firestarter810

I see all the TII into GSL-SE threads. I have an S5 (1991) drivetrain, sitting around, and an 1985 GSL(Whole car) to go with it. I was wondering if this is an easier/harder swap. How much of the turbo swap info is applicable to what I want to do?

I understand that this won't make as much power as the turbo (obviously), even after I have it ported and rebuilt, but its the parts I have lying around, so I figured I might as well put them to use.

84RX_Se7en

It's just a motor swap with less of the hassles of the turbo.... would be my guess.
Now I'm thinking a GSL-SE front housing and oil pan... that or modify the S5 cross member to fit under the front of an FB. Not sure how the S5 compares to the S3 or S4 motors

12akid

i would use a racingbeat carb kit, so you wont have to deal with the ecu wiring, gslse fornt cover and oil pan like 84RX_Se7en said, and costum trane mounts and drive shalf and that should be a fun a lil 1gen

82transam

iTrader: (18)

Pretty much all the info about T2 swaps applies, to physically install the engine/trans in there (that is the modified mounts, and shifter) and most of the wiring is the same as the turbo swap. It's easier in that you can still run a Fb sized exhaust pipe, and theres no turbo, and intercooler plumbing required. You still have the issue of the S5's electronic OMP to deal with though.... You can't run without it.....

firestarter810

It has to be the GSL-SE front cover and pan? I have the 12A motor still sitting in the car. I thought that I could ust the 12A cover and pan when I had my rebuild done.

I'd like to retain the "stock" fuel injection. I think in the long run, it'd be way less of a hassle then dealing with carb issues.

84RX_Se7en

Yes the 12a front cover and oil pan are not big enough. I believe that's about the only reason. A good one though.

firestarter810

Ok, so definitely a GSL-SE cover and pan, eh?

Since I'm not dropping in a turbo, and plan to retain the FI, this should just be a fairly easy swap then?

Like I said, it seems all I have to go by are the "Turbo into FB" swap threads, but because I'm not going turbo, it seems I read a bunch of things and they really don't apply to me. It seems a lot easier in my head, I just don't wanna have two "cars" apart and find out I'm missing a huge chunk of info.

trochoid

iTrader: (6)

Best bet is to follow Steve84GS's threads on his S5 TII swap. He has the best install for keeping the electronic mop and ecu functioning that can be problematic on the S5s.

Keep in mind that the oil pan and front cover are only a couple of the added parts/mods needed. You need to redo the fuel system, exhaust, tranny/mount, driveshaft and some wiring too. If you only have a drivetrain, and not a full donor car, you are most likely missing some needed parts from the engine bay.

firestarter810

I took everything from that car, and left only body sheet metal. I just started doing my reading on this swap, in preparation for this summer. I just wanna get all/most of my facts straight, and have a pretty complete parts/procedure list before I start wrenching.

84RX_Se7en

Okay so mount everything to the FB in place of the existing FB parts and use a GSL-SE front cover and oil pan to allow for mounting the motor in the same place. Then get a driveshaft made and figure out how you're going to fit the suspension unless you are gonna modify the existing axle to fit the FD torsen.

Rx-7Doctor

iTrader: (13)

You do not need a custom trans mount. The only thing you do if you want to use your S5 trans is swap the shifter housings from the 85 to the 91 trans and install. The trans bolt up the same and there is no need for a custom driveshaft. You use the 85 driveshaft.

trochoid

iTrader: (6)

Thanks for the correction Doc, I keep thinking TII tranny swaps, which need the mounting mods.

steve84GS TII

Its best to keep the stock EFI and intake.Going S5,then running a carb is pointless........the intake manifold,port tuning and quicker EFI is what makes the N/A S5 engine so great!

The swap is EXACTLY the same job as the S5 TII swap,except you dont have to install a big,turbo specific exhaust system and a TII trans isnt as important since even the S5 N/A is lacking a whole lot of torque.
Same wiring,same mounting,same fuel delivery system,same ECU mounting,same power distribution,same cooling requirments(for the most part),same OMP mods needed(except no turbo oil drain taking up space.)

A GSL-SE oilpan and front cover will get you started,but you have to adress how to mount up the S5 OMP to the SE front cover.I had my cover modded to accept the big electric S5 OMP,and retain the 1st gen style motor mounts.The SE oilpan will not bolt up to the engine if you retain the S5 front cover,and the S5 oilpan will not clear the front crossmember/steering if you decide to run 2nd gen style mid-engine mounts.Modding the SE front cover is the simplest way to mount the engine 1st gen style,and keep the 2nd gen OMP system the way the factory intended it to be........

fluffysheap

Never mind, wrong clutch size.

Rx-7Doctor

iTrader: (13)

Steve84GSTII is correct about trying to use everything S5 when it comes to the injection and ECU requirements.

You can however still use the Gsl-Se front cover and OMP if you get a known working S5 OMP and tie it off to the shock tower area and have it attached to the harness. If you do not do this when using the Se cover the ECU will set the check engine light and go into limp mode.

fluffysheap

There's got to be a more elegant way than that. I'm sure there's some combination of resistors and capacitors that will fool the ECU into thinking the OMP is there. Unfortunately, I don't know what that would be.

Rx-7Doctor

iTrader: (13)

When you figure it out you let the rest know because I do not know of any way.
You would first have to understand the complete internal workings of the electronic OMP before you could even start.

82transam

iTrader: (18)

You can modify the SE cover to accept a S5 omp and have it work correctly, just takes a little modification...

Rx-7Doctor

iTrader: (13)

Well, don't be stingy. Post up how to do it and have it archived.lol.

firestarter810

Thanks a lot guys. You're basically confirming everything I had read and understood to this point. Its always nice to hear you're on the right track before tackling a project like this.

Way better than getting halfway through and finding out there was stuff you hadn't even considered.

82transam

iTrader: (18)

haha ok I'll post a picture later when I get home from work, nothing too special really, anyone with a drill and some taps could accomplish it. I like steve's welded and machined approach much better, but mines the budget version

82transam

iTrader: (18)

ok here are two pics I have from when I first put this all together. Before putting the front cover on the T2 engine I put some copper crush washers and rtv on the bolts to keep things from leaking. Pretty self explanitory I suppose. Another memeber estevan62274 did more or less the same thing seen here: https://www.rx7club.com/1st-generation-specific-1979-1985-18/starting-my-tii-fb-swap-494720/
Comments/questions welcome.
Sean

steve84GS TII

I agree,the method of tying the OMP off to the side is not elegant.....nor do I usually recommend it as a long term solution.I did this on my S5 engine for a couple weeks and it did work.The engine ran correctly and there was no check engine light.But I could not garuantee that the OMP would last for an extended amount of time without lubrication circulating through it.When its plugged in,the internal workings are still moving,responding to ECU input.

The ECU's observation and control of the OMP is very complex and complete.There are 3 seperate OMP trouble codes that can be tripped,all of which set limp mode.The ECU observes the OMP position through a dedicated postion sensor on the OMP.Since the OMP position is always changing,so is the signal to the ECU.The internal condition of the stepper motor is also monitered,so the ECU will know that its working correctly and has not jammed.You might be able to duplicate the internal resistance of the stepper motor,but you would have a very,very tough time perfectly duplicating the OMP postion sensors output for every possible combination of RPM,throttle position,engine temp,and engine load.........it'd be easier to hack the ECU to delete the limp home mode altogether,and pull the bulb for the check engine light!

fluffysheap

Huh. That's a bummer. From your description it would actually be a simple electronics project but the hard part would be figuring out exactly what the sensor signals actually need to be to fool the ECU. After all the OMP just gets its signals from the ECU... it doesn't monitor all those other sensors, the ECU does and just tells the OMP what to do, so you don't have to care about them, just making sure you provide the right fake signal back to the ECU.

steve84GS TII

Thats the catch,its a closed communication loop between the ECU and OMP.The ECU might use all the other sensors to control the OMP,but the OMP postion sensor's output is made just for the ECU to moniter.Since that sensors output is constantly varying as the OMP stepper motor moves,it would be virtually impossible to duplicate.