Difference between S4 and S5 engine?
 

Is there a way you can tell by looking at the engine you can see if its an S4 145hp or S5 160 hp version?

YOu should do a search but. I guess the eaiest way is by looking for the OPM.(oil metering pump)

If it is mechanical it is an s4. works with the throttle body.
If it is electronic it is an s5. There is no link between the throttle body and the metering pump(ecu controls it)


HOpe this helps.

Look at where the BAC valve is. If it is on the drivers side attached to the dynamic chamber (plenum) then it is an S4. If it is underneath the intake snorkel on the passenger side, near the secondary fuel rail, it is S5.

Here is the BAC valve...

http://www.rotaryresponse.com/4sale/FC3S/BACTII.jpg

I imagine that BAC would be different on both N/A and turbo motors?

Yes. You look at the intake manifold, then smash your face into it.

I like this link: REALLY AWESOME THREAD!!!
It explains all the differences, and how to tell.

-Enjoy!

hahaha i should have searched first.

intake manifold is a huge one.

How would one tell the difference between s4 and s5 turbo models? Same things?

search, this gets answered a lot.

the S5 engines have the knock sensors over the spark plugs, 3 bolt electronic metering pump, plastic 3 bolt thermostat neck.

Its even detailed in the FAQs

I believe it is all explained in the thread you revived.

The easiest ways to tell:
S5 = Two TPS and an electrical MOP.
S4 = One TPS and a mechanical MOP.

(Yes... I say Metering Oil Pump, as stated in the FSM.)


Here is a good link...
Rotary Resurrection: Differences between 86-88 (S4) engines and 89-91 (S5) engines

if you really want the true answers from someone whose had both engines in all chassis including 3's pm me prolly know your setup off the top of my head or you can follow my build and for that I would pm it to you otherwise this posting would be at 100 pages allready id run outa room

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