Dan_s_young

iTrader: (1)

Just wondering if anyone has a picture of the two different series irons side by side.

When I purchased my engine I was told that it was a JDM S5 motor. Now my tuner is saying that my irons are from a S4 TII engine.

Would like to see what the difference is so I can identify for sure that I need to replace my iron to series 5 for higher boost (to avoid cracking the rear plate).

Thanks

Dan_s_young

iTrader: (1)

Does anyone have a picture or a description of how to tell the difference?

RotaryRocket88

iTrader: (7)

The two look very similar, but the easiest way to tell the center irons apart would be the knock sensor mounting location. S4s had the knock sensor mounted below the oil neck, while S5s mounted it on one of the housings.

bumpstart

s5 rear plate has this diagonal casting under the oil filter pedastel,, the s4 does not
this is to reinforce the dowel casting to help prevent cracking when the block stretches at high power outputs




the s5 front plate has this wide machined area for the front timing covers oil passage to the cooler hose outlets
this wide land is to suit the original O ring,, supported by a nylon or teflon outer support ring
s5 hence uses a unique gasket suit this large land

earlier engines ( s4 down ) have only a small machined land,, suit only the O ring

arghx

iTrader: (3)

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/just-measured-s5-turbo-rear-iron-factory-bracing-pics-795339/

Dan_s_young

iTrader: (1)

Now judging by what I am hearing, my engine sounds like a S5, but heres a couple pictures just to clarify, my tuner took one quick look at it though and said it was a S4, any ideas why?

DBookatay

iTrader: (1)

Very nice!!!

bumpstart

it may be because of your housings,, s5 have the threaded hole for knock sensor above the trailing plug,,, s4 do not

however,, just from what i can see,,, you may have odd housings,, at least one of them appears to be s4
( the one with the N318 moniker near the oil injection point on the housing )

if the OTHER housing lacks a threaded bung hole for knock sensor then you need to put BOTH housings on a flat bench and measure the leading plug position

if that NON N 318 housing is lacking a knock sensor threaded hole its likely to be from an NA s4 6 port ,, which has different spark plug locations to other housings

N318 housing will match to a s5 NA or s5 t2 housing,, as all are the same respects to plug position
( s5 NA will have an exhaust baffle )
-- none are the same as the N326 housing,, which lacks the threaded knock sensor hole in the housing,, and also lacks the N318 bossing

be sure that other housing is not N326/7 !

Dan_s_young

iTrader: (1)

The housing is a N318 housing. They are a different set of rotor housings than what came with this motor. The motor had blown a apex seal before, so the housings are new, I am just trying to figure out if I am safe as far as the rear iron goes or if I have to worry about it cracking under high boost?

Looking at older pictures of my engine build it looks like the knock sensor was originally on the front rotor housing of this engine as well. The more I look into this the more it seems like this is S5 irons... Just really confused as to my tuner taking a two second look from the drivers side and saying that it was a S4 rear iron...

Dan_s_young

iTrader: (1)

I took a better picture showing the rear iron on the car. Comparing this to the pictures shown previously this is S5 correct? I am mainly looking at the rear under the oil filter pedistal.

Dan_s_young

iTrader: (1)

Does this last picture help at all?

bumpstart

rear and front plates are definately s5,, though housing in pic ,, is not , appears to be n318 ( an s4 code )

Dan_s_young

iTrader: (1)

Perfect thank you very much for confirming that. The housings are from a different engine, but I was just worried about cracking a S4 iron, and the fact that my tuner said it was a series 4 rear iron...