11:1 SCR with E85. . . who's running this?

[Scotchington]

Who is running 11:1 SCR in their 3.0 street cars?

My car made 806whp @ 33psi using C16 with the following mods by Nenni:

-Stock short block (stock compression)
-SP Race intake manifold
-GSC S1's with BC springs/retainers
-CEA 6765 (.81, journal), BL exhaust manifold w/Tial 44mm WG
-AEM V2
-ETS 4" core
-HKS DLI
-1000cc inj.
-Straight 4" exhaust (BL downpipe w/ Virutal Works piping to an HKS C/TI can)


With the above mentioned, what is a realistic spool and peak power increase I could expect to see if I added 11:1 with e85? How much could I move the curve leftward? I understand that e85 loves compression, but just how much compression? The car would only see e85 as it's readily available in my area.

What would the pros/cons be with a motor like this? This car is a street car.

I'm looking for objective feedback from people who are versed in this topic.

[QTR_Supra]

I know the evo guys are doing it. a friend of mine picked up 200RPM from his older setup 10.5 and some tq. his horsepower for some reason didnt increase much. but this was an evo. I would guess with the 6 cylinder it will pick up more?? I have no experience with this but it should in theory?

[QTR_Supra]

oh btw what compression are you running on your current setup???

[Scotchington]

Stock short block.

[gilberjj]

e85 and high compression is AWESOME!

[Scotchington]

Wow. I would've thought this thread might have took off. Is there no one running 11:1 with e85?

[D'Bollocks]

I wOuld be, but my last builder royally did a complete hack job and my motor barely made it through break in before we realized how much coolant it was loosing and oil it was leaking. Should be back up shortly.

[FUZION84]

i talked to don about this and he doesn't seem to think that there is any real benitfit going with 11:1 over 9.5:1.-10.0:1. Just creating less room for error...

[Craig Bush]

^^^ Don (@ AP) built my stroker, and he told me the same thing.

trouble is, i would think you'd get a linear increase in power as you increase SCR. for example, going from 8.5 to 9.5:1 is an approx 12% increase in the SCR, and should result in a similar power increase (unless i'm misunderstanding). so going from 9.5 to 11:1 is an approx 16% increase (and an approx 29% increase from 8.5:1); should result in good gains, no?


craig

[superstock]

^^^ Don (@ AP) built my stroker, and he told me the same thing.

trouble is, i would think you'd get a linear increase in power as you increase SCR. for example, going from 8.5 to 9.5:1 is an approx 12% increase in the SCR, and should result in a similar power increase (unless i'm misunderstanding). so going from 9.5 to 11:1 is an approx 16% increase (and an approx 29% increase from 8.5:1); should result in good gains, no?


craig

Increasing SCR from 9:1 to 11:1 will net you about 3.2% increase in power only.

[Craig Bush]

^^^ oh, ok. why is that?

[Yota 3.0]

^ if this is true, then it doesn't seem worth it. IMO

[Craig Bush]

^ if this is true, then it doesn't seem worth it. IMO

agreed.

fwiw, my current setup with the stroker and 6766 made approx 950whp on SP's mustang dyno, which should equate to approx 1000whp on a Dynojet (obviously not impying this is definitive).

as this # is approx 10% higher than others have attained with the same turbo, i was attributing the 10% power gain to the 12% increase in SCR.

someone educate me - is not how it works?


craig

[superstock]

agreed.

fwiw, my current setup with the stroker and 6766 made approx 950whp on SP's mustang dyno, which should equate to approx 1000whp on a Dynojet (obviously not impying this is definitive).

as this # is approx 10% higher than others have attained with the same turbo, i was attributing the 10% power gain to the 12% increase in SCR.

someone educate me - is not how it works?


craig

An engines thermal efficiency is affected by the compression ratio but is centred around the adiabatic expansion for air. I would have to look up the formula if you really want it.The easy answer is the compression increases are a case of diminishing returns. To get a 10% increase from compression alone, you would have to go from 8.5:1 to16:1. aproximately. However if you were running high octane pump gas and 8.5:1 and swapped to E85 and 11:1 the E85 alone would be worth about 9-10% increasing the compression to 11:1 reduces the detonation safety margin, limiting boost increases possible with E85 and also limits ignition timing.

[Craig Bush]

^^^ thanks bro - i appreciate the insight.

[pretty ricky]

what about the low end increase(torque)

[Scotchington]

Have any of the big name Supra shops built an 11:1 3.0 liter before?

[1998jza80]

If you use the formula, your car going from 8.5:1 to 11:1 would make 864HP, or a 7% gain. Something to think about regardless of top end gain is the vast improvement in off boost driving.

[grandporschegt]

i would think that compression would be noticed the most in out of boost hp/tq, throttle response and boost recovery. personally if i can get twin gate setup that could hold 7-10 psi and still make 35+ i will go with 11/1ish compression. basically as high as i dare and still run on 91 octane(low boost) and then when i have a tank of e85 it will be game on!!

[D'Bollocks]

The out of boost driving is slightly better but not an earthshattering difference. Its kind of like you feel the car is accelerating where as low compression you almost feel like the car is "wallowing" and not really going if that makes sense. However rolling into boost the car immediatly starts pulling harder.....this means in the 2-5 psi range. From there the boost ramp is so fast its absolutely amazing....i have a borg 76mm which is lazy and fairly to regulate the boost with the gas pedal on a stock compression motor, on 11:1 it comes on so fast you cannot pull your foot fast enough once it is rolling through 10psi to not hit full boost. Im not sure if that makes sense but thats best i can describe the response difference. As for power output my motor didnt last long enough to make a trip to the dyno worthwhile, but at 18psi it pulled as hard as it had at 25psi with a much wider power band. My motor failure was not a result of the compression or tuning issues, but horrible machine work and assembly. My motor is being rebuilt and i am staying high comoression, i wish i had more concrete numbers to share but hopefully this gives a decent idea.

[leecheater]

If I remember correctly DaveH told me when I was trying to decide how high to go, that he was 10.5 to 1. That's on E98 though. Maybe he will chime in here.

[quake]

Who is running 11:1 SCR in their 3.0 street cars?

My car made 806whp @ 33psi using C16 with the following mods by Nenni:

-Stock short block (stock compression)
-SP Race intake manifold
-GSC S1's with BC springs/retainers
-CEA 6765 (.81, journal), BL exhaust manifold w/Tial 44mm WG
-AEM V2
-ETS 4" core
-HKS DLI
-1000cc inj.
-Straight 4" exhaust (BL downpipe w/ Virutal Works piping to an HKS C/TI can)


With the above mentioned, what is a realistic spool and peak power increase I could expect to see if I added 11:1 with e85? How much could I move the curve leftward? I understand that e85 loves compression, but just how much compression? The car would only see e85 as it's readily available in my area.

What would the pros/cons be with a motor like this? This car is a street car.

I'm looking for objective feedback from people who are versed in this topic.

are you after more peak power or off boost power?

[Scotchington]

^ Of course more peak power, but also curious as to how far I can move the curve to the left.

[Coutsi]

I'm just starting my build with 11:1 CR custom CP pistons, E85 is used.

[Scotchington]

^ Did you happen to finish your 11:1 build yet? If so, any numbers?