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What would be the estimated Hp gain by getting a tune for flexfuel and going to E85 from 93? Stock LT4 with a cai and headers.
At what HP level does the stock fuel system start to run out of steam on E85?
Search. Evil_V has a thread on this. I know he stated what he has done and people asked plenty of questions.


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You can get away with about E55


If you are lucky. With the cai I have to stay around 40-45 if the da is at all good.
 

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How does the V3 do compared to the V2 when going to E85? I know the V2's made a hell of a lot more power on E85 (well - up to about E60). My V2 makes about 80-100hp more on E85 versus 93, on the same hard parts, back-to-back dyno pulls. But that's with all the bolt-ons that I have.

I'm guessing the DI injectors on the V3 can do E85 just fine - but as usually you need more volume? How about the heads and other aspects of the LT4 - do they make the engine more or less favorable to corn?
 

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The better test will be the ZR1 coming out.

The V3 issues are the fuel supply and the blower is too small, unless you upgrade that as well.


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How does the V3 do compared to the V2 when going to E85? I know the V2's made a hell of a lot more power on E85 (well - up to about E60). My V2 makes about 80-100hp more on E85 versus 93, on the same hard parts, back-to-back dyno pulls. But that's with all the bolt-ons that I have.

I'm guessing the DI injectors on the V3 can do E85 just fine - but as usually you need more volume? How about the heads and other aspects of the LT4 - do they make the engine more or less favorable to corn?
In general from what I have seen the benefits of E85 are even more pronounced on DI motors.
Not sure exactly why but I suppose you get even more benefit because the fuel is vaporized inside the cylinder and removes a ton of heat from the combustion chamber fighting detonation even more than it does on a PI car.
Also, it might not make any real difference but I seem to remember reading that e85 being an oxygenated fuel takes up some of the space in the intake runner so I guess injecting direct into the cylinder leaves more flow for air. When I tried calculating the volume liquid fuel would take up in the runners even at 1000cc/min it seemed pretty insignificant compared to the CFM of air being moved but who knows, there might be more to it.

But as Karch said, on the LT4 a major problem is the blower being too small which generates tons of heat so I would expect the LT4 would LOOOVE corn even more.
 

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DI engines have higher static compression, so apt to benefit even more from higher octane fuels.

I am not positive, I’m not a chemist, but I think the oxygenated fuels carry oxygen molecules that release as its ignited, meaning it’s carrying oxygen into the cylinder by way of the fuel.

You want the most oxygen you can get into the engine, that’s what forced induction does, up to the limit of all the supporting hardware and fuel.

Why do you think top fuel used nitromethane?


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The DI cars are just more timing sensitive, especially the boosted ones. So if you can increase cooling and octane( timing) they will gain good. The issue being fuel supply which is more costly to deal with then it is on port injected LS engines.
 

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Why do you think top fuel used nitromethane?
Yeah definitely, they can run 4:1 afr so they don't need nearly as much air. Makes sense.

Oh also, DI engines have head design/intake runners that have very high tumble so they can get good mixing of fuel at low rpm/idle/cruise so they GENERALLY don't flow very well at high rpm like a good PI head.
So getting oxygenated E85 directly into the cylinder in high volume probably helps to overcome intake limitations in the head because the fuel takes some oxygen in with it.
 
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