+11ty
Escort GT/LXE to ITB?
- Thread starter tderonne
- Start date
+11ty
gran racing
Super Moderator
Just sayin' - Very well developed Prelude for sale - $6,900
Refreshed head is in the garage awaiting to be bolted in.
I'd also place money if I'm in it next year, it'll be going faster. Time to man up Charlie. Old tires isn't going to do it anymore. Or again, the "easy button: ain't that expensive above especially considering how much more money was spent developing / building it. I raced against one at the Glen last year and we had a fantastic battle racing right with each other. Totally either of our races. I got lucky that he made a mistake; that's it.
shwah
New member
Weird. That is pretty much what I understood to have happened to my car. Guess I do need to write a letter...
Warts and all. Horses for courses. etc. etc.
That said, while we are on the topic... An aero adder would not be much different than a torque adder, so why not?
On the original topic, regarding how the car is classified: any dyno sheets for serious builds? Regarding the apparent lack of success, any highly developed cars with extensive testing?
That said, while we are on the topic... An aero adder would not be much different than a torque adder, so why not?
On the original topic, regarding how the car is classified: any dyno sheets for serious builds? Regarding the apparent lack of success, any highly developed cars with extensive testing?
Flyinglizard
New member
The aero is so important with these cars. I spent a week cost down testing my last car. The initial coast down from 60-45 was 14.8 sec. My ending value was 17.5. sec.
This turned into around 400rpm, or 8-9mph.
Just dropping the rear of the Mk 2 Golf,2in, increases terminal speed about 2-3mph.
Funny, one of the racing games( Forza) comes up with the same values.
I Think that I could do a very simple equation using the glass angle/ width/ total height. It would be based upon a "zero car". Any cars outside of the standard value
( way better or way worse) could be addressed fairly easy.
This turned into around 400rpm, or 8-9mph.
Just dropping the rear of the Mk 2 Golf,2in, increases terminal speed about 2-3mph.
Funny, one of the racing games( Forza) comes up with the same values.
I Think that I could do a very simple equation using the glass angle/ width/ total height. It would be based upon a "zero car". Any cars outside of the standard value
( way better or way worse) could be addressed fairly easy.
A fixed-weight aero adder, like that used for torque, sounds fine. a way to apply it based on data showing better or worse aero than the norm for the class requires data that is not easily available for many cars, and statistics for the classes that we don't have. It's not really all that useful if we can't apply it.
gran racing
Super Moderator
Do you then judge aero with or without the allowable splitter and "undertray"? If a car that doesn't have as good areo stock, could that be overcome with a high quality IT allowed system?
We can infer what types of engine builds will produce what HP gains. I really don't think IT is a place to attempt this on aero.
We can infer what types of engine builds will produce what HP gains. I really don't think IT is a place to attempt this on aero.
Flyinglizard
New member
My short equation will assume that all of the allowed front aero is done. It will look only at the basic shape presented to the air.
It should only bump a # if the car varies much(10%) from the Norm/zero car.
It will be simply a % drag change from the norm ( I would use the Mk 2 Golf for the ITB norm), of the glass/surface area. Cars way better or way worse would bump the numbers. The adjuster could just be a percent value , times the car overall value.
I have not done the equation yet, But I dont see any reason it could not be done pretty well.
The values should hold up fairly well at different tracks also . As the poor Aero cars are also taller, affecting the cars at handling tracks near as much as top speed tracks.
If you look at published CD values large pieces of drag are the front tires, mirrors, etc account for around 50% of the CD. My equation will assume that all of these are equal.
The input #s needed are; hood height, glass angle , width in the middle of the glass , overall height.
Sorry about the poor reading/ writing as I am pretty heavy ADD. MM
It should only bump a # if the car varies much(10%) from the Norm/zero car.
It will be simply a % drag change from the norm ( I would use the Mk 2 Golf for the ITB norm), of the glass/surface area. Cars way better or way worse would bump the numbers. The adjuster could just be a percent value , times the car overall value.
I have not done the equation yet, But I dont see any reason it could not be done pretty well.
The values should hold up fairly well at different tracks also . As the poor Aero cars are also taller, affecting the cars at handling tracks near as much as top speed tracks.
If you look at published CD values large pieces of drag are the front tires, mirrors, etc account for around 50% of the CD. My equation will assume that all of these are equal.
The input #s needed are; hood height, glass angle , width in the middle of the glass , overall height.
Sorry about the poor reading/ writing as I am pretty heavy ADD. MM
StephenB
New member
where would you get all your info for your equation?
Also could you please use the equation and give us some examples. I would like to see the Golf2, Golf3, Volvo, Opel GT, Alfa Romeo (conv.), Audi Coupe, Prelude, 2002, 318, civic done through your equation then I can give input with more validity.
To be honest I really really think that it doesn't matter at our level of racing. Way to many other variables to worry about... like your reaction time from the gas to the brakes for example. but after you give us some data on the above examples maybe I can be swayed...
Stephen
Also could you please use the equation and give us some examples. I would like to see the Golf2, Golf3, Volvo, Opel GT, Alfa Romeo (conv.), Audi Coupe, Prelude, 2002, 318, civic done through your equation then I can give input with more validity.
To be honest I really really think that it doesn't matter at our level of racing. Way to many other variables to worry about... like your reaction time from the gas to the brakes for example. but after you give us some data on the above examples maybe I can be swayed...
Stephen
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JeffYoung
New member
Aero, by the seat of my pants driving, seems to matter about 110 or so. Total guess, that's what it seems like. So I agree aero matters.
Now, tell me where and how we are going to get "aero specs" for each of the 300 cars in the ITCS. You have a myopic focus on two cars which really highlights how impractical this exercise is.
This is not prod. We are not here to balance cars on a pin head. We get the power to weights close, and we apply some very basic adders/deducts (and I was with Kirk back in the day -- opposed to all of them) and you move on.
You start trying to calculate torque under the curve (the only way to do a fair torque adder/deduct) or aero like Lizard suggests and you are quickly stuck in a morass of minutiae.
Now, tell me where and how we are going to get "aero specs" for each of the 300 cars in the ITCS. You have a myopic focus on two cars which really highlights how impractical this exercise is.
This is not prod. We are not here to balance cars on a pin head. We get the power to weights close, and we apply some very basic adders/deducts (and I was with Kirk back in the day -- opposed to all of them) and you move on.
You start trying to calculate torque under the curve (the only way to do a fair torque adder/deduct) or aero like Lizard suggests and you are quickly stuck in a morass of minutiae.
...and EVERY additional variable that gets put into the mix is an invitation for monkey business - whether intentional or not.
"It matters" is a very different thing than, "we can manage it" or "it matters more than a lot of things we can't control for."
As someone who knows a little more about aerodynamics than the average Club Racer, I think it's a tangle with lousy benefit/cost returns, which we should stay FAR away from.
K
EDIT - Readers' Quiz Time!
How much difference do you think this air dam made at Road Atlanta, in back-to-back testing with the stock configuration? It included a to-the-max undertray:
Here's stock...
K
"It matters" is a very different thing than, "we can manage it" or "it matters more than a lot of things we can't control for."
As someone who knows a little more about aerodynamics than the average Club Racer, I think it's a tangle with lousy benefit/cost returns, which we should stay FAR away from.
K
EDIT - Readers' Quiz Time!
How much difference do you think this air dam made at Road Atlanta, in back-to-back testing with the stock configuration? It included a to-the-max undertray:
Here's stock...
K
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Flyinglizard
New member
My airplane flies @ 35-36mph.
http://pou.guide.free.fr/connaitre/gretchen/gretchen_mike_ogren.html
So yes it matters. But Only if you want it to
It occurs to me that i have lots to work with.
2 Mk 2 Golfs, One Jetta roadster, 1 SM miata, 1 Rocco. All take the same wheels/tires, all have the free running calipers. Big burps in drag( either way) will show up.
6000ft of runway.
Yes, I will need the input data listed above .
I have lots to do either way.
Not considering aero , big mistake IMHO.
But I spend a lot of time addressing it. Most dont.
http://pou.guide.free.fr/connaitre/gretchen/gretchen_mike_ogren.html
So yes it matters. But Only if you want it to
It occurs to me that i have lots to work with.
2 Mk 2 Golfs, One Jetta roadster, 1 SM miata, 1 Rocco. All take the same wheels/tires, all have the free running calipers. Big burps in drag( either way) will show up.
6000ft of runway.
Yes, I will need the input data listed above .
I have lots to do either way.
Not considering aero , big mistake IMHO.
But I spend a lot of time addressing it. Most dont.
ShelbyRacer
New member
Except for the fact that, as Dave alluded, some of these issues can be tackled with IT mods. How do we compensate for a car with large frontal area, and therefore what appears to be a drag handicap, that can drop it's ride height more than another car with a better stock drag that can't go much lower? What about the significant CD gain from an air dam on a car that had a poor stock CD, versus a negligible gain on another car with a good factory CD because of better air control? It seems to me that the cars that would stand to receive the biggest handicap are the cars that would benefit the most from a full application of the rules and some significant development work.
Oh, and then there's the question of even getting good numbers to begin with. In a quick check, I found that the "officially claimed" CD on the 1988 Rocco is .38, while the 1988 Golf is .34 from the same site.
Mike- your "formula" appears to concentrate on the front of the car. What about the rear? I realize that IT mods have little effect there, but stock shape does.
As Chip said, I don't object to the concept of an adder, I just question a way to apply it accurately and consistently.
Oh, and then there's the question of even getting good numbers to begin with. In a quick check, I found that the "officially claimed" CD on the 1988 Rocco is .38, while the 1988 Golf is .34 from the same site.
Mike- your "formula" appears to concentrate on the front of the car. What about the rear? I realize that IT mods have little effect there, but stock shape does.
As Chip said, I don't object to the concept of an adder, I just question a way to apply it accurately and consistently.
Flyinglizard
New member
The simple equation addresses the frontal area by the glass width, hood height, overall height..
The back of the car is similar in size as the front.
RE air dam; speed neutral, +-2, down force positive, should have more front bite and a lower lap time.
Still could go faster if you used my DRS.
The back of the car is similar in size as the front.
RE air dam; speed neutral, +-2, down force positive, should have more front bite and a lower lap time.
Still could go faster if you used my DRS.
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Ignoring aero and torque creates a set of rules created winners and losers. Which, if the allowable modifications had been set in stone and left unchanged would leave those who want to build one of the losers with no basis to complain. We've changed the rules on what can be modified and that has impacted the list of winners and losers after they've already tossed in their ante and matched on the first round of bets.
If the true aero penalty on a car is 75lbs, then allowing that car to remove anything less than 75lbs is a win. The current cars in the aero win list get "hurt", but I don't have sympathy for them because IMO eliminating an unfair advantage is not the same as eliminating an unfair disadvantage.
It's got to be after the allowed IT prep and that might make it more difficult to get the adjustment perfect. I'm not certain whether it makes moving the system closer to perfect impossible.
We don't process the Miata and a Chrysler K car to equate the performance+ ability of Price in the Miata to the ability of someone who would want to drive a K-car. Isn't the goal to equate what driver X can do in the Miata with what driver X can do in the K-car?
Is that at 110% or at 110MPH?
Because if it's the latter, I can tell you it matters in a C car at a lot lower velocity.
Insufficient or no evidence on additional/reduced gains under an IT-build gets you the default. Same could happen for aero -- you want it, produce the evidence otherwise it isn't even considered and the ITAC isn't going to ask for it.
If the true aero penalty on a car is 75lbs, then allowing that car to remove anything less than 75lbs is a win. The current cars in the aero win list get "hurt", but I don't have sympathy for them because IMO eliminating an unfair advantage is not the same as eliminating an unfair disadvantage.
It's got to be after the allowed IT prep and that might make it more difficult to get the adjustment perfect. I'm not certain whether it makes moving the system closer to perfect impossible.
We don't process the Miata and a Chrysler K car to equate the performance+ ability of Price in the Miata to the ability of someone who would want to drive a K-car. Isn't the goal to equate what driver X can do in the Miata with what driver X can do in the K-car?
Is that at 110% or at 110MPH?
Because if it's the latter, I can tell you it matters in a C car at a lot lower velocity.You (the ITAC) don't. The default is NADA on the omitted variables. If a car already is classified, then those wanting the change better bring the blue dress. If the car isn't already processed, then those asking for it either show that the glove fits or the car doesn't get the subtraction. Isn't that how deviations from the default HP-multiplier work on cars never before classified?
Insufficient or no evidence on additional/reduced gains under an IT-build gets you the default. Same could happen for aero -- you want it, produce the evidence otherwise it isn't even considered and the ITAC isn't going to ask for it.
except that we dopn't have a baseline to compare that submitted data against. we need to have an idea of what the drag (and more importantly, drag to hp) of the class is so we could modify a car's weight to compensate. we can measure mass. we can measure hp. so those are really good things to base such a process on, and we can find out when we're right and wrong because we can go back and measure them again later.
adding aero to the mix does nothing but create more winners and loosers.
and FWIW, the rocco and GTI are both "heavy" by process, and I think the realistic floor weight on the rocco is above that number. if someone writes a letter, we could maybe fix that, given support. self correcting problem. moving along.
adding aero to the mix does nothing but create more winners and loosers.
and FWIW, the rocco and GTI are both "heavy" by process, and I think the realistic floor weight on the rocco is above that number. if someone writes a letter, we could maybe fix that, given support. self correcting problem. moving along.
Pick it arbitrarily.
ITR: Honda S2000
ITS: Triumph TR8
ITA: Honda CRX Si
ITB: BMW 2002
ITC: Yugo GV
Car <> modifier is based on deviation from the drag:IT-HP of the "base" car.
How did the ITC hp:weight ratio get set? Certainly nothing to do with the cars actually in the class (who will need to lose 20-50% of their mass if reprocessed).