Looking for Engine Swap Tips
 

Folks-
I have a 89 RX7 NA Convertible with automatic trans and a tired 13b engine.

Recently purchased a 88 RX7 NA coupe with stick shift that has a professionally rebuilt 13b engine.

This is my first rotary-engine swap, I've done dozens of conventional swaps over the last 40 years. I'm guessing that I need to transfer all the electronics from my 89 engine to the 88, and was hoping to get any nuggets of info from this RX7 brain trust.

Also someone had cautioned about a "bolt in a hard-to-get location" but I didn't get any more detail. I've eyeballed under and over the vehicle, don't see anything mysterious.

Thanks for your comments!
Jim

Wait, what're you trying to do?

Swap the S5 [89-92] parts onto the S4 [86-88], or move the engine from the 88 to the 89?

If you're trying to move the 88's engine into the 89, it can be done but it isn't recommended.. You wont have high compression rotors [unless the rebuilder swapped over to them] and you wont have the correct timing [just barely, but it is slightly different].. The Oil Metering Pump on the front cover is also different, if you want to keep the mechanical one you have to swap the S4 throttle body onto the S5 intake [there's a bit on the bottom of the TB that has to be ground off] That's probably easier than swapping front covers. Also you would need to find an S4 automatic counter weight [different weight rotors = different counter weights]

^You can't run a s4 TB on s5 electronics.


If you are planning on swapping the 88 engine into a 89 car.... The entire intake/throttle body, and electronics will need to be swapped onto the 88 engine. The good news there is the 89 intake has the VDI(assuming its non turbo), so it will perform better than the stock 88 intake. You will need the 89 oil metering pump plugged in or the ecu will throw the car into limp mode.

My goal is to get the rebuilt engine from the '88/S4 into my '89/S5 convertible.
The original '89 engine barely has enough compression to start, especially when hot.
The engine from the '88 has a substantially better cranking cadence, ie, better compression.
Not sure about high-compression rotors, is there a way to tell without teardown?
As for the S4/S5 counterweights, is there any way to use the 89/S5 counterweight on the 88/S4 engine? Because the '88 engine has been rebuilt, maybe there's a way to confirm the compatibility of counterweights?
Thanks! Jim

OK, thanks, that's what I thought...move all the 89 bits onto the 88 engine.
Both are non-turbo.
Jim

Nate>> Ahh good point - I forgot about the TPS..

So! Like he said, swap the entire intake, swap the front cover and Oil Metering Pump, grind a bit off of the top of the rear plate[the S5 UIM will not fit otherwise], remove the rear engine loop [used for lifting the S4 engine], block off the EGR valve [again, UIM wont clear otherwise], and buy an S4 Automatic counter weight [Or you could do a manual swap and keep the manual flywheel ^_- which is totally worthwhile, and easier than people make it out to be.. So long as you source an actual S5 manual transmission]

You could weigh the flywheel from the S4 engine to see if it's an S4 or S5 flywheel [you'll have to search for the weight, I have no idea what it is], but most likely it's still got S4 rotors.
There is no way [that I know] to use the S5 counter weight on an S4 engine [you would have to add exactly the right amount of weight to it somehow..]

Jim, you are keeping the vert automatic correct? The possibility that the 88 engine got the upgrade to 89+ high compression rotors is awfully slim. You can retain the mechanical oil metering pump but you will need to still have the electric one plugged in to avoid limp mode. As far as mystery bolt im not aware of any. If you'd like the cleaner install and are mechanically inclined id just swap front covers. See mazdatrix.com about the front cover info they have a good writeup on it, also pineapple racing has a nice video covering endplay if you search.

Making Progress.....
 

Derek-
Thanks for the details. I found a weight chart here: http://www.mazdatrix.com/faq/rotorwgt.htm

Answered my own question on the 'hard to get at' bolt....it was a long bolt on the top of the bell housing....I had to remove the intake assy to get at it. Motor is now out and on the ground....not a terrible job, just a lot of disassembly of hoses, accessories, and such.

Thanks to all for your tips. Me thinks I need some professional help on this project, did not realize how critical the balance of rotors & counterweight was. I'm in NE Florida near Daytona, any good shops down this way?
Regards........Jim

you could swap the transmission if you're lucky, because most 89 verts have the mounting brackets to install the manual transmission crossmember.

dump the block and transmission in. swap driveshafts. install pedals and master cylinder. get a rtek 1.0 OMP delete chip. keep all your s5 manifolds,air pump, emissions, and electronics. use your S5 throttle body and rig a way so the mechanical omp rod works with it and be done.

then you can do the fun stuff. full RB exhaust, K&N drop in filter, S-AFC and make 180hp

For the bit to grind off look about halfway down on this page: http://homepage.mac.com/carldavis/intake/mod.html
That shows you exactly where you'll have to grind to get the S5 UIM to fit.

It's actually the weight of the counterweight that you would need to find out, but like Rx7Ridah said it's quite unlikely [I mentioned that it *could* be different because that's how we built my new engine last month.. I happened to have spare S5 rotors and counter weights laying around]

If you do have manual mounts in your car [look at the crossmember and see if there are two similar mounts just forward] it would eliminate the need to find an S5 manual [S4/S5 would both work and using the manual crossmember too].** Assuming you are inclined to do a manual swap.

It's all pretty straightforward. You shouldn't need a shop's help. [Plus I've never been to FL, so I can't recommend anyone ^_^'..]