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Hello everyone my name is Alexander I am 20 years old and I have recently purchased my first rx-7 FC (shell). This car was a NA s4 and I have purchased a s5 swap from an importer. *note* I purchased this before knowing that an s5 into an s4 car is not as PNP as I originally thought. Flame me for not doing my research I couldn't care less I like to learn and sometimes that just has to be the hard way. So now im kinda all in on this there really isnt much backing out of this so I am very determined to have this swap done before I leave for university in late July. So where im at now is I am replacing every single coolant/vacuum/fuel line on the swap. I have taken off the s5 throttle bottle to stick an s4 t2 one on (with tps) as well as an s4 alternator. Now from what ive read I will need to use an NA s4 engine harness on this to make it work. But im curious to see what anyone would have to say about just purchasing a whole harness custom harness to make this swap any easier? Another thing is I want to block off my OMP but if i do so do I have to remove the oil squirters or can I just leave them since they will no longer have pressure going to them? let me know. And yes I know there is plenty of write ups on this and plenty of information out there but I just like to ask things my self and go from there. If you hate that please just keep it to yourself I will not give you any mind. Parts I have already purchased are. 3Inch Downpipe, t2 to NA diff driveshaft, s4t2 ecu, s4t2 MAP sensor, block off plates, fuel pump.( will purchase a v-mount after doing hoodless street testing with top mount) rx-8 oil coolers. Just throw any hep out to me that you can provide I really am just winging this all by myself and feel lost very often but I try my hardest to get a better understanding about this very cool engine. so PLEASE be nice first time in my life posting on a forum
S5 to S4 shouldn't give you too big of a headache. The ECU and engine harness is pretty much separate from the body harnesses. There will be few intersections.
1. Leave the oil metering pump and "squirters" hooked up and running
2. Use the wiring harness and ecu for whatever engine you are going to run. If you are using an S5 engine, use an S5 harness and ECU.
3. Don't get rid of something unless you're sure you don't need it (you have 2). Don't go getting rid of stuff for the sake of getting rid of it, i.e. vacuum systems, actuators, solenoids, etc. I put a car together for a youngster that sold off all his "extra" parts to a buddy by having him buy them all back.
4. Replacing all the rubber hoses is a good idea.
5. Your intercooler (post says TII) will not work without airflow. Either get yourself a turbo hood or do a front mount. If you are running the stock turbo, run the stock intercooler with a turbo hood. Having spent over a decade in university, rx7's were a good learning experience in pinching pennies. These things can spend money whether its in your wallet or not.
Download and study the FSM for your car and engine. S4 to S5 will have variances in both body and engine.
Take pictures of everything you do, before and after. Keep us up to date and let us know if you have questions.
Good luck
It would be to your benefit to read those write ups and the information that is out there on this type of swap. Then ask about the things you're not clear on.You may not want to hear that and go ahead and ignore me if you must but people may not feel like rehashing things that have been covered many times before like this has. You've already bought things you didn't need from not doing research.
- Now onto my thoughts on this. I too would use a S5 ECU as IIRC there are just a few wires/pins that need changed on the S4 body harness connector to adapt the S4 body harness to work with the S5 computer. The S5 is a better ECU. You'll have to keep the OMP if you go this route though but as long as your S5 engine came with one that shouldn't be a deal breaker. Also if you need a harness for the S5 ECU a n/a one can be made to work by shortening and lengthening as needed. I think you'll need a S5 MAP sensor and MAF sensor as well.
- Keep the S5 alternator. It has 10 amps more output than the S4 and there is a write-up in the FAQ on how to wire it in. In fact you should've just gotten an FD one has they have 20 more amps and wire in like the S5.
- IIRC the 2nd gen oil cooler is better than the RX-8 ones so you can sell those.
- Also you mentioned a 3" downpipe. Is the rest of the exhaust 3" as well. If so you're gonna need a way to deal with the additional boost and fuel cut or your engine will have a short life. You have some searching and reading to do whether you like it or not.
Will for sure keep the OMP after further reading, not deleting anything im not 100% on all I've really done was just put a few block off plates on the intake mani. Also dont really plan on selling or getting rid of anything I know pretty much everything may come in handy one day so I tend to hold onto alot of things. Also about the inter-cooler I live kind of in the middle of no where so ill probably just end up taking the hood off and doing testing that way with the stock top mount to make sure everything is dialed but do plan on going with some type of front mount after some testing (taking fmic recommendations)
I haven't really read to many good things about s5 ECU's since my time going about all of this so from many write ups i read informed me to just convert the whole thing over to s4 meaning NA engine harness, alternator map sensor, and and a t2 s4 ecu?? But after two recommendations suggesting to stick with s5 management I think thats what Ill do then. I can shoot you a link to what guided me to do so and can correct me if its completely wrong This is what ive been reading off of
Take note that in the post you provided, the guy is placing a piggyback controller in with his S4 ecu. If you are running a stock engine (which I would greatly recommend as a college student), you should run the stock engine harness and ecu that goes with the engine. There are fewer complications, it will keep your costs down, and the unit should function as intended. Having the engine working like it is supposed to should be a critical path item. If you have everything running correctly, then you can start to modify and upgrade. The best recommendation I received starting out with these cars is to get them running well before making any changes. You've got sort of a mixed bag with S5 turbo in an S4 body. I have the same thing. However, you can consider the ECU, harness, and engine almost as a standalone set. These items can be installed together without having to change things and function independently from the rest of the vehicle's equipment. There may need to be some changes on the interior of the car so you have the right gauge cluster and wiring harness there, but the engine bay should be pretty straightforward. Let us know where your hangups are and we can help you through them.
I haven't really read to many good things about s5 ECU's since my time going about all of this so from many write ups i read informed me to just convert the whole thing over to s4 meaning NA engine harness, alternator map sensor, and and a t2 s4 ecu?? But after two recommendations suggesting to stick with s5 management I think thats what Ill do then. I can shoot you a link to what guided me to do so and can correct me if its completely wrong This is what ive been reading off of
Just to clarify I don't mean that the S5 ECU is great compared to more modern standalone ECUs. It is just better than the S4 and incorporates a knock sensor. Also you can use the same piggyback( APEXi SAFC for instance) as he was using on the S4. I too would agree to get it running in stock configuration first but the one issue with your potential setup is it sounds like you're going to 3 inch exhaust straight out of the gate. This will raise boost above stock levels and add additional fuel requirements. Because of this you'll need a SAFC and wideband O2 sensor at a minimum. Just until you get it running right you may want to get a stock diameter downpipe to tie into your n/a exhaust initially. Also it's not been mentioned but you'll want to upgrade your fuel pump to at least a TII one but a FD or Walbro may be a better path.
Honestly still can return that downpipe with no issue so not too worried about that now that I know that could be an issue. Stuck a 255 walbro in it just so I dont have to worry about that for a little. Do plan on going to a standalone pretty much been suggested adaptronics multiple times and leaning towards that but dont really wanna bite that bullet until I can get a stock set up going first. Thanks again man appreciate the input
Just run s4 t2 electronics and possibly with a safc. S4 t2 throttle body. I ran that for years on a s5 t2 block one a s4 na chassis before going to power fc.
I'm running a s4T>s5T swap. Long story short It's probably best to just go aftermarket ECU and wiring harness. I run the Haltech Sprint RE and kept all the s5 stuff on my motor. I did the emissions delete, everything except TB mod. Blocked off the OMP and yes I used bolts to block the oil injector/dripper holes. Full premix. Kinda a hassle mixing always but it is nice that my engine oil is engine oil, and my premix is in the gas. It's not the cheaper route but you will have a tune-able ECU forever.
02-23-20, 09:07 PM
NA s4 to s5 SWAP HELP ME GOD
