Compression ratio and pump gas
Compression ratio and pump gas Soon enough im going to pull of the heads, and i want to up the compression a bit. When i brougt this idea by my dad he blew up on me telling me thats the last thing i needed for a street car and it was going to detonate and whatnot. Now, i have come to understaind the compression ratio is about 10.1 : 1 in the Ls1 motor. I have also read the threads of about 3-4% torque and h/p gains through out the curve per 1 point compression which is why i wanto do this. So i ask, how high can I make my compression while running 93octane safley?
Some people will probably balk on my response. But in my opinion, for a primarily street-driven vehicle using 91 to 93 Octane, I'd leave the CR alone or not go beyond 10.5:1. If you want to run primarily on the street, and gain power and torque without changing the CR, a good small-runner CNC ported head with a well designed combustion chamber, a moderate duration/lift cam and a good tune will do more than anything. That way, you'll be able to run pump gas without a problem.
Steve
Steve
yhea i was trying to avioid the expense thing, i got the cam but i dont have money to get the heads ported or anything, i just know milling isnt that hard and its cheaper...
It all depends on your cam specs. I run 11.8:1 SCR with a large cam with a wide lobe seperation and my Dynamic compression is only around 8.5:1 which is only slightly higher than a stock Z06. With my smaller cam I ran 12.08:1 with a 8.76:1 DCR and still had no problems. You want to get your DCR to around 8.8:1 but no higher. I run 93 octane, and in the 100+* humid Southern weather I have no problem running 28* total timing.
I am currently working on a guys car that the wrong head gasket was used. He has a DCR of 9.03. It runs fine but I can only run 22-23* total timing with out detination. It makes peak power at 20* total. But a simple head gasket change and we are right back at 8.79:1 and we will be able to run some more timing and hopefully make some more power.
I am currently working on a guys car that the wrong head gasket was used. He has a DCR of 9.03. It runs fine but I can only run 22-23* total timing with out detination. It makes peak power at 20* total. But a simple head gasket change and we are right back at 8.79:1 and we will be able to run some more timing and hopefully make some more power.
