whats the benifit from porting and polishing the heads?
Registered User
Joined: Dec 2003
Posts: 2,514
Likes: 5
From: Marietta, Georgia
On modern Japanese engines very little is gained compared to the crude rough US engines of yore.
Computer aided machines have almost made factory production as precise as the absolute best experts spending weeks by hand polishing heads. And the factory output is consistent and reliable.
Cosworth Heads are probably better than any US human can produce and they only increase flow by 5%.
The problem is if you enlarge the ports their flow speed declines, thus bigger or smoother may not be any better.
If you super/turbo charge the extra flow may need larger ports to squeeze out all the calculated gain per psi.
Computer aided machines have almost made factory production as precise as the absolute best experts spending weeks by hand polishing heads. And the factory output is consistent and reliable.
Cosworth Heads are probably better than any US human can produce and they only increase flow by 5%.
The problem is if you enlarge the ports their flow speed declines, thus bigger or smoother may not be any better.
If you super/turbo charge the extra flow may need larger ports to squeeze out all the calculated gain per psi.
Registered User
Joined: Jul 2008
Posts: 110
Likes: 0
On modern Japanese engines very little is gained compared to the crude rough US engines of yore.
Computer aided machines have almost made factory production as precise as the absolute best experts spending weeks by hand polishing heads. And the factory output is consistent and reliable.
Cosworth Heads are probably better than any US human can produce and they only increase flow by 5%.
The problem is if you enlarge the ports their flow speed declines, thus bigger or smoother may not be any better.
If you super/turbo charge the extra flow may need larger ports to squeeze out all the calculated gain per psi.
Computer aided machines have almost made factory production as precise as the absolute best experts spending weeks by hand polishing heads. And the factory output is consistent and reliable.
Cosworth Heads are probably better than any US human can produce and they only increase flow by 5%.
The problem is if you enlarge the ports their flow speed declines, thus bigger or smoother may not be any better.
If you super/turbo charge the extra flow may need larger ports to squeeze out all the calculated gain per psi.
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