Gains possible from head porting ?
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 6,341
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From: Shelton CT
Gains possible from head porting ?
I am wondering what sort of gains someone can expect from a 3angle valve job or whatever it is called. If this stuff is worth spending a few hundered on usually, or just get a new set of heads? (Which is a LOT more expensive)..
Please give actual examples if possible..
Thanks as always :cheers:
Please give actual examples if possible..
Thanks as always :cheers:
Team Owner
Joined: Dec 2000
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From: SE NY
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Re: Gains possible from head porting ? (MrNuke)
You should notice some gains from a multi-angle valve job, hi-flow valves, pocket porting, chamber conditioning, port cleaning, etc.
How much gain depends on the engine setup, i.e. other mods.
Check out the results of L98 mods page on my site to see what can be gained from a set of worked L98 #113 heads.
How much gain depends on the engine setup, i.e. other mods.
Check out the results of L98 mods page on my site to see what can be gained from a set of worked L98 #113 heads.
Drifting
Joined: Dec 2002
Posts: 1,861
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From: Houston TX
Re: Gains possible from head porting ? (Ray383)
No gains from 3 angle valve job. Just no losses. Just a better seal, no better flow.
Le Mans Master
Joined: Mar 1999
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From: delmont pa
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Re: Gains possible from head porting ? (MrNuke)
a 3 angle valve seat job with a 30 degree backangle on the valves plus opening up the bowls(pocket porting) will get you 15/20 HP if the head guy knows his stuff. :chevy
Drifting
Joined: Jun 2001
Posts: 1,997
Likes: 1
From: Lake Ozark MO
Re: Gains possible from head porting ? (MrNuke)
I think a good porting job can be worth 20-30RWHP if the cams are similar.
Just recently I hit the dyno with about 6 other Vettes. There were three that had relatively similar setups. All spec'd out according to expectation.
The engine with the headwork (and all else similar) garnered about 20 rear wheel HP versus the factory garb.
The best GM setup (LT4 heads, Hotcam, Hooker shorties, 6-speed, 52mm TB) laid down a 337hp.
The worst GM setup (LT4 heads, Hotcam, stock exhaust, 48mm TB , A4 torque converter unlocked in 2nd gear) laid down a 309hp.
The setup that really cooked was the CNC headed, CompCam (spec'd to the heads) powered '95 Vette M6 that laid down a stellar 353hp. The idle sounded stock. This was through a 52mm TB and Hooker shorties. Torque was excellent throughout the range.
I'm sure better numbers could be had, but for a "real world" vehicle I think the numbers are very good.
Back to the point, I think the dyno shows that "Stage 3 Heads" with a similar bump-stick may be worth 20hp.
Just recently I hit the dyno with about 6 other Vettes. There were three that had relatively similar setups. All spec'd out according to expectation.
The engine with the headwork (and all else similar) garnered about 20 rear wheel HP versus the factory garb.
The best GM setup (LT4 heads, Hotcam, Hooker shorties, 6-speed, 52mm TB) laid down a 337hp.
The worst GM setup (LT4 heads, Hotcam, stock exhaust, 48mm TB , A4 torque converter unlocked in 2nd gear) laid down a 309hp.
The setup that really cooked was the CNC headed, CompCam (spec'd to the heads) powered '95 Vette M6 that laid down a stellar 353hp. The idle sounded stock. This was through a 52mm TB and Hooker shorties. Torque was excellent throughout the range.
I'm sure better numbers could be had, but for a "real world" vehicle I think the numbers are very good.
Back to the point, I think the dyno shows that "Stage 3 Heads" with a similar bump-stick may be worth 20hp.
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Re: Gains possible from head porting ? (Dan Parker '96)
Should free up 15-20hp. Maybe more if the heads are even close to being a restriction.
Drifting
Joined: Dec 2002
Posts: 1,861
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From: Houston TX
Re: Gains possible from head porting ? (65Z01)
Don't remember what year Nuke's car is, but if you have the 128 castings, you'll gain a little more than the aforementioned 15-20 HP because in stock form, the 128 heads are more restrictive than the TPI intake setup. That is not true of the 113's. I haven't dynoed my '87 since I ported the heads, but my flow went up ~15-20% over stock across the entire lift range. Before the ported heads, sidestepping the clutch at ~1200 RPM would bog the motor when I had the big Hooisers on the back, but after the head porting, the same procedure ROASTED the Hoosiers. Hopefully I'll get a chance to dyno the motor soon since I recently freshened it up.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 6,341
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From: Shelton CT
Re: Gains possible from head porting ? (CorvetteZ51Racer)
Thanks for all the info guys.
I have an '85 with the low compression, large 74cc iron smog heads.
The '624 casting. I heard good things about porting these heads..
I have an '85 with the low compression, large 74cc iron smog heads.
The '624 casting. I heard good things about porting these heads..
