Tube frame SA 13B turbo autoX/track car
 

I had removed the 13BT engine from the Caterham (my avatar) and needed to build something to put it in. So, I obtained a 1980 shell from a wrecking yard and built a tube frame to fit underneath it. Since it was going to be used primarily for autocross in E/Mod class, it would be using 10" wide fronts and 12" wide rears. So, the GTU wide body kit from RotaryEngineeringSB was the perfect fiberglass kit to use. The rear suspension is from an NA FC with a Miata torsen and 5.38 gear. The building began in October 2019 and has a been used in the local series in 2020 and 2021.

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I just completed lightening several of the components and managed to remove a total of 95 pounds. The sunroof top was replaced with a carbon fiber copy weighing 3 pounds. The doors were replaced with aluminum copies at 6 pounds each. The previous stock doors had been lightened to 26 pounds each. The B-pillar/quater panels were separated from all of the stock sub-layers as well as similar surgery on the rocker panels and rad support. The car now weighs 1900 pounds.
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Here's an in-car video of a run from last year:

Ooo I'm loving the metal work on this one. Awesome job! Will definitely be looking forward to more pics :)

Thanks for the compliment 82transam. Here are some more pics from the build process featuring the sheetmetal work.

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Wow....nice build .....and in that video ...uff.....that is a stupid fast 7....looks like a blast to drive ....

I'll keep checking the progress....well done brother!!

Fantastic work. What Solo class do you run the car in?

Thanks guys.
Yes, raven12aFB, when the course has a decent straight and the pavement has good traction, it accelerates at over 0.9 g's. :biggrin:
Scott, the car runs in E Modified.

Fab'ing aluminum doors from scratch is impressive. Very nice build.

Thanks kurtf.
The new panels have been painted, installed and decals added.
Here's a better pic of the engine.
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The car modifications and a new set of tires resulted in a much better raw time at the local autoX this weekend. The bold yellow "GoodYear" was the only thing that got any attention. I discovered that they will need a different camber setting than what I've been using on the Hoosiers for years. That will change before the next event. The change in brand was required cuz they stopped making the size of rear tire that I've been using.


I only made the morning runs, but my best time put me in the midst of the SM Evo's morning runs.

The weight reduction effort has continued over the last few months. The aluminum belly pan under the engine was 0.120 " thick and now it's 0.060" thick. The door posts were cut off and replaced by 0.050" aluminum channel sections with aluminum nut plates riveted in for the hinges. The radiator was downsized along with the fan going from a double 12" fan unit to a single 15" fan. The steel dry sump plate was replaced with an aluminum one. Lightening holes were drilled in the A-piller. The wing supports were revised. The front rotors had been FC 4-lug and were replaced with Wilwood sprint car rotors mounted on DIY aluminum hats. The 12 gal fuel cell was replaced by a 3 gal cell. (Since the local track has not been completed)
The car now weighs 1780 pounds.
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Absolutely love it. Looks fantastic!

As someone who has been strongly considering a garage built race car (Locost), what led you away from the Caterham?

The Caterham ( an S3) was fantastic, but it was getting hard for me to get into. So I sold it to build a Locost version (+331) but with D-Mod engine (2.0L max) . I missed the power of the turbo 13B, so the RX7 SA combo was chosen because I wanted to have a better car for open track use also.

love it