OP
Awesome! I look forward to reading your impressions of the Steve Wong chip.
The single pulley is an easy enough DIY. When I bought mine the parts were around $100 but that was four or five years ago. Sunset Porsche in Portland is where I ordered them. If you drive in traffic a lot this is not a good mod, but for the track it makes sense.
Even in traffic, the single pulley probably makes sense for me, since my shorter gearing means higher revs and the dual pulley was to turn the alternator pulley faster in low-rev circumstances. Cruising at 80 in my car means 4000 rpm in 5th gear (and there is no 6th).
The Steve Wong chip is awesome. I've never needed two cranks to start the car; idle is always great, cold or hot, and when I'm shifting gently or quickly, the problem of the idle dipping too low when the accelerator is suddenly released (which I used to get sometimes with my 964 motor) is gone. It's like driving a very modern car -- except that it's inside (in my case) a 38-year-old chassis.
I asked Steve about your situation, since I spent the day with him at the dyno. He explained that he got to see Porsche programming for the 993 models that came with lightened flywheels (I forget the specific race model designation right now), and that he got to see -- and adapt for street car use -- the way Porsche's engineers changed the programming for the lower-mass flywheels.
He spent the day with me optimizing the programming for my car based on air/fuel results as we dyno'd the car about 20 times. Maybe not surprisingly, the programming we ended up with was almost identical to his off-the-shelf 993 chip, which is based on (among other things) all of the 993's he's dyno'd and tested.
A stock 993 should dyno at about 230 at the wheels, based on the commonly-accepted (although no doubt inaccurate) theory of ~15% drivetrain loss. Porsche's figures are conservative though, and I've heard most 993s will dyno around 245 at the wheels. With Steve's chip, my best run was 264 at the wheels, which is not bad at all.
More importantly, my air-fuel numbers were flat as a board, from low revs to high. The factory chip line goes from too-lean down low to too-rich up high. But the factory has to make their chip function as a one-size-fits-all item for all 993 engines in every possible set of driving circumstances. Steve can target your car's particular setup and use.
I was so happy with the chip that I asked for a decal. Here I am at Willow Springs yesterday morning:
(Forgive my ugly home-made bolt-on wing and front splitter. But Willow Springs is a fast enough track that the aero stuff helps. You can see I also take off my headlights to feed more air to my oil coolers.)





