2nd gen in 1st gen

[85'12a-Blake]

sry if this is a repeaet but i couldnt find another forum tht had this......


okay so my 12a finally went and i've been lookin around for donors and all i can find is 2nd gens...i found a 88' and a 89' and both still runs and is drivable but wrecked in the ass end and 1 in the front driver counter panel...i was wanting to kno what all is needed to put either 1 of the motors in my 85' FB...i kno i need the motor mount bracket but what trans bracket would i need and also if the FB harness for the dash and stuff would work with the second gen or if all of it would need to be replaced with the 2nd gen's harness and wiring....this is first time doin so and dont wanna screw it up so the more info and advice the better...not doin anything crazy just a swap bc its a beautiful car and i love to drive it and want to get it back on the road asap safely

[PercentSevenC]

If you convert to a carburetor on the FC engine, it simplifies the swap significantly, but I can't really recommend it because carburetors suck. (Yeah, that's right, I said it. ) But I can't really help you with the stock EFI swap-over because I've never done it. Hopefully someone will chime in who has.

You'll want to take the motor including the alternator and whatever other accessories you may want, wiring harness, ECU, sensors, and you'll probably want the coil packs and maybe the fuse box (again, I've never done the EFI swap). You can grab the transmission if you want, but you can use the stock 12A one, too (you'll be using the rear of the 12A tranny either way). The FC trannies are geared a little taller; Mazdatrix has the gear ratios on their site if you want to look at them. You'll use the FC flywheel and clutch setup. The '89-92 (S5) engines are better than the '86-88 (S4) engines, but take a few extra steps to install in a first-gen because of the electronic OMP (you'll be using a mechanical one and will have to fool the ECU into thinking the electronic one is there and working).

For the engine mount, you'll be putting your stock 12A front cover on the 13B. The 12A OMP only has two outlets instead of four. This is okay; just block off the oil injectors in the 13B's rotor housings and run the lines to the ones in the intake manifold. Or you can tee the lines apart and use all four oil injectors if you prefer. If you have an S5 engine, you'll need to either fabricate a rod to lift the OMP arm when the throttle is opened, or take the easy way out and just wire the OMP arm to the 9 o'clock position. The S4 engine should already have an OMP lifter rod.

You'll also need a GSL-SE oil pan and any one of the following: a Racing Beat front mount bar, a GSL-SE crossmember, or some fabrication skills to slot the holes on your stock crossmember and front mount bar. The former is necessary because the FC oil pan will not fit in a stock first-gen chassis, and the latter is needed because 13Bs are 20mm longer than 12As.

Oh, and of course you'll need to modify your exhaust to fit a 13B. Or better yet, replace it with something that flows better. Not sure if the stock FC ECU relies on the O2 sensor being there; if it does, you'll have to add it to whatever exhaust you use.

Another issue is the auxiliary port actuation. S5 engines use the air pump and emissions rack to open them, S4 engines use exhaust backpressure. That means that if you use an S4 engine, you're going to need to add a backpressure sensing tube to your exhaust if you want to keep the auxiliary ports functional. This can be a problem with high-flowing performance exhaust systems because they don't have enough backpressure to open the ports. Kevin Landers has a writeup describing how to actuate the auxiliary ports electronically, eliminating the need for a restrictive exhaust. It can be found here. The other option is, of course, to just wire them open.

If your car is an '83-85, it's equipped with a "beehive" oil cooler, which uses coolant. You CAN use it on a 13B with some modification, but don't bother because it sucks anyway. Get rid of it and convert to a front-mount oil cooler. You can take this off the FC or an earlier rotary chassis.

Next you have to address the fuel system. Your stock fuel send line should be enough. The stock return line is only 1/4", which may or may not be big enough to keep your fuel pressure in check. You'll need an EFI-style fuel pump. A Walbro 255 (p.n. GSL392) is cheap and will flow far more fuel than you'll ever use without a turbo. An MSD 2225 pump would work well, too. Don't forget an EFI fuel pressure gauge and EFI-rated soft fuel hose.

Then rig up an air filter and that's basically all there is to it. You may have to play some games to get the tachometer and stock gauges working (not sure if the FC engines use different water temp or oil pressure senders; you may have to swap your 12A ones over).

Here's some more recommended reading. Especially take a look at the emissions removal guides if your region allows it, and the pulsation dampener elimination (the PD is the cause of a lot of FCs burning to the ground).
http://www.rotaryresurrection.com/2ndgen/techmenu.html

Let me know if you have any more specific questions.

[85'12a-Blake]

THanks for the help its greatly appriciated

When you say change out the the stock 12a cover thts to do it as a Carb conversion rite or is it needed to do a drop in too with the 13b as is.

And for the OMP it should be ok to put the blockin plate and run premix in the gas instead of tryin 2 figure all tht out

[PercentSevenC]

Originally Posted by 85'12a-Blake

When you say change out the the stock 12a cover thts to do it as a Carb conversion rite or is it needed to do a drop in too with the 13b as is.

You need to use the 12A front cover. That entire post assumes keeping the stock EFI system.

Originally Posted by 85'12a-Blake

And for the OMP it should be ok to put the blockin plate and run premix in the gas instead of tryin 2 figure all tht out

Correct.

[85'12a-Blake]

OH okay. well i'm not quetioning it but just askin y does the 12a front cover need to be used when the rest and everything will be the 13b. y cant the 13b front cover be used

[PercentSevenC]

FC 13Bs use side motor mounts. You need the 12A front cover to use front motor mounts.

[85'12a-Blake]

oh okay thnx

[one320fc]

Use 12A front cover with the dizzy and go with a carb will make your life and the swap so much easier. There are some good options find a used Racing Beat Holley intake and 600cfm carb new fuel pump and regulator, or find some used Webbers or a Dellorto DLHA 48.

[85'12a-Blake]

Okay i've come accross a complete front clip for an 93 rx7, other then the motor mount and oil pan. i should just be able 2 gut evrythin from mine and swap and install it and get it all to fit in there somehow...correct?

[PercentSevenC]

"Front clip" meaning what? You can install the engine, if that's what you mean. For the most part it's the same as any other turbo 13B swap. You'll have to figure out what sensors the ECU is expecting to see that the FB won't have, or just go with a standalone and convert the twins to non-sequential. Naturally, you'll have to redo the cooling system and the fuel system to support all that extra power. And like an S5 engine, you'll have to deal with the lack of an electronic OMP on the early front covers.

[Garfinkles Motor Works]

I have started putting a 1994 twin turbo motor and trans in a 1984 GSL-SE .I am using the 3rd gen motor mounts .with a subframe I am making .I do not trust the first gen front cover and stock motormount on a 400 hp motor.Pictures and post are on this forum 3rd gen section .