ITAC News.

[quadzjr]

I ams sure it has been explained before, but search is failing me. How come a strut suspension on the powered wheels of a FWD car gets a weight break but a strut suspension on the powered wheels of a RWD does not?

The problems inherit with the strut suspension are consistent no matter which wheels are driven.

What was the percentage diffference/standard deviation from the norm of the class to warrant a torque increase/decrease adder?

Also why are all these adders only applicable to ITR but not ITS-ITC?

[Chip42]

per the ops manual all classes recieve the following adders:
DW: +50
mid engined: +50
abnortmally small or large brakes: ±50

and these are class specific:
FWD Torque/diplacement low/high
ITR 6% -100/+150
ITS 5.5% -50/+100
ITA 2% -50/+100
ITB 2% 0/+50
ITC 0% 0/+50

ITR FWD and strut, -50
ITR rear solid axle, -50

I'm going to be long winded here on the of chance that someone reading this needs background you and I already know:
the DW/Strut concept is only for the front axle of the car. I agree with you that the strut is a hamper to the driven wheels more so than to the objective "front". particularly with front engine / rear drive cars, a front strut can be made to have a very acceptable camber curve, even at lowered ride heights. the typical transverse driveline (usually FWD) Mac strut is so space compromised it usually results in a poor or even detrimental camber curve. cars like the AW11 MR2, with a strut at the front and rear (driven) wheels which is ALSO a packaging compromise are rare - I think there are only 3-4 in the ITCS that are even close. so the process is blind to it. we could argue subjectively on a per case basis, but I think we have bigger fish to fry right now, both in general terms and with the MkI MR2 specifically.

[JeffYoung]

I say we junk all these adders/deducts.

I'm about 25% serious.

[Chip42]

I'm willing to rethink them but wihtout a process revamp that considers torque in the weight equation I want to keep some sort of torque adder. FWD deduct is also needed, but again, I'm willing to reconsider what it is.

the problem with my willingness is that it goes against stability, and I'm a bigger fan of stability than I am of "fixing" things that can't be perfect, anyhow. in the Case of ITR I personally feel that a change here, now, to bring it in line with what we have said for a year now is how we do things is more a nod to stability than leaving it alone and rewriting the ops manual to match. I also think the existing listings are biased heavily to RWD and that the ops process is better there, so it's a correction in my mind as well.

[Andy Bettencourt]

Chip,

Can we agree that we have proven that the Ops Manual is in error on the DW's in ITR? The classing shows it, the historical recollections support it and Josh's post finishes the debate off.

Can we please fix this?

per the ops manual all classes recieve the following adders:
DW: +50
mid engined: +50
abnortmally small or large brakes: ±50

and these are class specific:
FWD Torque/diplacement low/high
ITR 6% -100/+150
ITS 5.5% -50/+100
ITA 2% -50/+100
ITB 2% 0/+50
ITC 0% 0/+50

ITR FWD and strut, -50
ITR rear solid axle, -50

I'm going to be long winded here on the of chance that someone reading this needs background you and I already know:
the DW/Strut concept is only for the front axle of the car. I agree with you that the strut is a hamper to the driven wheels more so than to the objective "front". particularly with front engine / rear drive cars, a front strut can be made to have a very acceptable camber curve, even at lowered ride heights. the typical transverse driveline (usually FWD) Mac strut is so space compromised it usually results in a poor or even detrimental camber curve. cars like the AW11 MR2, with a strut at the front and rear (driven) wheels which is ALSO a packaging compromise are rare - I think there are only 3-4 in the ITCS that are even close. so the process is blind to it. we could argue subjectively on a per case basis, but I think we have bigger fish to fry right now, both in general terms and with the MkI MR2 specifically.

[JeffYoung]

There is a really good argument (Josh presented a paper on it) that torque does not matter. If you have a reasonably good gearbox and can keep the motor in the power band, torque doesn't matter. HP is how we measure output/work, not torque.

I'm actually not willing to rethink them and don't think we ought to adjust any of them. The Process has been too fluid for too long and it needs to settle, even with a lot of things in it I don't personallly agree with. But, even so, on the whole the Process works and it works well.

The best way to screw it up would be to constantly change it so that we lose the stability that IT is (at least) known for.

So I think at the end of the day we are saying exactly the same thing.

I'm willing to rethink them but wihtout a process revamp that considers torque in the weight equation I want to keep some sort of torque adder. FWD deduct is also needed, but again, I'm willing to reconsider what it is.

the problem with my willingness is that it goes against stability, and I'm a bigger fan of stability than I am of "fixing" things that can't be perfect, anyhow.

[ShelbyRacer]

So wait, the Mustangs get a deduct for poor brakes, but the non-1LE Camarobirds don't? They're stopping a 3500lb car with 10.5" brakes, and that's not poor? Yes, they have rear discs that are huge, but they don't actually have much to do with slowing or stopping the car...

A better way to go would be to allow the 1LE stuff with an adder for decent brakes.

Straight comparison-
3200lb. Mustang with 11" brakes is poor
3500lb. Camaro with 10.5" brakes is good

[scratches head]

Andy- I'd be very interested to see the actual gains made on the x-fire engine in IT trim. I have my hypotheses about potentials, and I'd love to know how close I am.

[JeffYoung]

Doubtful (to me). The committee discussed this on the last call. The rationale for not having it doesn't make sense. Couple that with not wanting to change the Ops Manual except in extraordinary circumstances and my guess is it stays.

Chip,

Can we agree that we have proven that the Ops Manual is in error on the DW's in ITR? The classing shows it, the historical recollections support it and Josh's post finishes the debate off.

Can we please fix this?

[benspeed]

Got some great advice on this thread and from my bud Andy. Just want to say thanks that this debate was online - super informative and really learned a bunch from you guys. The "proving a negative" approach vs proving what is "known" now makes a great deal of sense and has aligned the way I look at how to compare cars to how the ITAC approaches things.

Now I have a plan...

[quadzjr]

There is a really good argument (Josh presented a paper on it) that torque does not matter. If you have a reasonably good gearbox and can keep the motor in the power band, torque doesn't matter. HP is how we measure output/work, not torque.

I'm actually not willing to rethink them and don't think we ought to adjust any of them. The Process has been too fluid for too long and it needs to settle, even with a lot of things in it I don't personallly agree with. But, even so, on the whole the Process works and it works well.

The best way to screw it up would be to constantly change it so that we lose the stability that IT is (at least) known for.

So I think at the end of the day we are saying exactly the same thing.

Not puting a vote for or against the process that I like alot. However the idea that torque does not play a role in IT cars that cannot change their gear box is simply not true.

If you can adopt your transmission to match your output a torque disadvantage will be lessened but not eliminated. I do know that many pro racing sereis would disagree with this statement. Two within the last 10 years have had to have major revamps because the lack or torque control. The two that come to mind are the ex JGTC GT500 class and the ACO Lemans 24hr (ALMS / LMES).

When Nissan introduced the 350zwith 500hp and a rumored 750ft/lbs it dominate the GT500 class over cars that were still working with lower displacement boosted cars. By the end of the firts and into the second season it was limit the motor to 500hp and get as much torque as you could. Later rules were changed and the class was disolved and is now Super GT.

When Audi introduced the R10 Diesel they trampled the petro cars that had more hp. Consistently every year including this last year the petro cars have more hp and have a higher top speed however they need to get moving out of a corner. Many things have been done to try to reign in the diesel cars, the biggest one was last year that significantly reduced the power and torque of the disels but they still dominated.

We drive IT cars, we cannot change our gear ratios to better utilize our engines output, thusly we cannot work around a torque deficnecy like they have done in pro series. We are stuck with our stock tranmissions. For your assumption that torque does not matter would require the cars less torque to have a reasonably good gear box. This is simply not the case in the majority of the shit boxes in IT. Especially in the lower ranks of unsporty cars in the ITA,B, and C range.

[JeffYoung]

Show your math.

I'll see if I can find Josh's paper, but the calculation is how much time is spent in what area of the curve. For most reasonable five speed gear boxes, this seems to be a wash.

It's why an ITS Mazda RX7 with 180 whp and 130 wtq competes just fine with Z cars and my car with a lot more torque.

If you can adopt your transmission to match your output a torque disadvantage will be lessened but not eliminated. I am very opend minded but I do know that almost every other pro racing sereis would disagree with this statement. Two within the last 10 years have had ot have major revamps because the lack or torque control. The two that come to mind are the ex JGTC GT500 class and the ACO Lemans 24hr (ALMS / LMES).

When Nissan introduced the 350zwith 500hp and a rumored 750ft/lbs it dominate the GT500 class over cars that were still working with lower displacement boosted cars. By the end of the firts and into the second season it was limit the motor to 500hp and get as much torque as you could. Later rules were changed and the class was disolved and is now Super GT.

When Audi introduced the R10 Diesel they trampled the petro cars that had more hp. Consistently every year including this last year the petro cars have more hp and have a higher top speed however they need to get moving out of a corner. Many things have been done to try to reign in the diesel cars, the biggest one was last year that significantly reduced the power and torque of the disels but they still dominated.

We drive IT cars, we cannot change our gear ratios to better utilize our engines output, thusly we cannot work around a torque deficnecy like they have done in pro series. We are stuck with our stock tranmissions. For your assumption that torque does not matter would require the cars less torque to have a reasonably good gear box. This is simply not the case in the majority of the shit boxes in IT. Especially in the lower ranks of unsporty cars in the ITA,B, and C range.

[quadzjr]

Show your math.

I'll see if I can find Josh's paper, but the calculation is how much time is spent in what area of the curve. For most reasonable five speed gear boxes, this seems to be a wash.

It's why an ITS Mazda RX7 with 180 whp and 130 wtq competes just fine with Z cars and my car with a lot more torque.

What math would you like to see? I love doing math, I actually miss doing it at my current career

area under the curve is number uno. however I believe that is beyond the scope of the process, atleast currently.

There are alot of other factors in why one car is competitive v.s. another. Aero, suspension, CG, roll centers, brakes, etc.. all play a role in how the car will perform on track.

A better example is line the two cars in a drag race. See which car will win.

If you have two identical cars sans a difference in torque, the one with more torque will win. Comparing two completely different cars and making that for the basis of why torque does not play a role eliminates the affect of all the other factors.

Also not all 5 gear gear boxes are the same. I do understand that for the sake of the class some assumption would have to be made and in that case I agree.

My power band is roughly 1200-1500rpm. I can assure you that my gearbox does not work with that. However my motors output fails when it comes to area under the curve.

[chuck baader]

I do have some first hand experience from the ARRC in November last year. My car (so called torque monster), Brian Price's Miata, and the Mosher CRXs were identical down the back straight at Road Atlanta. The only way one would pull the other boiled down to whomever got on the gas sooner. By my calculations, all three cars were 1/2 a percentage point in hp/wt calcs, and ran that way on the track. Each car has its strong and weak points but for all intents and purposes extremely equal, torque be dammed. Chuck

[JeffYoung]

This:

If you have two identical cars sans a difference in torque, the one with more torque will win.

is true in a hyper technical sense, but wrong practically.

A better way to say it is the car that USES its torque the best will win.

Even with identical gearboxes and rear ends, if the low torque car is able to launch at higher rpm and get into and stay in the HP band quicker then it will be a wash, or a win for the low torque car.

It took me a while to get over the misconception that huge torque is a huge advantage. It is, some. It basically allows you to recover better when you fall out of your peak RPM band.

But that is about it assuming areas under the curve of the high revving/low tq car versus the low revving/high tq. car are the same.

[JoshS]

Actually, I didn't say torque didn't matter. Torque does matter, because it directly affects the shape of the hp curve, and that *does* matter.

What I said was that the PEAK torque doesn't matter, which is all we have. You simply can't derive anything meaningful and useful about the shape of the horsepower curve based on the two things we have available, which is peak tq @ revs and peak hp @ revs. In fact, you can draw exactly one conclusion about the HP curve: you can find a second point on it (the HP available at the torque peak) and you can plot a two-point HP curve, otherwise known as an "HP line". The slope of that line is an indication of how quickly HP falls off on the left side of the HP peak. But you know nothing about how quickly HP falls off on the right side of the HP peak.

I plotted these "HP lines" for lots of cars in the ITCS and found very little correlation between their slopes and what cars the world thinks of as "torquey". I concluded that the peak torque number can not be used to derive any meaningful conclusions about appropriate weights.

I have the paper on my computer at home, I can repost it this weekend.

[JeffYoung]

That is correct, and since we were only looking at peak torque in the Process, that's why I shorthanded that "torque shouldn't matter" (for the Process).

No worries. It's in the Process and we do not intend to change it.

Actually, I didn't say torque didn't matter. Torque does matter, because it directly affects the shape of the hp curve, and that *does* matter.

What I said was that the PEAK torque doesn't matter, which is all we have. You simply can't derive anything meaningful and useful about the shape of the horsepower curve based on the two things we have available, which is peak tq @ revs and peak hp @ revs. In fact, you can draw exactly one conclusion about the HP curve: you can find a second point on it (the HP available at the torque peak) and you can plot a two-point HP curve, otherwise known as an "HP line". The slope of that line is an indication of how quickly HP falls off on the left side of the HP peak. But you know nothing about how quickly HP falls off on the right side of the HP peak.

I plotted these "HP lines" for lots of cars in the ITCS and found very little correlation between their slopes and what cars the world thinks of as "torquey". I concluded that the peak torque number can not be used to derive any meaningful conclusions about appropriate weights.

I have the paper on my computer at home, I can repost it this weekend.

[lateapex911]

per the ops manual all classes recieve the following adders:
DW: +50, except ITR
mid engined: +50
abnortmally small or large brakes: ±50

and these are class specific:
FWD Torque/diplacement low/high
ITR 6% -100/+150
ITS 5.5% -50/+100
ITA 2% -50/+100
ITB 2% 0/+50
ITC 0% 0/+50

ITR FWD and strut, -50
ITR rear solid axle, -50

.

See above.

Ops manual is great, but it just has a typo. Simple as that. I think it should be fixed as a error. (Really, it's just a manual and you can do as you please with it, because, unless I'm mistaken, it's not in the GCR and needs no official approval.)
Regardless, a simple oversight.

Down the road, if you really think it's wrong, then correct it, along with all the cars affected by it. (A bunch will gain weight)

I'd like to see the count/spreadsheet of the actual cars changed, how many are DW, and how many are not.
There's already an allowance in there for the strut so it's a double whammy to add for DW.

[ShelbyRacer]

There are some conspiracy theorists that Chevy intentionally screwed the heads and kep the intake crappy so that the revision with TPI would look that much better. Not sure how much I buy into it but the heads are CLEARLY blocked.

My information points to emissions as the impetus. Given the inherent issues of a wet manifold design, I'd think the keeping port velocities up and inducing some swirl and tumble would be an attempt to address that.

[JeffYoung]

I found a long article from a GM engineer the other day that said just about this.

Supposedly the prototype L83 made about 300 crank hp. However, it had serious driveability and emissions issues.

The correction was the port blockage to increase velocity, and fuel and timing adjustments of let's say a "non-performance" nature.

The fuel and timing can be corrected of course.

The real issue is those ports. It still looks to me that the IT legal port job will remove most of that material, but I may see if I can get one of these manifolds off of eBay.

This car is possibly an overdog, if it responds to IT prep like other large displacement motors, 2 valve, emissions era motors. 25% for now was the right call without any other data, but it concerns me.

[Ron Earp]

A few on Ebay now. I've never seen inside one until the Ebay pictures, pretty interesting design.