Gill exhaust hp
07-31-2018 | 10:06 AM
#6
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Joined: Jul 2006
Posts: 874
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From: Charleston, il
So let's look at a 500 efi with an E-top style header. Works well with a header that is only a slight improvement over a good manifold. I would say it would be safe to say that a NA 500" with cam similar to 500efi wouldn't give up much power utilizing a good manifold and riser. Then you look at a 525 with full length sweeper headers. Can it be determined that somewhere between a 500EFI and 525EFI is where we draw the line for making good power with a good flowing manifold? To the OP I believe for you it is time for headers of some sort whether that be thunder and lightnings or cmi whatever something full length divided runner. Stainless marine has some options as well that support big power.
07-31-2018 | 11:12 AM
#7
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Joined: Nov 2006
Posts: 1,313
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From: Tygart Lake, WV
Vortec 8100 / 8.1L / 496MAG Mercury Marine Performance Parts Upgrade - Raylar Big Power
One of the best non bias tests out there. Later on bobl tested a set of 496 CMI sport tubes on the same dyno and they picked up a few hp over the dana's. The stock 496 manifolds are a individual runner Gill design and dump into a riser. The Dana setup is a much longer internal runner design that carries into the riser. As power levels rise, the difference between the two types of exhaust will only grow.
Your current setup will work fine. Are you leaving power on the table vs a long runner header? Absolutely! Hard to beat the price vs performance of these....
One of the best non bias tests out there. Later on bobl tested a set of 496 CMI sport tubes on the same dyno and they picked up a few hp over the dana's. The stock 496 manifolds are a individual runner Gill design and dump into a riser. The Dana setup is a much longer internal runner design that carries into the riser. As power levels rise, the difference between the two types of exhaust will only grow.
Your current setup will work fine. Are you leaving power on the table vs a long runner header? Absolutely! Hard to beat the price vs performance of these....
Last edited by Ryan00TJ; 07-31-2018 at 11:24 AM.
07-31-2018 | 12:46 PM
#8
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Joined: Mar 2012
Posts: 4,189
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From: Cape coral, FL
The gils work fine in his app but he will need to make more power to reach his goal. 650 with a gil would be closer to 700 with a true header. Now if it’s all about making 650 on a dyno with no accessories and dyno headers than that’s a different ballgame. When I think power numbers I think fully dressed in marine trim.
07-31-2018 | 01:31 PM
#9
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Joined: Apr 2011
Posts: 374
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From: mckinney texas
[QUOTE=Crude Intentions;4641019]
yes dyno rating undressed.
The gils work fine in his app but he will need to make more power to reach his goal. 650 with a gil would be closer to 700 with a true header. Now if it’s all about making 650 on a dyno with no accessories and dyno headers than that’s a different ballgame. When I think power numbers I think fully dressed in marine trim.
TE]yes dyno rating undressed.
