K&N Cone Filter

[danbuc]

I have a 98 STS with the corsa exhaust and was wondering about the K&N cone filter that everyone keeps talking about. So far what Ive gathered is that unless you have free flowing exhaust like the corsa, it doesn't pay to have the cone filter. With the airbox removed though the engine would now be breathing hotter air from under the hood which might lower overall performance gains that one might see from it. On the other hand, if I was to get the K&N air filter that fits in the airbox there is a chance that it would also boost performance due in part to the the colder air coming in from the outside. If anyone has experimented with boh setups, any results would be greatly appreciated. I also was wondering as a side note whether or not anyone has considered a high-flow catalytic converter such as the ones made by CATCO for example. If there is a chance that this could improve performance along with the exhaust and air filter it would be great especially since they are only around 60 dollars.

Any info on this matter would be great to. Thanks

[Bruce Nunnally]

In my tests on my 96 STS, the drop-in filters for the airbox did not improve performance. http://www.caddyinfo.com/airfilterstudy2.htm

I also found that just adding a 'bigmouth' cone filter did not help

http://caddyinfo.netgetgoing.com/airboxvscone.htm

Jason did some work on cone isolation with mixed results:

http://jadcock.oldsgmail.com/cadsls/filter.html

Greg found that for his Aurora the drop-in filter DID help nicely

http://caddyinfo.netgetgoing.com/dyno/4airboxtest.htm

and others have posted impressive acceleration results, usually including various intake mods: http://caddyinfo.netgetgoing.com/performancereports.htm

Please do post any test results.

Certainly a higher that stock flowing catalytic converter would help. I don't know of any objective testing to determine whether a particular aftermarket cat/brand is actually higher flowing than the stock one. Again this is an area where documented tests would be valuable.

[jazbo]

Just a thought or two on the "high flow" cat. I'm pretty sure they all use the same media or substrate configuration. The "high flow" versions just have a bit less I believe but apparently "should" still pass emissions. I have seen posts about people needing the fake-out sensor to correct this though. Apparently these may not do as good a job as the stock unit. Also, I've talked to someone at Exxon and he indicated that oils are being developed with lower phosphorous additives (I think that was it) so that the converters remain more efficient throughout their life. Not that they plug on a car that operates correctly, but the catalyst apparently can degrade over time. So, even if the SES light did not innitially come on, it seems that you'd be more suseptible to these problems with one of these converters.

Also, if these are bigger than stock, you'd really need to expand the drop pipe from the manifold gradually in order to pass the exhaust through the larger opening. Otherwise you'd just be shooting the exhaust through the same effective area of the converter with a stock drop pipe. Who knows, a larger converter mated to the stock drop pipe may even introduce turbulence in the flow from the sudden enlargement.

Anyway, I'd stay stock on the converter.

[MARK 99STS]

I completley removed the existing intake system and replaced it with a K&N cone filter. I made a heat shield of aluminum around it and ducted it below using a flexible downspout elbow cutting a hole in the plastic gaurd below. Acts like a ram air. Caution as to possible water intrusion going thru deep standing water.

I'll try to post some pics of the set up.

[Cupillac]

In October I put a free flow cat on my STS to help out the new exhaust. It seems to work good, and sounds good too. I was told I would have no trouble passing emissions.