i know the lt1's came with a pretty high compression ratio.. like 10.5 stock?? im just wondering how high i should go if i still want to use 93? ive seen people saying there at 12.0 to 1 and still use 93...

would i be ok at 11.5-11.8 or so to 1?? thanks guys!

 

The static compression ratio itself doesn't dictate what octane fuel you can run. You need to find the dynamic compression ratio by incorporating valve timing events from the cam specifications.

 

ive been working on cars for like 10 years now, everything from brakes to a resto on a 79 z28... but i dont know much about the technical part of building engines... thats why im here for help... so thanks for the help so far!

im just trying to put the bottom end together for now, looking for rotating assemblies and those parts..

so static compression is all i can determine for right now.. other than im leaning towards trickflow AI heads and a large SR cam

is there a general rule i can follow as far as static goes?, or a guide line?

 

and dynamic... how do valve events and timing have anything to do with compression? sorry not trying to sound rude or anything, just wondering how one affects the other? like i said im new

 

My best suggestion is to research other people's combos and see what's worked for them. My 383 is around 12.6:1 static, 9.6:1 dynamic. I'll give you more details of my 383 if you wish - just PM me.

Static compression is just that - a static figure. All it pertains to are the physical dimensions of the cylinder, i.e. the sweep volume. Dynamic compression ratio incorporates valve events to determine the actual sweep volume of the cylinder (the volume of air/fuel that is drawn into the cylinder), and is absolutely paramount in any build. Since the intake valve is still closing when the piston reaches BDC, the actual sweep volume is significantly less than what the SCR would indicate. It will always be a lesser figure than the SCR, something like 9:1, depending on the engine's components.

 

Seek and you shall find.

http://www.rbracing-rsr.com/comprAdvHD.htm

 

so dynamic is pretty much static compression but taking into account any of the air/fuel that gets pushed back out of the cylinder/chamber on the upward stroke of the piston?

id like to build the bottom end of the motor first, and then decide on a set of heads and a cam, but i know id like to use AI's trickflows, and a large SR cam... no clue on the specs of any of it...

so what kind of static should i shoot for when building just the bottom end? would 11.5-8 be ideal or should i be shooting closer to 12.5ish??? thanks guys

 

Ideally, you'll want to purpose-build the whole motor, not just the bottom end first and the valvetrain later. Like I said, the best thing to do is research what other people have done and use that as a guide.

 

If you are going to be running AI heads and cam talk to them before you build the bottom end, they will let you know what compression to run with the heads and cam package.