Just curious what the engines compression ratio is with a comptech supercharger installed? theres not very clear search results with that query. Also would it change with a 2.4 liter stroker kit?

 

Why would the compression ratio change with an SC installed? Only different pistons / head gasket / etc would change the compression ratio; unless of course your talking about effective compression ratio.

 

well i'm going to be building a 2.4 liter stroker with a supercharger and was wondering what compression ratio to shoot for with the motor build so when i install the ctsc the compression ratio wont be through the roof.

also what do you mean by effective cr?

 

Ask whoever is building your motor what compression ratio pistons they are using and that will answer your question.

Effective compression ratio takes into account your engine compression ratio and boost you are running. So for example 10 psi on stock compression is approximately the same as 18psi on a 3mm head gasket (I don't remember the exact numbers, there is a post somewhere with a full data chart).

 

see thats the thing, i plan on following the F24 Build in JDM Tuning...but I wanted even a little more oomph. I'll be doing all the assembly of the engine from block up, but once it comes time to swap and tune it will go to a shop. I think everything is set except i have to go different pistons because the compression ratio in that build is like 11:1 or so. From my understanding thats too high for a forced induction application. I still have some research to do on the subject matter, but I thought knowing the ball park compression ratio that is good for running a supercharger set up would allow me to start to look for pistons to use. I have the crank and full valvetrain figured out i think, but i was just looking at pistons earlier today and thought i would ask. I didnt find any books that were F20 specific, so the book i've been following is bits and pieces from s2ki.com, and i'v had tons of pm conversation with several members about that specific engine build, but i still have a lot to learn yet.

BTW Spec_Ops, before i was even a member of S2ki I remember watching your videos on youtube thinking "man i hope mine sounds like that one day" lol. i think that was one of your invidia videos.

Note to self: Find Effective Compression Ratio Data Chart

 

A lot of SC guys run max SC speeds (equaling about 14psi) on stock compression numbers with the proper tune so thats something to consider as well

 

thats what i was looking for...i'm looking to run the ctsc w/ a/c set up so maybe around 6.5psi?? i'm guessing that since i'm not going to use the oem H22 pistons/rods (speced in the f24 build in jdm tuning) and will be using aftermarket i can prolly go a higher boost??

also off topic i saw a post with a supercharger running a BOV, how does that work? i tried to find some threads on it but all i could gather is it doesnt work the same way a turbo BOV does. are there any sound clips available?

 

As I stated, people run up to 14psi on stock compression with SCs so take it for what its worth.

A bov will work the same on a turbo car as on a SC. (how could it possibly work different?)

 

[QUOTE=duanet85,Apr 13 2008, 10:00 PM] also off topic i saw a post with a supercharger running a BOV, how does that work? i tried to find some threads on it but all i could gather is it doesnt work the same way a turbo BOV does.

 

Theres the chart

However I must make one correction (atleast in my case). At idle, my blow off valve is open with a good amount of air BLOWING out of it menaing my turbo is still making "boost" even at idle.

A SC sounds different because usually, they simple don't produce enough PSI to create the typical "turbo blow off valve" sound. Let one of the 14psi SC guys stick a tial bov on their pipes and I bet you it will sound exactly the same