Alright, step 2 was to get rid of the old lean flash and get a new safer one into the car, so Church Automotive Testing here in LA made a new safe baseline 91 octane tune for my K16 with the Afterhours exhaust.

Safer AFR, less ignition advance than my old tune, driveability is just fantastic and they got another 5hp over the above (my old) flash. Again, dyno numbers must only be used at relative, as far as I measured so far with PBox, just this Afterhours exhaust and the Church safe street tune, power went up with appr 90 whp (based on OEM awhp being appr 360, my safe tune rwhp is appr 450hp doing a few PerformanceBox runs).

I have calculated vehicle weight using numbers from the weightloss thread but as soon as I have weighed the car I'll post up more numbers.

One note of learning experience: I used to have big issues with the 996TT clutch assist on my old tune, and now those issues are essentially gone(!). The tune is so smooth, the throttle control incredible, and all of a sudden no problem in uphill starts, shifting from 1st to 2nd never any of the weirdness that used to go on. It's like a completely different clutch even, although it only has to do with throttle control.

I'm very very impressed with what a good tuner can do even on just a short tuning session. I now recognize the type of feedback people give after getting flash upgrades from the good tuners active on this forum!

Next up will be a more aggressive race-gas tune once Afterhours mounted thermoelements in the headers so tuner can monitor exhaust temps.

 

Afterhours weighed the exhausts the other day.

OEM 45lbs.
Afterhours exhaust 26lbs.

The car also went back on dyno again last Friday and it pushes 493 rwhp, dyno hp, (after 2wd conversion). The dyno ppl themselves say readings are a bit high and for comparison only purpose. So comparing beyond just the exhaust:

AWD, OEM exhaust, 1.0 bar tune: 442 awhp.
RWD, Afterhours exhaust, 1.0 bar new smoother/safer tune: 493 rwhp

As another reference, on OEM program, the exhaust alone, no flash job and no drivetrain job, made 19.8 hp and 18.7 ft lb.

 

Great results MrWhite! Now I'm curious to know how she will perform on the track...


I have a little question about running on stock ECU program with a free flowing exhaust: is it dangerous to drive the car? Will the ECU adapt the fueling for the extra air going into the engine?Or is there the risk of running too lean?

 

Congrats and thanks for taking the time to keep this up todate.

 

Me too! (curious)

Stock ECU, open exhaust: I am sure a bunch of tuners can chime in, however as far as I understand, the lambda-sensors will measure AFR. If you go lean the ECU will compensate. With just an exhaust you'll go from 415-435 US hp (or 420-440hp), that's still way below stock injector capacity so the ECU has a lot of flow to keep up fuel flow to not run lean. If lean condition comes up, knock sensor is supposed to detect that and will change ignition timing to safeguard the engine.

IF ECU detects too much deviation from "should be" values, I think it can possible trigger an engine warning light and ECU will, for safety, add fuel to keep engnie combustion/exhaust relatively cool and possibly also change ignition timing to be on the safe side.

That's general theory and don't hold me responsible if you blow your engine up.

I'd appreciate if someone with A LOT of experience could confirm that these mechanisms are usually working in the 996TT OEM program or if you've seen cars getting trouble with this.

 

Dbl post weird internet connection here