GT/KA ? What class?

[trmnatr]

With 3,700-3,800 pound race weight what class would a 327/275 or 327/300 fall under? GT/KA ?

What ET would it have to run and would would be a record ET ?

It will consist of a TH400 Automatic with a Transbrake and the engine will be SS legal rods, GM crank, Bill Miller pistons with .031" rings and -291 heads at the min 57.5cc chambers

Some other questions are being it is Super Stock and not Stock, Can you run like a Holley double pumper with a choke tower or do you have to run a Q-Jet or is there a specific Holley you have to run or what?

[Adger Smith]

As posted on GT Thread
Looks like the 327 275 has been gifted with HP. (NHRA.com) The 1966 275 is now at 299 HP with OE heads & 304 HP w replacement heads. The 327 300 HP is at 285 w OE heads & 290 W Replacement heads. Might make the 300 a better choice, depending on the differences in the engine combos. If you know the shipping weight of the heavy car you want to use you can use Bill's GT calculator to figure out what classes it will fit. You have to know 3 things to figure the class w/GT calculator. 1. Shipping weight of the car you want to use. You can get the factory shipping weight from the NHRA classification guide. http://www.nhra.com/tech_specs/classification/ 2. The factored HP of the engine. (get the same place) 3. Either Auto or Man. The program works. It even gives you choices of which classes you can move to by adding or subtracting weight & the HP required to run. Pretty nice tool.
No Holley with choke horn removed. Carb must be type listed in classification guide for engine & correct bore size. The engine has to be built using the specified parts sizes & types for the HP claimed. You must use the base weight as listed in the classification guide for the body you use. You can't just throw weigh in a car & start out calling it heavy. Hope this helps.

[Adger Smith]

This is a stab at what class. In the PM you sent me I still didn't get enough info. I'm going to assume the car is a 2 dr cpe. If it's not that changes things. The 1970 Chevelle 2 DR Cpe has a NHRA factory shipping weight of 3372. That appears to be the heaviest small block in a 2 Dr Cpe. The 1966 300 HP 327 has a NHRA rated HP of 285 with the legal OE 291 casting head. According to the GT calculator the lightest class the car will fit in is GT/FA @ 3162.5 It will take 462 HP to run the index in that class and 613 to run 1 sec under. The heaviest class the combo can fit is GT/JA @ 3732.5 lbs. It will take 478.3 Hp to run the index & 626 to run 1 second under. The weight for those 2 classes includes the driver. The combo will fit GT/ G, H, I with the weight adjusted to fit those classes. Better check on those pistons. I'm not sure if the 300 hp 327 had 2 or 4 valve notches... A little CRS on my part. If I didn't miss any thing most of the other specs you gave me looked good. The carb on the 1966 300 HP 327 is listed as a Holley 3367A with throttle bores of 1.562 & venturi's of 1.25 and 1.313. You don't have to use the original part #, but have to use the correct bore sizes. It has to be built to SS legal specs. I hope I didn't screw anything up and this info helps you.
GT calculator
http://www.employees.org/~bhracing/g...ulator_1p1.xls

[Mike Voth]

Adger - Where do I find Bill's GT calculator?

[Chris DeGidio]

Mike,
It's in the other GT post that I started about how to configure GT class.It works real well.

[SSDiv6]

http://www.employees.org/~bhracing/g...ulator_1p1.xls

[Mike Voth]

Thanks guys. Want to see how accurate it is with our combo. Will report my findings later...

[JRyan]

Only TWO valve reliefs are required in Superstock for the Chevy engine.

Jerry

[Mike Voth]

Okay. Bill's GT calculator is good for figuring the class a car would fall in at any given weight, but it is NOOOOOOOOOOOO way in the park as far as HP numbers. Our car has gone a best -1.063 under the index (non corrected), and I figured to make the HP the chart says for -1.000, we'd actually be about -1.750. That Chrysler estimation equation used to figure HP is for the dreamers! But a good guide, otherwise.

[trmnatr]

Originally Posted by Adger Smith

This is a stab at what class. In the PM you sent me I still didn't get enough info. I'm going to assume the car is a 2 dr cpe. If it's not that changes things. The 1970 Chevelle 2 DR Cpe has a NHRA factory shipping weight of 3372. That appears to be the heaviest small block in a 2 Dr Cpe. The 1966 300 HP 327 has a NHRA rated HP of 285 with the legal OE 291 casting head. According to the GT calculator the lightest class the car will fit in is GT/FA @ 3162.5 It will take 462 HP to run the index in that class and 613 to run 1 sec under. The heaviest class the combo can fit is GT/JA @ 3732.5 lbs. It will take 478.3 Hp to run the index & 626 to run 1 second under. The weight for those 2 classes includes the driver. The combo will fit GT/ G, H, I with the weight adjusted to fit those classes. Better check on those pistons. I'm not sure if the 300 hp 327 had 2 or 4 valve notches... A little CRS on my part. If I didn't miss any thing most of the other specs you gave me looked good. The carb on the 1966 300 HP 327 is listed as a Holley 3367A with throttle bores of 1.562 & venturi's of 1.25 and 1.313. You don't have to use the original part #, but have to use the correct bore sizes. It has to be built to SS legal specs. I hope I didn't screw anything up and this info helps you.
GT calculator
http://www.employees.org/~bhracing/g...ulator_1p1.xls

So if we do the engine as a 327/275 we can run GT/JA ?

The car is a two door coupe