veduta

Been looking on E-bay and other forums for my first 911 and I've noticed a fair amount of SC's with large diameter holes drilled into the air box. Can anyone please tell me why some people do this and what if any are the advantages? Thanks!

mfyoung1086

to increase the airflow of he stock box

JackOlsen

More realistically, for the cool sound it produces. I've never heard about there being an actual restriction in any of the flat-six engines. But it definitely can't hurt airflow.

I cut the entire side off of mine, but that was partly because I needed clearance for the engine hinge.

User 4221

Wouldn't a cone filter attached to the AFM accomplish the same result?

theiceman

its all about posing and intake noise.. no other gains ..

race911

Uh, no cone filters or such for a CIS system.

(And yeah, what was the first one I did? A '74 circa 1980 that didn't do a damn thing other than allowing the air filter to get wet.)

KNS

The airbox covers for the CIS airbox are no longer available (NLA). When the time comes to sell your car the next buyer may or may not be so thrilled to see a bunch of holes drilled into it. Unless you're keeping your car forever you might want to source a nice, used second cover to drill into.

RedGTS

Ive wondered about this as well, I have 82sc with 3ltr
Just performance filter and leave it alone it sounds like

Bob Rouleau

It was shown that cutting 5 one inch holes in the airbox cover of a 993 gave a 7 HP increase. This was documented with dyno tests at PCA Tech Tactics and subsequently published in Panorama Magazine. I can't speak for other models.

theiceman

just shows the 993 wasnt optimised to begin with .. sad ..

Bob Rouleau

Ice, the gain was because Porsche had to stifle the intake to meet certain European noise regulations.

Steve Weiner-Rennsport Systems

We only measured 3 BHP on our engine dyno,...

Still,..its free power and combined with other things, well worth doing for Motronic cars, only.

JackOlsen

Plus, it sounds cool.

theiceman

why i actually have a spare cover for my SC .. think il go get my door hole cutter and go drill me some holes .. what could possibly go wrong