High Compression Boost Motor??
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Racer
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From: Rockville/Abington MD & PA
High Compression Boost Motor??
Could you use a forged motor with a C/R of 10:1 for boosting? I have heard of people doing this but never really heard if it lasted. Could anyone tell me what the lowest possible C/R on an LS6 motor with flat top pistons and 65cc heads could be with GM double thick headgasket? Id appreciate it since I still can't figure out how to work that damn online compression calculator. 
Last edited by dwalker011; Jun 3, 2006 at 03:11 PM.
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From: Elmhurst, IL (West Suburb of Chicago) & Home of MEGA Horsepower
St. Jude Donor '06
Yes you certainly can, but you cannot get stingy on the boost (would keep it to 12 to 14 lbs tops) and make sure you have a very stout forged shortblock, and that your tune is done by a pro and tuned according to the higher compression than you average guy runs on a forged boosted LSX application and of course that your fuel system is 100% up to snuff!.
Idealy, i would not go higher than 9:5 to 1, but it certainly can be done and will make more power with less boost. Right now i am doing it on a 10:5 to 1 compression stock LS6 motor on a STOCK BOTTOM END, without issue after 4200 miles, however I am not getting greedy with the boost (7 to 8 lbs) and i am running methanol injection which i CERTAINLY RECOMMEND that you do also if you with the 10 to 1 static compression ratio motor!!
Idealy, i would not go higher than 9:5 to 1, but it certainly can be done and will make more power with less boost. Right now i am doing it on a 10:5 to 1 compression stock LS6 motor on a STOCK BOTTOM END, without issue after 4200 miles, however I am not getting greedy with the boost (7 to 8 lbs) and i am running methanol injection which i CERTAINLY RECOMMEND that you do also if you with the 10 to 1 static compression ratio motor!!
Last edited by Mopar Jimmy; Jun 2, 2006 at 03:06 PM.
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From: Knoxville Tennessee
Originally Posted by minus500
Could you use a forged motor with a C/R of 10:1 for boosting? I have heard of people doing this but never really heard if it lasted. Could anyone tell me what the lowest possible C/R on an LS6 motor with flat top pistons and 65cc heads could be with 0.0xx headgasket? Id appreciate it since I still can't figure out how to work that damn online compression calculator.
With stock displacement motor, 65cc heads and stock MLS gasket that car is looking about 10.2:1 compression.
If you are going to buy pistons, why buy flat tops?
Melting Slicks
Joined: Sep 2004
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good point blown!!! some companies run stock bottom ends upto 15psi! also with a turbo this would help spool up no end! hummmmm
also, a bit off topic but never mind, some rally guys over here puch nearly 11:1 and run over 2 bar of boost! you can do it but you need a good engine under neath you and they run pupre race fuel!
thanks Chris.
also, a bit off topic but never mind, some rally guys over here puch nearly 11:1 and run over 2 bar of boost! you can do it but you need a good engine under neath you and they run pupre race fuel!
thanks Chris.
Thread Starter
Racer
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From: Rockville/Abington MD & PA
Thanks for the input guys. Im still a little scared of running alot of boost on a "higher compression" built motor. Blown, I was thinking they exact same thing about more low end power and better spool-up characteristics. Id still like to hear a few more opinions but, I think I might go this route and limit boost to 1 BAR.
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From: Crestwood KY
Originally Posted by minus500
Anyone tell me what the C/R of the above combo would give me?
3.905 cylinder bore
3.622 stroke
4.060 head gasket bore and .054 thickness on head gaskets
65cc heads
-2cc flat top pistons
.010 out of deck
compression would be
approx 10.3:1
if you used a -8.6cc piston
compression would be approx 9.5:1
Last edited by ForceFed HP; Jun 3, 2006 at 08:19 PM.
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Thread Starter
Racer
Joined: Sep 2005
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From: Rockville/Abington MD & PA
Originally Posted by ForceFed HP
with
3.905 bore
3.622 stroke
4.060 bore and .054 thickness on head gaskets
65cc heads
-2cc flat top pistons
.010 out of deck
compression would be
approx 10.3:1
if you used a -8.6cc piston
compression would be approx 9.5:1
3.905 bore
3.622 stroke
4.060 bore and .054 thickness on head gaskets
65cc heads
-2cc flat top pistons
.010 out of deck
compression would be
approx 10.3:1
if you used a -8.6cc piston
compression would be approx 9.5:1
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From: Crestwood KY
Originally Posted by minus500
This would not be not using a 4.060 bore though. This would be on the stock z06 bore.
I added some info to my original post to help clarify
Last edited by ForceFed HP; Jun 3, 2006 at 08:20 PM.
Thread Starter
Racer
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From: Rockville/Abington MD & PA
Originally Posted by ForceFed HP
head gasket bore size, not cylinder bore
I added some info to my original post to help clarify
I added some info to my original post to help clarify
Thread Starter
Racer
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From: Rockville/Abington MD & PA
Originally Posted by Demon SS
a custom Cometic gasket in say a 3.980 gasket bore and a .074 compressed thickness would put you at approx 9.9:1
Intermediate
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Originally Posted by #001 2001 Z06
The 750 rwhp version runs on pump gas.
The trick in the cooling and tuning.
The trick in the cooling and tuning.
Racer
Joined: Mar 2004
Posts: 382
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From: Arlington VA
Originally Posted by WallyC
The 750 HP version will put down about 650 RWHP. It's basically an aluminum 351 windsor with a pair of garrett GT35R's, and quite fun to drive. They run virtually zero timing and a ton of quench, which is why they can get away with boosting on pump gas. Scary to drive though, no ABS, no traction control, no nothing, and you realize you're cruising around in a car that costs more than most peoples houses
Does this provide:
Excellent off-boost performance?
Minimized turbo-lag?
Efficient use of each pound of boost?
Lower temperature of compressed air due to use of lower amounts of boost that needs to be run for a given power level?
One downside I can think of is the inability to up the boost later. That is, it seems if someone has a target goal of X amounts of HP/TQ then designs a motor with the maximum amount of compression and the minimum amount of timing and resulting minimum amount of boost to get there, then great, but upping the boost later is a no no.
If a person could promise themselves that they would be satisfied with a given level of performance is this the optimal way to go about it?
- Max
Melting Slicks
Joined: Sep 2004
Posts: 3,153
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Originally Posted by WallyC
The 750 HP version will put down about 650 RWHP. It's basically an aluminum 351 windsor with a pair of garrett GT35R's, and quite fun to drive. They run virtually zero timing and a ton of quench, which is why they can get away with boosting on pump gas. Scary to drive though, no ABS, no traction control, no nothing, and you realize you're cruising around in a car that costs more than most peoples houses
Chris.