NASA GTS rule changes - any thoughts?
#16
Jas0nn. I think your package with good gear ratios, a decent power curve, and some aero to keep that nose planted when you need it could be a good e36 contender. But indeed, there are some well developed and driven GTS2 e36s out there.
With that said, there has been a lot of e36 GTS2/3 to e46 GTS3 migration action in the past two years and I feel GTS2 is really again a good class that can be competitively campaigned on the e36 platform as well as several Porsches such as yours, the 968, well prepped 944T, and developed (read aero) Boxsters.
With that said, there has been a lot of e36 GTS2/3 to e46 GTS3 migration action in the past two years and I feel GTS2 is really again a good class that can be competitively campaigned on the e36 platform as well as several Porsches such as yours, the 968, well prepped 944T, and developed (read aero) Boxsters.
#17
A few months back I picked up a nicely set up e36 that was too nice and too cheap to pass up. I just got a race license and figured I’d spend the first year learning the ropes, so having a max’ed out front runner wasn’t my first priority. GTS is the most popular class at my home track. I had hoped that the new rules might allow me to squeeze my car into GTS2 with minimal ballast, but that doesn’t appear to be the case.
My e36 has a lightly tweaked S52. Putting my numbers into the calculator, I come up with about 228 HP, which is only 2 HP lower than peak value. That means my minimum weight for GTS3 would be 2500 lbs (impossible to achieve, without seriously hacking apart the car and/or spending a fortune on carbon fiber) or 3,300 lbs for GTS2, which seems as if it would be a pig with only 228 HP. So the car is kind of stuck in no man’s land for GTS. Looks as if I’ll just play around at the back of the pack for 2015 and decide if I’d rather do an S54 swap or switch to a different car altogether for 2016.
#18
My e36 has a lightly tweaked S52. Putting my numbers into the calculator, I come up with about 228 HP, which is only 2 HP lower than peak value. That means my minimum weight for GTS3 would be 2500 lbs (impossible to achieve, without seriously hacking apart the car and/or spending a fortune on carbon fiber) or 3,300 lbs for GTS2, which seems as if it would be a pig with only 228 HP. So the car is kind of stuck in no man’s land for GTS. Looks as if I’ll just play around at the back of the pack for 2015 and decide if I’d rather do an S54 swap or switch to a different car altogether for 2016.
#19
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.
"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.
(GT3 vs a Porsche 928)....... if both were 330rwhp, even though the torque was greater than hP on the 928, there is no reason for penalizing the 928, if the GT3 was able to keep engine RPM in the max HP range during its gear spacing.
I was a big proponent of HP averaging, as this is real answer here.
since acceleration at any vehicle speed is proportional to HP, it makes perfect sense. if you took a cars HP and averaged it over 4 data points ,that would be a fair way to asses HP. example, a turbo with 410rwhp might only have an average of 350rwhp with a peaky HP curve, while my car at 375rwhp might have the same average hp over its use range. averaging would make these two cars fair to compete, if they were the same weight.
Now, the other factor ive always fought for ,was an absolute weight concession, where handling and braking are huge advantages for more than 70% of a lap.
But, folks will continue to make complex algorithms and miss the most important weighted factors by a mile!
It seems that the averaging technique is now being used.... something I recommended many years ago.
I just hope that the absolute weight might fall into the factors too someday soon! (e.g. above 2200lbs to 2499lbs, 2500lbs to 2699lbs and maybe 2700lbs to 3000lbs all getting some type of weight concession or penalty)
Last edited by mark kibort; 12-28-2014 at 04:17 PM.
#20
http://www.nasagts.com/index.php?opt...per&Itemid=258
Oh boy....
"and horsepower is what matters for acceleration."
Oh boy....
"and horsepower is what matters for acceleration."
acceleration = HP /(mass x velocity)...... problem is, not many are able to grasp the simple physics identity! they shouldn't cry about it, they should accept it and if they don't understand it, they should try and figure it out so in their mind they can grasp the concept!
Love it! this guy gets it!!
http://www.nasagts.com/index.php?opt...per&Itemid=258
#21
Bingo!
sounds like a move in the right direction! close ratio gear boxes should be looked at too, because they can keep someone in the Peak HP range , to a greater level than someone with wide spaced gears.
sounds like a move in the right direction! close ratio gear boxes should be looked at too, because they can keep someone in the Peak HP range , to a greater level than someone with wide spaced gears.
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
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
#22
This. Restrictors are easy, and are trivially tunable. And they are non-linear in a good way: max power is reduced by a greater proportion than lower parts of the rev range, so you get a flatter power band.
#23
That was one of the reasons for only using 20% of the RPM band to compute the average power. In a typical car with 7000 RPM redline, 20% = a 1400 RPM slice of the power band, which helps account for cars with close ratios staying in a narrow band close to peak power.
#24
Flink and Magnetic: Thanks for the suggestion. I may give it a shot. My home track (NOLA) is fairly fast and I’m not sure how much fun it’ll be to drive something with even less power than I have now, but I suppose it’s all relative. GTS3 also has better field sizes than GTS2, but maybe the current trend of newer, detuned cars running in lower classes will push some of the current e36 GTS3 crowd down into GTS2.
#25
Ok, I'll admit it, I an technically challenged. How do we get the "Raw Data" from dyno runs taken after Jan 15?
Do we get a thumb drive and submit it? Do we now need new software to read this data?
Do we get a thumb drive and submit it? Do we now need new software to read this data?
#26
the problem there could be the higher reving cars could get a big break, becuause the lower reving cars could actually have to live with a 30% drop of RPM with some wider gears, and actually have a lower average hp utilization for the same Peak HP.
#27
I believe the top 20% (i.e. highest 20%) of the HP as per the dyno sheet will be used. Once that number is computed then it is averaged with the peak HP number. I am thinking once everyone sends in their dyno sheet electronically the program with do the computation automatically.
Reducing the range to 20% and then averaging was a way to get this "average hp" concept accepted vs a more progressive change which would have alienated a lot of people!!!
Reducing the range to 20% and then averaging was a way to get this "average hp" concept accepted vs a more progressive change which would have alienated a lot of people!!!
#28
I believe the top 20% (i.e. highest 20%) of the HP as per the dyno sheet will be used. Once that number is computed then it is averaged with the peak HP number. I am thinking once everyone sends in their dyno sheet electronically the program with do the computation automatically.
Reducing the range to 20% and then averaging was a way to get this "average hp" concept accepted vs a more progressive change which would have alienated a lot of people!!!
Reducing the range to 20% and then averaging was a way to get this "average hp" concept accepted vs a more progressive change which would have alienated a lot of people!!!
Good to see things moving in the right direction though.
#29
But, you can get the runs on a thumb drive and download the software and look at it yourself.
Thanks
Ed
#30
Mark:
While I agree the less weight is it's own advantage there are places like VIR and Road America where it seems like the heavier/more HP argument seems to do pretty good! I think that is a choice the driver will get to make for the foreseeable future!!!
While I agree the less weight is it's own advantage there are places like VIR and Road America where it seems like the heavier/more HP argument seems to do pretty good! I think that is a choice the driver will get to make for the foreseeable future!!!