Figured I might as well start a thread to record the progress.
The car:
'93 MR2 slicktop, PS, no ABS. Known as "Gumby" in some circles. Picture below of it in E-Street trim at the 2019 Finger Lakes Tour.
The plan:
Alex Wilhelm housings with custom valved inserts. More details to come, when they're available.
Megasquirt DIYPNP, with a custom break-out-board.
RacerX intake box with additional piping from the Vibrant catalog.
Currently I'm working on putting together the Megasquirt. Thankfully, the DIYPNP motherboard has everything necessary to run the 5S motors, but it took some research to be sure was going to work.
As far as I know, the 93+ ECUs for the 5S have a different PN, and have a different connector. This makes them incompatible with the 76 Denso kit that DIYAT sells. Fortunately, it seems that the connector for the 93+ connectors is still source-able, if you know where to look. Below, a picture of the progress so far.
New day, new event. I think the Yoks on the rear are done by heat death. They've lived a hard life, so I guess it was expected by now. All that means is that the 71RS will have to show up and replace the Yoks.
The Arizona Solo Region event today showed how dependent the car is on having good rear tires. On my first run, I was chasing the rear around (that must've looked really entertaining from the outside) and I spent the rest of the runs trying to figure out how to tame it, which really meant driving to the limit of the rear axle, which happened to be sorta low. My usual tactic of trailbraking and catching the car on power didn't really work that well, since I came off of every apex sideways. And if I didn't trailbrake it in, the front didn't quite get to the apex. Oh well, it's par for the course when developing and learning a new car. I talked a big game at this year's Nats that I was going to bring the MR2 out, so guess that means 2023 Nats is a go, hell or high water.
Another event in the books. Phoenix Area Solo Region laid out an interesting course that when I initially walked I thought "seems I won't have much braking to do", which turned out to be mostly true. Best recorded time was a 46.2 in the last heat of the day. A STS Miata (unknown prep level, but on Yoks) did a 45.8. I managed to eek out a 45.8 in Time Only runs in the afternoon with careful brake usage and leaving no distance to cones. However, a CS ND2 managed a 42.9 (basically same PAX), and I don't think there was much left out there to find three seconds on raw. It's a bit of a hard comparison, since the course on the surface seemed to benefit from having high steady state grip, but there was enough room out there (for smaller cars) to really stay on the throttle, which obviously means the ND2 wins that race. I'm not sure if the CRX or Civic could get it done either, but it would probably be closer. However, that brings up a really obvious point of improvement, which would be to improve the power. On courses with a lot of WOT, more power would help to close the gap.
The RE-71RS seems to work pretty well on the back of the car. It seems to run a little smaller, but I think that has more to do with the profile of the treaded area. It seems to tolerate higher tire pressures than the Yok with no center wear. Being able to run higher pressures (25-30 instead of 20-25) is important for this setup, since it could use a little more roll stiffness. I bled down once for my timed runs, and didn't check on the tires at all during my Time Only runs, and neither end of the car seemed to care about the extra heat. Some photos for comparison below (Tire Rack also measured the tread width on the RE-71RS, and found it was smaller than the Yoks). I'm not convinced that the 71RS is the "right" tire for this car, but it can be made to work. Note that the tread width may be smaller, but the tread to shoulder area is much more rounded. This should be good for camber limited cars or cars with bad camber curves (the MR2 checks both boxes, sort of).
Almost to the end of 2022. Went to Tucson for an event at their new site, which is a newly paved parking lot. Did OK in competition runs, but I wasted two of my runs making mistakes and generally over-driving. I had a co-driver to help me gauge how I was driving and provide insight on where the setup could improve. There was an ES Spyder and an STS Miata to compare against, and we were still 4-5 tenths off on a 34 ish second course. I figured it out a little in afternoon fun runs, but judging from this video and my co-drivers best scratch, I think there was another 4 - 5 tenths, so high 33's. To be top PAX, we would have to run a 32.4, so still pretty far off from the pointy end. Definitely not achievable with the car as it stands now, so I'll need to find some ways to extract that time from the car and the driver.
Struggled a bit with the car. The surface seemed a little green, so it was easy to over-drive the front axle and the rear axle. I probably should've taken some compression damping out to see if I could find a little more grip out there.
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