Rule Change Proposal: Section 4 Classification (for Diesels)

[ianacole]

Adjust the classification rules to include:

 

4.a) the horsepower value from the single run with the highest horsepower reading (for cars with higher horsepower than torque, and for diesels);

 

4.b) the average of horsepower and torque from the single run with the highest average of those values (for cars with higher torque than horsepower, excluding diesels);

[Lemming]

Before voting, can you give some details on this? Why are diesels exempt from B?

[ianacole]

The arguement is that deisels make their maximum torque at such a low RPM that they are getting penalized for a power rating that is unusable in racing. Therefore they should just use HP to calculate their car's classification.

[Eric W.]

The arguement is that deisels make their maximum torque at such a low RPM that they are getting penalized for a power rating that is unusable in racing. Therefore they should just use HP to calculate their car's classification.

 

cant you tune for that and/or run different gearing?

[juliancates]

The downside is that it gives diesels a free pass when it comes to torque. Say it's a 200hp car with 400 peak tq in the "unusable" range, and say... "only" 300 in the "usable" range. Of course I made these numbers up, but if I were to consider the type of hp/tq my last diesel truck made, it's not unreasonable. ANYWAY... my point here is that if there is some legitimate disadvantage, it shouldn't be rectified by giving a free pass and completely disregarding torque from the calculation.

[Jim P.]

Diesels rpm limits are usually below 5252 rpm which is where gasoline engines' horsepower exceeds the torque. In order for a diesel to make decent power it must cross the 5252 rpm line and most don't. The Audi racing diesels are reportedly in the 8000 rpm range so they would be comparable to a gasoline engine. So rather than lumping all diesel engines in one category - why not group all engines whose max RPM is less than 5252?

 

Link to explain why all engines Torque is more than Horsepower below 5252 RPM

[RSCoupe]

...The Audi racing diesels are reportedly in the 8000 rpm range so they would be comparable to a gasoline engine...

 

The red line of the Audi R15 TDI is 5000 rpm.

 

I vote to not allow the diesels an exception from 4.b.

[JSG1901]

...The Audi racing diesels are reportedly in the 8000 rpm range so they would be comparable to a gasoline engine...

 

The red line of the Audi R15 TDI is 5000 rpm.

 

I vote to not allow the diesels an exception from 4.b.

I agree. Or leave diesels out altogether.

[Lemming]

I voted no for lack of data and to keep from opening up a can of worms. If you remember from last year, there are a number of drivers that have cars that make high torque numbers down low and asked for this exception and were denied (Chuck B comes to mind but I believe there were others).

[rabbit_diesel]

The arguement is that deisels make their maximum torque at such a low RPM that they are getting penalized for a power rating that is unusable in racing. Therefore they should just use HP to calculate their car's classification.

cant you tune for that and/or run different gearing?

No, one can not. It turns out that for any given speed of the car, it is the available horsepower that makes it accelerate.

 

Ignoring air drag and rolling drag: (power / velocity) = (mass * acceleration)

 

For instance: if one had the tools to record every second the acceleration and velocity of a car as it made a wide-open throttle run on level ground with no head-wind nor tail-wind nor cross-wind, and knew the air-drag and rolling-drag for any given velocity, one could calculate the power being developed at the wheels by the engine at any given second.

 

Will

 

HP = T * RPM / 5252

MPH = (RPM * (tire circumference)) / (5280 * (overall gear ratio))

[John Graber]

Let's just drop the Torque factor all together.

[rabbit_diesel]

The downside is that it gives diesels a free pass when it comes to torque. Say it's a 200hp car with 400 peak tq in the "unusable" range, and say... "only" 300 in the "usable" range. Of course I made these numbers up, but if I were to consider the type of hp/tq my last diesel truck made, it's not unreasonable. ANYWAY... my point here is that if there is some legitimate disadvantage, it shouldn't be rectified by giving a free pass and completely disregarding torque from the calculation.

Gasoline engine:

200 HP @ 7500 RPM = 140 ftlb @ 7500 RPM

143 HP @ 3750 RPM = 200 ftlb @ 3750 RPM (assumed peak torque)

torque rise = 43%

(Note: this car is just below the (hp+tq)/2 rule.)

 

Diesel engine:

200 HP @ 4500 RPM = 233 ftlb @ 4500 RPM

143 HP @ 2250 RPM = 334 ftlb @ 2250 RPM (assumed peak torque)

torque rise = 43%

 

Because (power / velocity) = (mass * acceleration) the two engines would accelerate the same car in the same manner, under the same conditions.

 

The original intent of the GTS weight/power rule was to group cars by acceleration capability. The current rule has the unstated assumption that all engines make peak HP at the same RPM. Consequently, engines that develop peak HP at a higher than 'normal' RPM get a free pass --- while engines that develop peak HP at a lower than 'normal' RPM are unduly penalized.

 

Will

[JSG1901]

Let's just drop the Torque factor all together.

I don't think that's realistic, either. Consider that we have several GTS1 cars in Great Lakes (competitors of yours, JG), who have restricted their intakes to bring their horsepower down while keeping their torque very high. This is already gaming the rules a bit (legally) because it basically only costs them half the weight penalty for each extra lb-ft over the horsepower value.

 

For instance, we have one car which would normally be making somewhere close to 160 hp and 160 lb/ft which has been restricted to make only 134.1 hp and 156.9 lb/ft.

 

If that car, unrestricted, was 160/160, in GTS1 it would have to weigh 2,960 lbs. However, because of the way we calculate weight for cars with higher torque that horsepower, he is allowed to run at 2,692 lbs, a 268 lb improvement. If we were to ignore torque altogether, he could run at 2,481 (a 479 lb advantage over unrestricted) and be absolutely, completely, undeniably uncatchable.

 

Regardless of what rules we implement, somebody is going to try to figure out how to take advantage of them. That is, after all, what we do. We don't have any idea what following this proposal would do to the competitiveness of diesels but it is entirely possible they would become ultra-competitive, TOO competitive. And, without a known control factor (which is to say, the same driver) in the car, there's really no way of knowing until, potentially, it's too late.

 

I say leave this rule alone.

[cstreit911]

I'm not an automotive engineer...

 

...but how is a diesel making max acceleration power at 4 or 5k RPM any different that two different gas engines?

 

If my gas powered car makes peak power at 6k RPM, I'll gear it differently than the guy with the9k RPM motor. Should I also then get an exemption or an allowance?

[John Graber]

I'm with you Streit. Everytime I bring up something about GTS or ST rules I am reminded that the classes are basically unlimited and with enough cash you can overcome the issue.

 

I don't think that's realistic, either. Consider that we have several GTS1 cars in Great Lakes (competitors of yours, JG), who have restricted their intakes to bring their horsepower down while keeping their torque very high

That is a great idea. Now I just need to figure out how to lose 200 pounds to take advantage of it....

[Greg Smith]

The original intent of the GTS weight/power rule was to group cars by acceleration capability. The current rule has the unstated assumption that all engines make peak HP at the same RPM. Consequently, engines that develop peak HP at a higher than 'normal' RPM get a free pass --- while engines that develop peak HP at a lower than 'normal' RPM are unduly penalized.

If you want to talk about acceleration then you need to talk about trq numbers, not hp. A car will accelerate its fastest at its peak torque, not peak hp. I agree the classing isn't fair to every motor, but it would be impossible to make it fair for everyone.

[cstreit911]

I agree the classing isn't fair to every motor, but it would be impossible to make it fair for everyone.

 

Agreed. Therein lays the beauty of GTS. You can build a car that takes advantage of the rules as they are simple and easy to understand. The more we try and litigate, the less we enjoy it.

[911.racer]

Throwing out there a TDI Dyno graph link I found on the internet to see what they look like.

 

http://forums.tdiclub.com/showthread.php?t=43373

 

So based on what we are saying here, the hp/tq number this car would have to meet would be around 145 ?

 

I am thinking that I am voting no on this one. (either that for finding myself a nice turbo car). The rule was made for the cars where at some points the tq is higher than hp on the curve thus an average. Here you have where ALL of the tq currve is higher than the Hp curve. Substatially.

 

Ed

[scottbm3]

I agree the classing isn't fair to every motor, but it would be impossible to make it fair for everyone.

 

Agreed. Therein lays the beauty of GTS. You can build a car that takes advantage of the rules as they are simple and easy to understand. The more we try and litigate, the less we enjoy it.

 

Hey we agree on another thing..... I think we're up to at least 3 or 4 now....

 

 

-Scott B.

[KTL]

I voted no on account of my belief that the "useable" range argument is arguably BS. Since a diesel has torque EVERYWHERE, as evidence by that sample dyno graph which is likely the most common diesel we'd see, I don't see how they're being heavily penalized. Where is the handicap when the engine has grunt everywhere in the powerband? Are most diesel transmissions geared funky? Change some gears......

 

Switching gears from the TDI VW 4 cyl example, look at the the turbo diesel E90-something BMW 3 series. Those things haul ass. So why should they get a helping hand?

[rabbit_diesel]

I don't think that's realistic, either. Consider that we have several GTS1 cars in Great Lakes (competitors of yours, JG), who have restricted their intakes to bring their horsepower down while keeping their torque very high. This is already gaming the rules a bit (legally) because it basically only costs them half the weight penalty for each extra lb-ft over the horsepower value.

 

For instance, we have one car which would normally be making somewhere close to 160 hp and 160 lb/ft which has been restricted to make only 134.1 hp and 156.9 lb/ft.

Hmm, 157ftlb and 134hp, that's a right nice pair -- I imagine the torque peak is about 4400 RPM, because that will yield a rather flat horsepower curve from around 4400 on up to the peak power point, which I imagine is around 7000 or so (a moderate value). I notice that the car is being dinged with a 11 HP handicap.

If that car, unrestricted, was 160/160, in GTS1 it would have to weigh 2,960 lbs. However, because of the way we calculate weight for cars with higher torque that horsepower, he is allowed to run at 2,692 lbs, a 268 lb improvement. If we were to ignore torque altogether, he could run at 2,481 (a 479 lb advantage over unrestricted) and be absolutely, completely, undeniably uncatchable.

Because of the (HP+TQ)/2 rule, this engine is being assigned [edit:] 'a power' value of 145.5. Noticing that high RPM engines are not penalized, if somebody would like to out accelerate this car (in another of the same kind) -- then get an engine that has the peak torque at 5300 RPM (instead of 4400) and which will rev up to about 8500 or better. This engine could have 145 HP from 5300 all the way up to 8500, and have a peak torque of only 144 ftlb. Look at that, no more 11 HP handicap; and all according to the rules...

 

Think of it, two engines, both with wide flat horsepower curves, except one has 134 HP and the other has 145 HP; both right at the limit of the rules. With identical cars and drivers of equal talent, I would be betting on the car with more power.

 

I see the current voting is 13:2. Why are so many of you in favor of keeping a rule that has a loop-hole for high RPM heavily turbocharged engines?

 

Will

Edited October 1, 2010 by Guest

[cstreit911]

Because of the (HP+TQ)/2 rule, this engine is being assigned an HP value of 145.5. (cut) Why are so many of you in favor of keeping a rule that has a loop-hole for high RPM heavily turbocharged engines? Will

 

Will,

 

Two things, we are not assigning a HP value based on that calculation. We are assigning a nominal power value based on the average of HP and torque.

 

It was never intended to be a perfect calculation of acceleration or level the playing field perfectly for all cars. Sure, there is an advantage of doing things one way or the other. However since the formula is well known and has been consistent over the years our competitors have had plenty of time to determine what they consider optimum and build a car for it.

 

So it's unlikely anyone is trying to penalize a particular car or configuration, but it is also unlikely that it will be changed to favor another configuration. We HAVE had high horsepower turbo cars (Ed Baus in his 2.0L turbo Porsche) that did not show unfair advantages over other cars in the class.

 

So my recommendation to anyone looking to build a successful GTS car is to build a car that takes advantage of the ruleset to the best of their ability. When I entered GTS I tore my car down, engine, trans, body, suspension, and built the best car I could afford that was legal within the ruleset. Great aero, VERY light (because of the many short tracks), 250 HP and 225 TQ. I timed the cams and the engine spark to reduce peak HP and increase TQ, and then geared to to be effective within it's best rev range.

 

 

....and I still don't get the whole "You can't gear a diesel properly" arguement. EDIT: I read this explanation: http://www.houseofthud.com/cartech/torqueversushorsepower.htm and I think I'm starting to get an initial understanding here of what you are saying.

[rabbit_diesel]

....and I still don't get the whole "You can't gear a diesel properly" arguement. EDIT: I read this explanation: http://www.houseofthud.com/cartech/torqueversushorsepower.htm and I think I'm starting to get an initial understanding here of what you are saying.

Excellent article. Thank you for posting that URL. I wish I could have described things so well.

 

Will

[rabbit_diesel]

It was never intended to be a perfect calculation of acceleration or level the playing field perfectly for all cars. Sure, there is an advantage of doing things one way or the other. However since the formula is well known and has been consistent over the years our competitors have had plenty of time to determine what they consider optimum and build a car for it.

 

I am told:

1) That before the 2007 version of the GTS rules, that the previous classing rule was W/HP, only.

2) That in fall/winter of 2006 the (2*W)/(HP+T) addition was put into the 2007 ruleset.

3) That there was a HUGE objection in the forums.

 

(Not having been around at the time, I do not know personally; and the threads from that period are no longer on-line.)

 

Does anyone remember what year the GTS Challenge was begun? I did a bit of looking, and the earliest mention that I found on the web, was early in 2003.

 

Will

[sstecker]

http://craig.backfire.ca/pages/autos/horsepower