Max DCR for 91 octane?
Thread Starter
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Joined: Mar 2006
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From: Sarasota, FL
Max DCR for 91 octane? I did some searches on this but got no hits.
Any comments on what a good maximum DCR would be for 91 octane? I usually run 93, but there are places we hit when on vacation that only have 91 available.
Any comments on what a good maximum DCR would be for 91 octane? I usually run 93, but there are places we hit when on vacation that only have 91 available.
Thread Starter
12 Second Club
Joined: Mar 2006
Posts: 302
Likes: 1
From: Sarasota, FL
While digging through the results from another search that did bring up some hits, someone mentioned that 8.5 was considered about the DCR limit for 91 octane, and 8.8 for 93.
Anyone have comments or experiences about that? I'd be interested in hearing from those of you who live in hot places with 91 gas being all that's available.
Anyone have comments or experiences about that? I'd be interested in hearing from those of you who live in hot places with 91 gas being all that's available.
I run 8.6 on 91 octane and it's on the ragged edge. My engine likes 22-23 degrees of timing, It gets a little kr here and there but when I run on race gas, I don't get any kr but I don't get any gains gains in et either, so that tells me that I setting right where I want to be.
Thread Starter
12 Second Club
Joined: Mar 2006
Posts: 302
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From: Sarasota, FL
Originally Posted by Slicknic
I run 8.6 on 91 octane and it's on the ragged edge. My engine likes 22-23 degrees of timing, It gets a little kr here and there but when I run on race gas, I don't get any kr but I don't get any gains gains in et either, so that tells me that I setting right where I want to be.
I think I'm going to target 8.4-8.5.
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Thread Starter
12 Second Club
Joined: Mar 2006
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From: Sarasota, FL
Originally Posted by Slicknic
You need to keep the quench area to around .32-.030 that will help also.
So on an LS-1 with the deck height at -0.006 (out) you would need a compressed gasket thickness of 0.036 - 0.038, is that right?
Can you get head gaskets in that thickness?
Bear with me guys, I'm trying to learn this stuff.
Quench is the distance between the top of your piston and the cylinder head (correct me if I'm wrong) at tdc.
I'm running flat top JE's that are 0 deck, they do not stick out.
My quench came out to be .040, I was shooting for .032 but .040 was what I had to live with. Seems to work fine thought.
After saying all that, I woud say .030 to .040 range is a good quench distance.
I'm running flat top JE's that are 0 deck, they do not stick out.
My quench came out to be .040, I was shooting for .032 but .040 was what I had to live with. Seems to work fine thought.
After saying all that, I woud say .030 to .040 range is a good quench distance.
I'd just use a Cometic .040" It would be the close to what you are looking for. My 383 is 11.83ish to 1 and in the low 8.4 DCR range. I run stock gaskets with the pistons .010" out for ~.043-.045 quench and burn 92 octane with no problems. I could step up the quench and gain some compression, but it runs good so I'm fine with my results 
Originally Posted by Gannet
That's just the difference between the deck height and the gasket thickness, right?
So on an LS-1 with the deck height at -0.006 (out) you would need a compressed gasket thickness of 0.036 - 0.038, is that right?
Can you get head gaskets in that thickness?
Bear with me guys, I'm trying to learn this stuff.
So on an LS-1 with the deck height at -0.006 (out) you would need a compressed gasket thickness of 0.036 - 0.038, is that right?
Can you get head gaskets in that thickness?
Bear with me guys, I'm trying to learn this stuff.
