Hey guys last week I had some bad luck. My headgasket gave way, I now am taking out the high comp pistons and swapping them for 9.5:1 cp pistons the rest of the block and head was done before. Now the thing I need to know is, on the SOS kit the standard pulley was netting me 12-13 psi (13:1 comp and e85) now that I am dropping to 9.5:1 comp what sized pulley do I need for roughly 16psi?

Forgot to mention I am running the 1200 novi on a built f20c. What's the max psi you guys would run on the 1200 with a built engine?

Thanks in advance to everyone who responds.

 

you should talk to who ever is tuning your car and SOS since you need their pulley

 

Unfortunately most tuners we have access to here in Sydney don't know to much about these kits etc etc since there isn't many people who build s2ks here. But I will def get in contact with SOS. Thanks

 

SOS website says for every point of compression drop you lose 1psi of boost.
So you need roughly 2 sizes smaller than a stock motor would need to hit a certain psi.

 

Well, I'd max out the 18-20psi with that blower on a stock motor, so I'm probably the wrong guy to talk with.

 

Ok so if I was netting 0.85 bar which is like 12psi before, I have to take away 3.5 psi loss because of 3.5 compression drop. So the standard pulley will make 8.5 psi on a 9.5:1 compression motor on e85 does that sound right to you guys? It seems odd to me for some reason!

 

Why are you lowering compression if using e85?

 

I don't want to risk blowing the engine.. I am rather safe than sorry. My engine was 13:1 comp before because it was an all motor build which I wasn't happy with so I went sc instead.