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Old 08-13-2007, 08:15 AM
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Matching intake ports heads/intake

I ordred a summit brand intake manifold for my street rod build. I notice that the intake runner openings that match up to the intake runners on the heads are not square with each other and they are a little smaller than those on the heads.



Is this a big deal or is that how they make them?



Thanks,

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Old 08-13-2007, 09:09 AM
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It's not unusual for ports not to match perfectly. It's not a big deal unless you're trying squeeze every possible horsepower out of your motor. Some folks actually think the mismatch helps with fuel-air mixture by creating turbulence in the intake port at the expense of some flow. Probably OK for a street motor.
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Old 08-13-2007, 09:28 AM
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I have read more then once that smaller intake to larger head is ok, but not the other way around. Sounds like you're good to go.
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Old 08-13-2007, 10:15 AM
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Quote:
Originally Posted by Jmark
I have read more then once that smaller intake to larger head is ok, but not the other way around. Sounds like you're good to go.
I have read the same thing, something about velocity. You will be fine on a street motor as others have mentioned, if you really want to port match the two, it is really easy with a few hours of work.
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Old 08-13-2007, 10:53 AM
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Quote:
Originally Posted by dpjmw
I ordred a summit brand intake manifold for my street rod build. I notice that the intake runner openings that match up to the intake runners on the heads are not square with each other and they are a little smaller than those on the heads.

Is this a big deal ? or ? is that how they make them?



Thanks,
Unless you're a competitive racer needing every conceivable horsepower, this is fine. It's better to have the manifold a bit smaller than the ports such that the port never presents a 90 degree wall to the oncoming flow. The other direction where the manifold walls present a 90 degree surface to any reversion flow coming back up the port is beneficial to reducing this reverse pumping into the plenum and backward thru the carb where it causes stand-off.

Bogie
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Old 08-13-2007, 07:21 PM
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If you study fluid dynamics, you'll learn that it doesn't amount to a fart in a whirlwind anyway. Most of the flow goes down the middle of the port. There is a dead space at the surface of the port walls, like the flow in a river. Goes real fast down the middle of the channel, little or no flow at the bank.
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Old 08-13-2007, 07:29 PM
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Thanks for the replys

Thanks for all the replies. As usual, I was overthinking the whole damn thing. I'm going with it, thanks for the advise.
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