so im about to sell my S4 TII motor. Im planning to put in a new jspec, but had some questions. What all comes with a jspec? you get harness maf ect? the guy im selling to wants harness and maf. and i want to make sure im not sellin something im gonna need later Im thinkin that i want to put s5 tII in, and if i remember right, you can run S4 TII rear end. but yo need the s4 tranny on back or is it driveline? just checkin before i sell. Ill search faq some more too. thanks for the tips~!

 

Questions:
1. Depends you need to confirm that with whoever you buy the motor from
2. Depends you need to confirm that with whoever you buy the motor from
3. You can run a S5 block on S4 electronics if you want, I did it for mine. It was a cumbersome process since at the time there wasn't much info on it. There may not be that much info now

 

Yeah, you must ask the company what comes with the engine. Most of the time it's the engine, flywheel, clutch, manifolds, turbo, fuel-rails/injectors, rats-nest, OMP system, IC & bracket, alt., TPS etc. Just all of the stuff bolted directly to the engine. Other times they will sell a "long-block" which consists of the transmission and sometimes the driveshaft, uncut wiring harness and the ECU.

Do not give that guy your wiring harness and AFM. Typically J-specs won't come with the AFM, and I'm not sure if it applies to s4's, but with s5's the J-spec harnesses are difficult to use on a USDM car.

As far as I know, if you just use the Series 5 "keg", the only real differences will be slightly different spark-plug hole placement (IIRC) and you won't be able to use the s5 electical OMP--but if you also swap the front-covers and use your s4 cover, you should be all good.

Check out rotaryresurrection.com for some good basic answers regarding the s5 in an s4.

I would personally find an s4 engine because it will be cheaper and MUCH easier to find.

All turbo drive-line parts are interchangable, minus a couple minor things (tranny cross-member etc.) I believe the half-shafts are interchangable... Drive-line is just a nice was of saying every "mechanical" component (engine, tranny, driveshaft, rear-end, axles), it can also be used to describe everything but the engine.

 

hahah driveline, i meant driveshaft :P ill try and research some of my options whether or not they are long block or not. if i hold onto the s4 harness i can easily switch it out with the jspec and its all gravy right? It would make it easier to keep it s4 also, since everything in it was already s4, people in s5's switch their electronics to s4. whats the diff a lil horsepower? ill keep the afm for sure then.
this is totally off subject but why do some s4 TII owners put s5 mani's and turbo on? i know of few in the nw section have done it but have yet to understand why...fill me in plz. AND thank you erik and chixacan

 

I would personally not install a series 4 J-spec wiring harness without searching. I know for a fact that series 5 J-spec harnesses are *not* recommended nor highly sought after.

The difference between s4 and s5 engines is that the s5's have slightly higher compression and a stronger rear-iron (in case you detonate, it won't crack like the s4's). There are other differences, but they're technical and not too important.

s5 turbo's are also superior to the s4's because they have a larger "scroll" area (larger volume of exhaust flow) and a much better wastegate for preventing boost-spikes and achieving better boost control. They spool faster, usually are found in better condition and their wastegates don't need to be dramatically ported to keep the boost to a safe level if "full" exhaust and intake is installed on the TII.

 

I agree with eriksseven, stay S4 if you want simplicity. Keep your AFM, ECU, and harness for sure.

In my engine I'm using the S4 TB with S5 intake runners, barrel, exhaust manifold, and turbo. I used block off plates for just about everything including the OMP so I run premix. All S4 sensors were used including CAS, TPS, AFM, boost and S4 injectors were used. I wouldn't say that it's an ideal setup, but my car does start every time and does not have any problems boosting or anything.

 

hmmm. well i learned a little bout s5 turbo's well im gonna hold onto harness ecu and afm. i had an extra ecu ne way. so a s4 motor with s5 turbo and mani's are a pretty good set up then. i dont remember but i think tooshort88 ran a set up like that. this could be a dumb question, but im here to learn :P
so s5 motors are higher compression then s4's. but with higher compression = you cant boost as much right? because of an increased chance of detonation. so lower compression motor could boost higher, safer? ive also heard of some using na rotors in motors to increase compression, wouldnt that be even more risky seeing if your boosting on an already high compression motor, even higher chance of det? wouldnt that basically be the same problem with running na-t? thats alot of questions i know but you guys got my brain ticking lol.

 

Just make sure you have enough fuel to supply the demand.

 

umm earl what are you talkin about? lol