Streetable compression question!
Thread Starter
Racer
Joined: Nov 2001
Posts: 474
Likes: 0
From: Houston TX
Streetable compression question!
As most of you know my 382 Stroker broke a timing chain last week. We got the heads off today and got them to my head porter. Outta 16 valves all but 4 were bent. Im gonna have some cool paper weights for my desk.
My engine builder did the math and we found out the compression is right at 12.78 to 1 mighty high for pump gas and texas heat. I need to lower the compression. We are looking at some Cometic gaskets with a .60 crush size. Which should bring the comp ratio to 12.2 to 1. Is this streetable?
My engine builder did the math and we found out the compression is right at 12.78 to 1 mighty high for pump gas and texas heat. I need to lower the compression. We are looking at some Cometic gaskets with a .60 crush size. Which should bring the comp ratio to 12.2 to 1. Is this streetable?
Le Mans Master
Joined: Apr 1999
Posts: 7,820
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From: Burlington ON
Cruise-In I, II, III, IV & V Veteran
CI-I & II Auto-X Champ
Re: Streetable compression question! (kumar75150)
I wouldnt go past 11.0 - 11.2 if you want to run on 92 octane. Of course, if you choose a cam properly and run 94 octane you can get away with more compression.
My 436 is 11.0 and it runs great on 94... I had it at about 12.0 last year and it would detonate to death on 94, especially in the summer.. We went from flat top pistons to dish pistons to lower the CR and it works great now at the 11.0.
My 436 is 11.0 and it runs great on 94... I had it at about 12.0 last year and it would detonate to death on 94, especially in the summer.. We went from flat top pistons to dish pistons to lower the CR and it works great now at the 11.0.
Melting Slicks
Joined: Oct 2002
Posts: 2,855
Likes: 0
Re: Streetable compression question! (Mike TexaSS)
My new stroker will have 11.15cr and I could have taken it to 11.5 tops on 93, I also had ARE put a Cloyes la racing timing set in (about $400) so as not to chance the changing of the valves--as long as you have the heads off can't your heads guy shroud a little or even flycut the pistons as long as you are having all new valves I would think a bit out of the combustion chambers would solve your problem they are probably going to have to put new valve seats as well anyway--
Drifting
Joined: May 2002
Posts: 1,607
Likes: 1
From: San Francisco CA
Re: Streetable compression question! (Mike TexaSS)
A key factor is the overlap of the camshaft. The more overlap then the less compression pressure you will have. That is the reason Phil97SVT can run 12.3 and I cannot.
Safety Car
Joined: Nov 2002
Posts: 4,394
Likes: 6
From: Melbourne FL
Re: Streetable compression question! (SFVetteman)
A key factor is the overlap of the camshaft. The more overlap then the less compression pressure you will have. That is the reason Phil97SVT can run 12.3 and I cannot.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Re: Streetable compression question! (SFVetteman)
A key factor is the overlap of the camshaft. The more overlap then the less compression pressure you will have. That is the reason Phil97SVT can run 12.3 and I cannot.
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