Hello guys, tittle pretty much describes what im about to put down. I have a s5 that i ruined the engine in. Everyone says its a spun rotor bearing and seals due to knocking on the rear housing... "Knocking".... Who would have thought lol
so i found an 88 s4 NA engine with low miles to put in it while i re do my s5 motor with patience...
Is there any slight difference i should be aware of or anything in particular you guys could warn me about. Or is this a simple pull off/put in type of deal?... This is my first swap and first rebuild... And also the first time i use a s4 motor... All my rx7s have been 89 or 90. Thanks in advance for the help...
oh one more thing... S4 limits at 8k s5 at 9k... Is this a problem and something i should be aware of when running the car? Or does the s4 reach the 9k safely?

 

someone asked this question in the past and seems like there's quite a few differences and i think wiring was one of them. might be better asked in the 2nd gen section. with ur current post count, u have access to pretty much the whole forum now. i can move this to that section if u wish.

 

Lots of electrical & mechanical differences between S5 & S4, so this is not a trivial bolt in & go swap. Plus the S4 swap is a downgrade - less power/torque. Off the top of my head, the S5 ECU must be wired to a working S5 OMP which you won't have on your S4 engine. Lacking a work around for that, you'll be driving around in limp home mode which isn't much fun. Also, the S5 has the VDI intake and its associated electrical components, which the S4 engine does not - I'm not sure how an S5 ECU would behave lacking the VDI electrical gear it expects to be there. There are several other electrical wiring harness compatibility differences between S5 & S4 in addition to those mentioned previously (e.g., different alternator wiring, early S4 engines had low impedance FIs while S5's had high impedance FIs, some S5 harness connector plugs won't fit their S4 engine equivalents, different connector plug pin-outs, etc). In short, you'll need to be an electrical guru to be able to understand both S4 & S5 factory wiring diagrams and modify what you need to to make it all work.

 

Thanks for replying guys... The only thing im changing is the motor itself. Every other component like intake, injectors, etc, is gonna all be left in yhe car to run with the s5 ecu, so just the block is what im changing. Still think it would be as difficult as you said? I know s4 have a mechanical OMP which i would have to change to an electrical one according to the S5 omp. Also yes im loosing around 20 hp by getting it but its only temporary until my 90 motor is done... Would be nice to take the car out and be able to move it without a trailer lol. And yes feel free to post this wherever you think ill get the most help in. Im not too familiar with the site yet. And again tganks for replying