987 v 986 Air box

[Brad Roberts]

We trimmed it back a little farther. Can you show us how you made the cover for the opening?

[onaFLYer]

Originally Posted by Brad Roberts

We trimmed it back a little farther. Can you show us how you made the cover for the opening?

I just covered the hole with a piece of plastic and glued it on. Had visions of making a smaller muffler with the cut off part, but decided against it. I want it to make noise. With as much as I have going into this car and engine, I plan on keeping it for a long time. Not concerned about resale at this point.

[Brad Roberts]

We glued and bolted an aluminum plate over the hole Used the typical 10/32 cap head screw and some nylocks.

[DenverSteve]

I appreciate the information, and photos. But, I have to ask.... and what? Bigger doesn't mean better. Have you run flow tests on the two? Is there some expected result you were hoping for, and achieved? Thanks in advance.

[Brad Roberts]

I started with common sense

Hum.. I have a 3.4L CaymanS engine in a 986 Boxster, I wonder if I should run a CaymanS intake box? (question I asked myself)

We had a custom cone filter setup in the engine compartment, but they do not seal well to the engine lid or the chassis, and we would see intake air temps 40-50 degrees hotter after just 30minutes of running the car than we did in a stock CaymanS Cold air makes power (or at least closer to ambient)

I had been involved with CaymanS 3.8 conversions and knew the stock box seemed to work just fine with the larger GT3 throttle body on a 3.8

The stock box is too small for the 3.2..... about right for the 2.5 and 2.7 (same piston size in both engines)

When we see vaccuum at full throttle on the dyno, it means something in the intake system is too small and if the intake and the engine is stock..... it means the air box (to me)


B

[MileHighBoxster]

Thanks Brad. It could be common sense, with some of the follow up information not previously seen. Did that vacuum go away?

[Brad Roberts]

It's tough online to see me smiling when I post "tongue in cheek" comments Thanks for not getting offended. It was meant in jest.

Yes, it went away and the engine air inlet temp went WAY down. Down to what we expected to see based on a stock CaymanS. GM has a division dedicated to inlet air temp on the Corvettes. After meeting a person who works in that group, and what I have seen on professionally raced Boxster's and Cayman's... I take air inlet very serious (to the point of covering the entire intake/air box/piping in the gold foil to keep the temps down. Heat kills!!!

Porsche cut the nuts off the Boxster's and Caymans. The trend for larger throttle bodies and larger headers is well founded, but you have to match it with a larger air box. So far the CaymanS airbox has proven to be *good* up to 420hp. I have not tested past that (GrandAm M97 engine in a CaymanS)