Sloth

Thats the kind of sloppy mistake that ends up costing somebody a lot of money.

Philip in AL

Finally!!
Here is the deal (remember that I will only get about half of this story correct, but you will get the idea).

It is back to the drawing board for Unichip! The system has been removed and Unichip is aware that more work needs to be done before the system is compatible with the GT3. I will get this part wrong, but it has something to do with the GT3 having a closed loop system. When the car was on the dyno and the tuner assumed that it was "heat" that was causing the results to decrease with each run, he was wrong. It was the factory DME causing the unichip (slowly), to revert back to the factory setting. Something like that. It would happen slowly; that's why it would dyno worse and worse. Anyway, if someone wants more detailed info and who to call at Unichip, PM me.

Second, withe the BMC and some special tuning (which I will not discuss on this open board), here are the results:

Base: 327.1 hp and 238.64 ft lb at 7,200 rpm
after Filter: 334.2 hp and 243.74 at 7,200 rpm
After filter and tuning: Peak at 362.5 hp and 244.74 at 7,000

All said and done, I picked up 35.4 hp and 6.1 ft lbs!

I would bet money that these figures are correct. I have messed up the story over the past few days, and have undoubtedly made this tuner sound like a nut to some of you. He is not; he is very well respected, to the tune that the Porsche factory has involved him in some projects.

chris walrod

I would be very afraid to have this guy 'experiment' with a GT3, much even my 1995 993

Too many unanswered questions.. Would you care to tell us who is doing this to your car?

Dont want to dampen your enthusiasm for this tuner, but also do not want you ending up with a holed piston..

rockitman

I would try another dyno. either a dynapak, dynojet or mustang to confirm these results. My recommendation is refund and go back to stock. If your really want to do it right you would go with a Manthey Racing package consisting of new DME, equal length headers, new intake and race cats free flow mufflers. It will be close to 10K but you will get a real 25-30 hp increase. Just my 2 cents.

SundayDriver

There is something very wrong with the math on that last run. HP = Torque X RPM / 5252. The first two match, but with 244.74 ft-lbs at 7,000 rpm you get 326.2 HP. Either the torque and/or RPM are wrong or the HP.

Philip in AL

SundayDriver you are correct. In my haste to post, I made a mistake. It should have read: peak at 7,000 rpm's was 362.4 hp and 271.92. I messed up and quoted the torque figure from the base run at 6,900 rpms and 321.5 hp!
So from base, I picked up (at 7,000 rpm's) 36.2 hp (326.2 vs 362.4) and at 7,000, 27.18 ft lb of torque (244.74 vs 271.92).

Using a .19 multiple, I'm looking at about 431.26 hp and 323.58 ft lb at the crank. Now, while the peak hp was at 7,000, the peak torque occured at 5,000 rpms (289.69 vs 262.13 stock at 5,000).

Forgeting the rpms, peak hp is 362.5 and peak torque is 289.9 at the rwhp and 431hp and 345 ft lb at the crank.

I'll post the actuall charts over the weekend; in the mean time I have an idea for any one who is interested in participating. I have a Vector FX2 performance computer. What if we set it to gauge runs from say, 20mph to 100mph; it will hold 10 runs into memory. I'll make three runs and then overnight the computer to someone with a stock GT3, they make 3 runs and then overnight it to a third GT3 owner with some mods done. He mails it back to me, we average each persons 3 runs and then see what it looks like.

Even if the computer is way off, it will still give an accurate picture (comparison) of the three cars.

Anyone up for it?

Philip

Johninrsf

Philip in Al, I'm curious what your objective is, and why.

Philip in AL

I'm just interested in seeing what kinds of differences small adjustments and horsepower increases make. In other words, if I can spend $1,000 and make the car x amount quicker I would just like to be able to quantify that performance. I don't know, not being able to leave well enough alone has always been a problem of mine!

Larry Herman

If it ain't broke, don't fix it! I think that a GT3 motor falls into this catagory. It's a le$$on that my boys (22 & 20) are just starting to learn.

cosmos

I am no expert but .19 seems high for a rear engine rear drive car. What kind of driveline loss do you expect?

I have always used .12 for front engine rear wheel drive cars. I am thinking that maybe .10 for rear wheel, rear engine cars are more on the realistic side

Steve in FL

I believe the common multiplier for the GT3 is .15

Philip in AL

I worked it backwards. If base was 326.2, and these cars are supposed to be about 381hp (although some say that is slightly underated); 326.2 + 19% equals 388.17.

bob_dallas

Larry - it seems to me they understand that quite well...and your son knew you really wanted that RS wing but that you wouldn't replace it unless it was broken...

Johninrsf

Phil in Al,
Respectfully, FWIW, you're doing the math incorrectly.
326.2 is a 16% reduction from 388.17.
If you think there is a 19% loss from flywheel to rear wheels (which I strongly doubt --I would bet it's closer to 12%), you would divide 326.2 by .81 which yields 402.7.

Larry Herman

Thanks a lot, Bob. You may be right, but I could have done without the dents down the side of the car.