Air cleaner in Stock Class

[Todd Boyer]

There's another thread here about air cleaners with some interesting info about K&Ns and other HP filter systems. Worth a read.

http://classracer.com/classforum/sho...ir+cleaners%21

[Lew Silverman]

Thanks for the info - I'll check it out!

[mopar jeff]

So is it legal to just hose clamp a filter on the end of the throttle body?

[Jeff Lee]

The K&N filter top, worthless or not for HP, is allowable per NHRA. This was an issue when they first came out. The rationale is you do not need any lid so a K&N lid is acceptable.
I always ran one in D/S with the factory ram-air system. Can't say that it helped but it certainly didn't hurt. And Arizona is somewhat dusty so I always ran a filter.
I just noticed Todd put a link to the old discussion....

[The Hawk]

I remember this topic in early `03,and the Zane`s mentioned they were asked to remove the K&N top,I never had been asked. Sure enough,in Phoenix that year I was asked to remove it in tech. Still sitting in my storage unit.

[Swandog]

What about the definition of an OEM system for fuel injected cars? Can you simply remove the intake plumbing and bolt the filter on throttle body like mopar jeff suggested? Also, what about using common aftermarket "cold-air" style systems who use smooth mandrel built plumbing to replace the disruptive factory rubber tubing prior to the throttle body? Anyone have experience with legality and/or hp benefit of such a setup?

[LNorton]

Originally Posted by Swandog

What about the definition of an OEM system for fuel injected cars? Can you simply remove the intake plumbing and bolt the filter on throttle body like mopar jeff suggested? Also, what about using common aftermarket "cold-air" style systems who use smooth mandrel built plumbing to replace the disruptive factory rubber tubing prior to the throttle body? Anyone have experience with legality and/or hp benefit of such a setup?

I was told by IHRA that we are allowed to put a filter directly on the throttle body. I would ask them at your next race as I am not sure NHRA's ruling.

[442OLDS]

I know I race a pretty slow car,but a few years ago,I tried the K&N top during some "testing"

The car lost .03

[Michael Beard]

The effect of the filter +/- is going to depend on your tuneup. It's just like changing fuels: You can't just swap it in the tank and then assume that the new fuel is quicker or slower than the old. You have to tune for whatever you have changed in the system.

I have some Dynatech cone collector inserts that I have to run at one track due to a muffler requirement. First time I put them in the car, it slowed it down .03. Played with them again and it picked it up .05.... but I had the car jetted different.

In *any* case, it's a matter of tuning, and what you want to see. I specifically use my K&N to tune the car to what I want it to run, although I run it 95% of the time just to protect my engine.

IHRA is ok with the filtertop, and even the Quicktime air bell, but the "stub stacks" are a no-no.

[Pat Cook]

I have tested back to back with and without a air cleaner, my car slowed .03. I agree, some testing with jet change would probably pick it up.

I also use a air cleaner base from an old LTD Ford that has been trimmed to fit the engine, that is worth .03 doing nothing put putting it on the car. No element just the base.
The reason for using it, because of the nice radius into the carb.