I am looking at this shortblock, and i want to know some numbers. With 61CC heads the motor had a compression ratio of 10.4:1. Which is to high for me to run with my Supercharger. It is a 347 CID Stroker motor. I am curious how i would find my compression ratio if i used the current heads i have, which are a 65.6CC combustion chamber. I really want this motor, as its a good rotating assembly, i just got off the phone with the machine shop, he was really impressed with the quality of components the guy used. I have looked around, the stroker kit he used is about $1500 by its self. He bought a complete Eagle rotating assembly. Here is from Jegs website, which lists the kit for 1100 pluss shipping.
According this, i would be right about 9.8:1, is this going to be to high for a blown motor? I will be changing my pulley to the 6lb pulley instead of 8 pounds.

 

here is a link to a reallly good compression calc that I use a lot.
with 9.8:1 and 6lbs boost your not going to be buying cheap gas but it will work ok.

 

well, i am already running super all the time, but i dont want to buy anything above 92 octane....what link?

 

heres one:

http://www.bgsoflex.com/cr.html

 

sorry guess I forgot the link here is the one I was talking about.
http://raceabilene.com/kelly/hotrod/compression.html

 

Well, i used robs caclulator, according to the numbers i have
Bore 4.03
Stroke 3.4
Combustion Chamber 65.6CC's
Headgasket thickness(from frod racing, for the gaskets i will use) 0.040
Piston to deck(from PO) .086
Dome volume -6.5CC
I geta CR of 9.3, which i can live with.

 

You can live pretty well with that, and you might even be able to run it with a little more boost if you have a boost timing computor.

 

What I will do is when I get it tuned on the dyno, I will do it with the 8lb pulley. Then I will run around with the 6lb pulley for everyday driving, and throw the 8lb on when I wanna race or something.

 

You really need to get a boost timing computer on there. 9.3 compression with 6lbs of boost is still a 13:1 final compression. Even running high octane you're gonna be on the edge of ugly in terms of detonation. I wouldn't even think about running the 8lb pulley without bling bling race fuel. Is there any way you can get a piston with a slightly larger dish? I'd rather run lower compression and more boost to compensate than to risk detonation.

 

well, the motor is slightly used(read 400 miles). so, i would have to tear it apart, which would defeat the purpose of buying an assembled short block.

 

you could do a little massaging on the combustion chambers, and gain a little there if you want to reduce the compression (work around the valves to unshroud them some even if not really needed with a blower) but getting the boost timing computor, and will take care of most of it.

 

Anyone know where i could get a boost timing computer?