NASA TT4/ST4 tubular subframe legal in 2023...

Reply Subscribe

Thread Tools

Search this Thread

02-24-2023, 09:42 AM

Roda

Senior Member

Thread Starter

Join Date: Sep 2011

Location: Sierra Vista, AZ

Posts: 1,201

Total Cats: 295

NASA TT4/ST4 tubular subframe legal in 2023...

Haven't seen this mentioned anywhere yet, but this looks like it opens up TT4 for K swapped cars not using the stock subframe...

Quote:

Originally Posted by NASA 2023 rules

6.4.4 ST4 Non-OEM Front Sub-frame Swaps
Front non-OEM and tubular sub-frame swaps that mount to OEM mounting locations, for the purpose of facilitating a motor swap, will be evaluated by the National Director on a case-by-case basis requiring proof of OEM suspension geometry and with a -0.4 Modification Factor assessment.

Has anyone had their K swapped Miata 'evaluated' by NASA yet?

05-05-2023, 10:52 PM

Ben AZ

Junior Member

iTrader: (12)

Join Date: Feb 2018

Location: Prescott Valley

Posts: 69

Total Cats: 5

Quote:

Originally Posted by Roda

Haven't seen this mentioned anywhere yet, but this looks like it opens up TT4 for K swapped cars not using the stock subframe...

Has anyone had their K swapped Miata 'evaluated' by NASA yet?

Would the 5-10 WHP hit from going Z3 instead of A2 be worth keeping those .4 pts?

05-06-2023, 08:41 AM

Roda

Senior Member

Thread Starter

Join Date: Sep 2011

Location: Sierra Vista, AZ

Posts: 1,201

Total Cats: 295

Quote:

Originally Posted by Ben AZ

Would the 5-10 WHP hit from going Z3 instead of A2 be worth keeping those .4 pts?

I thought it was more like 15hp, but I think it would mostly depend on where you were able to use those .4 pts. My car pencils out at 216 ave hp with the .4 hit on Toyo RRs, which is right in the sweet spot for the A2.

05-08-2023, 12:13 PM

flier129

Elite Member

iTrader: (7)

Join Date: Jan 2008

Location: Statesville, NC

Posts: 2,738

Total Cats: 319

There are now ways for a K24Z3 to make K24A2 power. It's obviously not free $$ to do that, but the option is there to hit the same power goals and retain the 0.4.

I suspect the k24a2 + V8R/KP subframe to pass this rule though. Same pick-up points and all. I don't personally know of anyone that did this "inspection" yet.