Engine Swap Questions: BP + MSM head (BP4W) + Megasquirt in '90 Miata
 

With my MSM street car project nearing completion, I’m planning to start on my next build, a true full-on track car based on a ’90 NA6 chassis. Right now, I’m starting on building my next motor: a built NA8C BP bottom end with an MSM head (BP4W). The motor will be a turbo motor, but is unspecified on what turbo setup to use for now as I’ll decide what to you use later. The ECU will be a 1.6L Megasquirt. I assume that’s the one I need since the Megasquirt is specific to different wiring systems per chassis (am I correct to say that?).

Here are my questions based on what I have been reading about 1.6L to 1.8L swaps:

1. Will the TPS from the MSM work for this setup (I assume the MSM TPS is the same as ’99-’00) or will I have to resort to using the NA6C TPS or the NA8C TPS?
2. Is an additional CAS (NA6C or NA8C) needed for this swap (the BP4W head had a CAS in the front of the head)?
3. Is it required to use an alternator from a ’94-’97, or can the 1.6L Megasquirt control an NB alternator?

1. Yes (and then no to the second part). Use the entire NB throttle body.
2 No, MS2 code works with NB triggers. NA CAS = teh suck
3. You can use the NB alternator if you build a regulation circuit (which you can do in the MS' proto area), or you can use a NA alternator.

Refering to your answer in #2, you are telling me that the MS2 code can be inputted to a 1.6 version of the Megasquirt or I'd have to use another version of the Megasquirt?

You would use a MS2 Megasquirt configured to run what would essentially be a 99 motor.

You can use the 1.6 version of the megasquirt, but you'll need the FM 1.8 conversion kit. They have the parts needed for both a 99^ and a 94-97. I believe they have a writeup for it also. Theres a compatability guide somewhere too. Your build is identical to mine. 90', swap, ecu and all. I doubt I even helped here. http://flyinmiata.com/index.php?dept...0%20%201994-97

Completely wrong. Nothing needed here except maybe the EGR block off plate, and maybe the coil bracket--that's only if you're using the stock ignition.

Like I said, I doubt I helped lol

i'm kind of in the same situation. i'm going to be swapping a 1.8 into my 93, do i need to use a megasquirt for a 90-93, with an msq for a 1.8?

1. I don't see why you couldn't wire the TPS into the 90 circuit, i wired my 99 TPS into my 90 harness.
2. I have a mspnp, using a 1.6 CAS on the back of a 99 head in a 90 car. Works fine.
3. I had both a 94-97 alternator and a 90 alternator in my 90 car (with a 1.8 motor w/99 head). The 1.8 alternator, early one (94-97) had a slightly smaller contact point where that small 10mm bolt goes. Drilled it out and it fit/worked fine. However, if you are going to use a 1.6 alternator you will have to have the water pump pulley and crank pully from the 1.6 since the belts are different. A long/big/whatever 91.5+ 1.6L will work. I am currently doing it.