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intake port to intake manifold. match or mismatch?h

General engine tech -- Drag Racing to Circle Track

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CHT

Re: intake port to intake manifold. match or mismatch?h

Post by CHT » Tue Aug 31, 2010 9:36 am

Bob Hollinshead wrote:I thought the mismatch only helped with a sharp edge to create turbulence and promote a remixture now we throw the trumpet bell theory into the mix to increase airspeed and/or volume.... I'm all confused now :mrgreen: Very interesting stuff and I can see I'll be trying a few different intakes on my oval port engine if I ever get the thing together. Some dyno testing data sure woud be cool. Bob
Ive found the sharp step is better to reintroduce fuel

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Re: intake port to intake manifold. match or mismatch?h

Post by cjperformance » Tue Aug 31, 2010 9:36 pm

CHT wrote:
Bob Hollinshead wrote:I thought the mismatch only helped with a sharp edge to create turbulence and promote a remixture now we throw the trumpet bell theory into the mix to increase airspeed and/or volume.... I'm all confused now :mrgreen: Very interesting stuff and I can see I'll be trying a few different intakes on my oval port engine if I ever get the thing together. Some dyno testing data sure woud be cool. Bob
Ive found the sharp step is better to reintroduce fuel
Yes, sharp step, size the port opening to suit the port and application then just leave it as a sharp edge. But that said I have not tried just putting a small radius on the port entry to test it. I would 'think' that the sharp edge will work best for this purpose.
Craig.

Bill Chase
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Re: intake port to intake manifold. match or mismatch?h

Post by Bill Chase » Fri May 15, 2020 5:32 pm

This entire post deals with carbs and wet flow manifolds. How would this work with an efi setup that has a decent amount of overlap in the valve timing?

Would it help clear things up below tuned rpm, say you were built for 2800-6500 rpm.. would this kind of sharp step help get the fuel blown into the intake during overlap moving and give the engine a broader range of power?

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Re: intake port to intake manifold. match or mismatch?h

Post by 1989TransAm » Fri May 15, 2020 6:22 pm

I would think that the location of the injector(s) would have some say in the matter.

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Re: intake port to intake manifold. match or mismatch?h

Post by Bill Chase » Sat May 16, 2020 10:22 am

1989TransAm wrote:
Fri May 15, 2020 6:22 pm
I would think that the location of the injector(s) would have some say in the matter.
Lt1 style sbc intake, specifically it is a tpis miniram, looks to aim the injectors well into the port of the head, but definitely not directly aimed at the valve stem or bback wall of the bowl (as viewed from the intake manifold looking into the port.

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Re: intake port to intake manifold. match or mismatch?h

Post by 1989TransAm » Sat May 16, 2020 11:45 am

So the fuel is sprayed right into the intake port of the head. I cannot see having a mismatched port having much of a positive effect in this case. I would go for the matched transition of the intake manifold to the head for the most airflow.

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