GT class configuration...
 

How do you figure class for a certain engine/car combo?? Combo in question would be a 71 Plymouth Duster with a 1970 383/335Hp engine.

Re: GT class configuration...
 

Just pick what ever GT class you want to run and multiply the hp to the class you choose. With the ability to adjust the shipping weight in GT the door is wide open to put a combo where it will be competitive.

Re: GT class configuration...
 

If you have Microsoft Excel you can use my class calcuator to find out which classes a particular setup can run. You need to know the shipping weight of the car, the factored HP of the engine, and the trans type.

You can download or run from:
http://www.employees.org/~bhracing/g...ulator_1p1.xls

Re: GT class configuration...
 

To the original poster, I dont mean to jump in on the thread but i have the same question

With a heavy car, Which GT class would a 327/275 or 327/300 fall under with an automatic?

Re: GT class configuration...
 

Thanks for the info guys.

The calculator works great,and easy to use.

Also thanks to the mod that moved this.

Re: GT class configuration...
 

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.

Re: GT class configuration...
 

Chris,

I don't think you can the 383 in GT since it doesn't have a rating for GT, just superstock. The 340, and 340 six pack has ratings. Also 340's from other years.

This may not help, but here is the 1970 dodge page from the classification guide. If you are able to run that motor, please let me know, it would truly open up a lot of options for other Mopar racers.


DODGE 1970

198 225 225 318 318 340 340 340 340 340 383 383 383 383 383
* ** * ** * ** * * ** * ** * **
A A
Auto Stick
125hp 145hp 145hp 230hp 230hp 275hp 275hp 290hp 290hp 290hp 290hp 330hp 330hp 335hp 335hp
DART 111
Sedan 4 Dr 22.40 20.74 19.31 15.62 14.81
Sedan 2 Dr Swinger 22.36 20.70 19.27 15.59 14.79 10.48 11.15
Sedan 2 Dr Custom 22.28 20.62 19.20 15.54 14.74
Sedan 4 Dr Custom 22.40 20.74 19.31 15.62 14.81
CHALLENGER 110
Sedan 2 Dr Hdtp 22.04 20.52 16.08 15.25 10.51 11.18 10.93 10.90 10.72 10.72 10.72
Sedan 2 Dr TA 9.59 9.83 9.53
Convertible 22.89 21.31 16.70 15.84 10.89 11.59 11.12 11.29 11.11 11.11 11.11
Coupe 2 Dr Hdtp 22.12 20.59 16.14 15.31 10.54 11.21 10.96 10.94 10.76 10.76 10.76
CORONET DELUXE 117
Coupe 2 Dr 22.89 21.31 17.24 16.36 11.55 11.53 11.33 11.33 11.33
Sedan 4 Dr 23.11 21.52 17.41 16.51 11.65 11.63 11.44 11.44 11.44
Sta Wag 2S 26.56 24.73 19.73 18.72 13.26 13.21 12.99 12.99 12.99
CORONET 440 117
Coupe 2 Dr 22.96 21.38 17.29 16.41 11.58 11.56 11.37 11.37 11.37
Sedan 2 Dr Hdtp 23.15 21.55 17.43 16.54 11.67 11.64 11.45 11.45 11.45
Sedan 4 Dr 23.19 21.59 17.46 16.56 11.69 11.66 11.47 11.47 11.47
Sta Wag 2S 26.61 24.77 19.77 18.75 13.28 13.22 13.00 13.00 13.00
Sta Wag 3S 27.12 25.25 20.14 19.11 13.52 13.46 13.24 13.24 13.24
CORONET 500 117
Sedan 2 Dr Hdtp 17.32 16.43 11.60 11.57 11.38 11.38 11.38
Convertible 18.05 17.13 12.05 12.03 11.83 11.83 11.83
Sedan 4 Dr 17.53 16.63 11.74 11.71 11.51 11.51 11.51
Sta Wag 2S 19.64 18.64 13.08 13.04 12.82 12.82 12.82
Sta Wag 3S 19.89 18.87 13.31 13.25 13.03 13.03 13.03
CHARGER 117
Sedan 2 Dr Hdtp 24.04 22.38 17.96 17.04 12.01 11.98 11.78
Sedan 2 Dr Hdtp 500 24.04 22.38 17.96 17.04 12.01 11.98 11.78

S/SS Factor 125 135 145 185 195 299 281 328 320 330 290 295 300 300 300
6.28.05 6.28.05 8.26.03 1.1.07 7.8.04 2.13.06 6.2.03 5.30.02 6.2.03 5.30.02
GT Factors 288

SS Factor w/replacement heads 286 335
10.27.07 10.27.07
GT Factor w/replacement heads 293 335
10.27.07 10.27.07





A - P5007140 replacement head for SS only


* = Stock Factor

Re: GT class configuration...
 

Eric, this is untrue. You can run the 383 in a SS/GT class. You would use the same SS factor as defined for a non-GT. The only time there is an entry in the classification guide specifically for GT is when the AHFS has made an adjustment on a particular engine when it is used in a GT application. The more popular engines used in GT classes are more likely to have a GT specific factor, but only because there has been more opportunity to get hit. All of them started out as regular SS factors and have been enhanced sometime in the past.

Re: GT class configuration...
 

Bill,

Thank You for setting me straight. This is great news! Opens up a lot of interesting options for future fun..

Eric

Re: GT class configuration...
 

Would it be possible to repost this as a working link please?

Thank you,

pS

Re: GT class configuration...
 

Can someone repost a working link to this calculator?

Re: GT class configuration...
 

Rod, You have a PM

Re: GT class configuration...
 

Adger that 327/275/299 is the stick hp. Been at that hp for several years. I ran that combo 2006 to 2012.

Re: GT class configuration...
 

To calculate GT combinations:

1) Go to www.classracerinfo.com
2) Register as a member if you have not done it already
3) Go to link for Technical Tools
4) Select NHRA Classification Tool

5) Select your car year-model (1971 Plymouth, 1987 Camaro, etc) from the drop down boxes

6) Click on the specific make-model-engine combination from the classification page (looks like an NHRA class guide page)

7) You will see Stock-Super Stock classfication information. At the bottom of that classification information page is a button titled "GT Classes". Click on it.

8) Select the engine you want to use from the list that is displayed and click on the button "Classify"

9) Ta-dah! All the GT classifications with weights, classes and indexes for each eligible classes.

http://i39.photobucket.com/albums/e2...ps4561a8cf.jpg

Re: GT class configuration...
 

Dwight, you've been commended on other threads for this great tool and in my futile attempt to find a traditional SS car within my budget I have started to get more serious about making it a GT class car in order to use some of my inventory. The tool you created is absolutely phenomenal in terms of time savings for the racer looking to find a good competitive GT combo. Thanks!!!

Re: GT class configuration...
 

Gee thanks, Jim! I'm humbled by the complement.

Re: GT class configuration...
 

I agree, thank you for this tool.

Sean

Re: GT class configuration...
 

We should all be half as smart as Dwight

Re: GT class configuration...
 

Jim, We are!! :~) He sure has made it easier to select classes. Great stuff!!

Re: GT class configuration...
 

Does anyone see a button for GT Classes? I don't. I have emailed Dwight.

Re: GT class configuration...
 

Dwight this is a great tool and maybe I'm missing something but what if you have a replacement head and NHRA has added hp how do you look that up?

Re: GT class configuration...
 

Okay I see it now. You have to click on the specific p/w factor for the body style and engine to be used, the negotiate from there.

I see , for instance a 66 Chevy II, 2 dr sedan with a 283 , can run three classes in SS, but five classes in GT. Then if the hp rating is lower in GT, you can get back to the weight break where you were in SS , at a lighter weight than when you left, with the same index.
Does this make any sense to anybody?
Also , seeing GT class was formed to allow a different year engine than the body you are using, would you have to claim the 283 as a 65 engine, or don't they care about that either?

Re: GT class configuration...
 

Mark,
Where you need to pay attention is the min and max combo weight calculations in GT, as you are only allowed to be 250lbs above and below the natual class, at least that what I have found. It's a very helpful tool to play with what combo's could work, and what not to build! Dwight has really made looking at combos very easy.

Thanks Dwight!


Sean

Re: GT class configuration...
 

Mark -
Current rules do not require that the engine be a different year, so the guys with the Chevy IIs that run GT/K and L are just using the option to run a softer index with the same weight.

Re: GT class configuration...
 

Rusty, what is the combination you are looking for?

Re: GT class configuration...
 

Just about every engine that I could use in my 1967 Fairlane or 1969 Mustang with aftermarket heads has hp added. I know how to look it up on NHRA's site and today was the first time I looked at your site and was surprised that it was only listed with stock heads. It is a lot easier getting aftermarket heads when building these classic cars. I want to say again that you have done a great job putting this all together.

Rusty