resjsu

I did search but its hard to find exactly wut im looking for.

I have 84 rx7 gs and want to swap.
2 options 2 motors:

1] 13b 4 port like 1974-1976 - $200
-or-
2] 13b 6 port 1987 gxl motor plus tranny - $300

My concern- assume they are in average condition- not super or horrible

Which will cost more and need more fabrication to install?
It seems obvious the 6 port is the better buy, is this true?

Anything else that would help.

1984 rx7 gs all stock motor.

Thanks a lot.


Aure

southernrunner

All you need to do is to change the front cover of the motor and the oil pan off of an -se. As far as running EFI, I think you have to cut into the harness. I am not sure on the EFI part though. I am putting an s5 engine in my car, which i an 84 gsl. I have to buy a new oil pan and front cover. It puts the motor mounts in the right area so you dont have to modify anything.

64mgb

iTrader: (1)

I did the 6 port and was told (on this forum) that it's the most desirable motor to use. You'll need an oil pan from an SE, a 12A front cover and oil metering pump, and an offset engine mount. Otherwise it's pretty straight forward. I used a carb though...on top of a Camden blower. It's probably a little more complex if you stick with the fuel injection. You'll also have to match up the proper radiator and heater hoses...here's a thread I wrote detailing the hoses I used:

https://www.rx7club.com/showthread.p...ighlight=hoses

Rich

trochoid

iTrader: (6)

The 4-port has more power potential when ported and carbed, but that could add another $2-2500 to the cost of the install, with the rebuild, new carb and exhaust, with you doing the work. Most of the older 13B 4 port engines do not have nitrited plates and are worn past step wear limit by 70k miles. You can run the SE fuel pump, use a Mallory 4309 fpr to bring the fuel pressure down for the carb.

The 6-port will give you 146 fwhp without exhaust, but if you want 200 rwhp, you will spend more than 3k with a rebuild, porting, exhaust and stand alone. Install will be similiar to the TII install threads that can be found. You will need the SE front cover to run the FC 4-port mop, the 12A mop does not inject as much oil.

Just reread your post, since you have a 12A now, you will need to upgrade the fuel pump and all soft fuel lines for FI, and not let the tank get below 1/4 on hard cornering. Or install an SE tank and hard lines, better option.

Druken

If you go with the 6-port FI, fill me in on how you set up the wirings.

resjsu

Ok as far as transmission goes, people told me that if i got the 13B 4 Port i shoudl keep the 12A tranny. What if i went 13B 6 port? new tranny?

Becuz i could get the 13B + Tranny for 350.... should i just get engine for less?

resjsu

i need an answer, sorry 'BUMP'

trochoid

iTrader: (6)

If the tranny is good, it's worth the extra 50 and the clutch would be a freebie. You will need the flywheel with either engine. The S4 tranny will need modded to fit the FB.

resjsu

So you meen i need a new flywheel for each engine? ok.

resjsu

Damnit! I have been reading! But everyone seems torn over this question still. What i've gathered is:

The 13B 4 port:
*Has more potential when ported
*But b'cuz of age (mid to late 70's) probably needs some rebuilding
*porting is very very expensive
*mates with 12A tranny
*mild fabrication eeded

The 13B 6 port:
*Most popular swap... (someone said that inna search)
*Found out from RotoryX that with a 6 port you don't really gain much from porting (saves money)
*its about 10 years newer then 13B 4 port


So cmon guys is the 6 port the obvious and best choice?
*I want a streetable car that i will prolly never take to track.
*200Hp would be great but 160-180 is also good.
*Would be daily driven Daily driven.
*Just want decent power under the hood
*and i am going through with swap so please dont say "just stick to 12A." I have done my reading but still come up short.

BTW what are archives because all i do is search? If anyone can point me to a thread that is very very similar to my problem (where they debate 13b 4port and 6 port) id be very thankful.


Thanks again,
Aure

resjsu

So dont just stand there bust-a move! (more entertainging then "Bump")

gsl-se addict

iTrader: (3)

The actual installation of either engine is the same as far as the oil pan and front cover is concerned. For the tranny, the 87 NA tranny is nearly the same as the 12A one with a bit different gearing. I would keep the 12A tranny if the tranny works fine. Either engine will bolt to it. If the 87 comes with a tranny, you could keep the tranny as a spare or sell it.

To keep the FI on the 87 engine, you will need the ECU, wiring harness, EFI fuel pump, and so on to get it working. You could setup either engine with a nice carb, but will need an upgraded fuel pump and fuel pressure regulator.

It is a bit of a toss up as to which option is better. Assuming both enigine are in relatively good condition, the 4-port with a Weber (or similar carb) and exhaust would be a pretty easy install and give good power. The 4-port allows for more porting than the 6-port when it comes time for rebuilding/porting. You probably would need a rebuild and porting to get to the power levels that you would like. The 4-port will likely be in more need of a rebuild than the 6-port, but this doesn't really matter if you are rebuilding from the start. You can use 12A sideplates on the 4-port when you rebuild to gain the nitrited surface.

I assume both engines include the flywheel. If not, the flywheel needs to match the engine. Probably the best option with this regard is to get a lightweight flywheel and the counterweight can be changed to work with either engine.

Either engine will require an exhaust that will bolt to the 13B. The Racing Beat exhaust is the most recommended (bit expensive, though).

What kind of budget do you have? How much time can the car be down for the swap? Would you rebuild now or wait until later?

The 1st gen archive is here: https://www.rx7club.com/1st-gen-archive-71/
The 1st gen FAQ is here: https://www.rx7club.com/1st-gen-archive-71/1st-gen-rx-7-faq-page-507782/

Kent

JIMMY54

iTrader: (2)

Buy a J-spec T-2.... they generally come with a tranny attached meaning you get a clutch. Call around to engine importers.

Next you can piece together the ecu and harnesses and ingition coils for usually 200-250 bucks.

Next swap front covers and oil pans. You'll get an awesome tranny and the input shaft cut off (which you will need, they leave it on so the tranny doesn't leak if it ain't there they get it off another turbo tranny they have lying around, or get a driveshaft from a forum member/scrapyard )

The driveshaft has to be modded which is Cheap, Basically replace the input shaft on your stock driveshaft, becuase the lenght stays the same. Cost us 150 bucks Canadian which is nothing in US!! LOL

You'll have 200+ hp and enless parts.... not to mention lots of fun, when you are done.


Believe me, If I could go back in time... I would have gone T2 along time ago.

I poured so much money into my n\a se motor and it was still slow. 146hp is nothing... I had more than 146 hp. Blow-thru turbo 12a makes more power than that.

B4 you shun the 12A consider this............

Save money and port the hell out of your 12a! I'd say contact Rotaryshack... They are well proven with making power on 12a's and everybody that deals with them always have great things to say.

Keeps car somewhat original and lighter than any 13b!

146hp is pretty much the same as driving a gsl-se with any little mod. I'd say contact a member near you to take you for a spin. You are gonna be disappointed!!! After all the money and time on a swap... waste of time!


I may sound harsh but trust me I got burned.... I built a t2 car and I'm working on a 6-port turbo at the momment.

resjsu

Ok so im getting the 13b 6 port with stock 12A tranny:
I will need:
*se oil pan
*se front engine cover (which is what exactly, ?)
*Im going carb so i need a bigger carb, fuel pump, regulator and filter
*13B exhaust


This covers it right? Anything else please post!!!

Thanks

resjsu

I know jimmy but you probably spent a whole hella of a lot more then i will. Im getting 13B 6 port for $300. PLus other parts It will total bout $250. Someone is helping me put in engine so no money for labor. Porting a 12 or 13b 4 port alone is $1500 i was told by RotaryX. I think this is my best option. 146 hp with a stock 13b 6 port is good enough 4 me. 146 > 105, lol yeah im good with that. Thanks though maybe in the future i could get into turbos and porting.

85rotarypower

You need to add an aftermarket intake manifold to mate the carb to the 6 port engine. While your at it, you might as well just get a RB header. With the 6 port, this setup is probably good for anything from 160-180 hp at the flywheel. To give you an idea of the potential of these engines, my streetported 6 port from an 88 made 150hp at the rear wheels with the stock FI system and crappy intake manifold. Thats about 180 at the flywheel. It should be known that the stock intake manifold is a very shitty design. I think my engine with a 600 cfm carb is going to make about 200hp at the flywheel.

resjsu

Alright and I also have this http://mazdatrix.com/f-writng.htm the one that is "street strip" and the clutch disc to match it. Would it be smart to use this still?

Ok couple of questions as im getting closer to getting the engine i want to know a few things.
1]Any tutorias on how to remove Fuel Injection componenets since i want to go carb?
2] what the hell is a front engine cover?

resjsu

bump

64mgb

iTrader: (1)

This is from a 13B, but the 12A front cover is similar.

Rich

resjsu

Oh damn, it is like part of the block, i thought i was some other less important cover thing, damnit.

resjsu

where in the engine is this part exactly?near the radiator or the transmission?

64mgb

iTrader: (1)

Hmmm...there's a reason they call it a FRONT cover...it sounds like this is not something you should be trying to do yourself.

Here is a 12A cover on the front of a 13B.

Rich

resjsu

No no I am going to do it. Just need a little research first. Ok, so i need a SE cover to put on the 13B so that it will fit, got it.

resjsu

confused a little. 64mgd says i need a 12A cover and offset engine mounts and others says i need an SE front cover and engine will mount fine. If both are true, is getting the SE cover easier?

gsl-se addict

iTrader: (3)

The SE front cover is nearly the same as the 12A one. The only real difference is the Oil Metering Pump (OMP). The SE has 4 output lines whereas the 12A has 2 output lines. The SE and the later 13b engines (like the 87) normally inject oil into the rotor housings and into the intake. For this reason, I would go with the SE front cover and OMP. Two lines will go to your carb and the other 2 lines will go to the oil injectors on the rotor housings.

Mounting the engine is the same for either cover. The 13B engine is about 20mm longer than the 12A. You can slot the mounting bar or you can get a specialized adapter for this situation from Racing Beat.

Most everything else is pretty simple. Remove all the EFI stuff, add a carb/mani that will fit. I believe the 87 has an EGR port the needs to be blocked off. You will probably need an upgraded fuel pump and fuel pressure regulator. Some guys on here can recommend a good fuel pump/pressure regulator. Just little stuff mainly.

I would also look into upgrading to a front mount oil cooler (you can use the one from the 87, fab some mounts).