1.6 to 1.8 swap electrical hassle
 

Hey all,

to start off, I have a 90' Miata with 1.6 in it (well, it started to burn a lot of oil) so I decided to upgrade to 1.8. So I bought a BP-4W engine from a 00' Miata with very low mileage on it. I've got the engine, intake, exhaust, AFM, ECU and all the engine harness.

So the question is, I've searched a lot about these swaps and I could only find swaps that use the 1.6 ECU, harness, TB, TPS and other things related to electrical stuff.

Is it possible to swap the engine harness from a 00' Miata? I know, that newer Miatas have immobilizers, but that's easily removable.

Am I doing it right or should I go with the butthurt method and using the 1.6 stuff?

Need answers, because i'm a little bit stumbled. Because my old engine uses a short nose, so that means I have to find somewhere a 94-97' alternator, because the one on the 00' engine is being controled by the ECU (which I do have). So what should be the easiest and less time consuming approach?

Thanks, Slimas.

Swapping the '00 harness into your 1.6 is a bad plan. Use the sticky entitled "VVT Swap into 90-97 Megathread" at the top of this section.

^ What he said. Here's another resource that may be helpful.
https://www.flyinmiata.com/support/i...sc/1.8swap.pdf

I've done a lot of reading and the biggest headache was the alternator. Since in my country it's practically impossible to get any Miata parts, I thought I had a problem there. Since my Miata is 90' in the production but the first registration is 91" I thought I had the short nose crankshaft, which meant I had to find a 94-97' alternator, which is impossible. With further investigations I found out that my 1.6 motor has an 8 point crankshaft pulley so I can just switch that one from my 1.6 including the alternator to the 1.8 engine.

Other question, does the 1.6 ECU manage the 1.8 engine properly? I will not get any power losses (except the VICS not working)?

No, the 1.6 ECU will not properly manage a 99-00 BP4W. Follow the steps outlined in the thread I linked you to.

I read the thing a million times. I know what things to take from the 1.6 for the 1.6 ECU to control. But I was asking if the 1.6 ECU will control the 1.8 engine so that I could use all the 103kW from that engine (except the VICS)

Best case, you give up power when compared to a standalone. Worst case, the 1.6 ECU doesn't safely run the BP4W. Are you trying to avoid a standalone ECU for some specific reason?

I will use a standalone ECU later on, but it will be few months before that. i've read that a lot people are running 1.8's on 1.6 ECU with no problems, I was just wondering what's the power loss

You can get the new engine started on the 1.6 ECU, but the standalone will be worth 8-10whp over what the 1.6 ECU will do.

I know that. The question was if bp-4w outputs 103kw with 1.8ecu and stuff, 1.8 with standalone ~110kw. So what should be the power output with 1.6 ecu?

I have absolutely no idea. Probably somewhere in between those two numbers, but that assumes that the AFRs are safe, and that's not an assumption you should make.

Thanks for the honesty :D

Anytime :giggle: