Worth my time (miata content)

To make a long story short, a person that owes me money runs a local salvage yard. They have a fairly picked over 1997 Miata that I get to take parts off of. I've already claimed the seats which are in much better shape than mine, some 15x7 borbet wheels which will probably end up on my civic, and pending whether it has a torsen or not, the rear end and neccesary parts.

Now on to the questions.

My miata a 91, has the vlsd. It seems to help, a little. If the 97 doesn't have a torsen should I still grab it? From what I understand, the torsen differential itself will drop in, so down the road I could upgrade. The 4.10 gears would help my gas mileage a little, and the larger ring gear is a good thing.

The car has 97,XXX miles on it, the motor can be mine if I want it. Now the wrench in the gears, I have a MSPNP that is going in soon on my 1.6, can I run the 1.8 easily on the 90-93 megasquirt? What else do I need to swap the motor? And finally is swapping the early BP worth it? My car has a E36 M3 load of miles on it but the motor itself is only at 60-70K miles, I kind of enjoy the peaky nature of the 1.6, but some more lowdown grunt never hurt. Given that the motors would more or less put out the same power, is the unknown commodity and work of dropping it in worth it?

In reply to bigbrainonbrad:

The '97 is an OBD2 motor/wiring harness so it won't match up to the '91 electronics and your MSPNP wont PNP. If you still want to pull the '97 take the whole harness & ECU with it and sell the MS.

I would say it's not worth the trouble to do the motor swap.

The swap is easy and worthwhile. Use the 1.6 electronics, not the OBD-II. The engine doesn't care about the wiring. In fact, the 1.6 MS works much better with the later throttle body so it'll work better than it would with the 1.6. Also, the motors won't put out the same power unless you're comparing a modified mill to a stock one. The 1.8 will make more, about 10% more which is also the approximate difference in displacement. FM sells a motor swap kit that will get you what you need for the changeover. From the donor car, get the exhaust manifold, alternator and maybe the cat if you can. Also grab as much of the intake plumbing as you can to make life easier, and the metal motor mount brackets.

As for the rear, go for it. If you get a Torsen, great. If not, then you get a stronger ring gear and more relaxed gearing.

As far as cooling is concerned, is the only difference the hoses? I see that the radiators are the same, but the hoses have different options based on year. Am I better off using the 1.8 thermostat housing and hoses or sticking with 1.6 stuff?

The 1.8 thermostat housing sits in a slightly different place, thus the different hose. They can be interchanged, I don't think one is superior to the other.