Grudge racing weight break? How to calculate it?

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Jan 31, 2006
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I got called out ( and I talked smack) by a friend that has a badass old school Mustang the car is a turbo V8 and huals ass. The car is also about 1000 pounds lighter than my car.
What would be a fair way to calculate a weight break for me?
 
Well, I know that this is grudge racing and once the smack talking starts you are on your own :-) :-). However, I would start like this. One formula for average rwhp is 197 * weight going down track / et^3. Your sig says your best et is 11.74 and I'm going to guess a total weight with you at 3600 lbs, so use those to estimate an average rwhp (if you have better numbers, use them instead): rwhp=197 * 3600 / (11.74*11.74*11.74) = 438 rwhp. Now use that hp and subtract 1000 lbs and calculate a predicted et for your car at the new weight: et=cube root of (197 * 2600 / 438) = 10.53. So, if your car were 1000 lbs lighter your et would drop from 11.74 to 10.53, in theory. This ignores all kinds of things like gearing, 60', wind resistance, etc, but it is a place to start. So, if you are doing this as a grudge race at a track and they will set up the tree, give yourself a 1.2 sec head start to compensate for the weight difference. If this is going to be, um, less formal (:-)), then (I'm skipping more boring math) a rough estimate is to give yourself a 210 foot head start. Regals are 17' long so that's about 12 car lengths. That puts you on equal footing for weight, so now it comes down to hp and traction and driving. Be safe and good luck.
 
Well, I know that this is grudge racing and once the smack talking starts you are on your own :) :). However, I would start like this. One formula for average rwhp is 197 * weight going down track / et^3. Your sig says your best et is 11.74 and I'm going to guess a total weight with you at 3600 lbs, so use those to estimate an average rwhp (if you have better numbers, use them instead): rwhp=197 * 3600 / (11.74*11.74*11.74) = 438 rwhp. Now use that hp and subtract 1000 lbs and calculate a predicted et for your car at the new weight: et=cube root of (197 * 2600 / 438) = 10.53. So, if your car were 1000 lbs lighter your et would drop from 11.74 to 10.53, in theory. This ignores all kinds of things like gearing, 60', wind resistance, etc, but it is a place to start. So, if you are doing this as a grudge race at a track and they will set up the tree, give yourself a 1.2 sec head start to compensate for the weight difference. If this is going to be, um, less formal :)-)), then (I'm skipping more boring math) a rough estimate is to give yourself a 210 foot head start. Regals are 17' long so that's about 12 car lengths. That puts you on equal footing for weight, so now it comes down to hp and traction and driving. Be safe and good luck.

i can't make heads or tales of your calculation can you plug in 3840 for vehicle weight (that includes the driver)

last time on the scales (about 6 weeks ago) the weight of the car with me in it was 3840
 
Need more info on his car....what size V8, what size turbo, what has it ran.

Tell him to bring it down on the 17th.


Billy T.
gnxtc2@aol.com
 
Well, I know that this is grudge racing and once the smack talking starts you are on your own :) :). However, I would start like this. One formula for average rwhp is 197 * weight going down track / et^3. Your sig says your best et is 11.74 and I'm going to guess a total weight with you at 3600 lbs, so use those to estimate an average rwhp (if you have better numbers, use them instead): rwhp=197 * 3600 / (11.74*11.74*11.74) = 438 rwhp. Now use that hp and subtract 1000 lbs and calculate a predicted et for your car at the new weight: et=cube root of (197 * 2600 / 438) = 10.53. So, if your car were 1000 lbs lighter your et would drop from 11.74 to 10.53, in theory. This ignores all kinds of things like gearing, 60', wind resistance, etc, but it is a place to start. So, if you are doing this as a grudge race at a track and they will set up the tree, give yourself a 1.2 sec head start to compensate for the weight difference. If this is going to be, um, less formal :)-)), then (I'm skipping more boring math) a rough estimate is to give yourself a 210 foot head start. Regals are 17' long so that's about 12 car lengths. That puts you on equal footing for weight, so now it comes down to hp and traction and driving. Be safe and good luck.

i can't make heads or tales of your calculation can you plug in 3840 for vehicle weight (that includes the driver)

last time on the scales (about 6 weeks ago) the weight of the car with me in it was 3840

Sorry. If you ran 11.74 at 3840 lbs you averaged 467.5 hp, and if your car was 1000 lbs lighter and averaged 467.5 hp you would run 10.62, so if you get a 1.12 sec (or 11 car length) head start you will be even based on weight so the car with the most hp will win.
 
11 car lengths!! lol good luck suggesting that lol

That's why I started my reply by saying that once the talking started I knew the physics didn't matter :-). It was just something interesting to calculate and I have a hard time resisting those even when I know the answer will never be used as written.
 
In grudge racing terms. You need the back tire, the hit and the gap and if its a decent running V8 turbo car that still won't be enough in an 11 second car.

The back tire means you stage with the back tire, he stages with the front.

The hit means you leave first. He can't leave until you do.

The gap means he has to put a gap between your front bumper and his rear bumper.

This would give you about 5-7 car length advantage.

If you can argue for extra lengths, I'd take them also.


Posted from the TurboBuick.Com mobile app
 
In grudge racing terms. You need the back tire, the hit and the gap and if its a decent running V8 turbo car that still won't be enough in an 11 second car.

The back tire means you stage with the back tire, he stages with the front.

The hit means you leave first. He can't leave until you do.

The gap means he has to put a gap between your front bumper and his rear bumper.

This would give you about 5-7 car length advantage.

If you can argue for extra lengths, I'd take them also.


Posted from the TurboBuick.Com mobile app
I like this
 
Is this a street race.If it is I think most of the race will depend on how the cars hook on the street.
 
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