Jump to content

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


heavychevy

Recommended Posts

I'll do the same for a the C5Z and TT for the TTS class.

 

Z06 in TTS:

 

350 rwhp - 3200-3300 lbs

 

 

996 TT in TTS

 

350 awhp - 3650-3700 lbs

 

I think you're doing something wrong. Maybe you're mis-applying the weight correction? I get these weight to hp ratios for your examples:

 

Z06 --- 9.14 - 9.42

996 --- 10.42 - 10.57

 

Then you reduce the ratio by .45 - .55 for the weight and you get:

 

Z06 --- unchanged

996 --- 9.97 - 10.02

 

That's a difference of .83 - .62 'points'.

 

A 996 should be just 0.5 'points' higher if all other things are equal. Someone correct me if I'm wrong as I go a bit cross-eyed while doing most of this in my head.

 

So to re-tune your ratios it would be:

 

Z06 in TTS:

 

350 rwhp - 3200-3300 lbs

 

 

996 TT in TTS

 

350 awhp - 3340-3420 lbs

 

---------------140-120lbs

 

Not as bad, but still a considerably larger mass to corner, brake, and accelerate. It gets worse at lower ratios.

 

At 7:1 ratios, the disparity becomes:

 

Z06 in TTS:

 

457 rwhp - 3200 lbs

 

 

996 TT in TTS

 

457 awhp - 3360 lbs

 

-----------------140lbs

 

At 5.5:1 ratios, the disparity becomes:

 

Z06 in TTS:

 

582 rwhp - 3200 lbs

 

 

996 TT in TTS

 

582 awhp - 3400 lbs

 

-----------------200lbs

 

 

But keep in mind this is just peak hp, this doesn't take into account the massive torque that can be made with a V8 powerplant. I think we can kill two birds with one stone. Most AWD cars use an Inline 4 or small V6. A lower AWD penalty would make up for the lack of torque these cars produce compared to the majority of RWD cars that have a V8 or larger V6 motors. The FWD cars can keep their point give-back to make up for their lack of torque. Seems fair to me and it would benefit the majority of the cars that are raced.

Link to comment
Share on other sites

  • Replies 233
  • Created
  • Last Reply

Top Posters In This Topic

  • StealthTT

    46

  • slowoldpoop

    31

  • 1LapSRT

    24

  • kbrew8991

    19

178lbs is a big deal when cornering, braking, and accelerating that extra mass.

 

Agreed, it does have an effect. But I still disagree with it being a huge one - at our level in these cars. The TTA national champion was over 100 lbs heavier than the 3rd and 4th place cars, and for tires ran 275 square as opposed to 295 or higher on the others. Of the three cars on which I know the data the HP numbers were all within 10. So...is 178 lbs the difference between first place and "shouldn't bother to try?" I say no way.

 

SOP did use 275 tires. Several of the TTS Vettes do too from what I hear. That helps if your competitor is using bigger tires, but several guys found they could do better with a better weight:hp ratio and the 275 tires.

 

If SOP is using 275 series tires then the AWD penalty is all but nullified. Now the difference in weight will be a meagre 36 lbs. That's less variance than a tank of gas.

Link to comment
Share on other sites

Nothing trick about a leaf setup, it's still just a leaf spring .

Race cars are built with coilovers

 

you read corner-carvers alot don't you?

 

...and your point?

Link to comment
Share on other sites

Nothing trick about a leaf setup, it's still just a leaf spring .

Race cars are built with coilovers

 

you read corner-carvers alot don't you?

 

...and your point?

 

well, you can tell hes a reader and not a poster because he just fires back with opinions instead of facts

Link to comment
Share on other sites

Because of the penalty, my 3230 lb AWD car had to dyno at 355 to fit into TTS, where I run against 3100 lb 410 hp Z06es (re: previous post above) That was on a NASA-certified dyno at AMS, so it is an accurate number.

 

Where in the heck are you getting these numbers? A 410 hp car needs to weigh 3567 lbs to stay in TTS..

 

Just answering querstions, not arguing.

 

The Evil Doctor (2nd at Nationals in TTS) told me his Mallet Vette had been detuned to 410 hp to move from TTU to TTS. I dunno what he weighs. I was using the numbers listed above for the weight of a Z06.

 

If he is 3567, then he is 230 lb heavier with 55 more hp, for whatever that's worth.

Link to comment
Share on other sites

I'll do the same for a the C5Z and TT for the TTS class.

 

Z06 in TTS:

 

350 rwhp - 3200-3300 lbs

 

 

996 TT in TTS

 

350 awhp - 3650-3700 lbs

 

I think you're doing something wrong. Maybe you're mis-applying the weight correction? I get these weight to hp ratios for your examples:

 

Z06 --- 9.14 - 9.42

996 --- 10.42 - 10.57

 

Then you reduce the ratio by .45 - .55 for the weight and you get:

 

Z06 --- unchanged

996 --- 9.97 - 10.02

 

That's a difference of .83 - .62 'points'.

 

A 996 should be just 0.5 'points' higher if all other things are equal. Someone correct me if I'm wrong as I go a bit cross-eyed while doing most of this in my head.

 

So to re-tune your ratios it would be:

 

Z06 in TTS:

 

350 rwhp - 3200-3300 lbs

 

 

996 TT in TTS

 

350 awhp - 3340-3420 lbs

 

---------------140-120lbs

 

Not as bad, but still a considerably larger mass to corner, brake, and accelerate. It gets worse at lower ratios.

 

At 7:1 ratios, the disparity becomes:

 

Z06 in TTS:

 

457 rwhp - 3200 lbs

 

 

996 TT in TTS

 

457 awhp - 3360 lbs

 

-----------------140lbs

 

At 5.5:1 ratios, the disparity becomes:

 

Z06 in TTS:

 

582 rwhp - 3200 lbs

 

 

996 TT in TTS

 

582 awhp - 3400 lbs

 

-----------------200lbs

 

 

But keep in mind this is just peak hp, this doesn't take into account the massive torque that can be made with a V8 powerplant. I think we can kill two birds with one stone. Most AWD cars use an Inline 4 or small V6. A lower AWD penalty would make up for the lack of torque these cars produce compared to the majority of RWD cars that have a V8 or larger V6 motors. The FWD cars can keep their point give-back to make up for their lack of torque. Seems fair to me and it would benefit the majority of the cars that are raced.

 

 

View the weight list, going from any weight and adding .5 and seeing the corresponding weight is the same as adding roughly 450 lbs.

 

http://www.nasaproracing.com/rules/Time-Trial-Rules.pdf

 

 

So if I have a TT and Z06 with the same power and tires. My TT has to run 350-450 more lbs to be at the same correction factor. It's not complicated. Take the weight you are looking at and add .5, then look at the weight next to it. That gives you the corresponding change for AWD penalty in weight.

 

 

For example

 

3450 lbs is +.2

 

add .5 = .7

 

that is 3850 lbs at .7

 

 

+ 400 lbs

Link to comment
Share on other sites

View the weight list, going from any weight and adding .5 and seeing the corresponding weight is the same as adding roughly 450 lbs.

 

http://www.nasaproracing.com/rules/Time-Trial-Rules.pdf

 

 

Yeah, I believe you've flubbed your algebra somewhere. Think about what each modifier does. The AWD penalizes. The over weight rewards. You can't just look at the table and see what weight cancels out the AWD penalty. You have to work the formula.

 

You have to find the corrected weight to power ratio and then you can figure either the weight or hp based on which one is a given. The corrected weight to power ratio is found by adding penalties and subtracting rewards. For instance a reward of .10 is given for a car weighing between 3350 and 3399lbs.

 

Conversely you can flip the equation around and find new corrected weight to power ratios, but since we're comparing cars built to the limit, we'll do it the first way.

 

So a car that is AWD and 3360lbs is +0.5 + -0.10 = +0.40 modifier

A + modifier makes the car slower as there is either more weight, less hp, or both.

 

So take an 8.0 weight to power ratio and add 0.40 to get 8.40. Now you're comparing two cars. The first is RWD and 3200lbs. The second is AWD and 3360lbs. We'll find the hp that the rules say is equal.

 

So.....a RWD with 3200lbs and 400hp = 8.0 weight to power ratio

And an AWD with 3360lbs and 8.4 = 3360 / 8.4 = 400hp

I guessed good.....okay, actually I did some chicken scratches to get equal hp for this comparison.

 

Anyway, in this case the penalty is in the form of more weight.

 

It could be a penalty in the form of less hp. The steps stay the same.

 

+0.5 + -0.05 = +0.45 modifier

 

So.....a RWD with 3200lbs and 400hp = 8.0 weight to power ratio

And an AWD with 3300lbs and 390hp = 8.45

8.45 - 8.0 = .45 penalty

 

See the weight reward drops because the weight drops to 3300lbs. You have to do some algebra to get easy numbers like this. However, in the real world you'll be leaving a comfort zone in case you come in underweight or overhorsepower.

 

Anyway, here's another example of a car with both more weight and more hp:

 

Say 3800lbs so a -0.65 modifier giving a total adjustment of -0.15.

 

Same RWD with 3200lbs and 400hp = 8.0 weight to power ratio

Now an AWD with 3800lbs and 484hp = 7.85

7.85 - 8.0 = -.15 adjustment

 

In this case 600lbs is combined with 84 more hp. I'd hate to be on the AWD side of that match up. All other things equal, no AWD system is going to be able to compensate even with an extra 84 'peak' hp. This large mass must be cornered, braked, and accelerated. Extra hp only helps in one area. This car might win on the drag strip, but not in roadracing.

Edited by Guest
Link to comment
Share on other sites

I just noticed there's a weird step between 3450 and 3500lbs. It jumps a whole tenth (0.1) instead of the normal half tenth (0.05).

 

 

 

3300 lbs +0.05 3550 lbs +0.35 3800 lbs +0.65 4050 lbs +0.9

3350 lbs +0.1 3600 lbs +0.4 3850 lbs +0.7 4100 lbs +0.95

3400 lbs +0.15 3650 lbs +0.45 3900 lbs +0.75 4150 lbs +1.0

3450 lbs +0.2 3700 lbs +0.55 3950 lbs +0.8 4200 lbs +1.05

3500 lbs +0.3 3750 lbs +0.6 4000 lbs +0.85 4250 lbs +1.1

 

I'd love to see that changed as I think my tank will be over 3500lbs with me and the cage in it.

Link to comment
Share on other sites

We need to keep something constant so the full weight can be realized.

 

It doesnt matter what car it is, if yo utake out all of the variable EXCEPT AWD.

 

 

Let's try and eliminate the weight penalties altogether so yo ucan understand where I'm coming from.

 

 

A Z06 or TT that has 580 rwhp and 3200 lbs (no weight penalty, .05 reward is neglegible and we will consider it of no affect) will have hp/weight ratio of 5.5

 

The Z06 is safe to run TTU the TT is NOT and has a AWD penalty of .5 and the only way to get that back is to add .5 worth of weight which in this case equals 3750, so the TT has to add 550 lbs.

 

 

I dont see how it is that complicated.

Link to comment
Share on other sites

  • National Staff
I just noticed there's a weird step between 3450 and 3500lbs. It jumps a whole tenth (0.1) instead of the normal half tenth (0.05).

 

 

 

3300 lbs +0.05 3550 lbs +0.35 3800 lbs +0.65 4050 lbs +0.9

3350 lbs +0.1 3600 lbs +0.4 3850 lbs +0.7 4100 lbs +0.95

3400 lbs +0.15 3650 lbs +0.45 3900 lbs +0.75 4150 lbs +1.0

3450 lbs +0.2 3700 lbs +0.55 3950 lbs +0.8 4200 lbs +1.05

3500 lbs +0.3 3750 lbs +0.6 4000 lbs +0.85 4250 lbs +1.1

 

I'd love to see that changed as I think my tank will be over 3500lbs with me and the cage in it.

 

1) It's there for a purpose

2) It will help you if your car weighs more than 3500 lbs, not hurt you.

Link to comment
Share on other sites

I just noticed there's a weird step between 3450 and 3500lbs. It jumps a whole tenth (0.1) instead of the normal half tenth (0.05).

 

 

 

3300 lbs +0.05 3550 lbs +0.35 3800 lbs +0.65 4050 lbs +0.9

3350 lbs +0.1 3600 lbs +0.4 3850 lbs +0.7 4100 lbs +0.95

3400 lbs +0.15 3650 lbs +0.45 3900 lbs +0.75 4150 lbs +1.0

3450 lbs +0.2 3700 lbs +0.55 3950 lbs +0.8 4200 lbs +1.05

3500 lbs +0.3 3750 lbs +0.6 4000 lbs +0.85 4250 lbs +1.1

 

I'd love to see that changed as I think my tank will be over 3500lbs with me and the cage in it.

 

1) It's there for a purpose

2) It will help you if your car weighs more than 3500 lbs, not hurt you.

 

Dang it! You posted before I could delete it. I was just sitting there eating and realized I goofed.

Link to comment
Share on other sites

Greg, what were the TT rule changes from 06-07, this is seperate from out discussion here.

 

Just that would relate to hp/weight ratio for TTU? Did they change at all?

Link to comment
Share on other sites

  • National Staff
We need to keep something constant so the full weight can be realized.

 

It doesnt matter what car it is, if yo utake out all of the variable EXCEPT AWD.

 

 

Let's try and eliminate the weight penalties altogether so yo ucan understand where I'm coming from.

 

 

A Z06 or TT that has 580 rwhp and 3200 lbs (no weight penalty, .05 reward is neglegible and we will consider it of no affect) will have hp/weight ratio of 5.5

 

The Z06 is safe to run TTU the TT is NOT and has a AWD penalty of .5 and the only way to get that back is to add .5 worth of weight which in this case equals 3750, so the TT has to add 550 lbs.

 

 

I dont see how it is that complicated.

 

Are you Stoned? I thought that they don't smoke much weed in Georgia?

 

Yep Stealth, I just got HeavyChevy also.

 

At 580 hp, and 3750 lbs, the mythical 911 TT would have an adjusted wt/power ratio of:

3750/ 580= 6.466, then subtract your 0.5 (for AWD)= 5.966, then add another +0.6 (from the table), and you get 6.566 compared to your Z06 that has an adjusted ratio of:

3200/580 = 5.517 minus 0.05= 5.467 = Illegal for TTU (the car must actually weight 3201 to avoid the "neglegible" "reward" that makes it an illegal car for the class.

 

HEAVIER= reward

Lighter = penalty

 

If you wanted to ignore the fact that in the rules we account for and reward heavier cars with a better wt/power ratio, then you should have used this calculation to figure out the weight:

5.5 +0.5 = 6.0 x 580= 3480 lbs.

 

But, you CAN'T ignore it. If you want to figure out a competition weight this way, you need to use some algebra. But, if you know the weight (or fix the weight as the constant instead of the hp in your examples), you can do simple arithmetic to figure out the difference in hp.

 

Example:

Both Z06 and 911 TT weight 3155 lbs. Question: what is the max hp for each in TTU?

 

Answer:

Z06= 5.5 +.05= 5.55

3155/ 5.55= 568 hp

 

911 TT= 5.5 +.05 + .5= 6.05

3155/6.05= 521.48 hp

 

Now 46.5 hp seems like a lot. But, it is less than a 10% difference, and there is up to a 15+% difference when measuring power on common AWD dynos compared with 2wd Dynojet dynos.

 

Now let's see about figuring out the weight of the 580 hp 911 TT to max it out in TTU:

x= weight

y= mod factor for weight reward

x/580 -0.5 + y= 5.5

y= (x-3300)/1000 (but this is screwed up because we use a quantum step up in the mod factors by 0.5 (yes, except for the one that Stealth found). So, it ends up being easier to do a few trial and error runs to figure it out.

 

Oops, got lucky on the first try :

3400/580 -0.5 +0.15= 5.512

Link to comment
Share on other sites

  • National Staff
Greg, what were the TT rule changes from 06-07, this is seperate from out discussion here.

 

Just that would relate to hp/weight ratio for TTU? Did they change at all?

 

2006 TT Rules:

The TTR class is designated as a truly unlimited racecar class. It is intended for purpose built, tube frame, never street legal, and very high-end modified streetcars with a low weight/hp ratio. Modifications are completely unlimited, although open wheel cars are not legal. The TTU class is the “unlimitedâ€

Link to comment
Share on other sites

In addition to the cars listed below, the TTR class includes: any tubeframe, never street legal, or purpose-built racecar or vehicle not approved by the DOT or TUV for street use, that is not otherwise classed below.

 

 

Well, as long as this subject came up, let me float this one by the group. A local NASCAR race shop told me they could build a road-racing version of an ASA or ARCA car. It essentially would have a perimeter tube frame (not offset for roundy-round, but with equal offset for road courses), full cage, plastic Ford or Chevy body, ASA/ARCA crate motor, and all the safety equipment. We guess it would come in at 2800 lb with choice of crate engines from 350 (ASA) to 650 hp (NASCAR).

 

Would something like this be competitive in TTR against the Evos?

What would be the associated race group? (I don't think it fits into American Iron)

Has anyone ever brought a car like this to a NASA event? If so, how did it do?

 

We were kicking around the idea of building a reasonably priced ($35,000) race car that was simple (carbureted), easy to work on, could have a sealed crate engine in case a spec class developed around it, and lent itself to either being a turnkey car for sale or a rent-a-racer for ROWGs.

 

Customers ideally would work their way through HPDE, TTR and into a spec race group. Such cars could be built around the country by any NASCAR shop, because--to them--they would just be building another ASA car on a perimeter frame.

 

Just wondered what you guys thought of this idea. It's kinda like Spec Miata on steroids.

Link to comment
Share on other sites

Ken

Not trying to start anything here , I'm not a chassie builder eather, I have been around racing my entire life and have yet to see a race car built around anything other than coilovers or torsion bars . The 50's don't count anymore.

Leaf springs are for production cars , they are cheap to build . The Vett has had the bennifit of a good design and thats it . It is still a production car .

Never heard of the reading material you mentioned ,and I'm not sure what reading and posting have to do with spring or chassie design. Try changing you car over to leafs and see how well it works .

 

As for the awd issue, I have been for a ride in my class leaders awd Evo and that thing rips around the corners . I don't have much simpathy for the awd crowd. They might not be competetive in the uper classes but should do well from TTA and down . But we don't get Vetts in A at NorCal events . Lots of Evo's and STI's

Link to comment
Share on other sites

sure, let me massively redesign the entire suspension and get sent straight to TTS for my trouble . You can skin a cat a few different ways, but when theres a different way to do it that has some pretty slick advantages, I can't help but like it... even if its not "the way its always done". My semi-educated $0.02, and I'd really just let it go if I could see that you could get your noggin around the fact that truck leafs are about the same to the transverse setup as a 5hp go kart is to an F1 car

 

back to your regularly scheduled argument about the AWD correction factor

Link to comment
Share on other sites

In addition to the cars listed below, the TTR class includes: any tubeframe, never street legal, or purpose-built racecar or vehicle not approved by the DOT or TUV for street use, that is not otherwise classed below.

 

 

Well, as long as this subject came up, let me float this one by the group. A local NASCAR race shop told me they could build a road-racing version of an ASA or ARCA car. It essentially would have a perimeter tube frame (not offset for roundy-round, but with equal offset for road courses), full cage, plastic Ford or Chevy body, ASA/ARCA crate motor, and all the safety equipment. We guess it would come in at 2800 lb with choice of crate engines from 350 (ASA) to 650 hp (NASCAR).

 

Would something like this be competitive in TTR against the Evos?

What would be the associated race group? (I don't think it fits into American Iron)

Has anyone ever brought a car like this to a NASA event? If so, how did it do?

 

We were kicking around the idea of building a reasonably priced ($35,000) race car that was simple (carbureted), easy to work on, could have a sealed crate engine in case a spec class developed around it, and lent itself to either being a turnkey car for sale or a rent-a-racer for ROWGs.

 

Customers ideally would work their way through HPDE, TTR and into a spec race group. Such cars could be built around the country by any NASCAR shop, because--to them--they would just be building another ASA car on a perimeter frame.

 

Just wondered what you guys thought of this idea. It's kinda like Spec Miata on steroids.

 

road course ASA cars are pretty popular in SU. IN/OH has a couple regulars. Here's one out on the coast:

 

http://www.nasaforums.com/viewtopic.php?t=17426

Link to comment
Share on other sites

For Slwoldpoop.

Just what I'm in the process of doing now . Buying a used team of high end SWT cars that are straight up chassies, and a full complament of spairs less engines .

The only cars that I think will cause threat are the sports racers .

The pair of cars I'm looking at are #2500, and told by the ex crew cheif they could be lighter .

The main reasion I'm going this direction is repairability and the fact that they don't eat up brake parts and chassie parts like my tank of a production car . They have coilovers and lots of different controlarms to play with . The parts are cheap when you compair them with production car parts . Not real thrilled about trunning in TTR but that where they belong .

ASA has broke away from NASA , but as the NASCAR guys move onto the COT , the current cars are being sold pretty cheap . They are #3500 cars though. The ASA or Southwest Tour cars are the way to go here .

2005 the GTA champ in SCCA was in an offset car . I think that was in the San Francisco reg. not sure about nationals

Edited by Guest
Link to comment
Share on other sites

Not to re-direct this thread, but leaf springs can actually be preferable when done right. Contrary to what has been said a few posts above, they cost a lot more than coilovers. They do have some disadvantages, but those have nothing to do with the handling.

SWT, or similar tube chassis "stock", cars can be crazy fast when setup for TTR or SU. They will cost way less than any production car and with proper setup and driver it will be tough to beat if not entirely dominant. The ASC cars have fairly low hp and hard compound tires yet they are the fastest cars on track for the most part.

 

-V

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...