Question about the Viability of a Tub Car in GT3

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CodeRed7o7
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Question about the Viability of a Tub Car in GT3

Post by CodeRed7o7 » Fri Apr 28, 2017 5:18 pm

Hello all,

I am currently building a tub Miata and have narrowed down the classes I am interested in running to STL and GT3. Is a tub Miata capable of being competitive in GT3? or are tub cars an exercise in futility? When I say competitive, I mean being within a second of the top tube frame car's lap times on a course such as Road America.

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Re: Question about the Viability of a Tub Car in GT3

Post by CARSHouston » Fri Apr 28, 2017 8:23 pm

Personal experience with Tom Thrash on his first gen RX7 is yes it is possible. He ran the car in EP and GT3, with a change of the carb, splitter and the addition of a rear wing.
He passed at the 2009 June Sprints, so I can't give you data on the car setup from that event, but at TWS he was about to break John Saurino's GT3 track record and at MSR Houston he was faster then Jimmy Burke's GT3 track record. If you compare the results between EP Miatas and GT3 cars at Road America they are close enough in lap times that it is possible.
But if you're trying to run STL and GT3 I don't know if that's possible, you may have too many limitations with the STL rules. I haven't read the STL rules closely enough to see if you can make enough changes to be close an EP or GT3 car.
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CodeRed7o7
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Re: Question about the Viability of a Tub Car in GT3

Post by CodeRed7o7 » Fri Apr 28, 2017 8:52 pm

CARSHouston wrote:Personal experience with Tom Thrash on his first gen RX7 is yes it is possible. He ran the car in EP and GT3, with a change of the carb, splitter and the addition of a rear wing.
He passed at the 2009 June Sprints, so I can't give you data on the car setup from that event, but at TWS he was about to break John Saurino's GT3 track record and at MSR Houston he was faster then Jimmy Burke's GT3 track record. If you compare the results between EP Miatas and GT3 cars at Road America they are close enough in lap times that it is possible.
But if you're trying to run STL and GT3 I don't know if that's possible, you may have too many limitations with the STL rules. I haven't read the STL rules closely enough to see if you can make enough changes to be close an EP or GT3 car.
Thanks for the information. I wouldn't be running both STL and GT3 as the performance differences between the two are too great. I would commit 100% to either class. Engine-wise, the car is nearly stock so I'm trying to determine which class I want to run before I start spending money.

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zchris
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Re: Question about the Viability of a Tub Car in GT3

Post by zchris » Fri Apr 28, 2017 8:58 pm

What gen Miata and what engine do you plan to run. Might make a diff in your success.
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Re: Question about the Viability of a Tub Car in GT3

Post by CodeRed7o7 » Sat Apr 29, 2017 1:18 am

zchris wrote:What gen Miata and what engine do you plan to run. Might make a diff in your success.
First gen Miata. I would run a 1.6l, 1.8l, or 13b. Speaking of engines, what oem miata engines are legal in GT3?

The GCR lists the B6D and BP being legal, however according to wikipedia, the 1.6l miata engine is the B6ZE(RS). Additionally, would the BP-4W engine from the 1999-2000 miata be legal?

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Re: Question about the Viability of a Tub Car in GT3

Post by zchris » Sat Apr 29, 2017 8:10 am

I would start by saying, bigger is always better for lots of mid range torque. I use a 2.3 MZR/Duratec engine in my NB bodied Miata. You could even use the 2.5 engine with no weight penalty. And I know they can be made to fit in the NA as a local guy has done it. Any Mazda engine listed in the GT3 engine specs can be used in any Mazda bodied chassis. And those 2.5 engines can be had for under $500 with low mileage.
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