81 Rx7 value, turbo 12A or 13B jet boat
 

Hello! I've rolled a few questions into my first post. I recently acquired an 81 Rx7 that had the motor out. I bought it mostly for the motor, but i've been thinking the car itself is in such good shape, I should just put the motor back in it, and sell it.

I was looking to use the motor for a jet boat I want to build. I've got an open bow 17ft v-hull that currently has a OMC 4-cyl and outdrive. The engine/drive is very heavy. I want to replace it with a rotary engine and a jet drive to lower the weight, do something different, and not worry about the prop.

Anyway, I've done lots of hours of searching via google and reading what I found, but haven't found much about running a rotary with a jet boat. It seems I really want to turbo the engine to reduce the exhaust noise and increase the power.
Given a turbo, I'm think the 12a isn't the best option, I should sell it, and find a EFI'd 13B to use instead.

The older Rx7's seem to be getting harder to find. I'm thinking it would sell for a good price if running good, and I could find a later model to use the engine from.

I appreciate any input!

Jack

Contact Atkins Rotary (Atkins Rotary - Rx7 | Rx8 | Mazda | Rotary | Engine | Parts). They have a load of experience running rotarys in boats and offer a number of products that make it easier. Not really cheap though, since much of this stuff is very low production.

If you are going to turbocharge it, the easiest thing to do is to start with a turbo rotary to begin with. Probably the 13B-T from the '86 - '92 TII RX-7. Easy to find, easy to run. Make mounting easier by using the front cover from a 12A or GSL-SE (but you'll need to modify it for turbo oil drain).

i've looked for a turboII for quite a while, and never found any that were in my low budget, under $1k. From what i've read, the 13b w/o turbo can't use the computer, so if not a turboII, then i can just use the 12A right?

but what is the value of the 81? if I put the motor back in I should be able to sell it for $2k? then maybe I can afford to buy a turboII motor? :)

I plan to build my own computer control for the engine, so I'd think the 12a is good.
What internal differences are there between the 13b and 12a, other than the wider rotor?