If you have two bare blocks sitting side by side, how can you tell the difference between the S4 and the S5?

(I have looked in the archive and tried the search).

Thanks

 

There is a round piece on the front iron, closer to the spark plug side, on the top, that is there on S5 NAs.

Also, the water temp sensor holes are different threads.

If the front cover is on and original, the area where the mop bolts on is different, id look for pics of that.

Spark plug locations are different.

Rotor housings have different printings on them, if you need to know, i can go look, but its dark outside right now.

 

quickest visual difference would be, on S5 there will be a threaded hole for knock sensor above trailing plugs.
And stated above, if front cover is still on, the S5 has an electronic oil metering pump.

 

If you turn the E shaft by hand you will feel that the S5 will have more horsepower

 

On every S4 motor that I have seen the housings are stamped on top with Mazda Corporation and NSU Wankel. The S5's don't have that.

 

Great, thanks guys.
So is the knock sensor is on both NA and turbo engines?

 

yes

 

Thank you all!
JEB

 

Spark plug holes are in a different location!? I don't think so.... pictures coming.

Also, EGR passage on top of middle iron is solid and blocked off on the S5 engine, open or with EGR installed on S4.

S4 on left, S5 on right.


S4 on left, S5 on right.


Enjoy.

 

Spark plugs are in a different location. The S4 holes are closer together. They moved them apart a few mm in the S5 to avoid crossover spark.

Brian

 

^ The center housing casting for the EGR is a good way to tell.

BTW, are y'all sure the S5 NA has the knock sensor holes above the spark plugs? I thought they didn't...

 

Yes the the spark plug location is different on S5 than S4. I made this mistake a few years ago when i built a block.
Ran fine though.

IIRC the leading on S5 & S6 are lower a few mm, as stated above.

Micaheli- if you took them pics, take one straight on the plugs holes.

 

I'll do that tonight. But, I looked at them and I couldn't really tell a difference.

 

found one.

 

Yeah, I guess they are a tiny further apart... Guess I'm just retarded.

What would be the pitfalls of using S5 irons on an S4 ignition system because of this? I can't imagine this hurting your timing if its only a couple mm off. but I suppose if your port timing was a couple mm off, it COULD.... so...

 

Its not really hurting timing. It would still fire at the same time, but at a different location in combustion chamber.

 

Yeah. true... whats the point?

 

Just to clear things, when i built the block i had one of each S5 & s4, still ran fine though, until the dowel pin o-ring leaked. When i tore it down i matched the housings.

 

No point, just bored.

 

So the S5 NA housings have the holes for the knock sensor too? Are these already threaded? I guess the casting is the same as the Turbo ones?

 

i don't think that n/a's had knock sensors.nor the threaded holes for it.it will only have it if the motor was rebuilt and used T2 housings.but if it's the propper housings,they never the threaded holes for the knock sensor.

 

My motor is an S5 but I built it with S4 rotor housings. It runs fine.