Drilling holes in the air box?
#1
Instructor
Thread Starter
Drilling holes in the air box?
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!
#3
Race Car
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.
I cut the entire side off of mine, but that was partly because I needed clearance for the engine hinge.
#6
Rennlist Member
(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.)
#7
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.
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#9
Still plays with cars.
Lifetime Rennlist
Member
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.
#11
Still plays with cars.
Lifetime Rennlist
Member
Ice, the gain was because Porsche had to stifle the intake to meet certain European noise regulations.
#12
RL Technical Advisor
Still,..its free power and combined with other things, well worth doing for Motronic cars, only.
#14
Team Owner
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