Hi, I posted a thread in the 2nd gen section but thought I may get more help here.

https://www.rx7club.com/forum/showth...hreadid=177233

Anyway, I did a search and really didnt come up with any useful information. My friend may be picking up a 84 -SE with a blown engine, and I am getting a good running 87 N/A. I would like to know what all would be involved in swapping the engine into the FB?? Will the -SE manifold bolt right up to the S4 engine?? If so I wouldnt need to really do anything but swap blocks and front covers (oil pan?). Basically I just want to know the easiest way to get it in there. Ive heard that the engine mounts arent the same, but you can bolt up the FC crossmember and it will work, but no definate answers. Ant help would be appreciated, thanks

 

there is much much more to this swap than you think.

You aregoing to have to swap the SE front cover on the S4 motor, becuase you cannot mount the engine in the same way as you would in an FC with out a shitload of fab work.

You are going to have to swap over the GSL-SE oil pan as well. You wont need the racing beat 12-13b mount adapter, because you are putting this in an SE.

The SE manifold will bolt up to the block and visa versa, but the ports are a different size so you are going to have to do some porting work if you want to make some kind of crazy manifold/engine combo.

The best route is just to swap the whole FC engine in there. You are going to have to decide what kind of computer control system you want to use. You can go with an aftermarket system, which would be easiest, but you can use the stock s4 ecu system if you want.

If you decide you want to use the S4 ecu, you are going to have to do a shitload or wiring. You are going to need wiring diagrams for both cars, and strip what you dont need out of the FC harness, and then connect the connectors for the SE harness that you need to the FC harness.

You are going to also have to swap over the GSL-SE exaust manifold, if you want to keep your stock SE exaust system. The FC exaust is a different size and bolt patern. I'm not sure on this one, but if you keep the GSL-SE exaust, you may have to remove and block off the EGR valve.

Thats all I can think of for now.

 

OK, thanks. Thats really not what I wanted to hear, I thought it would be fairly easy. Yes I was planning on using the stock S4 ECU and wiring. Maybe it will just be alot easier to rebuild the -SE engine. Thanks.....

 

Hmm,yeah, I was hoping it would be a little more straightforward than that. I can deal with swapping covers and pans, and exhaust manifolds, that doesnt' bother me. Wiring bothers me, I don't like to deal with wiring.

I was under the impression that I could take the full wiring harness from the FC, keep it with the motor, and do very minimal wiring to things like the tach and such. And ECU of course.

Maybe I would be better off to rebuild the current motor, probably have more money in it unfortunately.

And then there's the V-8 swap, a whole other story.....

 

the ecu is exactly what makes the wiring hell. You have to think, you have wiring that goes to the drivers side of the car from the ecu, and then the stuff that goes out to the engine itself. You have to redo most pf the stuff that goes to the drivers side of the car.

Keep in mind that FC engines do not use a distributor like the FB ones. They use a crank andgle sensor in its place that allows the computer to control the ignition coils.

The swap is much easier to do is passing emssions is not a problem. But if you live in an emissions controlled state like me, you'll be cursing those enviornmental assclowns with every wire connection you make.

 

i could be wrong, but couldnt you do this:

take the s4 engine and intake manifold, use the stock SE wiring harness and all the stock SE stuff like injectors, mass air flow, TPS ect. And put it all on the S4 manifold. It must be similar.

But if I was going through that trouble I would use the s5 engine, better power.

 

I really doubt you could, becuase the emission controls are completely different of the SE's and the s4's. And yes all that trouble is exactly why I went with an s5 setup.

 

If you go thru all that touble you might as well do a TII conversion and get a bunch more HP.

That's what I'm planning on doing. And yes there is alot of wiring, but I know how. All said and done I'll probably have 3 weeks of just figuring out how to do the wiring. Being very careful--I just don't want to cook the turbo ECU and don't want any mysterious running problems.

I plan on posting the rewire info when I get it all figured out.

 

Oh yea, if I could have found a S5 I would have used it. But then again I hear parts are getting harder to find and more expensive for S5 vs S4.

 

well the turbo conversion costs alot more to do, and is alot harder do to the amount of custom work you have to do.

I chose N/A because reliability was an issue. My car will be my daily driver. Time and money were also a problem for me. I also didnt know jack about RX-7's when I started this project. Just look at my first posts, its quite obvious.

I dont regret my decision to go N/A one bit. I just didnt want to get in over my head on my first project. I allready plan on getting another FB when I move out, and doing a turbo project.

EDIT:

As for S4 vs S5, I had everything for the s5 but the bare block itself. Those parts are easy to find. The S5 blocks are not. When I bought my core from pineapple racing in november, they said that they could get a S5 core, tomorrow, or 2 months from now. They just didnt show up all that often.

Also most of the power gain in the S5's were from the intake manifold. Not the higher compression rotors. The higher compression rotors did help, but not much. At least in a stock setup.

As soon as my car runs, which should be next week or so, I'll post the write up I have made on how to modify the s5 wiring.

 

Now this is good, the forum will have a write up for the wiring for the N/A and turbo S5 conversion. Thanks for offering to do the turbo rex4life!

This is something I think we should have had a while go.

 

Thanks guys. I basically thought it would be very straight forward since they are both 13Bs, I just thought there may be some issues with the intakes and ECUs that i will have to work out. Now that we've found out what a PITA it will be, its probably not going to happen. We'll either rebuild the original engine or V-8 swap it....*zips up flame suit*..

 

that way works, but it blocks off all the smog equipment passages. the car wont pass smog.

mike

 

How would that work with the S4 manifold, since the UIM has ports for the secondary injectors, whereas the -SE only has 1 set of injectors?

 

good point, with that in mind I dont think you could pull it off that way that easily

 

you can block off the holes for the injectors, its a rig but ive seen it done

mike

 

doing it that way would be more trouble than its worth... and the wiring isnt that hard anyway.

You just look at the connectors you know you wont be using, and remove all the wires to them. The harness has wires to the headlights, winshield wipers ETC. This is stuff that allready works fine, if it ain't broke dont fix it!

 

As 82Street Racer already said...

Use the FC block only. Everything else from the FB, including the distributor, intake, exhaust, FI, etc.

Don't make it harder than it really is. The ports will be very slightly mismatched, but I doubt you'll ever notice the differance.

 

Throw in the new engine and do a carb conversion, no wires to mess with.

 

that's def. the easy way out, but FI has it's advantages to a daily driven car.

 

That's not what he said. He also said about using the S4 manifold as well. Which you can't do because of the extra injectors. And I'm not rigging this car if I get it, i want it done right.

If you can use just the block I would consider that. Now the horsepower difference between the two engines, what exact arrives at that. Is it just the higher compression rotors, or do other things figure into it as well. I dont' care about the difference, it is minimal, but I would like to kno what I'd be dealing with using only the S4 "block".

Sure, I could do that, then I can watch my state emissions tester go then fail me. This car needs to stay smog legal, if I wasn't going to drive it very much, I wouldn't worry about it. Where I live, if you drive your car 5000 miles or less a year, you're emissions exempt. Unfortunately for me, I put and average of just under 30,000 a year on.

 

I believe the HP gains on the S4 motor were due to the revised dynamic chamber, so if you put the SE chamber on, you're probably down to the SE hp numbers. That being said, I'd go with DirectFreak's suggestion, as all attachments from the SE motor should bolt onto the FC block.

 

Exactly.

 

The slightly larger AFM and throttle body of the S4 has helped too... for an 11 HP gain over the GSL-SE system.. is it really worth the trouble to convert for that? Im nutty enough to consider it being in the smog capital of the country.. Go with an S5 if youre gunna go

 

How well does the -SE manifold flow?? If we do a rebuild I was considering using S5 N/A rotors. 9.7:1 CR and lighter. Would the -SE manifold flow well enough to take advantage of the rotors?