Gt3stig

The 07 997TT has 473 hp and 502 lbs of tq. Does anyone know how this is achieved?

What is the difference between the engines.

Many thanks!

CincyScott

Lots of stuff is different. Turbos, intercoolers, cams, intake, etc. The biggest difference are the turbos, though.

Fishey

Boost Pressure is the biggest difference.

Kevin

Smaller turbine wheels spinning up faster due to the VNT, which in turn generate more RPM sooner over the rev range. This will generate more boost sooner/quicker which develops more low RPM torque.. The compressor wheel is more efficient and larger vs the K16 or K24 wheels.

And finally the factory mapping allows over 17 psi (Sport Chrono of boost pressure vs 7 psi (stock).

dprantl

I suppose this would be a good place to ask. Has anyone fitted stock 997TT VNT turbochargers to the 996TT, or would that require more work than it is worth with all the other turbo upgrades available (especially if the focus was to reduce lag and increase low RPM torque)?

Dan

Kevin

yes, it's a mod.. However an expensive one at that.. Price out a set of 997GT2 VNT's.. Building efficient K16 hybrids with the 997GT2 compressor will give you useable boost off idle..

powdrhound

Kevin's K16/997GT2RS zero clearance turbos will give the VTGs a run for their money. They are custom built by Kevin with ported housings funneling more air to the turbine. They spool just about as fast as VTGs and pull all the way to 7500+ without let up or overspeeding. Mid range torque is huge. Note that these turbos are at 500whp at 4000rpm rising to almost 600whp by 7500. This is a run with Kevins 91 octane tune running 1.25 bar on my 3.8L Mezger. Engine is 100% emission legal. Output is limited by the capacity of the MAF. I have over 60hrs of hard track use on these turbos and they have been flawless. I would not go to the trouble to install VTGs which I consider to be more fragile than traditional turbos. A friend last weekend granaded one of his VTGs after running them hard at the track over the last year. He probably had 15-20 hrs of track use on them.

Fastboy

672 ft lbs torque--wow!

gophaster

Powder, so you are running a tuned oem ECU correct? Not a stand alone system. Has your car always been K16 based?

I wonder how the GT2RS wheels compare to the 16g/billet wheels some of the other tuners run. I'd imagine they are somewhat similar in overall performance. Anyway, that sounds like a really great/strong setup and I know you love to use oem parts. Very cool

powdrhound

SYes, OEM ECU. My car came from RUF with their write protected ECU and their K24 hybrid turbos. I swapped both for Kevin's programming and turbos. My understanding is that the billet compressor wheel is a little heavier than the OEM 997GT2RS wheel. I think Kevin is the only guy that actually ports the hot side housing to funnel more air flow to the turbine. There is a lot of custom work and hand porting that goes into Kevin's turbos. Everyone else pretty much just stuffs a bigger billet compressor wheel in there and calls it a day. This and the zero clearance process are the little things that make a difference in the end in my opinion.

gophaster

Thanks for the details. Very interesting stuff. Amazing what can be done with those little k16's in the right hands. Yeah, from what I have found with other tuners the hot side is typically left untouched. Thanks again for the always great (and often very enlightening) info

powdrhound

K16 hot-side is actually huge compared to the VTG hotside. Those are tiny in comparison.

asmperformance

Just curious as to what type of fuel you're running on to get away with what looks like .9 lambda?

powdrhound

The A/F ratios on the graph are wrong. They are actually right at 12.0 (about 0.8 lambda) instead of 13.0. I have a quad tip exhaust and the exhaust probe was not inserted far enough into the exhaust stream on the this run which gave it a false reading. When we noticed that we pushed the probe further in so it was fully within the exhaust stream and the reading was right at 12.0 across the board which also matched what we were showing on our datalogger.

asmperformance

Thanks, I figured it was something like that. I always use an O2 bung or install one just for that reason.