Alright boys here's the deal. I'm an rx7 newbie but I'm hitting the ground running pretty fast. I bought a 1990 Turbo 2 swapped GTU. It wasn't running when I bought it because of electrical issues but I got them sorted out and then I ran into another issue.... Detonation. Needless to say my rear rotor only has 35-40 psi. The front is unknown because I stopped after the bad news on the back rotor. The car still runs and pulls good so I'm guessing the front is not completely gone. Also this is a rebuilt motor with 1600 miles on it. . . yeah it sucks but whatever I guess. I needed to learn how to rebuild a rotary anyway .

Now we get down to the real meat of the issue I have a s4 turbo engine to swap in the car. It is supposed to be rebuilt and ported but I picked it up with no documentation. So is there a way to look at the porting without pulling the engine apart?

Next, from what searching I've done I can only find s5 engines into s4 cars and not the s4 engine into an s5 if there's any build threads that missed in my searching I'd greatly appreciate a link. I do have a microsquirt ecu to throw in the car if I need to, which was set up on the s4. I have the flywheel and a clutch for the s4 engine.

As for the turbo on the car I have a S5 turbo of course, it has some shaft play along the axis as well as rotational shaft play so I need to rebuild it. And then I have a whole different beast a holset vgt turbo off a circa 2008 cummins to play with as well but it scares me. The cummins turbo is on a rx7 manifold which came with the s4 engine.

Back to the issue at hand I found a general guide to do the swap Swapping an 86-88 (s4) engine into an 89-91 (s5) car (s5ās4 swap) But I'm open to any and all input on the subject. The way I see it is the more info the better. I'm not looking to make a bunch of horse power I just want a reliable car I want to retain the stock ecu for now and TMIC but I'm not against doing a Vmount either. I obviously need to do some fuel system upgrades to keep the car from having troubles again. I'd like to keep my budget for getting this swap done and some upgrades around 1500 or less.

 

Is it just me or is that an A/C dryer assembly over by the overflow bottle?

I have never seen that before. 0_o

Edit: Also, where the hell is the radiator cap? It also seems like the duct work that goes in front of the radiator is missing.

 

There is no radiator cap. The car has a s4 radiator from what I can tell and an s5 engine. It came with a koyo radiator but it leaks... which is a real shame cause the po didn't tell me it leaked. And I put it in then filled it up and it leaked. As for the duct work I don't know where it is, and the dryer being up front I didn't know that it was in the wrong place, the ac works tho. This a Swapped car and rx7's are new to me .

 

You need to get an S5 radiator then. You can't use the S4 water pump neck on an S5. You are going to have serious issues unless you correct the 2 problems I brought up. Here are some links that will help you rectify those 2 issues.

(I will probably analyze the pics more, but for now...)

http://www.ebay.com/itm/like/251729572114?lpid=82
https://www.mazdatrix.com/getprice.asp?partnum=2006-RAD

 

Oh and to add, I would use all of the S5 **** on the S4 keg.

 

X2

Most people don't do an s4 swap into an s5 chassis because it would be downgrading essentially.

I believe youll need to s4 harnesses to make the swap fully compatible, but Don't quote me lol

Also, the I believe in 88.5 they changed the low imp injectors to the high imp injectors the s5 uses.

The only thing I do enjoy about the s4 is they had mechanical omp system.

Good luck w/ the build

 

You'll be an expert by the time you're done.

 

If he uses all of the S5 equipment from the original engine and just bolts it to the S4 keg he should be good to go.

The S4 keg is so similar to the S5 keg, most of it is only differentiated by the S5 accessories (intake, sensors, wiring harness, ecu). If he retains ALL of the S5 stuff, slapping it onto an S4 keg is cake.

If I was in the same situation, I'd say **** that to replacing the ecu and wiring harness. The only downside to the S5 is the electric OMP, but replacing that with a brand new unit equals the cost of trying to rewire the car for an S4 keg and replacing parts to make it work.

 

He needs to tear the S4 engine he has down to this...

http://www.rotaryengineillustrated.c...teardown/3.jpg

The take all of the S5 accessories from his old engine and bolt it to the new naked keg I posted above.

 

Looks like stock S5 location to me.

 

Thanks for the input boys! For now I'm just trying to get a good parts list going for this swap. If you guys think of anything that I should need to make this swap go smoothly as possible let me know. Also I'd like to be be able to use the greedy BOV that I have. Is there a way I can plumb in the BOV with the stock TMIC?
So far:
-FD fuel pump
-Mazda RX7 FC3S Aluminum CNC Radiator Cooling Panel
-fix the koyo radiator
-fuel filter

 

Alright what is everyone's opinion on these radiators?
http://www.ebay.com/itm/1989-1991-Mazda-RX7-Aluminum-2-Row-2-Radiator-RX-7-FC3S-/181443251637?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ARX-7&hash=item2a3edc4db5&vxp=mtr

 

The bov should be able to go where the stock "bov" goes. I know I used to have a blitz bov that had a tube to replace the stock one.

Pretty straight forward.

My buddy that picked up my t2 just put an hks one on his too using the stock tmic.

Instead of fixing the radiator I would get a replacement. I never have been into fixing a radiator (as I'm not a aluminum welder lol) especially when it's a very important cooling part for our cars.

 

Mine isn't there, it is near the passenger side firewall.

 

JJ if you look at the picture of the duct plate you linked earlier to on ebay it has the dryer in that location as well.

 

I see that. Weird, mine is up near the passenger side firewall near cruise control and wiper motor.

 

Well I found some time to do a compression test on the engine I got around 60 on the front rotor and around 50 on the rear this time which sucks. I dumped a bunch of octane booster in the tank and got it warmed up I did get into some boost but couldn't get the car to detonate at all. But I wasn't pushing my luck. What sort of a rebuild should I be looking at doing if the cars been detonating? The car has RA 2mm apex seals, would the side seals go before the apex seal? Or is it usually all of them?

 

It's understandable your detonation problem has subsided with the compression being that low since many times low octane fuel and incorrect mixture causes the detonation. Most people would go ahead and do them all since you have the engine opened up. Theoretically you could do a thorough inspection and just replace what's damaged.

 

Not to get your hopes up, but keep in mind that compression numbers will be lower when you do the poor man's compression test with a regular piston engine compression tester. You're more looking for even bounces.

Are you getting 60, 60, 60 in the front and 50, 50, 50 bounces in the back? Also, throttle all the way open (gas pedal pushed in) when testing, and make sure the battery is fully charged. Compression will be lower on a cold engine btw AFAIK. Some people take out both plugs on the opposite rotor not being tested. Also, it's good to try the test again after a spoon of oil into the chamber. You pulled out the EGI fuse to disable fuel? Yeah, lots of points to remember, make a list if needed.

I used to always forget the 'hold throttle open' bit.

 

You probably have the Nippon condensor, which I believe was a dealer add-on item. Most people have the Sanden compressor which has the dryer in that location.

Also, I'm going to second the "swap all S5 stuff onto the s4 keg" option. The one thing you will need to remember is that the S5 ECu needs to see the S5 OMP or it will put the car in limp mode. If you use the s5 OMP, you will need to make sure you use the s5 front cover as well. If you go with the s4 OMP, you can zip tie the s5 OMP out of the way so its still plugged in. You would then need to connect the mechanical OMP linkage to something on the TB. The easiest would be to re-use the s4 TB, but then I think you would have to find a way to mount the s5 TPS and I'm not sure about how that is done as I have very little experience with the s5 TPS. You might also be able to swap over the part on the s4 TB that the linkage connects to. Sorry if that got a little confusing, lol.

 

I did not pull the EGI fuse I did unhook the coil packs. When I did the compression test I did the fron rotor first, I pulled the front leading plug screwed in my tester on a warm engine, the rear rotor leading plug was still in. I had a friend turn over the engine with no throttle. Then I used the same procedure on the rear rotor. I had the the front leading plug reinstalled. So to sum it up I had did three things different i did not pull the EGI fuse, I did not test the compression with WOT and I did not have both plugs leading plugs pulled when I did the tests.

Also the readings on the compression tester were taken with the check valve removed. The gauge showed the readings as pulses all of the pulses were even.

 

I had planed on just using the s5 front cover and OMP I want to keep everything somewhat stock. I want a reliable daily driver/ autoX car. I'm not looking for 1000 hp just a fun car to root around in on nice days.

Is the electric OMP with the s5 reliable? or should I run some premix as well?

 

The ECU will make you very aware if there is something wrong with the OMP. I personally run the OMP and premix at the same time. I do a half ounce of TCW-3 per gallon of gas.

 

Yeah, the ECU will let you know if there is something wrong, so as long as its working you can stick with it. Its not a bad idea to premix, though, as the oil doesn't get to the housings evenly. I ran 256:1 (.5oz per gallon) when I had my OMP and run about 100:1 now that its removed.

 

Pic for BOV reference.