Custom Airbox Fabrication
Thread Starter
Joined: Jul 2004
Posts: 600
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From: Carnation, Washington
Custom Airbox Fabrication
Thought some of you might like to see how we fabricated a custom airbox for my German RX-7. The engine is so small compared to the original 3.0 liter four-banger, that the engine compartment looked a bit empty, and we wanted something stylish to fill the space. We fabricated the airbox with the shape of a rotor, but were trying to decide between 2.5 vs 3.0 inch tubing when Lloyd (SlammedGSL) offered me some tubing he had, which turned out to be 2.75 inch, fit right into the inlet of the Porsche filter. I was trying to keep this whole thing looking as OEM as possible, but the polished tubing looks so nice I will just have a little bling!
We made the airbox from flat steel sheet, used a flanging tool on the top piece, formed the side pieces by bending around a rod, then put the curve in using the shrinking tool shown in the one photo. My welder, Sean O'Brien, tig welded everything, and I smoothed it out with Polyester filler (Bondo). The rubber elbow and connector are things I picked up at PullAPart. Thanks to Peter Ivanyi who made the 9 inch vinyl decal, just the perfect finishing touch.
The carb and intake manifold are 1976-78 style RX-4, actually from an old Cosmo I junked back in the 1980s. We have not yet tested this for power, but with the porting and parts we used, I am guessing we have about 160-165 horsepower, and the car weighs about 3,000 pounds, so performance is about like a stock 2nd gen car. Handling is excellent, and the stock Brembo brakes are outstanding. Doesn't have the Go-Kart feel of a 3rd gen, but it is the best handling car I have ever owned. The Porsche guys tell me that in stock form, the 968 is the best handling car Porsche ever made.
We made the airbox from flat steel sheet, used a flanging tool on the top piece, formed the side pieces by bending around a rod, then put the curve in using the shrinking tool shown in the one photo. My welder, Sean O'Brien, tig welded everything, and I smoothed it out with Polyester filler (Bondo). The rubber elbow and connector are things I picked up at PullAPart. Thanks to Peter Ivanyi who made the 9 inch vinyl decal, just the perfect finishing touch.
The carb and intake manifold are 1976-78 style RX-4, actually from an old Cosmo I junked back in the 1980s. We have not yet tested this for power, but with the porting and parts we used, I am guessing we have about 160-165 horsepower, and the car weighs about 3,000 pounds, so performance is about like a stock 2nd gen car. Handling is excellent, and the stock Brembo brakes are outstanding. Doesn't have the Go-Kart feel of a 3rd gen, but it is the best handling car I have ever owned. The Porsche guys tell me that in stock form, the 968 is the best handling car Porsche ever made.
Wait? WTF... It looks like a porsche but it has the heart of an rx, wait... is it a porsche? 
I didn't even think it had a rotary when I first looked at the pictures, but it does.
And it is neat, what ever it is...
I didn't even think it had a rotary when I first looked at the pictures, but it does.
And it is neat, what ever it is...
