CosmosMpower

Has anyone run a 997.1 GT3 in NASA time trials? The current classing for GT3 is TT1, TT2 or TT3 based on power to weight and +/- based on tires and a few factors.

I'm hoping to fit my car in to TT3 which is 10:1 power (whp) to weight (with driver). If you take peak hp at 8500, 8000, 7500, 7000 and average the 4 it should be about 360 rwhp. Stock weight for a US sunroof car is around 3,250 with a full tank of gas. I have a OEM club sport back half cage (40 lbs) but lighter Recaros and I weigh about 155 so I should be about 3400.

3400/360= 9.44 but using factory aero you get to add back .4 so 9.84 which is really close to 10:1. Anyone been able to limit power a bit or add a little weight to sneak in to TT3 at 10:1?

Spyerx

Weigh and dyno your car. I think it may weigh less and make more power than that. Mine does on both. Maybe could get a tune that dials it back...

CosmosMpower

The weight is with driver, I'm pretty skinny though. What did your car weigh without you in it? Also the power isn't just peak, it's at redline then subtract, 500 rpm, 1000 rpm, 1500 rpm and average the 4 I believe.

You may be right though may need to detune a little bit.

Spyerx

3040 w a half tank so about 3230 with me and gear on
Id have to pull a dyno grap. HP was flat at about 7500 to redline tho.

CosmosMpower

That seems abnormally light for a .1. I read quite a few posts at 3200-3210 with 1/2 tank no driver.

AudiOn19s

The power average is not based on redline. It's peak power on the graph, then measurements every 500 rpm up to 1500 rpm away from peak power but this includes both sides of the graph away from peak power.

So your car is going to make it's peak around 7400-7600 meaning you'll get at least one measurment after peak power as well. In the end the power is pretty flat at the top of the curve in our cars. My average number was almost the same as my peak number. I'd expect yours to be more like 370 if I was taking a stab at it. not a huge difference but that much further away from the 10:1 goal.

Bottom line our cars fit well in the old rule set at 9:0 :1 with factory aero. They just aren't a great fit at 10:1 esp since it's not easy for us to be able to tune the car differently to adjust power values.

Just bolt on slicks and bigger wings and take as much weight as possible out of the car and try for TT2 instead. You can do every trick in the book and still not be at at the 8:1 for TT2.

CosmosMpower

I don't think the car will be competitive in TT2. The car just can't make enough power and I don't want to strip a street/semi-track nice GT3 into a race car to run TT. Does anyone make a tune that could get the car down to around 350 average whp? Then you can run around stock weight and make 10:1 with the factory aero.

Sterling Doc

At your weight, it looks like you escape the rear engine penalty.
If you run 275 or less tires, you get 0.3 back. BFG's run very wide in the 275/35/18 size, and may work for you.

However, you'll want to have a little cushion for dyno variability - the penaties for going over are pretty harsh, and ramp up quickly.

CosmosMpower

I don't think I can run a 275 on the back of a 997 GT3, that's like a Cayman rear tire size. My rear wheel is 18X12 also, that would be a hell of a stretch.

Surfbum

isn't there a sequential penalty?
My cup ended up as TT1 and I am a lot heavier than 155.

Surfbum

Sorry, I thought it was a cup

CosmosMpower

Nope just a poverty .1 street GT3

Thundermoose

What kind of times are you running in current trim? Tires?

Spyerx

My RS is a stripper (literally 0 option with halogen headlights). This is with 1/2 bar, seats, harnesses, bbs wheels, iron brakes. Full interior though.

SG_M3

Why not make a couple of restrictor plates and see what A/F does on the dyno?