AudiOn19s

Since this community is about sharing and the only other instance I've seen of this was deep in a 4.0L build thread I thought I'd share.

I recently installed the 82mm Throttle body off of the 997 GT3 onto my car. I did so WITHOUT the use of the $850 IPD plenum. The parts I used are as follows:

Bosch Throttle Body - 0280750473 (has GT3 part number on it but it's not sold as the genuine part hence much cheaper). < $140 if you shop around a little
Throttle Body Gasket - 997.110.319.90 $4.50
MAF pipe - 997.110.321.92 - $72
Rubber Sleeve - 997.110.621.90 - $20

For the Plenum - I used the stock plenum and paid a fabricator friend of mine $75 to hand port it. We agreed that hand porting was the best bet because of the small wall thickness that's left on the stock piece, didn't want to chance having it in a machine and going too thin so he did everything by hand measuring frequently along the way to make sure we didn't go too thin in any spots. I actually had a spare OEM plenum that I traded some labor for (thanks Doug!) but you don't need a spare one for this job unless you can't have the car down while the work is being done.

Ported Plenum pictures:



Driving impressions and Disclaimer - I've always been pretty skeptical of the claims of the Plenum, there have been tests here that show mid range gains but zero up top. I'd have to say my seat of the pants driving experience shares the same impression. I don't think it's any better on top end power but it does seem to feel a little better in the middle. It's certainly not a ground breaking power breakthrough for our cars. To be honest I've had the parts sitting there for awhile and finally just decided to do it as there's really not much else to do to the car. What I can tell you is that it integrates flawlessly. The car started up first attempt, idles no different, no CEL, no nothing it just worked and away I went.

I'll be back to Mid Ohio in September where I have loads of data from over the years, that's where I'll be able to tell if it really makes a difference on the stopwatch or not. The car ran without issue being hot lapped by 2 drivers this weekend at Pitt Race though so no complaints.

What i wouldn't suggest to someone is to do this as one of the first modifications they do to the car. Do it after you've done the stuff that improves the car drastically like suspension, brakes and exhaust.

Nickshu

Good work and great feedback. I have one of the IPD GT3 plenums sitting in a box on my desk, have been hesitant to bother to install it. I had one on my C2 and on that car my experience was similar to you...added a little in the middle but not much other difference noted (but if course that's a whole different engine).

RossP

Would be interested to see Dyno charts on this. Mid-range gains are still gains!

AudiOn19s

Me too...but I'm not interested enough to pay for dyno time to do back to back runs to compare :-)

If I get time in September I'll swap TB's at the track and can run back to back sessions to compare data, that'll be the better judge to me to see if I get any difference in acceleration rates off of slow corners.

tom03

Thank's Andy for sharing this. Great details ! I'm very interested in the results.

I know a company which changes the 76 mm Throttle body to 79 mm (an expensive solution). Together with ported Intake Manifold and ported heads (or RS heads) this will gain some torque/power (with an remapping)

Tom

Blitz128

I did the 82mm throttle body and IPD plenum on my '04.... results same as others above...and the "upgrade" was after exhaust.... thinking both go together... no dyno results but seat of the pants tells me that money better spent in my case on improving my driving ...

RennOracle

of course there isn't, you need to port the intakes too lol. They are tiny. Check here again after you do it. If you want measures to guide you, check the 4.0 rs ones.

IanM

https://rennlist.com/forums/996-gt2-...results-4.html

I did before and after dyno testing of the IPD w/ 82mm TB - made power everywhere, including +30hp at 6000rpm, and peak +17hp and +23ftlb. An additional healthy bump when I removed the cats. I'm still very happy with the upgrades.

StephenB

Andy,
Please let us know your thoughts from your track day. During my search for a GT3 nearly a decade ago, I came across one with 380rwhp with the larger throttle body plus tune and a stack of dyno sheets to prove it. I passed on the car since it had 23K type II overrevs due to the raised rev limit to GT3 cup specs. I purchased the list of parts for my GT3 (except Cargraphic headers) but never installed any of them. I couldn't find the old emails that had the tuner info and I was not able to find any further info from vendors. I may just install the parts sans tune and see what happens if your experience is positive. I need to go out to the garage and dig out the parts...

Edit:
I dug the parts out of the bin last night. I think this is all of them:
997.605.116.01 throttle body
997.110.319.90 dichtung
996.110.116.90 verteilerstueck
997.110.321.92 rohr
997.110.621.90 gummimuffe
996.110.686.50 gummimuffe
996.110.685.52 gummimuffe
999.702.246.40 grommet
999.702.221.40 grommet
O-ring with part number missing