I've read about various things to do to the air cleaner housing to give "better" performance. Has anyone really seen any improvements from:

• Disconnecting heater hose to not let in the warm exhaust air
• Disconnecting air pump (smog) hose (I read the smog air reduces performance?)
• Turning the air cleaner cover upside down
• Replacing the whole housing with an open air filter

I mean some of them make sense but I've not been able to find anyone that says "Yes it works!".

What do you think?

 

OK, first of all, the requirement is to ensure that the air cleaner does not act as the most restrictive part of the intake tract. A new 14" diameter, 3" tall air filter should flow enough air to support most stock V8s. Modified engines can use the taller truck elements and/or two filters stacked, but that runs into hood clearance problems on most cars.

The air cleaner housing is designed as much for noise control as for air flow. The snorkel is usually shaped to attenuate some intake noise, resulting in some restriction. The hot air pipe, if working properly, only supplies hot air when the engine is cold, so removing it only hurts cold engine driveability with no performance gain.

The hose from the A.I.R. pump to the air cleaner housing is only a dump line that diverts air from the exhaust nozzles to prevent backfires during closed throttle deceleration. It has exactly zero impact on performance. Removing the entire A.I.R. system will save the whopping 2 HP or so it takes to turn the A.I.R. pump.

Flipping the air cleaner lid or going to an open element air cleaner makes the car SOUND faster, but we've all learned that the "butt dyno" is notoriously inaccurate. In particularly if the stock air cleaner has a cold air hose to the core support, flipping the lid or changing to an open element unit may actually hurt performance due to the ingestion of hot underhood air. Tests have shown about a 1 HP increase for each 7-10 degree decrease in inlet air temp. Finally, the internal shape of the air cleaner housing is designed to smoothly turn the air into the carb. Flipping the lid disrupts this flow, which can cause more harm than good (despite what the "butt dyno" is telling you due to the louder inlet noise).

Your best choice is a good low restriction air cleaner housing with outside air ducting. In fact, it probably looks just like the factory 1968-69 O.A.I. housings.

 

Cool, thank you! I figured most of them weren't very effective...lol. I did turn the air filter cover over and it gives the engine more of a growl that was kinda cool.

 

that pretty well sums it up!


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