AWD (no flaming please), and no mention of the Audi

[heavychevy]

I just want to know where the penalty is substantiated? As we know that better tires yeild better times (tire sizes are another story) , how different compounds will affect the car and I think the penalties are substantiated because it's obvious.

 

But AWD's traction advantage really only pertains to street tires, RWD cars get much more gain from adding R comps from what I have seen. And with the complexity of many AWD systems today, many act as RWD unless you are sliding around and the object is to make it handle like a RWD car. (this is pretty simplified), but I think there is an imbalance in the penalty.

 

You have an AWD car:

 

- more weight

- less benefit from r comps

 

but a big penalty (the only one bigger is tires, or HUGE weight losses), I'm not saying there should be one, but what method of determination is used to come to .5 as a penalty?

 

No flames here please, I am just seeking clarification. Rules are made for a reason,(preventing unbalance and advantages) and therefore should be able to be substantiated by logic related to performance gained thereof.

 

TT is said not to be catered to street cars, and there isnt much AWD in racing (for a very legitimate reason that isnt centered around advantages). I know if I was racing and had AWD creating more heat and strain on the drivetrain yet penalized heavily for it, I wouldnt be so happy.

 

If there was a lesser penalty, would it give AWD cars a distinct advantage? I think if the answer is no then it should be removed, rules are in place to prevent distinct advantages or am I mistaken?

[loudes13]

Please explain your logic ( AWD isn't an advantage).

 

I've driven 400hp rwd cars that could not put power down. I've also driven 300 hp awd cars that could spin the inside tires in a corner (and still accelerate like a scolded cat).

[kgobey]

..

Edited February 23, 2010 by Guest

[heavychevy]

Please explain your logic ( AWD isn't an advantage).

 

I've driven 400hp rwd cars that could not put power down. I've also driven 300 hp awd cars that could spin the inside tires in a corner (and still accelerate like a scolded cat).

 

 

If you have 400 hp and cant put the power down, your suspension or downforce is bad and/or you need new/different tires.

 

I dont think were are racing worst case scenarios here. Once you get to TTU/TTR level the power levels are such that you can get just as much wheelspin in a AWD car, front (push) and rear (oversteer).

[Slowwrx]

In TT there is no standing start.

 

I'm not sure about other cars but the STIs center diff goes full open under braking, I would imagine that the EVO does it the same.

 

I personally don't think that there is any advantage on most tracks. The awd advantage is usally greatest on low speed corner exit where you would experince wheel spin in a rwd car. The only corner at Road Atlanta where it becomes an advantage is 7, everywhere else I would just assume have a rwd car.

[heavychevy]

This is a very circumstantial comment, but if you remember when the AWD cars ran in British Touring Cars against FWD and RWD cars they had 2 advantages...

 

1. At the start - all starts from a standing start - they were able to accelerate more quickly as they had to manage wheel spin less, and more importantly, they were able to do this in more slippery track conditions, some thing that in England is all too common.

 

2. AWD, while not an advantage once weight transfer is occuring as much as you'd think, it was an advantage under breaking. The limited slip mechanisms used are capable of reducing single wheel lockup. This is an unintended benefit, that does pay off.

 

Is this something we need to adjust our rules for? Yes, if as drivers we were that good and that close in skill-level to make it matter.

 

Most NASA races are rolling start correct? And standing start has no relevance in TT, so IMO that isnt a factor.

 

Is there any substantial evidence to support #2, I have never heard that. AWD Porsches dont brake any better than RWD Porsches with the same brakes. That is the only reference I know.

 

 

But why .5, is AWD + R compounds 5 points better than RWD w/ R-comps? I really doubt that.

[Falcon]

The only corner at Road Atlanta where it becomes an advantage is 7, ...

 

Yea, but that's the most important turn at Road Atlanta. The following straight is loooonnnng.

[kbrew8991]

Mid-Ohio has some lower speed corners where IMHO awd could be an advantage

 

I notice an advantage with MR over FF guys in those certain corners the last 2 trips there, and AWD is just a little bit better...

[heavychevy]

Mid-Ohio has some lower speed corners where IMHO awd could be an advantage

 

I notice an advantage with MR over FF guys in those certain corners the last 2 trips there, and AWD is just a little bit better...

 

 

This may be, but what about the other parts on track where AWD is a disadvantage, for example the straights, the additional drag from front drivetrain components, additional power loss from the drivetrain. You still have extra weight, so cornering is affected as well.

 

And I dont care what you say, AWD will push to some extent somewhere at almost every track.

 

Even if you discount all that, is a few turns here and there worth 5 points?

 

I guess I just want to know the rationale?

[Greg G.]

There are a bunch of reasons for the -0.5 modification factor. First, whether you agree or not, AWD is a significant advantage in the corners (huge over FWD, and less so over RWD), especially when the vehicles have high hp, and wheel spin is more likely. This advantage is, of course, variable depending on other factors. AWD Audis, Lancers, WRX's, Eclipses (of the same weight and whp) perform better than their 2wd counterparts. With AWD 911's, perhaps not, but the rear engine in that case makes a big difference in how that vehicle performs anyway.

 

Next, you cannot say that AWD is a disadvantage in the straights because of front drivetrain "drag" and powertrain loss, unless you are talking about trying to even cars out by using flywheel horsepower. The extra weight of AWD is all down low, and weight is already accounted for in the adjusted wt/power ratio, so saying that they weigh more is also a spurious argument.

 

But, here is a big one, that at least for now is just the way things are because there are not enough Dynojet AWD's in the USA. Most of the AWD's end up getting dyno'd on Mustang or other Dyno's that can read anywhere from 5-15% LOWER than the Dynojet dynos that FWD and RWD cars are required to use. So, a Corvette that dyno's 400 rwhp on a Dynojet, and an Evo that Dyno's 360 awhp on a Mustang Dyno can be (and probably are) putting out the exact same wheel HP. Now, we do state that the AWD's must be compliant on any type of the Dyno's we have listed, but in practice, there are many regions that there are no other Dyno's around, and specifically, no Dynojet AWD dyno's. So, perhaps the -0.5 mod factor is not even high enough.

 

Now, if you want to use the "drivetrain loss" argument, then here is something to consider. Lets ignore the above argument about Dyno brand /model differences for now, and assume that we test an AWD and a RWD on a Dynojet AWD dyno model. They both put out 400 whp. The flywheel hp of the RWD car is likely around 440-460 hp. However, the flywheel hp of the AWD car is likely around 500-525 hp. Now, if we were taking motors out of vehicles, and testing them on engine dyno's, then I would agree that the AWD's would be at a power disadvantage compared to both FWD's and RWD's. But, we aren't doing that.

[phoenixR34]

 

If you have 400 hp and cant put the power down, your suspension or downforce is bad and/or you need new/different tires.

 

 

Apparently you haven't driven a 400hp Porsche 944 or Nissan 240SX.. now *that* is a joke. I drove DynoComp's Subaru STi (480hp, 2800lbs) for a day and nearly cried for a week, knowing I spent years developing my 400hp Nissan and thought it could ever compete with something like that. It was absolutely ridiculous how well the STi put power down on corner exit.. it simply wasn't an issue, vs. anything RWD where you're checking your line, paying attention to throttle, waiting for tires to warm up..

 

Flat torque curves and more rear weight bias help, like an S2000, Vette or BMW, but it's a whole different ball game. On most courses power delivery is everything.. hence the reason 911s are so fast.

 

At a TTC-TTA level I'd partially agree that it's not a huge difference.. But when you get into the TTS-TTR levels, definitely yes, there needs to be a penalty.. which makes sense because the rules are written that way.

[heavychevy]

There are a bunch of reasons for the -0.5 modification factor. First, whether you agree or not, AWD is a significant advantage in the corners (huge over FWD, and less so over RWD), especially when the vehicles have high hp, and wheel spin is more likely. This advantage is, of course, variable depending on other factors. AWD Audis, Lancers, WRX's, Eclipses (of the same weight and whp) perform better than their 2wd counterparts. With AWD 911's, perhaps not, but the rear engine in that case makes a big difference in how that vehicle performs anyway.

 

Next, you cannot say that AWD is a disadvantage in the straights because of front drivetrain "drag" and powertrain loss, unless you are talking about trying to even cars out by using flywheel horsepower. The extra weight of AWD is all down low, and weight is already accounted for in the adjusted wt/power ratio, so saying that they weigh more is also a spurious argument.

 

But, here is a big one, that at least for now is just the way things are because there are not enough Dynojet AWD's in the USA. Most of the AWD's end up getting dyno'd on Mustang or other Dyno's that can read anywhere from 5-15% LOWER than the Dynojet dynos that FWD and RWD cars are required to use. So, a Corvette that dyno's 400 rwhp on a Dynojet, and an Evo that Dyno's 360 awhp on a Mustang Dyno can be (and probably are) putting out the exact same wheel HP. Now, we do state that the AWD's must be compliant on any type of the Dyno's we have listed, but in practice, there are many regions that there are no other Dyno's around, and specifically, no Dynojet AWD dyno's. So, perhaps the -0.5 mod factor is not even high enough.

 

Now, if you want to use the "drivetrain loss" argument, then here is something to consider. Lets ignore the above argument about Dyno brand /model differences for now, and assume that we test an AWD and a RWD on a Dynojet AWD dyno model. They both put out 400 whp. The flywheel hp of the RWD car is likely around 440-460 hp. However, the flywheel hp of the AWD car is likely around 500-525 hp. Now, if we were taking motors out of vehicles, and testing them on engine dyno's, then I would agree that the AWD's would be at a power disadvantage compared to both FWD's and RWD's. But, we aren't doing that.

 

Ok....... that is a legit explanation though I do disagree with some parts of it. That is all I was looking for. Thanks.

 

 

But for the sake of discussion (not arguement please), which lancers and WRX's are you talking about? I dont consider a modded RWD lancer w/ same hp to match an evo, same with the sti to wrx. There is more to why those cars are better than the base models than hp. If EVERYTHING else is the same, only AWD vs RWD, there would not be a distiguishable difference in speed.

 

I do understand the first part of the dyno assessment, but are the different dynos taking into consideration when you are presented with a dyno sheet? Is there a conversion factor implemented? If so what is it? There are so many factors and discrepancies on dynos, I'm sure that would be a headache.

 

As for the second part, I'd bet you wont find many evo's/sti's etc trapping the same speeds with 400 awhp as the 440- 460 rwhp for the corvette would do ( I like to use trap speeds as an accurate determination of hp taking into account altitude etc, to get past all the dyno debates). And these 400 whp awd cars will get walked on the top end because the AWD cars fall flat after 3rd gear (for the most part). This is why most of them are turbo'ed, because the turbos promote top end, it either will to be turboed (STI,WRX,TT, etc), or high revving (Lambo, RS4 etc), or will rally struggle. I know NASA cant do trap speeds, but that should be taken into consideration when looking at hp sheets because it would have a big effect on the straights.

[phoenixR34]

As for the second part, I'd bet you wont find many evo's/sti's etc trapping the same speeds with 400 awhp as the 440- 460 rwhp for the corvette would do ( I like to use trap speeds as an accurate determination of hp taking into account altitude etc, to get past all the dyno debates). And these 400 whp awd cars will get walked on the top end because the AWD cars fall flat after 3rd gear (for the most part). This is why most of them are turbo'ed, because the turbos promote top end, it either will to be turboed (STI,WRX,TT, etc), or high revving (Lambo, RS4 etc), or will rally struggle. I know NASA cant do trap speeds, but that should be taken into consideration when looking at hp sheets because it would have a big effect on the straights.

 

Turbo's don't "promote" top end. A properly sized turbo can help on the top end, but it's not an instant guarantee.. study popular turbo engine dyno charts and you'll see what I mean. Most stock turbos (STi, EVO, Audi, VW) give up top end to make them more driveable at lower RPMS.

 

Are you assuming that losses or mechanical "drag" due to the AWD system is what kills top end? Since they never made an STi or Lancer in RWD, I'm wondering if you are really up to speed on what you're talking about here in the first place (no offense).

 

Again, after driving a few AWD cars (and DC's STi), I'm not buying the "top end" argument. If there is some factual basis for the statement: AWD cars fall flat after 3rd gear (ie. you have real trap speed data of cars with similar HP/WT ratios), my guesses are the following:

 

1. A Subaru STi is shaped like a shoebox, whereas a Corvette is not.

2. STis and EVOs usually have huge wings on the back and larger frontal areas (see #1), which again, create huge aero drag at high speeds.

3. Gearing.. I haven't studied gear ratios, but if a car falls flat in 4th gear, it's probably because the 4th gear ratio itself isn't optimal.. 400hp is still 400hp, 3rd gear or 4th.

[loudes13]

Ok....... that is a legit explanation though I do disagree with some parts of it. That is all I was looking for. Thanks.

 

 

But for the sake of discussion (not arguement please), which lancers and WRX's are you talking about? I dont consider a modded RWD lancer w/ same hp to match an evo, same with the sti to wrx. There is more to why those cars are better than the base models than hp. If EVERYTHING else is the same, only AWD vs RWD, there would not be a distiguishable difference in speed.

 

I do understand the first part of the dyno assessment, but are the different dynos taking into consideration when you are presented with a dyno sheet? Is there a conversion factor implemented? If so what is it? There are so many factors and discrepancies on dynos, I'm sure that would be a headache.

 

As for the second part, I'd bet you wont find many evo's/sti's etc trapping the same speeds with 400 awhp as the 440- 460 rwhp for the corvette would do ( I like to use trap speeds as an accurate determination of hp taking into account altitude etc, to get past all the dyno debates). And these 400 whp awd cars will get walked on the top end because the AWD cars fall flat after 3rd gear (for the most part). This is why most of them are turbo'ed, because the turbos promote top end, it either will to be turboed (STI,WRX,TT, etc), or high revving (Lambo, RS4 etc), or will rally struggle. I know NASA cant do trap speeds, but that should be taken into consideration when looking at hp sheets because it would have a big effect on the straights.

 

you still haven't used ANY evidence or facts to support your plea. Your comments about turbos going flat is bs. Trap speeds, this isn't drag racing, which is probably leading to your confusion. Coming off corners (AWD's strong suit) is a big deal on the road course.

Edited October 22, 2007 by Guest

[QUASAR]

I don't understand what the talk about driveline efficiency has anything to do with this, WHEEL hp is WHEEL hp, flywheel hp is irrelavant.

 

And can't it be assumed that straightaway hindering drag created from large front ends and big wings is also helping you on every other part of the track? So its a wash.

[StealthTT]

More often than not the engine is placed in front of the front wheels in an awd layout. Weight distributions of 60/40 is not uncommon, but that doesn't tell the whole story. This weight is not only in front of the center of the car, but waaay out in front. This problem is shared by the fwd cars. Push is only countered by reducing rear grip enough to make the car neutral.

 

To not leave anything to chance, an awd car should be tuned to be legal on any dyno. This means making a "correction" for the possibility it could be checked on a Dynojet if it's dyno'ed on any other. I suppose there are those who would take advantage of this, but those interested in playing fair, will do just that.

[slowoldpoop]

Gee, I don't understand all this technobabble. All I know is that, in TTS, being 55 hp down to Z06es and M3s makes me uncompetitive. Their superior, race-car-like suspensions more than make up for any alleged advantage of AWD in my Eclipse. How about a 5 pt penalty for Z06 and M3 suspensions? I think they are unfair!

[John Graber]

All I know is that, in TTS, being 55 hp down to Z06es and M3s makes me uncompetitive. Their superior, race-car-like suspensions more than make up for any alleged advantage of AWD in my Eclipse.

 

Then upgrade the suspension. In TTS suspension is free and only limited by your budget.

[Spectator Racing]

Gee, I don't understand all this technobabble. All I know is that, in TTS, being 55 hp down to Z06es and M3s makes me uncompetitive. Their superior, race-car-like suspensions more than make up for any alleged advantage of AWD in my Eclipse. How about a 5 pt penalty for Z06 and M3 suspensions? I think they are unfair!

 

The Corvettes have race car suspension? Are you kidding? They still use leaf springs.

[kbrew8991]

Gee, I don't understand all this technobabble. All I know is that, in TTS, being 55 hp down to Z06es and M3s makes me uncompetitive. Their superior, race-car-like suspensions more than make up for any alleged advantage of AWD in my Eclipse. How about a 5 pt penalty for Z06 and M3 suspensions? I think they are unfair!

 

you could add 1,000 points in TTS, TTU, or TTR if you want... it doesn't matter. Meet the adjusted horsepower:weight and you're fine

 

run any tire you want (within the adjustments), run any suspension you want (Without completely tube-framing the car), and get some aero stuff while you're at it...

 

sorry you picked a mega-bucks class man, but thats what its going to take to be seriously competitive

 

TTF cars are cheap

[kbrew8991]

The Corvettes have race car suspension? Are you kidding? They still use leaf springs.

 

there is a MASSIVE difference between transverse leaf spring and regular leaf springs. One you'll find on your trucks, the other is actually pretty technically superior to coil springs

[StealthTT]

Stock Corvette's don't have 'race' suspension per se, but they do have good weight balance, low polar moment of inertia, low center of gravity, a wide track, and so they're able to use massive amounts of power with little traction loss. I'd say it's an easy class winner unless you highly mod the suspension of lesser cars. The M3's are similar in their stock abilities at laying down the power.

 

Try as we might, simple rules will not allow any car to be competitive in any class. I do feel the AWD penalty is too strong when you take into account the inferior weight balance, polar moment of inertia, and inability to lower or move that weight. However, I love the awd platform too much to choose another car solely to take an "easier" path. I'm just forced to redouble my efforts to overcome this obstacle.

[slowoldpoop]

[Then upgrade the suspension. In TTS suspension is free and only limited by your budget.

 

*sigh* There's that budget issue again. I guess if you pour enough money into any car, you can make it competitive.

 

I thought the whole idea of NASA was to equalize more or less stock cars through points and penalties so as to keep down the cost of makng expensive mods in TT. The fact that Z06es won TTU (first 2), TTS (first 3) and TTA (first 4) at the Nationals tells me they don't need no help in overcoming the overwhelming advantage of an old 4-cylinder car with AWD.

 

Results at http://www.nasachampionships.com/pdf/2007-GroupI.pdf

 

The best AWD cars did was 5th in TTA, 4th in TTS and 6th in TTU. The AWD penalty sure works! You have effectively eliminated the top AWD cars in the country from competition. And me, too. My 1990 Eclipse is no longer competitive, even at the regional level.

 

Geez, if I was the owner of a $65,000 Z06 with a big honkin' V8 generating 410 hp at the wheels, running on Hoosiers with upgraded suspension and brakes, and aero front and rear, I'd be a little ashamed to admit that the only way I can beat a 17-year-old clunky, high-off-the-ground Eclipse is to cripple that old car with a horsepower penalty.

 

All seriousness aside, as Brother Dave used to say, I suppose I could spend a couple thousand on new coilovers, cut and flare the fenders to drop the Eclipse to within a few inches of the ground, and spend a couple more thousand on front and rear aero. Those options are certainly open to me, I admit. Or I could just go back to running HPDEs for fun.

 

I can't wait for next year, when Slinky supercharges his S2000 and blows the doors off all those Z06es in TTS. I'm sure you'll come up with a suitable penalty for him, too. I'll be watching from HPDE4 and laughing my butt off.

[StealthTT]

 

sorry you picked a mega-bucks class man, but thats what its going to take to be seriously competitive

 

That's the gripe I hear over and over. Guys want to go really fast, but not get into a spending war against the megabucks guys. Maybe the weight to hp needs to shift lower than 8.7:1 to allow this group of people room to play against each other in a class that still has points for aero, suspension, etc.

 

8.7:1 is about 370hp at 3200lbs.

7.6:1 is about 420hp at 3200lbs.

7.1:1 is about 450hp at 3200lbs.

 

Those last two numbers are easily attainable and would make for a fun class.

[cosm3os]

The rules don't guarantee that any car (stock or modified) will be competitive. It's up to you to make it competitive.