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Discussion Starter #1
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.

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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.
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Oh man, that's pretty exciting to see actually. I need to get on this Megasquirt plan and see if it works any better than the Greddy. Of course, I should maybe try again to get the Greddy working. Anyway, glad to see you're giving it a shot though and that Gumby still exists! (I recognize those wheels...)
 

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Discussion Starter #3
Thanks! I'm hoping that the MS can squeeze a few more lbs-ft more torque out of the 5S. Fortunately, I know of a really good tuner local to me that has done a lot of Megasquirt stuff that should be able to get the most of the 5S. I've more or less accepted that the 5S isn't going to be making 95% of peak torque at the rev limit.
However, with the 25" diameter tires on the rear, it should put the 30-50 mph range in the 3800-5200 rpm range, if I recall correctly.

I've put in a rule request/clarification to see if it's possible to get allowances for Federal cars to use Cali cat locations. I've got a header plan for that too... I'll put a picture of that up when I have it in hand. It's pretty much the ideal design (by the Book) without asking Burns to draw something up from scratch. I'm hoping to improve peak torque, and if nothing else, match torque-to-weight ratio with the Miata/Civic (optimistic, but possibly achievable; I'm prepared to be disappointed).

I refreshed the front brakes last year with OE like pads, which are surprisingly really good (street/autox pads, not race pads), so I'm going to stick with that up front and put the Raybestos R-4S on the rear to hopefully maintain good trail-braking. I think the rear brakes are Hawk HPS now, which I never really liked on my Mazda3, since it felt like they needed to be heated or bedded each time before the first run. I recall a run at a local event where I forgot to take that into account, and there wasn't a braking point until a 180 sweeper which required slowing from 50 ish to 30 ish. I stood on the pedal and barely made the corner 😜

Current preliminary suspension/wheels/tire setup (some money committed, some theoretical):
225/50/15 Yokos on Rota Slipstreams (5x114.3, +37). Hoping for no spacers up front. Option for 225/45/15 BFG scrubs from last year on the same wheels.
225/45/17 Yokos on heavy Enkeis. I bought some huge rear spacers to bring the offset to +20. Option for 225/45/17 new BFGs on the same wheels.

The suspension (plan) is kinda different from what everyone else has done.
  • 400/600 lbs/in F/R spring rates (nothing terribly unusual here)
  • Going with a TRD front bar and stock rear bar (I think the math checks out. The first runs will be very entertaining)
    • Basically, I'm going to try and keep the front at near stock ride height, and get the rear down in the 1.5" from stock on 23" diameter tires. So, it'll be around 0.5" lower with the 25" diameter tires.
  • Wilhelm housing and camber plates
  • I'm only replacing the inner LCA bushing with poly, and I impulse bought some replacement rubber bushings for the rear radius rod to LCA. I'm going with SuperPro bushings (I guess alllllllll those "influencers" have done their job). My plan to replace the front radius rods with new OE arms only partially succeeded; I only have the LH side. Apparently, Japan doesn't have any more.
  • Custom single-adjustable Penske inserts to fit the Wilhelm housings. I should have that in hand fairly soon, I think. Once the charges hit the card, I should know for certain!
  • Initial alignment settings are up in the air, and are likely to change.
 

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Discussion Starter #4
Finally got around to wiring the break out board to the mainboard. I also wired up 12V and the CAN bus to the DB15 connector for a Racecapture. I'll probably just dual lock the Racecapture to the case of the Megasquirt.
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Discussion Starter #5
First bench power on the Megasquirt passed with flying colors. Loaded fresh firmware, and I got a laptop for tuning and logging.
The header came in as well. I'm hoping this and the Megasquirt will boost mid-range torque to the 150 range.
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So, you decided on a 3s header after all? Looks good! I was wondering whether that would provide some better options. Be interesting to see how the cat welding all turns out and what response you get on the Cali cat location.

Looking forward to seeing how the MS does when you get it into the car. (y)
 

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Discussion Starter #7
Sloooooow rolling process. I sent my valve cover off to powder coat, and it's not quite done yet. The weather also hasn't quite broken yet. I need to finish the intake plumbing, and fab a bracket to hold the box in place. I also need to fab a bracket to hold the MS in place. So, instead, I'll post a picture of the wrapped header. 🤤
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