I'm really curious.. I heard parts for the late ones ('89 and later?) are super expensive (like one of the pumps was a couple hundred bucks new).. I don't know really.. I'm going to drop one of them into a '79, which one should I get and why? Do the later ones make more power?

One more thing, I heard there was a 12A turbo, is it any good? Should I try to get one of those if I can? So many questions..

 

The main differences in the 88-91 motors over the 86-88 motors is.)

86-88 runs 8.5:1 compression rotors
88-91 runs 9.0:1 compression rotors

-88 runs smaller exhuast housing on the turb
88+ runs larger exhuast housing on the turbo

-88 doesn't have the extra webbing around the top dowel area on the end plates that is found in the 88+ motors

88+ motors have hardend stationary gears in them

the 88+ has a slightly higher flowing throttle body

12A turbo came from japan in the cosmo's and some series 3 rx7's
they are a reasonable performer

 

In addition, 89-91 motors had lightweight rotors(9lb vs 11lb) as compared to earlier motors. The TPS on the newwer motor is different and more xpensive. They also used an electonic oil metering pump, which costs $200 used($500+ new). Timing between the plugs holes in the rotor housings changed a small amount too I think.

The 87-8 motor made 182hp, the 89-91 made 200. Most of that is made by the high compression, plus the higher stock boost level(accomplished by better turbo and manifold).

I have heard of that jspec 12AT motors but dont know anything about them. Id think for a 1st gen that'd be the way to go, though I wonder how well a turbo works with a carb.

 

cool, so basically the 88+ turbo motors are "better" motors, more power, better refined.. although higher compression rotors may prevent higher levels of boost, wouldn't it? I suppose getting the '88+ is a better choice.. just having it rebuilt in two years is going to be a pain on my wallet. I guess I can live with that, cause by that time I'll be graduated and should be working a cool job that pays loads of cash.

 

DEFINITELY go with the 89+ motor, but if you want to go budget and are porting the motor then, you can save a little money by getting rotor housings from an 87-88. and you don't need 3rd gen rotors, they're the same as the GT-X's.