What is the highest compression ratio can you run in an all aluminum LS1 with a big cam and lots of overlap? 232/238 111 lsa XER. If you have run over 11.0:1 post your cam and final compression ratio.
Phillip

 

I think ~12.5 is possible...not sure how long it will last on pump gas...

 

When you say how long it lasts, what does that mean? Assuming the car is tuned correctly.
Phillip

 

I'm putting my ls6 together at 11.9 to 1, with a bigger cam than you mentioned.. I'm hoping I'll be ok..
Bryan

 

I think PSJ ran 12:1 with a splash of race gas at the track.

 

i am running 11.1:1 on 93 stock cam right now! 224/224 .581 .581 112 next week!!!!!!!!

 

I think if one gets a bad batch of pump gas there is more risk at ~12.5 than 11 because the PCM can only pull so much timing out...just closer to the edge...probably should have worded it that way.

 

29 DEGREES OF TIMING, on sunoco 94
see sig.

 

Muscratmauler,
Have you ever done a compression test?
Phillip

 

I do run on 11.2 - 1 compression (milled stage IIx heads) and 230/230 .578/.578 112lsa cam.

 

I'm running 11.4 to 1. .....055 milled heads with a 60cc chamber...car has mild cam 220/220, 564/564, 110 lsa cam

...car is not tuned and runs rich (A-Tap).


NO KNOCK - EVER on 93 octane **** gas.

 

whatever .040 off 5.3L heads works out to be (high 11.x) and a 232/232 112 camshaft. Never had a problem on 93

 

12.2:1 CR and a 243/250 cam :-D I run on 91 octane with lots of timing pulled for the street, we dynoed it and it made 465rwhp, for the track it's 28* of timing and 103 octane, which the car made 511rwhp on the dyno.

 

LinearVelocity,
What kind of timing do you run on the street?

Fireball,
Have you ever tried race gas and upping the timing?

My setup uses a 232/238 XER 111lsa cam and ~12.0:1cr.
Phillip

 

I have tried that but found no gains going over 28 degrees.

 

I don't quite remember off the top of my head, it's either 14* of timing or 18. Anyhow the CR will drop a little as I'm going with a thicker head gasket.

 

Probably at 18 degrees. What head gasket are you swapping to. I thought you already had a .052 felpro which is pretty thick.

 

I run 11.2 to 1 with 93 mobil or 94 sunoco no problem. I run 32* of timing, never any knock even running 3.42 gears all this time.Car weight is min. 3460lbs but i have raced in stock streettrim at 3650lbs still with good tune no problem. My cam is MMS custom grind 220*/220* .585"/.585" lift on a 112* with 2* advance.My compression figures from 62.5cc chambers .042" head gaskets, flat top pistons, stock +.007" deck height. I turn 7000 rpm occasionally with min. shift of 6700 rpm.