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I didn't see any threads on this subject already so i decided to start one. A friend of mine in the PCA has upgraded his 2007 Cayman S with an IPD plenum. I have a 2004 986 Boxster S. He offered his old TB and plenum to me for a very low price and said that there may be a small performance gain by doing so. (Bigger Inside Diameter?) Has anyone tried putting a 987 TB into a 986 before? If so, does it fit, and does it actually provide more HP? Thanks for reading! Look forward to your feedback.
don't recommend a 987 plenum as there is a resonance flapper on it that your ecu doesn't have the logic to control (you could try slaving it to the flapper on your intake manifold, but from what I've read they open and close at different times). you could mebbe just remove the flapper and plug the holes? what folks are doing here is using a 996 or 997 plenum instead - the 987/996/997 throttle bodies are all the same. you will have to do some creative plumbing to get from the throttle body to your air box - some suggestions include a silicone reducing elbow off of the throttle body (3.25" to 3" if I recall correctly) and removing the tab on the engine bay that tends to interfere.
Thanks for the quick feedback TRK. So, it sounds like the TB itself may be of some use, but the T plenum would be better off being omitted. Would the 987 TB fit and attach directly to my 986 intake plenum as it is"? "Creative plumbing" definitely would be required on the intake side! LOL. It appears that the TB location is not the same in the 987 & 986 model, so i was expecting that the snorkel would need modification or replacement. I have no idea how to slave the 2nd butterfly valve...
I don't *think* the bigger throttle body will fit on the original plenum. Pedro offers a throttle body boring service if you want to make your original larger, or a 997 plenum is only $40.
the resonance flappers are pneumatic, so all you would need is a vacuum 'T' fitting and some vacuum line to tie it in with your other flapper.
Thank you for the feedback. i think i will pass on the inexpensive Throttle Body & T Plenum offer from my friend. If anyone needs one for a 987, i can give you his contact info. Id rather save up and get the Techno Power 2 Kit instead.
