Fr-s with subaru turbo?

[70NYD]

Originally Posted by serialk11r

Emphasis on the E. Okay I guess the Exige S 240 is an example that runs on pump gas and has more power, but it's barely over 25% improvement. Like I said, that would be the most you can hope for.

On a side note, with a supercharger I hope there's a way to remap the accelerator pedal so that the bypass is open but the engine is putting out maximum NA torque earlier, and then pushing the pedal past that gives you boost. That would give better efficiency and truly linear response.

Yeah E for E85
But correct me if I'm wrong, don't you have to run higher boost with E85 since its got a lower energy content, but since ethanol has a higher AKI you can compress it more?

[serialk11r]

Originally Posted by 70NYD

Yeah E for E85
But correct me if I'm wrong, don't you have to run higher boost with E85 since its got a lower energy content, but since ethanol has a higher AKI you can compress it more?

Half right half wrong, it's more knock resistant, I think partially because the flame spreads slower, but the high latent heat of vaporization cools the charge down a ton increasing efficiency and power. It has lower energy content per unit volume and mass so you need to inject more, but ethanol is 8/23rds oxygen by mass so I believe the total heat of combustion supplied is around the same per unit oxygen supplied (aka, per quantity of air supplied). Because it has a much stronger cooling effect, you can get a slightly more dense and cool charge, and even without a compression ratio increase to take advantage of the anti-knock properties you get more power due to a denser charge and lower working temperatures which improve thermodynamic efficiency.

Alternatively, if the fuel delivery is flexible in a way that allows this to happen, I believe it's possible to extract a tiny bit more thermal efficiency by trying to have the ethanol vaporize during the compression stroke, which will increase efficiency further. I have a hunch gasoline direct injected engines attempt to do this too but with gasoline it doesn't work as well.

[70NYD]

I agree there. But does not deter from my original point of adding forced induction on a high compression ratio, high revving NA engine. But we (that I am aware off) still aren't aware of what the dynamic compression ratio is of the d4s equipped fa20.
In any case, I think with direct injection, it allows for a localized cooling by vapourisation when injecting the fuel, allowing to compress the air more, but preventing knock. That's the way I see it, and what I think by using CFD to get fairly accurate mappings of dispersion of fuel molecules in air, and possibly a fairly accurate heat transfer from air to the fuel, you could time the injection duration and design the pattern to get the latest possible injection period, while preventing fuel to reach the flash point prior to spark ignition.
But that's just my point of view, I'm not well versed on direct injection to begin with, so I could be way off. That's just what makes sense in my head when I think about it

[serialk11r]

Yea you're right, but I wouldn't count on the dynamic compression being lower than "normal" (if you get what I mean by that), the torque peak does arrive well before the redline afterall and it seems like it would be a relatively high lift profile.

[70NYD]

Yeah I get what you mean and your right, after all this isnt a Atkins or a miller cycle :p
I just can't wait to drive this car all this talk is making me excited just wish that here in oz they gave some info out.. But they are fairly slack. Alot of pol are loosing interest here.. Shit happens I guess