Compression ratio
Thread Starter
Instructor
Joined: Feb 2004
Posts: 241
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From: Ravenna Ohio
Compression ratio
I'm trying te get all my parts together for my 540 and i was looking a JE pistons. I'm trying to shoot for mid 800 horse, I saw that the GM572 is a 12.5:1. Will 13:1 work for me? Thats with 118cc heads. I already have my rods so if i need more comp. then i would have to send them back. Any ideas on a cam i was going to call a couple of manufactuers and ask their guys. I want the horse but the motor is going to see a lot of street. Let me know what you think and any ideas you have Any info is appreciated.
Thanks
Josh
Thanks
Josh
Drifting
Joined: Sep 2003
Posts: 1,325
Likes: 6
From: FRANKLIN GA
That's some serious compression. I'm not saying it can't be done but you are going to run into problems running 12.5:1 on pump gas. 13:1 nothing less than race gas, probably 110, would keep it from pinging.
Maybe, but you would need a cam with a LOT of overlap, which would kill your bottom end and make it hard to drive on the street, and at anything less than wide open.
If this motor is really going to see a lot of street time and your determined to have the HP, I would back off the compression a little and run a shot of nitrous or maybe a supercharger on it. It would be a lot more street freindly.
Maybe, but you would need a cam with a LOT of overlap, which would kill your bottom end and make it hard to drive on the street, and at anything less than wide open.
If this motor is really going to see a lot of street time and your determined to have the HP, I would back off the compression a little and run a shot of nitrous or maybe a supercharger on it. It would be a lot more street freindly.
Team Owner
Joined: Jul 2001
Posts: 182,997
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From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
I'm running 11.71 : 1 compression on my engine and I'm going to run 112 octane leaded in the engine at the track...
Pump gas should be ok if I jet the carb a little richer and retard the timing..
Pump gas should be ok if I jet the carb a little richer and retard the timing..
Drifting
Joined: Sep 2003
Posts: 1,325
Likes: 6
From: FRANKLIN GA
Well this changes the picture entirely, 13:1 is very do-able on good gas. It ain't gonna be cheap running it though. I know I pay $6.00 a gallon for VP 110. You should be ok with high quality parts, it wouldn't hurt to O ring the block and heads with those compression #'s, the cylinders are going to see some pretty high PSI's. I would definatly O ring it if considering nitrous with 12:1 and up. I think you can go up to 14:1 NA before you have to switch over to alcohol.
