Switching back from K&N cone filter to OEM box and paper. Will I lose some power?

[movin]

I've had the K&N cone filter on so long I don't remember if there was any real power increase. I'm tired of not being able to drive in the rain and having to put a Baggie over the filter every-time I wash the car. The type I have has a 90 degree aluminum manifold and the cone, putting the filter under the air intake in the hatch. The other type come straight out from the MAF leaving the cone tucked into a dead air pocket back in the engine bay, not good either, so I just what to return to the stock airbox/filter. So what power loss should I expect?

[Rot 911]

You will have no loss of power. Probably longer engine life due to the OEM filter doing a better job of filtering.

[Steve@Rennsport]

Originally posted by movin
I've had the K&N cone filter on so long I don't remember if there was any real power increase. I'm tired of not being able to drive in the rain and having to put a Baggie over the filter every-time I wash the car. The type I have has a 90 degree aluminum manifold and the cone, putting the filter under the air intake in the hatch. The other type come straight out from the MAF leaving the cone tucked into a dead air pocket back in the engine bay, not good either, so I just what to return to the stock airbox/filter. So what power loss should I expect?

No losses; a gain!

You'll pick some HP back up again,....the K&N cone filters do not work as well as the factory airbox.

[sammyg2]

Nothing that you will notice.

[yelcab1]

Just smoke and mirror

[Wil Ferch]

The stock intake box has an internal intake trumpet that helps smooth the airflow to the butterfly box. If your cone filter simply bolts a flat ( square) flange onto the mating flange of the metering box, ..then you'll likely even pick up a bit ( not much) with the stock box.

- Wil

[jmohn]

C'mon you guys, he's going to lose 15%-20% of his engine's horse-power; after all, that's what K&N says he gained when he put their filter on. Of course, the good news is, he can get that horse-power back by just using a higher octane gasoline.

And whatever happened to the electric super-charger? I heard "big oil" bought them up 'cause they were just too efficient.

With tongue firmly in cheek,

Jerry M
'78 SC

[Miguel Antonett]

IMO the so called trumpet helps some because the original air box neck is assymetrical where it connects to the metering box. The trumpet allows to "sort of" distribute the air going into the plunger 360* instead of from the air filter side - which is closer and wider.
On the other hand, the least air restrictions in flow the better off you are. Extreme scenario, no filter at all = best flow intake.
Regarding the filter brand name, I believe K&N allows more flow but filters less that the OEM. M2c's.

[Zef]

The only thing you will loose is easy access to that side of engine...

[Zef]

The only thing you will loose is easy access to that side of engine...

[Duckworth]

It sensed on my 911 that there was a 'tiny' boost with the K/N filter. And psycholgically - it felt good having it in the car.

The only time I received a 'seat of pants' gain from K/N was (is) on an old 7 series Bimmer. However, I went from a paper filter that was a medium size - and into the 'BIGGEST' Bucket round K/N I could find - for a greater AREA of filtration. One thing further - the 7 series did not respond much at all until I added a performance fuel pressure regulator. Pressure went from stock 36 psi - to around 46 psi. So, a little extra fuel/air helped finally get that car out of it's own way.

Some of the cones out there on 911's are somewhat bite-size
filters - while the stock filter in many cases has (%) more area than the K/N.

____________________

'82 Targa - sold
'80 928