the only problem with lower compresion is he will need a blower that can push some air. i dont know much about blowers, will a D1 push that much air? like 15psi on a 427?

 

Your car will make the most power with low enough compression so that you can spin the blower to the max and move the most air, without detonating, period. You WILL make more power, more torque, and more power/torque under the curve with an 8:1 or 8.5:1 motor on pump gas than you will with a 9:1 or 9.5:1 motor on pump gas. I would bet my house on it. Keep in mind that with less compression you're going to run more boost, and spin the blower harder. Using a smaller blower pulley you're spinning the blower faster at any given RPM, so boost comes on sooner which basically nullifies the "More compression for more low end" argument.

 

The D1 supposedly flows up to 1400cfm, can support about 900HP and spin around 60,000 to 65,000 RPM.

 

NOGO said it was like 900cfm. Guess ill have to give ATI a call and see what CFM the D1 flows.....

 

Looked at the web-site and it was 1400 CFM on the D-1SC.... That should be enough for a 427 then right?...

http://www.procharger.com/models.shtml

 

The biggest issue won't be 'how much boost should you run', but 'how much boost can a reasonable setup make'. Then figure out the CR for that. Otherwise you'll spend thousands on trying to make boost, and you could've saved some money and ran higher CR instead.

From an ATI document:

 

I've just been reading Eviltwin's comments, I'm with him 100%.

You have to sift through the generalizations when you design an FI setup.

A boosted 427ci could make 800rwhp on pump gas no problem. Keep the compression low. Go 8:1. One point of compression reduces power by 3%. That's not very much. When folks talk about laggy low compression engines they are talking about heavy 4 and 6 cylinder cars.

Tangentially my 746rwhp setup made 600rwhp at 5200 rpms. I was making 550 around 4800 rpms. So I probably make about 450rwhp at 4000 rpms.

Whenever I see folks advocate more than 9:1 compression for an LS1 I don't think they have personal experience with this stuff and are just passing on what JoeBobBuilder told them.

Back on target. Well I think an 8:1 348ci could hit 800rwhp on pump gas with a FMIC and no alky. I think a 427ci could do 900rwhp at 8:1 without aids, maybe a little help. Remember we are modding one of the most effecient and well designed engines that has come out of GM or Japan in the last 20 years.

 

Sounds good. I guess ill go with an 8:1 CR on the motor and buy the F-1.. That should be enough boost.. I think the ATI procharger is the best on the market for boost that i have seen. What do you guys think? FMIC?? What does sthat stand for Pro Stock John?

 

The D1 flows up to about 1400 CFM. It is the ATI intercoolers and piping that I say chokes at around 900 CFM (despite what ATI says).

-Kevin

 

One of the Truck guys in our forum replaced his ATI intercooelrs with a bigger unit from a Duramax Deisel and gained around 30-35rhwp and much lower IATs. There were no other changes made to tuning or anything.

 

Hey NoGo.. Whats your setup on your 383? CR & S/C/Turbo. Nice numbers by the way.

 

8.25 CR
D1 SC Supercharger @ 14-15 psi at peak HP.

There's another thread floating around where I posted all the specs.