 93 octane boost set for 8psi.

Been driving for about a year like this. Not a track car but driven with "Spirit" often.

-M

 

I've just built something similar for a swap into my MG and have a baseline (engine) dyno of 265 horse 185 torque at 10ish PSI on an unknown hybrid compressor. If you're keeping intake temps in check via water injection (I'd suggest pre turbo as the intake track just isnt long enough for a reasonable flash) it will be fine, though from my previous experience in building and dynoing these engines the tiny inlet and outlet, as well as hard 90* turn down into the TB is killing flow. In the future I'll probably re-core the intercooler cage, rethink the TB elbow, and run like a 2.5" in 3" out with a slightly thicker core as I would have expected closer to 290-300 horse and 200-210 torque from previous builds boost using free flowing front mounts. I'll also be waiting to plumb WI when I strap this to my chassis dyno.

P.S. Car isn't running yet, these were dyno'd on a stand.

Final assembly in between projects

Don't judge my medusa hair of plumbing and wiring, it's just dyno rigged :P

 

For what its worth, I remember seeing around 70 degrees C intake temp when I still ran the oem IC.