Was thinking I'd see some discussion here about the recent rule changes but didn't see anything. Rules are definitely now written to take some of the advantage away from the detuned cars.

Anybody run their numbers through the calculator to see the impact? Any thoughts?

 

I'm starting NASA GTS2 next season (in an E36 M3 w/ S52) and it's been a bit frustrating waiting on the rules to be officially published as it's delayed decisions on where and how to modify the car.

 

Thanks for the update, I didn't even know the new calculator had been posted. I'll need to go get my dyno sheet which is 100 miles away. I've been running my 3.4 SP996 in GTS3. Curious what effect this change will have as I was planning on focusing on NASA this year.

 

can you summarize the change?

 

http://www.nasagts.com/index.php?opt...per&Itemid=258

Oh boy....

"and horsepower is what matters for acceleration."

 

Very interesting, we were prepping the car to run GTS in 2015, looks like I keep the car over in SCCA ITR, where it the car is competitive.

 

Or just run in ST where they still go by simple HP/Weight.

 

I doubt an ITR car would be competitive in ST or GTS - no air, no brakes, or even decent shocks. It would probably be in PT somewhere.

This should be a pretty good benefit for P cars. Maintain a bit higher hp number since it is using an average. My old GT3 really ramped up in higher rpm but still had a 30 hp spread from the top. Figure that would take about 15 hp off the top with the new calculator or about 120 pounds. That is not insignificant. I hope more Porsche racers come out and run. GTS4 would be perfect for early 996 cup cars or 944 turbos.

 

Pretty simple Mark.

"Power" (in the power to weight ratio) is not calculated as area under the curve. So rather than just take the peak (HP+TQ)/2 the formula looks at the HP data points from the peak 20% of the cars power band. (It's a bit more complicated than that but that's the gist of it)

The reason behind it is this:

When GTS started basically all curves had the same "inverted hockey stick" dyno curve so peak HP was a consistent measurement. With the advent of e-throttle, detuning, and the coming Turbo engines, it was determined to not really represent a consistent power number for the cars in GTS, so it was changed.

Now we don't believe that the formula we have truly measures power differentials based on the simulations we ran on identical cars with different power profiles, but in order to prevent people from gaming the system and creating the same problem in a different way, it had to be watered it down a bit.

 

968's are very competitive in GTS-2. The new power formula helps any car with a "normal" power curve and a 968 sure fits there!

 

I agree with Mike and Chris. The new change should help with the horsepower number for any car that does not have a flat line Hp curve. And, if you do have that, then it does not hurt you at all. At worst it would show no change at all. The change should help with the competitiveness of a 968.

As Chris said, 996 cup cars run in GTS4 nicely. Some restricting, but with the rule change a little less restricting. I have been running a 996 in GTS4 for 3 years now. Came in 3rd at nationals east in Atlanta behind John Graber in another 996 cup and Randy Mueller from Epic Racing in a BMW.

And, Mike, Still love those wheels.

Thanks

Ed

 

I ran the calcs on my car real quick the other day just using a pdf dyno sheet and I only lost like 35 pounds. I bit less than I was hoping. So with a 234 peak rwhp curve nowhere near flat, I am still stuck in GTS3 with non-DOT to be anywhere near competitive. Last year I ran consistent podium times in clean laps but in traffic or on the green drop, the differential was a bit frustrating.

 

Pablo - is there anyway for you to add weight and run GTS2? I'm in the same boat in 4 - only 300hp running light. If I'm ahead it's all good, but passing is tough when I'm down 30-50 hp to the rest of the field.

 

I'm hoping to run a couple of GTS events here in the northeast with my 78 3.0 911 - I run prepared in E, so I have upgraded brakes, a wide body and a 3.8RS wing. (Otherwise, it's pretty tough to run a stock car across the two series). I'm planning to bolt on some taller uprights and a proper 60" wing (along with a front splitter), so that I'll be somewhat competitive against the e36 m3s.

At 190whp, I should be able to run 100 pounds lighter than in PCA - perhaps more with the new formulas! But those e36s have so much development ...

 

Exactly. It is the same here... To run GTS-2 I have to be at like 3350 or something along those lines on DOTs. For DOT GTS3, about 2570 if I recall correctly. I think I am at about 2800 race weight, maybe 50 or so less if I skip Texas Roadhouse the night before.

If I take the RS Barn cams out, then I can do GTS2 with a about 200 lbs of lead on the passenger side and a full tank to start. Which actually feels really porky/heavy and almost unnatural for my beloved 968 to toss around. But it is certainly doable, and has proven competitive in the past. I do have a lot of tire to handle it.

As Mike mentioned before, without a purpose-built motor, the 968 fits best in GTS2 even with the new adjustments which are really not earth-shattering even though they probably will on average will benefit Porsches more when compared to BMWs and other more tunable engines in general.

I will likely return to PCA GT5 in 2015 where I may have some more success as long as one of them pesky well-driven overpowered 1,110 pounds-when-wet air-cooled crappy RS-looking concoctions does not show up )))