Aspire airbox mods

[TominMO]

Today I went out and did a couple of mods to the stock Aspire airbox. Like all airboxes on modern cars, for noise reasons it is more restrictive than is useful for the engine to efficiently take in air; i.e., the hole coming into the airbox is much smaller than the hole going into the VAF, and the black tube going over the valve cover.

1. Undid the wing nut holding the black tube to the upper rad support; undid the hose clamp (10mm) connecting the black tube to the VAF; disconnected two electrical connectors on the VAF; snapped off the four clips holding it to the lower airbox piece; set it aside.

2. Pulled out the air filter--it's new; removed one 10mm nut and one 10mm bolt securing the lower airbox piece; pulled it out.

3. On the front of the lower piece is an intake horn, secured by three phillips screws; removed it, saw a much bigger hole in the lower piece than on the intake horn. This mod alone will probably give a noticably easier-revving motor. I then drilled fifty 1/4" holes in the front and fender side of the lower piece. This will give plenty of air flow, probably more than the stock filter can use: an extra 2.45 square inches, not counting the larger stock hole revealed by removing the intake horn.

4. Replaced everything except the wing nut pieces on the rad support; in fact I removed the bracket that was there. It seems unnecessary, and a minor hassle.

5. Went for a drive. When I stomp on it, there is definitely more intake roar, so it's getting more air. It does seem to rev more freely above 4000 RPM, but that's subjective; no real numbers here. This mod will of course not affect fuel mileage if you are driving for economy; it only makes a difference above about 4K RPM. I do this type of mod to every car I own.

[TominMO]

Reinstalled the bracket with the wing nut that secures the black tube, because it isolates the VAF from engine vibration.

[getnpsi]

I went even more agressive with my aspire when I had it. I extended the MAF wires and placed a cone filter in front of the radiator. I retained the factory air tube by cutting it in half and splicing it back with large hose. It led to some ping@moderate throttle with 87 octane, which taught me to back off, leading to much improved mileage. At WOT there was no ping due to factory throttle enrichment.

[nonamekid]

When I stomp on it, there is definitely more intake roar, so it's getting more air.

Intake roar does not correlate to getting more air. I could make my car whistle really loud and it be getting less air. Intake roar is caused because you got rid of the system designed to quiet the air intake so that it would not be heard in the cabin. Also the air, as it goes through all those little holes you drilled, will whistle causing intake roar.

[TominMO]

Some further notes

Took it all apart again to make some measurements. When removing the intake horn on the front of the airbox, two holes are revealed: one is .75" and the larger one, 2.25". The black tube, where it enters the VAF, has an inside diameter of 2" (not counting the larger section right on the end, where the hose clamp fits on). So we can get some meaningful numbers.

Holes going into the airbox (with horn removed), .75 and 2.25, have an area of .44 square" and 3.97 sq" respectively, for a combined air intake total of 4.41 sq". The black tube at the VAF has an area of 3.14 sq". So the intake with the horn removed is 1.27 sq" more than the black tube's capacity to accept air.

From this I conclude two things:
1. in this case, drilling all those holes does nothing for improved intake airflow; just removing the horn does all than can be practically done; and
B. putting on a cone filter, or even installing a stock-sized K&N in place of the stock air filter, is a waste of money; the only reason for a cone is cosmetic.

[TominMO]

Intake roar does not correlate to getting more air. I could make my car whistle really loud and it be getting less air. Intake roar is caused because you got rid of the system designed to quiet the air intake so that it would not be heard in the cabin. Also the air, as it goes through all those little holes you drilled, will whistle causing intake roar.

I agree; but it does seem to be revving more freely above 4K.

[eurotiva]

A k&n will improve airflow, and is washable.

[TominMO]

A k&n will improve airflow, and is washable.

With the airbox opened up, the difference between the stock filter and a K&N on such a small motor is probably negligible; maybe 1 to 2 HP. I'd love to see a dyno comparison on pre- and post-mod, and post-mod w/K&N.

[TominMO]

Went out and measured the air filters for Aspire and Festiva EFI (they are the same BTW). Went to the K&N site, which lets you search by size to find a match. Turns out there is no K&N filter to replace the stock EFI filter. The K&N filter part # I have seen quoted here before must be for the carbed Festys.

[Glow_Mouse]

y'know you could always do this, I mean if you own an aspire. Look at what i did.



My setup's changed since then. Modifying to a turbo setup once i get everything sorted..
but there's something to think about.

EDIT: btw, current intake pictured was done on a 97 festiva WD model. Can make intakes to suit WB,WD,WF or ill even have a crack at a WA.

[bhazard]

Thats all drawing in hot engine bay air though. Also IMO all that shiney piping looks gaudy in a stock engine bay.

[blkfordsedan]

Went to the K&N site, which lets you search by size to find a match. Turns out there is no K&N filter to replace the stock EFI filter. The K&N filter part # I have seen quoted here before must be for the carbed Festys.

I have an EFI with the panel filter and got a K&N from the local McParts store. They have no listing, but I did the search by size and found it. They had to special order it, but that was 5-6 years ago. Don't know what part number you found in the search, but I think it was like 32222 or something. If you still can't find it, I can go out and read the number off mine.

[TominMO]

^ Someone said it is 33-2222. Haven't gotten around to going to the parts store yet

[nonamekid]

It is that the filter for the beretta? I think it had a filter that was similarly sized.

[TominMO]

It is that the filter for the beretta? I think it had a filter that was similarly sized.

I did a search on the 1995 Beretta air filters, both motors; it came up as a different part #.

Did find this tho:

http://www.knfilters.com/search/applications.aspx?Prod=33-2222

So this looks like the right K&N air filter to use.