Adding heads to boost
Thread Starter
Racer
Joined: Dec 2019
Posts: 310
Likes: 41
From: Chicagoland
Adding heads to boost
My LS2 is on 7psi boost, E and 222/228 dur. .561/.577 cam and all supporting mods making 605whp behind a 6A trans.
If I add as cast PRC 225cc port and 68cc chamber volume what power gains can I expect?
I know theres more and better but my question is as above.
Thanks all.
Edit for punctuation
If I add as cast PRC 225cc port and 68cc chamber volume what power gains can I expect?
I know theres more and better but my question is as above.
Thanks all.
Edit for punctuation
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,341
From: Gilbert AZ
Very little to none. Boost will drop, and then if you pulley down to make up the lower boost, you will gain maybe 30-40hp, but you could just do that now without touching the heads and get same result. Boost is just a measurement of restriction, and you are lowering the restriction. Your gains will be from slight efficiency increase unless you spin the blower faster, because even with new heads it will spin the same speed. So do you care if it is 7psi or 9psi?
Burning Brakes
Joined: Mar 2019
Posts: 833
Likes: 176
From: Indianapolis Indiana area
I think with boost the biggest benefit from better heads would be a more efficient package. Making the same or more power at lower boost makes it easier to control iat's and better power when you're out of boost. I'm also doing cam and lifters, so the heads are coming off anyways. Looks like you've already done that, not sure I'd pull the heads back off at this point if I was in your shoes. I'd prodably do flex fuel first unless you already have.
Le Mans Master
Joined: Dec 2005
Posts: 6,995
Likes: 1,680
From: Southeast TX
A more budget friendly package would be to have your heads ported. Mill them 10 or 20 thou and use a .040 cometic head gasket putting it back together. That would get your static C/R up close to 12:1. That would better take advantage of the extra octane and cooling effect that E affords. Pulley down a notch and that would be one nasty little Vette.
Burning Brakes
Joined: Mar 2019
Posts: 833
Likes: 176
From: Indianapolis Indiana area
A more budget friendly package would be to have your heads ported. Mill them 10 or 20 thou and use a .040 cometic head gasket putting it back together. That would get your static C/R up close to 12:1. That would better take advantage of the extra octane and cooling effect that E affords. Pulley down a notch and that would be one nasty little Vette.
Le Mans Master
Joined: Dec 2005
Posts: 6,995
Likes: 1,680
From: Southeast TX
I have a hard to understanding how you're only seeing 7# of boost with a 2.75" pulley. Is your current crank pulley underdriven? I ran a 3.3" (9.5psi) and a 3.2" (8.5psi) pulley on TVS2300's blowing into LS3's. Bigger engine, better heads, and bigger blower cams. The boost would be higher than that with those pulleys blowing into an LS2 with a smaller cam and stock LS2 heads.
You probably need to figure out what's going on with your current setup before deciding on how fast you want to spin the blower. It just about has to be a boost leak, faulty rotors, or a bad boost gauge. And I'm going to assume Indy isn't 5000' above sea level. Even then, you'd see more than 7psi.
You probably need to figure out what's going on with your current setup before deciding on how fast you want to spin the blower. It just about has to be a boost leak, faulty rotors, or a bad boost gauge. And I'm going to assume Indy isn't 5000' above sea level. Even then, you'd see more than 7psi.
Burning Brakes
Joined: Mar 2019
Posts: 833
Likes: 176
From: Indianapolis Indiana area
I have a hard to understanding how you're only seeing 7# of boost with a 2.75" pulley. Is your current crank pulley underdriven? I ran a 3.3" (9.5psi) and a 3.2" (8.5psi) pulley on TVS2300's blowing into LS3's. Bigger engine, better heads, and bigger blower cams. The boost would be higher than that with those pulleys blowing into an LS2 with a smaller cam and stock LS2 heads.
You probably need to figure out what's going on with your current setup before deciding on how fast you want to spin the blower. It just about has to be a boost leak, faulty rotors, or a bad boost gauge. And I'm going to assume Indy isn't 5000' above sea level. Even then, you'd see more than 7psi.
You probably need to figure out what's going on with your current setup before deciding on how fast you want to spin the blower. It just about has to be a boost leak, faulty rotors, or a bad boost gauge. And I'm going to assume Indy isn't 5000' above sea level. Even then, you'd see more than 7psi.
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Racer
Joined: Aug 2018
Posts: 458
Likes: 96
My LS2 is on 7psi boost, E and 222/228 dur. .561/.577 cam and all supporting mods making 605whp behind a 6A trans.
If I add as cast PRC 225cc port and 68cc chamber volume what power gains can I expect?
I know theres more and better but my question is as above.
Thanks all.
Edit for punctuation
If I add as cast PRC 225cc port and 68cc chamber volume what power gains can I expect?
I know theres more and better but my question is as above.
Thanks all.
Edit for punctuation
Le Mans Master
Joined: Dec 2005
Posts: 6,995
Likes: 1,680
From: Southeast TX
I think he's about where he should be power wise. Stock LS2 heads, very mild boost, smallish low lift blower cam, and all through an A6 transmission. He's actually doing pretty good.