367 + 15psi + pump gas = which compressionratio?
Thread Starter
On The Tree
Joined: Aug 2007
Posts: 112
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From: Finland
367 + 15psi + pump gas = which compressionratio? I have a 6.0 engine project which is supposed to make 1000 fwhp on pumpgas (european 98oct, compares your premium?) with following parts:
-stock crank and block
-mahle 4.020 dish pistons (9.2 cr w/ 64cc heads, 8.5 cr w/ 72cc)
-eagle 6.125 h-beams L19 bolts
-hyd cam XER281HR 232/234 lift .595/.598 lsa 112 (maybe more lsa?)
-arp studs allover
-patriot 6.0 stageIII heads 64cc (or 72cc?)
-homemade turbo kit (1.75 pri 2.5 coll & crossover) for B&W S480 T6 1.32 a/r
-megasquirt II
-boost 15 psi
-air-to-air intercooler 12x24x4 w/ 3" piping
Question is which comp.ratio is better for me, 8.5 or 9.2?
Is my camchoice acceptable or what?
My head order going forward next monday, so would need some opinions before that.
-stock crank and block
-mahle 4.020 dish pistons (9.2 cr w/ 64cc heads, 8.5 cr w/ 72cc)
-eagle 6.125 h-beams L19 bolts
-hyd cam XER281HR 232/234 lift .595/.598 lsa 112 (maybe more lsa?)
-arp studs allover
-patriot 6.0 stageIII heads 64cc (or 72cc?)
-homemade turbo kit (1.75 pri 2.5 coll & crossover) for B&W S480 T6 1.32 a/r
-megasquirt II
-boost 15 psi
-air-to-air intercooler 12x24x4 w/ 3" piping
Question is which comp.ratio is better for me, 8.5 or 9.2?
Is my camchoice acceptable or what?
My head order going forward next monday, so would need some opinions before that.
I'd go 8.5:1 to give yourself an added safety margin which is always good when dealing with pump gas. Unless the fuel quality is better in europe. Do you have strict fuel standards there?
My turbo 9.1:1 small block chevy detonates when hot at 15psi with US premium pump gas (93 oct). Your combo is more efficient (aluminum heads,and reverse flow cooling) so you may be okay at 9:1, but get one tank of bad fuel and you could be in big trouble.
My turbo 9.1:1 small block chevy detonates when hot at 15psi with US premium pump gas (93 oct). Your combo is more efficient (aluminum heads,and reverse flow cooling) so you may be okay at 9:1, but get one tank of bad fuel and you could be in big trouble.
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Thread Starter
On The Tree
Joined: Aug 2007
Posts: 112
Likes: 0
From: Finland
Thanks for your opinions!
The cr will be either 8.5 or 9.2 depending on chambers I choose.
Any other thoughts about the cam (and especially the lsa)?
I think our 98 will compare to your 93, rating is somehow different. Our gas is quite stable, so we can rely that it truly has advertised octane rating.
The cr will be either 8.5 or 9.2 depending on chambers I choose.
Any other thoughts about the cam (and especially the lsa)?
I think our 98 will compare to your 93, rating is somehow different. Our gas is quite stable, so we can rely that it truly has advertised octane rating.
Thanks for your opinions!
The cr will be either 8.5 or 9.2 depending on chambers I choose.
Any other thoughts about the cam (and especially the lsa)?
I think our 98 will compare to your 93, rating is somehow different. Our gas is quite stable, so we can rely that it truly has advertised octane rating.
The cr will be either 8.5 or 9.2 depending on chambers I choose.
Any other thoughts about the cam (and especially the lsa)?
I think our 98 will compare to your 93, rating is somehow different. Our gas is quite stable, so we can rely that it truly has advertised octane rating.
i believe you have an lq9 or something else with 4 bolt per cylinder setup ? if you do try not to push the engine past 1000 whp because there will be a big risk of lifting the heads and blowing the head gaskets. and get heads with a big combustion chamber, they will help prevent knock. and go with 8.5:1 CR good luck
When dealing with pump gas the general rule of thumb is lower compression and more boost. You will be able to make more power safely for a given octane. I doubt you would notice the difference from 8.5 to 9.2. You will definately notice the difference with 8.5:1 and the extra 1-2psi you can run on the same octane though.
I wish my own motor was 7.8:1 instead of 8.7:1
I wish my own motor was 7.8:1 instead of 8.7:1
Goal??????
I think you can sneak up on 700rwhp with 8.5-9.0:1.
I ran a 8:1 346ci and compared to a friend's 6.0 setup that had more compression I think that 9:1 is fine. Some shops might even say 10:1 is fine, but again it comes down to goals, what gas you will be running for the most part. If you plan to make 650-700rwhp then you can get there on pump gas though I'd run some race gas at the track to be safe. If you want to make 800rwhp on pump gas you need to talk to folks who have actually accomplished that, and who's cars run the number.
If I build a 364ci today, like an LS2-based engine, I'd run 9:1 or somewhat close, and if it was more like 9.5:1 it wouldn't bother me but I think 10:1 is too much and I'm not an advocate of 8:1 either. A 364ci LS- based engine is a very powerful engine in the grand scheme of things, and highly efficient too.
I think you can sneak up on 700rwhp with 8.5-9.0:1.
I ran a 8:1 346ci and compared to a friend's 6.0 setup that had more compression I think that 9:1 is fine. Some shops might even say 10:1 is fine, but again it comes down to goals, what gas you will be running for the most part. If you plan to make 650-700rwhp then you can get there on pump gas though I'd run some race gas at the track to be safe. If you want to make 800rwhp on pump gas you need to talk to folks who have actually accomplished that, and who's cars run the number.
If I build a 364ci today, like an LS2-based engine, I'd run 9:1 or somewhat close, and if it was more like 9.5:1 it wouldn't bother me but I think 10:1 is too much and I'm not an advocate of 8:1 either. A 364ci LS- based engine is a very powerful engine in the grand scheme of things, and highly efficient too.
I don't think you will make 1000 crank with pump gas and your stated parts. You'd need more engine.
I made 867rwhp with race gas and my engine thru a TH400, but that was at way more boost than 15 lbs.
I made 867rwhp with race gas and my engine thru a TH400, but that was at way more boost than 15 lbs.