chillindrdude

Hi all.

had my mk2 GT3 in the shop to have the coolant lines pinned. also took the opportunity to have the lsd rebuilt (it had degraded to 'open') and a function-first shifter installed.

i received a complimentary dyno, just to make sure everything wasn't leaking at load.

dyno-stock by Neil Lee, on Flickr

alittle dismayed by the results, as were the shop. they kindly, cleaned the MAF, reset the ECU and redyno'd. results were about the same.

i see dyno figures of stock 997.2 GT3 anywhere from ~410-ish to 370s WHP. those that got the higher figures insist that Porsche understates the power output.

the 370s WHP is what i'd expect if the 435 CrankHP state figures are correct, and the assumed 15% drivetrain loss.

it was postulated that it was likely fuel quality. Due to recent foul weather, the car did sit for about a month. And I use Shell, which I was told, not as good as Exxon/Sunoco.

Do you think I should run a bottle of detergent fuel cleaner to flush out the lines/injectors? In addition to running the tank nearly dry and try again with (hopefully) better gas? I use 93 octane only.

I also assume, even for a 6 year old, 38K mileage engine, power outputs should still be within 1% of what it was brand new?

Lastly, anyone think this is something more ominous, a red flag on the engine health? Car PPI'd clean, but no compression test, mainly due to seller reputation and clean DME (only range 1 revs)

audipwr1

Mine makes 400 and was told that was high side figure

Dynos not all created equal should try to dyno with another GT

Spyerx

you'd really want to get other 997 gt3 on THAT dyno. Really they are only good for comparison of A to B changes. For example, on Cobbs socal dyno, my 997.1 (stock except for cup headers and cobb tune) on 101 octane did 408 wheel. That's probably a bit high. BUT, the variation to the 91 tune and no headers, those #'s are about what you'd expect as deltas given the comparisons. So, really only useful to show the GAIN/LOSSES, not really the raw numbers compared to other dynos.

I wouldn't worry too much.

chillindrdude

Sorry for freaking out. I appreciate the collective reassurances/knowledge share.

jaundice

I had my 2010 GT3 on Cobb's Mustang dyno here in Texas. With their stage 2 custom tune and catless headers/center bypass, I made 415 rwhp. They said most stock GT3's make 370-390 on their dyno. This was with 93 octane. My car also has 50,000 miles on it.

golfnutintib

i personally think its the yellow paint job

guards red cars have highest hp

jk

bogey1

Has TPC not had another 997 GT3 on that dyno? Seems like they would have given all the great work they do on track cars and the exhaust products?

nwGTS

Tom had his .1 GT3 on (I believe) that dyno. Check out his thread for numbers.

Spyerx

I will say this. The power curve looks weird. Is the intake resonator flap working? Can be tested with piwis or durametric.

chillindrdude

per TPC, they suspect the knock sensor being triggered by bad gas and killing power.

hope to redyno in the spring. may have a cobb tune by then.

ClickClickBoom

Looks like the vtec didnt didn't kick in. Seriously something started to pull power at 6200 and quickly. I'd lean toward that knock sensor. I googled 'gt3 dyno tpc'. Other charts look different than yours and are making 380-90ish.

MC 968CS

I think there is a problem, the curve should rise significantly more from 6000. Worth looking into it more.

F1CrazyDriver

unfortunately it's not as direct- as comparing to other vehicles in other location with other dynos.
that said like some have stated -the up tick should be much more visible in th dyno in later rpm. change o2's - cheap insurance.should be change every few years anyway for best performance. make sure air filter is good/new. spark plugs/ coil packs / reset tb position, check exhaust no leaks - and do over.
Log if you can.

Wolfk

Just out of interest, what does the bottom graph represent? Peculiar in that graph, the readings between the two runs are mostly the opposite of each other, and that they go off scale several times during the run.

chillindrdude