ITR Growth

Which is surprising to me Folks usually prefer to run the car at the lower weight in the lower class if it is acheivable. I agree it is a close call on whether this is acheivable, but the car looked more competitive in R (to me).

I'd love to have these cars and more drivers in S. If there are folks who want to race them in S, tell them to write in with tha tinterest and explain the R weight is not achievable and why.

seckerich said:
The difference being there were drivers ready to race them in S, No interest in making the R weight. Entrants lost for no good reason.
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1984 C4 Vette. Cross Fire injected 350. 205hp. 4 speed.

205*1.3*11.25+100lbs for torque IIRC from other V8's in ITR (only way CRB would let them in).

3100lbs in ITR. (or 2985lbs at 25%)
****************************

1978-79 Porsche 928

219*1.3*11.25+100

3305lbs. (or 3180lbs at 25%)
 
JeffYoung said:
Which is surprising to me Folks usually prefer to run the car at the lower weight in the lower class if it is acheivable. I agree it is a close call on whether this is acheivable, but the car looked more competitive in R (to me).

I'd love to have these cars and more drivers in S. If there are folks who want to race them in S, tell them to write in with tha tinterest and explain the R weight is not achievable and why.
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Didn't I do that for you already? GAC cars and weights, MX-5 Cup cars and weights...

Not achievable. It's an S car. Has ANYONE said anything but?

170*1.25*12.9=2740.
 
I've heard people say that yes.

Curb weight is 2410. While it is in the middle, it sure looks like it could make ITR race weight.

Andy Bettencourt said:
Didn't I do that for you already? GAC cars and weights, MX-5 Cup cars and weights...

Not achievable. It's an S car. Has ANYONE said anything but?

170*1.25*12.9=2740.
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2006, 2441lbs, 170 hp. 140ft lbs.
212.5hp x 12.9= 2741.
2741 plus 50 (double wishbones) (Andy, help me out here....the 'base ITS' car is the RX-7, right? if so, does the MX5 get a DW adder?)

Lets assume it does: 2790 race weight, in ITS.

In ITR: 170 x 1.25 =212.5
212.5 x 11.25 =2391
and just to be consistent, 50 for DW.
2440..which is the exact GCR weigh, how about that...

OK, now, subtract a cage and a driver: 280
It needs to weigh 2160 before cage and driver, in race trim. So that's 300 pounds of stuff getting ripped/changed out. In such a small car, and one where the seat isn't structural, the windows are minimal, and even sound deadening is minimal. 300 pounds is ALOT.
 
lateapex911 said:
OK, now, subtract a cage and a driver: 280
It needs to weigh 2160 before cage and driver, in race trim. So that's 300 pounds of stuff getting ripped/changed out. In such a small car, and one where the seat isn't structural, the windows are minimal, and even sound deadening is minimal. 300 pounds is ALOT.
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And add in 40lbs for a hardtop. I know it's not required, but it is 'required'.
 
The race weight is essentially the curb weight. That's pretty much standard procedure for us.

I do find it hard to believe you couldn't get 300 lbs out of the car with seats, carpet, consoles, sound, lighter wheels, spare tire, etc. That's pretty typical in my book for an IT build.

I'll check on the 50 for DW. I can't remember what the Operations Manual says about that. I do remember us believing a higher percentage of cars have a DW in ITR but I'm not even sure if that is true. BMWs are struts right? 300z. Others? Regardless, the manual says what it says. If we don't do the +50 in ITR I'll write a letter to get it taken off.

lateapex911 said:
2006, 2441lbs, 170 hp. 140ft lbs.
212.5hp x 12.9= 2741.
2741 plus 50 (double wishbones) (Andy, help me out here....the 'base ITS' car is the RX-7, right? if so, does the MX5 get a DW adder?)

Lets assume it does: 2790 race weight, in ITS.

In ITR: 170 x 1.25 =212.5
212.5 x 11.25 =2391
and just to be consistent, 50 for DW.
2440..which is the exact GCR weigh, how about that...

OK, now, subtract a cage and a driver: 280
It needs to weigh 2160 before cage and driver, in race trim. So that's 300 pounds of stuff getting ripped/changed out. In such a small car, and one where the seat isn't structural, the windows are minimal, and even sound deadening is minimal. 300 pounds is ALOT.
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The letters were written for ITS, not ITR and it would be a good fit. It runs well at the S weight and is a reasonable build. Why insist on making it so hard to build one for ITR? Why not list it both ways, there are enough Miatas on the track you never know if they are ITS/ITA/SM anyway. :D Either way my friend just sent me the for sale info on his rather than go ITR. That should tell you something. Please listen to the drivers with skin in the game instead of theoretical builds by non drivers.
 
We had one, maybe two guys ask to class the car. They didn't express a strong preference for either class. Without that, it almost always makes sense to put the car in the faster class at the lower weight.

If the drivers want the car in S, I'll support that but they need to write in.

Otherwise, normally speaking, forcing a car to run 300, 400 or 500 lbs of ballast is a recipe for no builds. If the group of guys who want to run this car want to do that, fine, but they need to let us know.
 
Weight rating for ITR?

Since I'm new to this concept, I wonder if anyone would be so kind as to mention what the various numbers in the formula represent?

I have devined the first to be Hp, the second to be an assumed power increase after "ITifying", but the third...11.25, or some other number like that...is not so easy to figure out. Also, what are the adders, or subtractors to the final score? I can't find a list of them by searching. Will we get a sticky for this?

Thanks, Guys.

Bill:024:
 
JeffYoung said:
I'll check on the 50 for DW. I can't remember what the Operations Manual says about that. I do remember us believing a higher percentage of cars have a DW in ITR but I'm not even sure if that is true. BMWs are struts right? 300z. Others? Regardless, the manual says what it says. If we don't do the +50 in ITR I'll write a letter to get it taken off.
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This is precisely why we need the classing info put on the spec line. There is supposedly some manual, but even the committee doesn't check it before classing a high profile car?

In the original ITR proposal the only adder used was for FWD. OVER half the field (and most of the current builds) are strut type front suspension, yet it was assumed that DW was the standard for the class - so no adder. Now ONE car gets that penalty?

Let's have some consistency folks - THAT IS THE POINT OF THE PROCESS RIGHT?
 
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billf said:
Since I'm new to this concept, I wonder if anyone would be so kind as to mention what the various numbers in the formula represent?

I have devined the first to be Hp, the second to be an assumed power increase after "ITifying", but the third...11.25, or some other number like that...is not so easy to figure out. Also, what are the adders, or subtractors to the final score? I can't find a list of them by searching. Will we get a sticky for this?

Thanks, Guys.

Bill:024:
Click to expand...

Bill, the "process" is a system used to get cars into a 'pocket' by power to weight. By 'pocket' I mean it's not a straight formula. Adders and subtractors like DW's, FWD, etc are applied at the end of the caclulation to compensate for design differences.

Power to weight targets are:

ITR: 11.25
ITS: 12.9
ITA: 14.5
ITB: 17.0
ITC: 18.84

Now, a big mistake would be to try and back calculate numbers from the ITCS. First, most cars in ITB and ITC have simply never been run through. The ITAC is currently working on this issue. Second, cars with the same motor can - and do - have different power to weights depending on the adders. Let's take an example:

140hp car. Looks and smells like an ITA car. Running the numbers for 2 cars, one with FWD and struts, and one with RWD and Double Wishbones:

Stock HP*estimated power increase in IT trim*ITA target P/W +/-adders = IT weight
140*1.25*14.5-2% for FWD=2486.75 Rounded to 2485.

140*1.25*14.5+50lbs for DW=2587.5 rounded to 2590.

Both cars have the same motor and HP potential remember (actually the FWD car would probably put about 2-3% more to the ground given traditional drivetrain losses but that isn't factored here).

So the long answer is that the "process" is a power to weight calculator with allowances for mechanical differences and tries to put cars into the same 'pocket' performance-wise - ON PAPER.
 
Grafton, settle down please. We are busy folks trying to get this stuff right. Occasionally, we make mistakes.

1. I'm in favor of putting the classing info on the spec line.

2. There is not "supposedly some manual." There is an Operations Manual laying out all of the inputs into the weighting process. We check it and use it before classing every car. However, we are people -- volunteers -- and on occasion mistakes are made.

Consistency is my number one goal. It's not always achieved, but we are doing our best. Call us out on it when we miss something but do so politely.

Thanks.

Jeff

GKR_17 said:
This is precisely why we need the classing info put on the spec line. There is supposedly some manual, but even the committee doesn't check it before classing a high profile car?

In the original ITR proposal the only adder used was for FWD. Nearly half the field (and most of the current builds) are strut type front suspension, yet it was assumed that DW was the standard for the class - so no adder. Now ONE car gets that penalty?

Let's have some consistency folks - THAT IS THE POINT OF THE PROCESS RIGHT?
Click to expand...
 
The below is all correct and a good explanation of things.

Andy Bettencourt said:
Bill, the "process" is a system used to get cars into a 'pocket' by power to weight. By 'pocket' I mean it's not a straight formula. Adders and subtractors like DW's, FWD, etc are applied at the end of the caclulation to compensate for design differences.

Power to weight targets are:

ITR: 11.25
ITS: 12.9
ITA: 14.5
ITB: 17.0
ITC: 18.84

Now, a big mistake would be to try and back calculate numbers from the ITCS. First, most cars in ITB and ITC have simply never been run through. The ITAC is currently working on this issue. Second, cars with the same motor can - and do - have different power to weights depending on the adders. Let's take an example:

140hp car. Looks and smells like an ITA car. Running the numbers for 2 cars, one with FWD and struts, and one with RWD and Double Wishbones:

Stock HP*estimated power increase in IT trim*ITA target P/W +/-adders = IT weight
140*1.25*14.5-2% for FWD=2486.75 Rounded to 2485.

140*1.25*14.5+50lbs for DW=2587.5 rounded to 2590.

Both cars have the same motor and HP potential remember (actually the FWD car would probably put about 2-3% more to the ground given traditional drivetrain losses but that isn't factored here).

So the long answer is that the "process" is a power to weight calculator with allowances for mechanical differences and tries to put cars into the same 'pocket' performance-wise - ON PAPER.
Click to expand...
 
JeffYoung said:
Grafton, settle down please. We are busy folks trying to get this stuff right. Occasionally, we make mistakes...Call us out on it when we miss something but do so politely.
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You have to understand my frustration, it is very difficult to find any mistakes when the classing guidelines aren't published and seem subject to change. Then it appears those same guidelines are applied inconsistently.

I understand you're all volunteers - I put my name in that hat also, but never heard back.
 
It's ok -- I understand the frustration. I am (personally) working as hard as I can to get as much of this stuff published as possible. I think it should be and I think you point out the key reason why members should have it below.

We do make mistakes. 99 times out of 100 though it is simple oversight rather than anything else.

Your resume remains on file, and your willingness to serve on the committee is appreciated. I think right now with Josh as the ITR guy on the committee, the feeling was we needed folks from other classes.

Thanks again for poitning this one out. I missed it myself.

GKR_17 said:
You have to understand my frustration, it is very difficult to find any mistakes when the classing guidelines aren't published and seem subject to change. Then it appears those same guidelines are applied inconsistently.

I understand you're all volunteers - I put my name in that hat also, but never heard back.
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