Open air filter on truck vs stock snorkel unit

blue_tractor_man · May 24, 2018

What are the plusses and minuses to an open "hot rod" air filter on a V8 pickup engine vs the stock snorkel type? I will lose the little heater thingy from the exhaust manifold and the fresh air pipe from the grill. I guess the open filter will pull warm air from under the hood, but it will be unrestricted. The reason I bring this up is I installed a Sanden AC compressor to replace the old R4 pancake unit. The air filter snorkel now hits the AC compressor.

Steve@Advance · May 24, 2018

The purpose of the short snorkel is sound reduction, gets rid of the roar or air rushing in.

The long fresh air type is to bring in cold air, which improves performance as cold air is denser. But denser air needs more fuel...

The warm air tube is to help with cold performance. Warm air is less dense, requires less fuel, atomizes fuel better. Helps get through the cold engine/some choke needed phase of warm up.

You probably won't notice much difference other than the noise, and some find that preferable.

What you do have to watch for is passing inspection if the emissions are checked in your area. Possibly you could modify the bottom of the air cleaner so it could be turned slightly, replace the formed steel heat tube and cold air duct with flex.

MarkB_MI · May 24, 2018

Carbureted engine or fuel injected? The purpose of the "heater thingy" is to prevent carburetor icing.

Hobo,NC · May 24, 2018

The hot rod filter is used because its unrestricted as long as the filter lid is not to close to the opening/throat of the carb... Modify yours no need to buy a hot rod filter unless you want one...

blue_tractor_man · May 24, 2018

It's a 91 GMC throttle body injection. Thanks.

4play · May 25, 2018

Like mentioned, you will not notice a difference other than hearing more sound under heavy throttle. There are also two locator tabs on the mounting base that you can grind/cut in order to reclock the filter housing if you simply wanted to turn it. Lots of guys used to flip the filter lid over to get unrestricted flow and sound.

MarkB_MI · May 25, 2018

> It's a 91 GMC throttle body injection.

TBI is fairly resistant to intake icing. I don't remember my '88 Chevy with TBI having a hot air intake.

ss55 · May 25, 2018

The engine will be pulling warm air from behind the radiator and air conditioner evaporator instead of cool air from ahead of the radiator (or right fender well?). The computer may reduce the fuel flow a little to compensate for the warmer less dense air. On a 27 year old vehicle you probably won't notice much difference other than extra intake noise.

DR. EVIL · May 25, 2018

Not sure what you mean by "Open Hot Rod air filter", but if you mean any one of the oiled cotton gauze type filters like a K&N, Stay AWAY! They Claim up to 99.9+% effectiveness, but the OEM pleated paper filters will beat them every time. I ran oil analysis on my '96 7.3L PSD with both the OEM pleated paper element and a drop-in K&N oiled cotton gauze filter. OEM tested 0 and 1 ppm silicon, AKA Dirt! K&N tested 3-4 ppm. This was when the truck was my daily driver on mostly interstates or divided state highways, very very limited off road. Same brand oil & oil filter, only change was air filter.

Greg K · May 25, 2018

I had one on a pickup once, in winter sometimes it would plug up with snow all the way around. That's the only drawback I ever found.

sotxbill · May 25, 2018

Oil covered filters have a problem of coating the mass air flow sensor, assuming your car has one. The maf will eventually fail and throw a cel... you can cold wash the maf with alcohol and sometimes recover it. Almost everyone who runs one will eventually get the cel light, usually within a year. Diesels with maf are included. Cleaning and over oiling the filter will do it sooner. Never cleaning it, will postphone it or may avoid the cel.

If your car is old enough, then its down to cold air and cleanliness.

David G · May 26, 2018

The purpose of the hot/cold snorkels is to maintain a correct air temperature for optimum combustion, you will get too hot of air is summer and too cold in winter.

buickanddeere · May 26, 2018

If the engine has closed loop feedback with a working exhaust O2 sensor . The ECM will adjust the fuel injection pulse length to compensate for cold or hot intake air . There should also be an intake air temp sensor on there too.

Open air filter on truck vs stock snorkel unit

blue_tractor_man

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Steve@Advance

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MarkB_MI

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Hobo,NC

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blue_tractor_man

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4play

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MarkB_MI

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ss55

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DR. EVIL

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