Project 987.2 Cayman S: Getting More Out of the Engine to Chase the GT4 Part 3

The IPD plenum uses the 82mm throttle body from a GT3 model. This is much bigger than the stock 74mm one.

We had the Fabspeed cold air intake but we found with the IPD race plenum and the large throttle body that it didn’t fit. We used the carbon fiber airbox plate and the cone filter but had to make our own large diameter intake tube.  The 82mm throttle body was bigger than the 75mm or 3″ tube and we didn’t like this neck down.

We used 3.25″ 90 degree silicone elbows from HPS to make up part of our new large diameter intake tube.

We also used a section of 3.25″ aluminum tube, also from HPS to make the intake.

The Dundon runners were bolted to the heads and the plenum but into place.

The runner clamps were attached to join the runners to the plenum amd all the lines, wires, dash pots and vacuum lines reconnected.


  1. If the dimples in the IPD work, great, but I doubt they make a big enough difference to justify the added costs of adding them. I’d much rather them make the plenum out of a heat resistant plastic.

  2. I’m pretty sure that the dimples work, as it is well known for golf balls. My argument was about the fact that the golf ball is rotating. I guess that you could argue that in this case the dimples are located in turns and transitions (from what I can see), so the flow is rotating. I suppose at maximum intake velocity the dimples are going to have some effects. I know that they can help with fuel atomization near the injector, if you have port injection.

  3. Really looking forward to seeing how the finished project performs on track- the articles and the video released thus far for this project have been some of the most interesting at MotoIQ (all of the articles here are informative and interesting though!).

    Also, thank you Mike and the MotoIQ staff/contributors for the knowledge and information that you share here. I am a long term reader, first time poster, but I’ve read your technical articles since the days of SCC Magazine in the 90’s. I don’t keep up to date with the automotive industry as much these days, but I frequently check this site for interesting tech articles, and the stories your share. Truly appreciate the effort and dedication of all the staff/contributors at MotoIQ.

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