I'm just posting because I'm so stoked that my car should be running well again shortly. After 10 months of waiting and trying to understand what was wrong a compression check was done by the new shop I have just started working with. These guys are great! National Speed, Inc. Look for them on TV with a build show this year.

Anyway, back to my ride. Having all forged internals installed and hopefully will have a safe engine with good power again soon.

Oh yeah, one of my cyliders only held compression of 110. By the end the car was making 247hp na but only about 258 with the Vortech installed.

I'm having 8.5:1 pistons put in. I know this will reduce my power slightly, but does anyone know how much power I might lose. I had 375 before with stock internals.

 

Good luck with the build and i hope it turns out great for you.

 

just went through this subject with a engine builder, with turbos 8.5:1 is optimal. with a supercharger you want to drop compression as little as possible. if i decide to stay with my s/c and i build i will stay 10.3:1 and run 100 octane. if i had to run pump fuel 9.5:1 would be the lowest i would go for a s/c. thats just me........

 

Yeah that's what I hear. The shop was having a hard time finding anything in the 9:1 or 9.5:1. I think I may go twin turbo down the road so we are going with the 8.5:1. Is there a reason besides power loss to not use the 8.5:1 with a supercharger.

 

you have to make a considerable amount of boost on a dropped compression engine to make power. like on a turbo application all you pretty much have to do is adjust your waste gates to gain more boost ( as long as you stay with in the efficiencey rage of the turbo ) but there are also some other variables that i just do not want to get into it right now. with a s/c running high boost numbers you run into problems with high parasitc loss with high boost, belt slipping issues and the s/c having high discharge air temps due to the load on the supercharger. im sure sentry65 can elaborate more on this subject.

 

We have a few sets on the shelf if you need one 9.0:1: http://www.forgedperformance.com/sto...cat=249&page=1

 

Thanks Sharif.

 

Good luck Rob.....

 

Thanks robin. I hope this will fix everything.

 

awesome man your car will be great

 

good luck.

 

Power loss may be close to the 1- (ratio of new CR to stock CR )..

1- 8.5/10.1= 16%

 

That's a lot of help! Thank you.

robby

 

GL with build

 

I think I have decided to go with custom 10:1 ratio. Hope they really dont take 6 weeks to come in. Anyone have experience with this wait?

 

I would go 10:1, as long as the car is tuned properly you won't have any detonation issues. We have made close to 500rwhp on a stock block Vortech car with 100 octane, so I think 10:1 would be optimum for a SC car.

Hopefully you go this route so we can see the results! I am sure you will be happy as well with the turn out...

-George
GT Motorsports

 

That's great to hear George. Thanks for the advice. I originally ordered the 9.5:1 but have changed the order this afternoon 10:1.

 

i wonder if that is my car?

 

Sorry I was referring to Sentry's car Hopefully we will beat his record with your car though!

-George
GT Motorsports

 

Fortunately, that is not how the math works. The power loss is far less than that...I don't have the chart in front of me...but its about 3% between 10:1 and 9:1