Ported Head vs Bigger Valves
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,912
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From: S.D. CA
Ported Head vs Bigger Valves
Which would yield better HP results.
Mildly Ported Stock 243 Heads(By Hand) or a Valve Job(Larger Valves)?
Mildly Ported Stock 243 Heads(By Hand) or a Valve Job(Larger Valves)?
Last edited by sallen619; Feb 11, 2011 at 10:46 PM. Reason: add word
Safety Car
Joined: Jun 1999
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From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
The other important thing about bigger valves is they may actually reduce air flow because of "shrouding" of the valve. This means the valve may be very close to the cylinder wall or combustion chamber thus restricting air flow. A smaller valve may actually flow better under this case.
If you look closely at CFM specs of ported or after market heads, they often state what cylinder diameter is used. If the flow numbers listed are on a larger cylinder than your engine, it may not be the best head for you.
Conclusion: Bigger valves don't necessary mean more flow and power.
Thread Starter
Drifting
Joined: Sep 2004
Posts: 1,912
Likes: 33
From: S.D. CA
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Multi-angle cuts to the throat (3 angle to 5 angle) with a back cut to the valve to increase air flow at low valve lifts. Hand blending of the cuts.
Link:
http://www.alaniztechnologies.com/headterms.html
Link:
http://www.alaniztechnologies.com/headterms.html
Last edited by Mez; Feb 12, 2011 at 12:04 AM.
