Been pondering some upgrades to my '83 to get towards the pointy end of F-Class in ChampCar. F-class is a limited prep, so I have to be careful about my points usage. Current front of class is very minimally prepped Miatas (open air filter rules, open tuning, maybe a header). Without doing anything, we can easily hang with them with the mildly ported, tuned Nikki 12A. Yes, cornering speed will help us get to max velocity sooner, but we're not going to be able to spend tons of practice days to tune the car and get more seat time.

So with the above knowledge, here's my concept:
Fresh 12A build with increased porting. Big street port or bridge port.
RX8 4 port intake manifold (may be only 25 points, may be 50 points depending on tech ruling) Would need to make an adapter to match, but the ports on these are pretty close as is.
Microsquirt EFI (FC CAS for setting ignition timing)

I know that I could go to a DCOE or something along those lines, but EFI (and tuneable igntion) gives us more flexibility to build in some safety and tune in a more cost effective manner.

My other option would be to "convert" to a GSL-SE 13B and Microsquirt that. Unfortunately, the GSL-SE starts 100 pts higher, so there's not really a big benefit there.

I would also consider going to an RX8 6 speed, but I'm a little unclear which counterweight would be necessary with that. Yes, I know the shifter location is farther forward.

So is my concept sound? TIA!

 

the Rx8 trans keeps the same counterweight you have now, but you need to run a turbo (or Rx8) sized flywheel and clutch.
if you had an SA, the Rx8 shifter would probably be pretty close

so questions, how many points do you use if say you bridge ported the engine and just used a nikki? the IMSA RS cars used this and were ~180hp
how many points is a Weber IDA? or maybe its better to ask if the rule is EFI or changing the intake? like if you run EFI on the stock intake manifold is that the same as running EFI on the Rx8 manifold?

if your points depend on a tech ruling you should ask before you do it too.

 

I've built a few EFI 12As for people. I personally think you'd be much better off using an IDA style manifold and ITBs (assuming this is legal), if you're concerned about cost and have the ability there are a few options available that aren't completely bolt on but are much cheaper than some of the known IDA ITBs. Racehead is one in particular:

https://racehead.com.au/product/ida-...rottle-bodies/


Edit: Or you could just be a dummy like me and spend more than you bought the car for on an ECU that can control dual DBW throttles and use some bike throttles:

 

Rules are 25 points for intake manifold, 25 for throttle body, 25 for carb. So I could run an IDA (or DCOE) setup for 50 points. I could also run an IDA or DCOE manifold and EFI ITBs for 50 points. The grey-area that I'm trying to work toward is that the RX8 manifold (and TB) may be able to squeak in for 25.

Easy button would be stock manifold with Holley Sniper or similar system for only 25 points. I would much rather go with an ECU that gives me ignition control as well.

 

I generally wouldn't say this, but for all out racing in an NA application using gasoline you don't need much more than 25* advance and good/new/real stock coils - it's essentially what I do most of my baseline configs for E production engines I build when doing run-in on the dyno, flow of the Sniper system is another matter entirely - I have zero experience with them other than trying to help a few people remotely with stupid hackery.


Edit: For clarity, I'm not saying that you'll get max performance out of that stock coil and dizzy setup (with no vacuum advance), I'm saying if you're concerned about easy mode apply the 80/20 rule - which in this case is probably 90/10 - 90 percent of the desired result with 10 percent of the effort.

 

That Ducati TB setup with the shower injection looks amazing. I really like that, nice work.

 

you should ask about that.

 

Question has been submitted.

 

Thanks! The throttle PIDs have been figured out on the bench but it's taking too long to actually get the time/desire/drive to strap it and the ECU onto the car. 'Spose I should start working on the harness again :|