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Topic: HP diff for cold-air intake vs. not?

in Forum: C3 Engines


HP diff for cold-air intake vs. not?

Posted: 4/21/05 10:23am Message 1 of 3
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Edgewood, KY - USA
Joined: 10/26/2003
Posts: 339
Vette(s): 1981, Black/Black, Engine bumped to about 400HP.Ext/int mostly stock.
I have a currently stock '81.  It has the factory twin air ducts to bring cool air from in front of the rediator into the air cleaner and carb.  As I start replacing the top-end with high HP parts, I would love to clean-up the look of the engine by replacing the air cleaner and cold air ductwork with a simply chrome aftermarket air cleaner with no ductwork, but then it would be sucking warm/hot air that has been through the radiator.  Of course many of the classic muscle cars do not have cold air ducting...  Anyway, does anyone have a solid idea of how many HP I'd be giving up if I went this route?  This anemic '81 350 needs every HP I can squeeze out of it!


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HP diff for cold-air intake vs. not?

Posted: 4/21/05 11:26am Message 2 of 3
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
I have the same setup on my '78 L82. Supposedly the cold air induction does help the horsepower, but I've seen where some people have removed the ductwork to clean up the appearance and go with a chrome air cleaner and have claimed an increase in responsiveness. I guess it's an individual car thing.

I do know after '78 Chevrolet added the second cold air duct to the L48 engine and claimed a 5 horsepower increase over the previous year. I also understand most cold air inductions really only make a difference at wide open throttle, not at low throttle openings.

I've kept my car using the original ductwork, and am happy with its performance (I do have a low restriction K&N air filter element installed). I do admit it makes for a crowded looking engine bay.

If nothing else, maybe you can borrow an aftermarket air cleaner from a friend, swap it for the ducted parts in your car and compare the difference in responsiveness. Make your mind up then.

To be honest...it will likely take more than an air cleaner change to get you the performance increase you seem to be looking for...different intake, full dual exhausts, maybe a cam, etc. There's lots you can do, it just depends on how much you care to invest.


HP diff for cold-air intake vs. not?

Posted: 4/21/05 12:14pm Message 3 of 3
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Cool air is denser than warmer air,  so you get more air in the cylinder, and thus more power.

Air ducting has more restriction than an open air cleaner, so you get less air, and less power.

It could go either way.  Yea, it can be a crap shoot.  If you want to experiment, just pull the air filter off and go for a drive.  See how it acts.  Then make your choice.

Cold air intakes don't really make any difference until you are close to wide open throttle at higher rpms.  Until there is not enough restriction to make any difference. If the throttle is closed at all, even at just under wide open throttle, the greatest restriction is the throttle itself.  At lower rpm it engine simply does not need as much. 




in Forum: C3 Engines


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