GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

Why not just use the tool Dwight developed?

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

Re: GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

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.

Re: GT Classification Worksheet
 

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.

Re: GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

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....

Re: GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

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

Re: GT Classification Worksheet
 

Fire Sale,

If you car is a convertible then 3369 is correct. If not then 3267 is the shipping weight to use. With the engine rated at 335 the your non convertible would run C @3185 or D @ 3350 or E @ 3520. A convertible would run C @ 3285, D @ 3350, E @ 3520 or F @ 3685. These weight are class minimums. The convertible can't get to the top of C and would have to run 100 heavy for the class.

Re: GT Classification Worksheet
 

It's a GT build. A 68 Mustang coupe using the engine specs of the 302/230 found in the 68 Cougar. The rules say to use the heaviest gas engine body as the shipping weight, which is the 68 convertible 428/335 . That's where the 3369 comes from. The engine is rated at 220 with 10 added for the AFR 1399 heads.

As I understand it, GT is like building a car that never came off the production line even though it has the right brand parts in it. So a weight is assigned to the body and the class is determined by the engine factor. It could have been the actual weight of the body used (68 Mustang coupe) or an average 68 Mustang weight, but someone decided on using the heaviest one available. I guess.

Dale

Re: GT Classification Worksheet
 

The heaviest coupe weight is 3241, which is what you would use for calculation. You would not use the convertible shipping weight for a coupe body.

Re: GT Classification Worksheet
 

Thanks. That's a further clarification. The rule just says heaviest vehicle and dosen't differentiate between heaviest 68 Mustang (the convertible) or heaviest vehicle you are using (68 coupe).

Thanks again.

Dale

Re: GT Classification Worksheet
 

Actually the rule doesn't say the heaviest vehicle, but rather "Shipping weight will be determined by using the
power to weight factor of the vehicle with the heaviest gasoline engine and appropriate transmission." The vehicle with the heaviest engine is usually the heaviest vehicle, but not always... just something to keep in mind.

Re: GT Classification Worksheet
 

I think the wording is meant to imply the vehicle in question. In this current example the vehicle in question is a 68 Mustang coupe. Don't try to make their wording more technically legalistic than it is. The opening description of the rulebook section states "Cars will be classified using the shipping weight of the body divided by thehorsepower or performance rating of the engine used." The body in that statement is the body you have, not anything else. The intent is to use the heaviest shipping weight of the particular model-body you have. So, for example, you can't use the shipping weight of a 4- or 6-cylinder Camaro when calculating the class when the V8 models were heavier.

Re: GT Classification Worksheet
 

Hi Guys,

Sorry to hijack this thread but I am in the process of building a GT car of my own and I am new to this class stuff... But anyways, I just wanted to have some sort of clarification or maybe confirmation on what I calculated for shipping weight/classes I can run personally.

Here's the combo:

LS1 Body style Camaro COUPE (1998-2002)
Automatic
327/275HP 1968 Camaro motor (OEM Heads) - 299HP factor (I believe)

Using your tips from the templates,

If I read correctly,

The heaviest coupe is 3370 in 1998. the factor is 12.08 and the HP is 285.

So 12.08 X 285 = 3443 (Shipping Weight) divided by my 299 HP is 11.514 which is my base for classes? So I can run the car at 3443 + or - 250. More specifically, my weight would be the minimum ratio for the class X 299HP + 170?

I would hopefully just like to confirm this and make sure that I am using the right shipping weights and base ratios (3370 lbs and 12.08)

Thanks in advance for the help!

JP

Re: GT Classification Worksheet
 

Given the info from this thread, the original template I posted isn't accurate in regards to weight. Reread the entire thread. especially post 16 from Dwight.

Find your car on the Stock Classification Guide and take the shipping weight
from that car's heaviest gas engine with the trans you are going to run.

If your body is a 98 Camaro coupe auto, use the shipping weight of the one with the biggest gas engine offered. I don't have data here, but if they sold it with a six and a 427, use the weight of the 427.

Once you have your shipping weight, remember what they keep telling me. It never changes, just the factors with different engine combos.

Take your shipping weight to the engine listing at the top of the classification guide and divide the weight by various HP ratings to get class factors. Be sure to use the GT factors in regards to HP ratings. Find the posts here about HP weight factors for replacement heads, too.


EDIT: LS1 shows up in the Guide starting in 99. You need to pick a year to get the body weight right. It looks like that would be a Z28 coupe with the LS1 engine? I'm a Ford dude...

99 Camaro Z28 Coupe 427 auto weight 3291

327/275HP 1968 Camaro motor (OEM Heads) - 299HP factor (I believe) Yes

3291 / 299 = 11

GT/GA


Dale

Re: GT Classification Worksheet
 

Thanks Dale!

Re: GT Classification Worksheet
 

Go to www.classracerinfo.com Register as a user and use the tools there. Much easier, faster.

Re: GT Classification Worksheet
 

Under the Stock and Super Stock section of this forum is a "sticky" at the top with a link to the tool mentioned above. Registering for the forum won't get you access to all the goodies, you have to register with the site at that link. It would be nice if a link to the Tech Tools Dwight developed could be included along with the other links (NHRA, IHRA, ect. at the top of the site page or under Quick Links.

Dale