gt class question

[jaf2021]

running a 66 chevy2 327/275 auto in ss/ia. i see some of the 283/220 running in gt class. what would i have to do to change to a gt class still running the same 327 engine?

[Mike Pearson]

Nothing. The HP is now the same as a regular super stock. The index will be .05 to .10 faster. The guys that do that do it so they can run all out and not hit the trigger.

[jaf2021]

Hey Mike the GT hp rating for 66 is 295 and regular is 307. Don’t you have to claim a different year combination?

[Mike Pearson]

I have run both with my Camaro. It has a 327/275 combo rated at 295. When I ran GT/IA before I had to claim 299 hp and add 40 lbs plus take a .05 hit on the index. I think I read where they lowered the 327 GT factor back to 295. Yes you might have to claim it as the 68 combo. Check the guide.

[JeremyDuncan]

Originally Posted by jaf2021

Hey Mike the GT hp rating for 66 is 295 and regular is 307. Don’t you have to claim a different year combination?

You do not have to claim a different year engine than body year. Also the 327 275 GT factor was lowered to 295.

Be careful figuring the class for GT. The shipping wt rules are different than traditional SS.

In your case since your running IA that your claiming 66 Nova SS to fit in SS/IA.

In GT you have to claim the heaviest engine shipping wt for your body style and transmission type. Your allowed to adjust the shipping wt 250 from this. In a 66 Nova SS the heaviest shipping wt engine combo is the 327 275hp combo at 2917lbs.

You are allowed to either subtract the 250lbs from this or add the 250lbs to the shipping wt to figure the classification.

So 2917lbs minus 250 is 2667lbs. *(You cannot adjust shipping wt below 2500). Take the 2667 ÷ by the GT HP factor of the engine being used which is 295. Which is 9.04 that gives you your power to weight factor and what's the lightest class you can run. Which is GT/GA in this case. Please note that unlike traditional SS you can not automatically go to the "bottom" of a class weight break just because it fits that class. GT/ GA is 9.00 to 9.49. so your min in GT/GA would be 9.04*295+170 driver wt. = 2941 adjusted down to nearest 5lbs scale weight or 2940.

To find the heaviest GT class you add the 250 to shipping wt and divide by GT HP of motor claimed Factor to get power to weight factor.

So 2917 + 250 ÷ 295= 10.73 power to weight factor. GT/JA is a 10.50 to 10.99 class and would be heaviest class your combo would fit.

Your min. Wt in GT/JA would be 10.5x 295+170= 3267. Round down to scale wt of 3265.

You can run also run any class between GT/GA to GT/JA.

I would think GT/JA would be a good choice for your car. You would only have to add 25lbs from your SS/IA min wt and go from a 10.70 to a 10.80 index.

[Mike Pearson]

Originally Posted by JeremyDuncan

You do not have to claim a different year engine than body year. Also the 327 275 GT factor was lowered to 295.

Be careful figuring the class for GT. The shipping wt rules are different than traditional SS.

In your case since your running IA that your claiming 66 Nova SS to fit in SS/IA.

In GT you have to claim the heaviest engine shipping wt for your body style and transmission type. Your allowed to adjust the shipping wt 250 from this. In a 66 Nova SS the heaviest shipping wt engine combo is the 327 275hp combo at 2917lbs.

You are allowed to either subtract the 250lbs from this or add the 250lbs to the shipping wt to figure the classification.

So 2917lbs minus 250 is 2667lbs. *(You cannot adjust shipping wt below 2500). Take the 2667 ÷ by the GT HP factor of the engine being used which is 295. Which is 9.04 that gives you your power to weight factor and what's the lightest class you can run. Which is GT/GA in this case. Please note that unlike traditional SS you can not automatically go to the "bottom" of a class weight break just because it fits that class. GT/ GA is 9.00 to 9.49. so your min in GT/GA would be 9.04*295+170 driver wt. = 2941 adjusted down to nearest 5lbs scale weight or 2940.

To find the heaviest GT class you add the 250 to shipping wt and divide by GT HP of motor claimed Factor to get power to weight factor.

So 2917 + 250 ÷ 295= 10.73 power to weight factor. GT/JA is a 10.50 to 10.99 class and would be heaviest class your combo would fit.

Your min. Wt in GT/JA would be 10.5x 295+170= 3267. Round down to scale wt of 3265.

You can run also run any class between GT/GA to GT/JA.

I would think GT/JA would be a good choice for your car. You would only have to add 25lbs from your SS/IA min wt and go from a 10.70 to a 10.80 index.

SSIA minimum weight for 327/275/295 is 3120. At least that is what it is in my 68 Camaro. I have been running that for a few years. Not the best combo for sure but that is what I have right now. The 327 is harder to dial than the 350 was and falls off more in the heat.

[JeremyDuncan]

Originally Posted by Mike Pearson

SSIA minimum weight for 327/275/295 is 3120. At least that is what it is in my 68 Camaro. I have been running that for a few years. Not the best combo for sure but that is what I have right now. The 327 is harder to dial than the 350 was and falls off more in the heat.

327 275 in 67 Camaro is 295, but a 66 Chevy II is 307 HP in SS with OEM heads. Only 300hp with replacement heads. Original poster stated he had a 66 Chevy II Nova.

[FireSale]

The car owner does not specify if it is an SS or not. For GT shipping weight the starting point is the body with the heaviest gas engine (same trans -auto).
For the 66 Chevy II it's 2878 and the 66 Chevy II SS clocks in at 2917. Careful with the weight and HP math in GT.


EDIT: The GT HP rating for the 66 327/275 auto is also 295. Replacement heads boosts it to 304HP. This is from the GT HP box at the top of the 66 Classification page.

[JeremyDuncan]

Originally Posted by FireSale

The car owner does not specify if it is an SS or not. For GT shipping weight the starting point is the body with the heaviest gas engine (same trans -auto).
For the 66 Chevy II it's 2878 and the 66 Chevy II SS clocks in at 2917. Careful with the weight and HP math in GT.

EDIT: The GT HP rating for the 66 327/275 auto is also 295.

I assumed an it was an SS cause the original poster stated he runs SS/IA and that's the only version of the 66 Chevy II/Nova that will fit in SS/IA with 327 275/307hp.

The non SS 66 Chevy II 327 275/307HP is natural SS/GA car. Can only move up or down one class in traditional SS.

[FireSale]

Originally Posted by JeremyDuncan

I assumed an it was an SS cause the original poster stated he runs SS/IA and that's the only version of the 66 Chevy II/Nova that will fit in SS/IA with 327 275/307hp.

The non SS 66 Chevy II 327 275/307HP is natural SS/GA car. Can only move up or down one class in traditional SS.

Then you are probably right. Where did you see 307 as the GT factor? I found 304.


Only drag racers split hairs over 3 HP and 39 lbs......