GT Classification Worksheet

[FireSale]

I took the wording of the rulebook under GT Super Stock and used it to make up a worksheet for figuring out classes of a GT build. Please check this out and let me know if I did it right and if it would be of any help in planning a car. One is the worksheet and the other has the weight info for my 68 GT Mustang.

Thanks

Dale

[jmcarter]

Why not just use the tool Dwight developed?

http://classracer.com/classforum/sho...t=54726&page=3

[FireSale]

Originally Posted by jmcarter

Why not just use the tool Dwight developed?

http://classracer.com/classforum/sho...t=54726&page=3

That will give you links to NHRA spec sheets, but no place to jot down info and play with figures. Part off what I wanted to do was to put the formula and data on one page.

Dale

[FireSale]

A question that has come up in my PMs about this is that the Stock Car Classification Guide contains shipping weights and they don't match the weights you get if you use the formula contained in the GT weight rule.

My heaviest gas engine version of the 68 Mustang is the 428 convertible auto at 3369 lbs. If I use the factor times HP formula mentioned in the rule (8.87 X 335) I get 2971. If I use the Super Stock with replacement heads HP (8.87 X 383) I get 3397 lbs. Which of these should be used for the shipping weight?

Dale

[Mike Carr]

The HP penalty for a replacement head doesn't change the classification of a car; it is added after the fact. For example: A 1969 Camaro 427/425. You divide the shipping weight by the 425 to get the class; Class weight x 425 + 170. You add the 10 hp after. SO, in A/SA, you add 80 pounds (8 pound class, 10 hp penalty) after the fact.

The shipping weight never changes; it is what it is. If the shipping weight is 3,369 pounds, you will always use that number; divided by the HP (with OEM head) of the motor desired. You then add the hp penalty weight after. If a car falls into, say, GT/EA. 10 pound class. If an aftermarket head is permitted, with a 5 hp penalty, the aftermarket head version weighs 50 pounds more than a car with the same motor and an OEM head.

If I am wrong, someone can correct me, but I believe that is the way it works.

[Dwight Southerland]

Originally Posted by FireSale

That will give you links to NHRA spec sheets, but no place to jot down info and play with figures. Part off what I wanted to do was to put the formula and data on one page.

Dale

You must not have signed up as a member. If you will register on the website, it will do all the calculations for you faster than you can write any of them down.

[FireSale]

Originally Posted by Dwight Southerland

You must not have signed up as a member. If you will register on the website, it will do all the calculations for you faster than you can write any of them down.

Guess I was registered for the forum but not as a member of the site. I followed the instructions on your page and re registered and got all the info I will ever need in one place.

Thanks.

Dale Shearon

[FireSale]

Originally Posted by Mike Carr

The HP penalty for a replacement head doesn't change the classification of a car; it is added after the fact. For example: A 1969 Camaro 427/425. You divide the shipping weight by the 425 to get the class; Class weight x 425 + 170. You add the 10 hp after. SO, in A/SA, you add 80 pounds (8 pound class, 10 hp penalty) after the fact.

The shipping weight never changes; it is what it is. If the shipping weight is 3,369 pounds, you will always use that number; divided by the HP (with OEM head) of the motor desired. You then add the hp penalty weight after. If a car falls into, say, GT/EA. 10 pound class. If an aftermarket head is permitted, with a 5 hp penalty, the aftermarket head version weighs 50 pounds more than a car with the same motor and an OEM head.

If I am wrong, someone can correct me, but I believe that is the way it works.

So:

Weight: 3369
Stock: 302/220
SS w/replacment heads: 302/230
HP added: 10

3369/220 = 15.31 GT/MA

If this is right and M is the last class, where does the extra 100 lbs for the HP hit go? does my car need to weigh 3469?

Dale

EDIT: Now that I have them working right, I ran my build through Dwight's Tools and came up with GT/KA through GT/MA depending on weight up or down. That makes more sense to me than trying to decipher the fine points of the rule book's English.

So....never mind....

[Dion Hildebrandt]

Originally Posted by FireSale

So:

Weight: 3369
Stock: 302/220
SS w/replacment heads: 302/230
HP added: 10

3369/220 = 15.31 GT/MA

If this is right and M is the last class, where does the extra 100 lbs for the HP hit go? does my car need to weigh 3469?

Dale

Dale

yes 3469, but I do believe we are supposed to round to the nearest 10....so 3470

[FireSale]

Originally Posted by Dion Hildebrandt

yes 3469, but I do believe we are supposed to round to the nearest 10....so 3470

Shipping weight is 599 lbs lighter than that for the stock version of the 302 coupe. What was I thinking when I bought aluminum heads??? At least I won't have to worry about the weight of my mild steel cage any more...

Dale