Cam duration vs head flow?
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Laughing Gas
Joined: Dec 2003
Posts: 900
Likes: 3
Cam duration vs head flow?
Hello,
A lot of performance cams back in the day were designed with more duration on the exhaust side to benefit factory heads that flowed poorly through the exhaust. My question is, with modern aftermarket heads flowing within 70-80% of the intake, at which point is it desirable to run a cam with intake and exhaust duration figures much tighter, or even single pattern cams? Is there a formula or rule of thumb to go by? Thanks.
A lot of performance cams back in the day were designed with more duration on the exhaust side to benefit factory heads that flowed poorly through the exhaust. My question is, with modern aftermarket heads flowing within 70-80% of the intake, at which point is it desirable to run a cam with intake and exhaust duration figures much tighter, or even single pattern cams? Is there a formula or rule of thumb to go by? Thanks.
Elder User
Joined: Nov 2009
Posts: 666
Likes: 0
From: Chicago area
I think the answer to your question is in your post. "Back in the day" when good HiPo heads for a Ford were rare, engine builders figured out that they could extract some extra power by doing what you described above.
The HiPo heads for the Windsor engine, both Fords and the aftermarkets are all designed to correct the exhaust flow so why use a cam designed for a cylinder head that your not using?
The HiPo heads for the Windsor engine, both Fords and the aftermarkets are all designed to correct the exhaust flow so why use a cam designed for a cylinder head that your not using?
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