JohnBradley

iTrader: (30)

10:1 depends on octane level. When you only have 92 octane the limit is around 21-22psi with a 10:1 motor, 93 might be able to run more boost at the same timing. Pumpgas gets diminishing returns real quick though since being octane limited the timing drops enough in some cases that you are down power at the same boost level as a similar 9:1 motor.

Aaron

Svendiesel

iTrader: (25)

Best on Buschurs dyno was 420 ish.

SmurfZilla

iTrader: (33)

High compression combined with bigger displacement makes the car perform better off boost. I liken my car to a fast NA Honda and when the boost kicks in. a rocket ship. LOL.

I also when long rod as well so I spin my motor to 8000+. Though to be honest I rarely ever take it that high since things start to get too fast to process. Driving the car around town I short shift at 4k and I still outpace most drivers (even aggressive ones) on the street.

ScorpionT

iTrader: (1)

Depends on the tuner, but it can be done with a Black.

You are thinking of it backwards. A larger more efficient compressor will be safer on high boost.

Boost is related to volume and temperature. If the volume and pressure remain consistent between two turbos (eg, Black and 42R) and the larger turbo moves more air, the temp will be lower. The Black will have higher temperatures, making the window for safe tuning smaller.

sparky

iTrader: (1)

I am in agreement that higher SCR tends to delay turbo spool up.

browningderek

iTrader: (7)

11:1 here. Hta 86 and 2.3L. 20psi @ 4100 and 26 psi @ 4400. Not a slow spooler by any means.... 575whp on 93 oct. Timing was -3 @ peak tq. And 13 degrees @ peak power. Runs like a champ! I was also worried about eunning high compression, turns out its all good.... and it runs super strong off boost.

selp

iTrader: (6)

Im in need of help and making a decision as to what I want to do. I am getting ready to build my engine and I am stuck deciding what I want to do for compression ..

I am currently stock turbo, possibly the highest ill go would be a green or a red. For the moment the build will retain the stock turbo. (porting intake manifold and tb), also running GSC S2 cams, with springs.

I want to do a 2.3L. I was thinking of getting a 10.5:1 CR for the pistons with a 85.5 bore, but im still a little concern as to what to do. I will be running 2 maps, E85 and 91 octane (Arizona). This car is my daily driver and I would like to keep it safe, especially since I take trips to the snow on the winter. This car is street driven, and sees rare track or strip use.
I have been told to run 10.5:1, 10:1 or 9:1, hard to make a decision when the choices are all over the place.. I would like to get the most of what I can, but still being safe. I don't care about not making high horsepower on pump, that is why I will be running a second map that runs E85 at full boost.

sparky

iTrader: (1)

selp: Read Aaron's post #16(in this thread) above.

masonh

iTrader: (8)

all things being equal an inrease of a point in SCR is good for 3.2% increase in thermal-conversion efficiency,read more power,however 1psi more boost is good for 3.5% in mass-air flow,read more power and 2psi more is good for 7% increase and so on and so on.so theoretically if you can gain 2psi boost by losing one point in SCR you will make more power.

however on ethanol and race gas the point is basically moot.i would rather have the extra point of SCR and the free 3% increase in power and the better overall driveability.also again if you are setting up a low boost car,say 20psi max on a GT30 turbo,then again,go for the extra SCR.

if you are going to try and tune for 93 at max boost,you would probably be better off with a lower SCR,but why would you unless you can't get E85?

as far as the affects on spool,i would say the difference in spool from a 1 point increase in SCR is negligible if any at all.

masonh

iTrader: (8)

skip the 9:1 in your case and keep the 91 octane tune soft.

sparky

iTrader: (1)

A 10.5:1 build on 91 octane pump gas would require limiting peak boost level to about 17 PSI, wouldn't it? But, peak boost isn't the only forseeable problem area. Obviously a static C.R. of 10.5:1 will require extremely retarded ignition timing in the lower midrange and midrange. With a stroker motor and a small turbo such as the Green turbo spoolup will be immediate maybe he'll see 20 PSI by 3000 RPM, so the dynamic CR will be well up over 11:1 by 2800-3200 RPM. The problem is going to be preignition even at relatively low boost levels and low engine speeds on the 91 octane pump gas.

Joshs EVO

iTrader: (46)

DB is building me a 11:5 CR 2.4LR for my new setup. Should be pretty sweet. Not to hijack or anything. What are you guys thinking.

sparky

iTrader: (1)

What fuel will you be running in your 11.5:1 motor?

Joshs EVO

iTrader: (46)

E98

DBallz

iTrader: (7)

jesus!