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Discussion Starter #1
Swapping intakes today I found out the edelbrock performer bbc has an exhaust crossover. Duh. In hot dallas weather.

Anyhow, the new manifold has no crossover and is also an airgap style. Does anyone know how much power one can pick up by not having that xover in the intake?
 

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Oh ..at least 8.5 hp

Sorry I've had a few....
I'm not sure about horsepower but I used an air gap on a big block once to cure a fuel perk problem we had with a Q jet carb.
In theory a cooler air charge = power but as to how much exactly ?
 

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Discussion Starter #3
I would like to know how much power too as I can imagine that bbc exhaust would heat the manifold pretty good
 

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Not so much power as change in air density.... the change will be felt across the entire RPM range....

there will be a noticeable extended warm up time with the iron heads and blocked heat riser...

you may see from 1 to 5hp depending.... not something most consider any more for HP value.... I have been blocking heat risers since the 70's..... I dont think I have ever seen a HP value place on the blocked riser... for a given engine.... its a accepted practice these days and common knowledge that providing a cooler intake charge raises HP, just to the extent it has, has so many variables it's hard to calculate.... given.. elevation, current atmospherics, state of tune... etc...

But you can bet your BBC.. it will have a positive effect... to the extent of measurable HP???? anybody's guess
 

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Not so much power as change in air density.... the change will be felt across the entire RPM range....

there will be a noticeable extended warm up time with the iron heads and blocked heat riser...

you may see from 1 to 5hp depending.... not something most consider any more for HP value.... I have been blocking heat risers since the 70's..... I dont think I have ever seen a HP value place on the blocked riser... for a given engine.... its a accepted practice these days and common knowledge that providing a cooler intake charge raises HP, just to the extent it has, has so many variables it's hard to calculate.... given.. elevation, current atmospherics, state of tune... etc...

But you can bet your BBC.. it will have a positive effect... to the extent of measurable HP???? anybody's guess

Venu, I would be surprised if its not more than 5hp, the intake used to get so hot you couldnt lay your hand on it. even the carb was hot. Im thinking this is probably the crossover causing this. come to think of it, the rpm airgap has no crossover and usually shows a few hp more. I wont be surprised if its becuase of this.
 

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i wouldnt expect the lack of a heat crossover to be the reason for a power increase on the airgaps,,.. they seem to have better designed intake runners givining a straighter shot to the intake valve...
 
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