Technical Chrome Air Filter vs Traditional Round Air Filter

[stevenk9958]

I have a 1978 Fiat 124 Spider and got two air filters from my seller. One is the small chrome air filter, and the other is the traditional round housing that takes the circular paper air filter. I'm assuming I use one or the other but not both. What's the difference in performance if any? Is it just a personal preference or would I choose one over the other? The traditional round one is a rust nightmare (the attached is a stock photo - mine is significantly worse) and needs sandblasting while the chrome air filter is brand new. Thanks for any advice.

 

[s130]

A major difference will be in intake air temperature. The traditional round housing has two inlet ports. One is to take cooler air from a location away from engine and other heat sources (e.g. from behind vehicle front grille) the other is to take warm air (for winter use) from probably somewhere near the exhaust manifold.

The chrome one will just take air from above the engine.

Cooler air = higher density & fuel charge = better performance. How much better performance could be academic in normal road driving with differences only being measured on a rolling road.

Another difference will be in induction noise. The chrome filter will sound really sporty and even if it gives no better or worse performance the sound will make the car feel faster

If you live in a cold climate, especially deep winter, then the chrome filter may make the car more lumpy etc. till the engine bay warms up.

 

[stevenk9958]

A major difference will be in intake air temperature. The traditional round housing has two inlet ports. One is to take cooler air from a location away from engine and other heat sources (e.g. from behind vehicle front grille) the other is to take warm air (for winter use) from probably somewhere near the exhaust manifold.

The chrome one will just take air from above the engine.

Cooler air = higher density & fuel charge = better performance. How much better performance could be academic in normal road driving with differences only being measured on a rolling road.

Another difference will be in induction noise. The chrome filter will sound really sporty and even if it gives no better or worse performance the sound will make the car feel faster

If you live in a cold climate, especially deep winter, then the chrome filter may make the car more lumpy etc. till the engine bay warms up.

Thank you for such a great answer! I live in Southern California's desert and we have a mild winter here with coldest days 40F. Do you think a potential buyer will care either way?

 

[s130]

Thank you for such a great answer! I live in Southern California's desert and we have a mild winter here with coldest days 40F. Do you think a potential buyer will care either way?

I suspect not as besides cosmetics and induction noise (which they may like) they are probably not going to appreciate the finer details of air induction, charge density, etc. and if the car drives OK they will be happy and none the wiser

 

[PuntoHowTo]

The filter in the big round canister is likely to be much bigger also which would be less restricting of airflow compared to the smaller square chrome one, whether or not it would make a difference is really dependent on how much air the engine is drawing in, there comes a point where having a bigger filter wouldn’t make any discernible difference to the overall airflow.

 

[s130]

The filter in the big round canister is likely to be much bigger also which would be less restricting of airflow compared to the smaller square chrome one, whether or not it would make a difference is really dependent on how much air the engine is drawing in, there comes a point where having a bigger filter wouldn’t make any discernible difference to the overall airflow.

Often difficult to ascertain unless one can take proper airflow or pressure measurements.

The chrome filter looks like a typical K&N mesh and filter material injected with oil. These tend to have a slightly better airflow compared to paper filters, but not always. Surface area is important in both filter types. Also in the case of the old metal housing the carb is having to breath through a defined orifice of some CSA (cross sectional area) of a couple of inches. Sometimes this can be more restrictive than the filter. Again very difficult to judge without proper airflow / pressure testing.