Pump gas vs E85 on engine strain
 

I've heard around 215kw/300hp is the safe zone for stock internals and transmission, but I often see cars hitting this, but also going way over with E85, so I was wondering if E85 lets you push more power with less strain on the engine?

Or does pushing a certain amount of power put the same load on the engine no matter whether petrol or ethanol based? Maybe a silly question but just curious since I often see this kind of stuff and am not sure if I'd be putting my engine at risk

For example I'm interested in going for this Harrop SC and it lists the power output as 225kW. I wanted to go flex fuel too but I'm afraid that pushing >225kW with E85 would be risky

The strain on the internals is the same. You have to run more boost to get the same power on pump gas because you can't be as aggressive with your timing as e85 allows.

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So if I just wanted to stick at 225kw, then it would make sense to just not bother with E85?

Or would needing less boost mean less strain on the engine? If I was running 8psi or something to get 225kw and then ran 8psi on E85 for more power, would that strain be the same?

If the tune is safe then it should be the same stain. You can achieve your goals with less boost on e85 though. I don't believe higher boost adds strain because cylinder pressures during combustion far exceed those 8psi.

Maybe someone with more tuning knowledge can confirm my claims here

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Fair enough. I guess I'm just trying to figure out if it's safe to run flex fuel/E85 and exceed 225kw.
Not sure where I got the 215kw number but I just want to keep things reliable and I'm completely ok staying with pump fuel at 225kw if going higher is risky

The higher the power, the more risk. E85 just makes it easier to get those higher power numbers but it is possible on pump gas

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Thanks for the explanation, think I might stick with non-flex fuel pump gas when I decide to go FI then

As Ashi says there is no real "safe" way of increasing power and there are no certain numbers that you can safely target. As soon as you start adding power you start increasing the risk of something failing.
Also as he said E85 allows you to gain more power through more aggressive timing. The problem with gas is that as you increase boost you increase the probability of preignition resulting in knock. It is knock while boosted that has the biggest possibility of blowing rods apart. The E85 is not as susceptible to preignition which means less chance of knock so you gain power. It is all in the tune of course.

In that case do you reckon the power increase risk with e85 would offset the risk of blowing rods? I'm pretty keen to supercharge is and take the risk with e85, if the risk isnt ridiculously higher

I guess it all depends on the tune, I'll have to do some more research

There is less risk of knock with E85.

Detonation/pre ignition(LSPI) is the most likely cause of bending a rod. This is due to cylinder pressures rising to quickly. With E85 it will burn slower and you will have lower cylinder pressure but keep the pressure up longer throughout the power stroke. So at the same power level E85 will have less stress on the engine. Yes do research on the tune this is the most likely cause of a blown engine.

I didn't know about the slower burning. That's good info

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