Compression ratio limits with milled heads?
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 1,224
Likes: 3
From: San Jose Ca
Compression ratio limits with milled heads?
I have an 03Z, looking to do Heads/Cam/LG'setc.
I have a line on some GMPP heads CNC'd and milled by Lingenfelter and they're now 60cc. Ed at LPE said that equates to 11.3:1 CR, which is quite high. I do a lot of open tracking and I'll be adding a 125hp dry nitrous kit on there as well.
What's the max CR I should run, given the above and ****&y Calif 93 octane fuel? (Don't want to run race gas) How much can a thicker head gasket lower that CR?
What haven't I thought of in this equation? I'd like near 450RWHP N/A and want it to be very reliable.
Thanks much,
Phil
I have a line on some GMPP heads CNC'd and milled by Lingenfelter and they're now 60cc. Ed at LPE said that equates to 11.3:1 CR, which is quite high. I do a lot of open tracking and I'll be adding a 125hp dry nitrous kit on there as well.
What's the max CR I should run, given the above and ****&y Calif 93 octane fuel? (Don't want to run race gas) How much can a thicker head gasket lower that CR?
What haven't I thought of in this equation? I'd like near 450RWHP N/A and want it to be very reliable.
Thanks much,
Phil
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Static compression ration isn't as important as dynamic compression ratio. You can run 12:1 SCR and still have low DCR if you have a big cam with a tight lsa. You want to keep your DCR between 8.4:1 and 8.8:1. Another important factor is quench height. The tighter you can keep your quench and not have piston to head contact the better. A good tight quench will help prevent ping and be good for a few extra hp.
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If you can keep your DCR up and use a tight quench you will have good low end torque. DCR is determined by valve events, SCR, and quench height.
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If you can keep your DCR up and use a tight quench you will have good low end torque. DCR is determined by valve events, SCR, and quench height.
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
np. Try these links. This is where I picked up a lot of good info
1)Cam info.
2)Discussion of SCR and DCR They even have a program that figures your DCR out if you know the variables.
Good reads.
1)Cam info.
2)Discussion of SCR and DCR They even have a program that figures your DCR out if you know the variables.
Good reads.
