S4 or s5 t2?
 

Hello I know technically I'm an older member on the new members tech section but my reasoning behind it is that I'm basically a newbie when it comes to cars and after 5 years I've been able to keep my rx7 running thanks to you guys and this forum. So on to the topic so I bought a jdm t2 engine and am planning on doing a engine swap later in the summer after I buy the rest of what I need. But in order to know what year to buy the stuff for I need to know if I have a s4 or s5 engine and after reading around I'm a little confused as to which one I have. So I was hoping you guys could help me out with that. I heard that if it has a hole above the trail spark plug where a knock senor goes it's an s5 and if it's missing an egr valve which again I'm a rookie so I'm not sure where that's located so I'll post some pics and hope for the pics. Thanks for your help in advance.

That looks to be a series 4 engine. An easy way to tell is by looking at the thermostat filler neck (where the top radiator hose connects). If it has a little radiator fill cap "thingy" on the neck it is a S4 engine. The series 5 engines do not have the little radiator cap on the neck. They only have a fill cap on the radiator itself.

Is that usually 100% correct observation? If so you just blew my mind on how easy that was to figure out. Lol

Assuming that is a factory OEM engine that does not have any mixed matched parts, then it is safe to assume that those observations are 100% correct. You my good sir, have a Series 4 engine from 1986-1988. Determining which year exactly is much more of a hassle, but it is safe to say you have a S4 not S5 engine. Good luck and enjoy my fellow Rotor-head!

Another way you'll find out is when you tear it apart for rebuild, the rotors are a dead give away

S4 engine have the EGR on the middle plate, s5 don't have one at all

is that true for JDM engines as well? i thought all JDM engines were/are without an EGR system.

Very good point, that slipped my mind

So where would I find the if the egr is missing or not? Where is the mid plate located and what does an egr look like? And thanks for your help devil it's greatly appreciated.

the EGR on USDM was located on the middle iron, drivers side at the top. I would think mazda would of left the casting there, but not have it opened up

If you look up the FSM on foxed.ca, you can find a decent picture of what the EGR looks like

Or goto any autoparts website, look up a 86-88 rx7, and search for it, should show you a picture

the T2 EGR is on the back of the lower intake

my bad, I'm so used to thinking N/A

Thanks for everyone's help i greatly appreciate it! Thanks for that website iduely it has a lot of information I need to mull over so I can better comprehend what I'm getting myself into.

you have no idea what your getting into yet :lol: