LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

ported intake manifold opinion?

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Old Apr 14, 2009 | 02:10 PM
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mikemassi's Avatar
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ported intake manifold opinion?

(94 camaro z28,A4,full exhuast)i recently just bought a ported intake manifold off my friend. will i notice any differeence in power with this. i also am goin to purchase a throttlebody and injectors and get it tuned. what kind of power increase should i be expecting with everything all said and done? thnaks
Old Apr 14, 2009 | 02:29 PM
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If the ports are opened up larger than the head ports you could notice a LOSS of power.

Intake is not something that should be an early mod on an LT1, even on heads and cam cars porting seems to only be of modest value.
Old Apr 14, 2009 | 02:51 PM
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Besides major mods to the intake, about all that is useful is matching it to a larger throttle body and port matching to your heads. These are worthwhile, power gains will vary with the combo.

Rich
Old Apr 14, 2009 | 09:46 PM
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about how much power would you lose if a bad port job was done to your heads?
Old Apr 14, 2009 | 09:54 PM
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possibly ALL of it if bad enough
Old Apr 14, 2009 | 09:56 PM
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Im just asking cause i ported my intake myself last year, and i matched it to the gasket. I did not however match it to the heads. My heads are ported and i dont know if they match the gasket or not, so i was just curious how much hp i might be losing.
Old Apr 15, 2009 | 05:07 AM
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Originally Posted by BCdawg57
Im just asking cause i ported my intake myself last year, and i matched it to the gasket. I did not however match it to the heads. My heads are ported and i dont know if they match the gasket or not, so i was just curious how much hp i might be losing.
Well, if the manifold is bigger than the port in the head, that's a bad situation where a lot of power can be lost. Most people actually like to leave the a lip on the manifold that is 0.020-0.030" smaller than the port to help prevent reversion and to surely avoid the opposite situation (a lip on the head protruding into the port) which screws up airflow.

Rich
Old Apr 15, 2009 | 05:17 AM
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Originally Posted by mikemassi
(94 camaro z28,A4,full exhuast)i recently just bought a ported intake manifold off my friend. will i notice any differeence in power with this. i also am goin to purchase a throttlebody and injectors and get it tuned. what kind of power increase should i be expecting with everything all said and done? thnaks
Whether you will gain anything by changing the injectors depends on the engine's power level. You haven't told us anything about the mod's except "full exhaust". If you aren't over 360HP at the flywheel, the stock injectors are more than adequate. Many have taken them beyond that power level and not had problems. The "tune" is always a good idea. Even on a stock engine you may gain as much as 15HP simply by leaning out the power enrichment (PE) mode target A/F ratio.

If all you have is an exhaust, leave the throttle body and the intake manifold alone.
Old Apr 15, 2009 | 01:11 PM
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the mods done to my car arent to extreme. i have full exhuast, undrives, a/c delete. egr delete,cai,3.73's,msd ignition, and rebuilt stock heads with RR's. The intake manifold is ported but only the throttle body opening seems to be alot bigger, all the ports match the stock intake mani gasket perfectly. will i lose power?
Old Apr 15, 2009 | 03:20 PM
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If the intake is gasket matched and the heads not that would certainly be a bad thing.

The underdrive is pointless as is the MSD.
Old Apr 15, 2009 | 04:55 PM
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Originally Posted by rskrause
Well, if the manifold is bigger than the port in the head, that's a bad situation where a lot of power can be lost. Most people actually like to leave the a lip on the manifold that is 0.020-0.030" smaller than the port to help prevent reversion and to surely avoid the opposite situation (a lip on the head protruding into the port) which screws up airflow.

Rich
a reversion lip on the intake runner?
Old Apr 15, 2009 | 05:16 PM
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There is such a thing as intake reversion. Without that argument though it still makes some sense to leave the manifold smaller than the head because since they are not doweled there is likely some missalignment.
Old Apr 15, 2009 | 06:03 PM
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Originally Posted by MikeGyver
a reversion lip on the intake runner?
Yes. It's a bit of a safety factor against slight misalignment. Just 20 thou or so is what many people (myself included) do when port matching a manifold. Gives a little anti-reversion, which is good, and prevents the manifold being larger than the port, which is very, very bad.

Rich
Old Apr 15, 2009 | 06:34 PM
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X2. Or is it X3?
Old Apr 15, 2009 | 07:54 PM
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