TweakGames

iTrader: (3)

Hello. I just got an engine and I would like to find out if it is s5 or s4. I am currently not home, but am going to be buying a replacement housing for the one that wasn't in the best shape from the engine. I need to know if its, s4 or s5, and if its s4 if its front or rear that is the bad one.

Here are the pictures.

Picture 1 - 5 are the throttle body. I was thinking that we should be able to tell by that if it had the VDI? I currently don't have a s4 NA TB here to compare sorry.












Ok next pictures 6 is a picture of the exhaust side of my 3 housings I had my dad take a picture of. From left to right. Known s4 NA housing, My bad unknown NA housing, and my good NA housing.




Next is the same thing, but the spark plug side. This time the order is reversed. Left to right, GOOD unknown NA housing, BAD unknown NA housing, s4 NA housing.




Is there any way with the pictures above to tell if my new engine was s5 or s4? I was thinking that the spark plug location would be different from s4 to s5, but they look almost exact...

Thank you.
~Tweak

NCross

iTrader: (18)

They all look identical to me...

kungfuroy

iTrader: (6)

all three of those housings are s4, the s5 have locations for knock sensors abve the t plug

that throttle body is s4 as well

RETed

No VDI in the intake manifold, so it's an S4.
Also, look at the injectors...
rectangular -> S4
oval -> S5


-Ted

TweakGames

iTrader: (3)

awesome, thanks guys, saved me from buying the wrong housing! BUT now I need to figure out how to tell if the bad housing is the front or rear, seeing how they are different on S4 NA. How would I go about doing this?

Thank you. (the bad housing is the one in the middle)

(mazda say this about s4 NA)
Front N326-10-B10 86-88 N/T
Rear N326-10-B50C 86-88 N/T

slo

iTrader: (1)

you can tell by the EGR port that the first 2 housings (going left to right) are rear housings.

It doesn't really matter though (front or rear) if not using the EGR just use and S5 exhaust manifold gasket then you can swap around at will.

TweakGames

iTrader: (3)

Ok, the EGR might be the only thing I block off. If I remember correctly, that is just purely for emissions control, and doesn't have anything to do with 5/6th port or anything like that. I have had my share of NA motors in my past, and have found out the hard way how important the 5/6th ports are.

Thanks guys, so I am in search for any s4 NA housing. I will have to delete all my WTB s5 housing threads haha.

slo

iTrader: (1)

you could use S5 housings if you want.

I have used S5 NA housings in S6 engines (changed the exhaust diffuse of course, and engine was ported) really I wouldn't mix S4 and s5, but if you use all of one or all of the other, and the EGR and port air injection are deleted it doesn't matter so much.

NCross

iTrader: (18)

There should be an "F" or an "R" stamped on the top of the housing.

cezonetheillest

on my 4 port turbo block the "F" and "R" were stamped on the bottom where the oil pan goes. i don't know if this is different between na and turbo.

NCross

iTrader: (18)

Mine came from my 87 Sport.

HAILERS

Both my series four turbo and series four non turbo have either a F or a R stamped on top of the rotor housing.

The front and rear rotor housings are different in the area where the ACV feeds the air to the exhaust port SLEEVE area. It feeds the ACV air thru the front and rear side housings TO the rotor housings in a triangular area where those two housings mate.

If the front and rear are mixed, then the ACV air will not get to the exhaust port sleeve area i.e. the hole inside the exhaust port sleeve where it spills into the exhaust gases.

Download the TRAINING manual from this site. The ENGINE section. Page 1-7. It's called the Secondary Air Passage. IF the housings are swapped that passage is Blocked. I'm NOT talking EGR passage i.e. that small half inch hole below the exhaust port.

OR in the words of that manual: "Note that front and rear rotor housings are not interchangeable due to the different positon of the Air passage in relation to the exhaust port. For easy identification, the letter F (front) or R (rear) is stamped above the MAZDA mark."

If you care not about emissions, the move 'em around at will. If you do care, then don't move 'em around at will.

slo

iTrader: (1)

Good information, I mentioned that above when I said port air injection.

But I'd also like yo add.

I have disabled the port air injection on a number of cars and had them pass smog just fine. I have worked on a number of cars where the ACV goes bad, my (quick and dirty) solution for this was put a hose between the air pump outlet and cat converter feeding only and directly the cat converter with air.

Port air injection just helps with the warm up with the pre cat, and it helps distribute the load between the precat and main cat. But its certainly not needed to pass. Infact the japenese and other non US rx7's had no precat.

HAILERS

I'll just say that we'll just have to agree to disagree. You can drive the car hours on end (pre-cat certainly isn't cold by then) and anytime you come to a stop and idle, you have Port Air. Port Air is meant to mix with the rich idle mixture of the RX so that the afr entering the converter is closer to a 14.7 ratio (ref page 4-42 of the Fuel Emissions Training manual). That, as stated in the manual, is where a converter works at it's most efficient.

Most of the daily driving is with the relief valve open dumping air into the silencer in the fender i.e. no air going to the ports or the split air pipe. So their we agree in that you don't need air at all under most circumstances. Port air isn't needed during constant speed conditions because there is feedback correction of the afr to 14.7 by the interface of the 02 output to the ECU.

But anytime you leave the stop sign you'll have a mixture of Port/split air for around 120 seconds whereupon the relief opens and you have no air once more. Come to a stop sign, same routine all over again.

In other words "whatever".

EDIT: I spend an inordinate amount of time looking at the RTEK2.0 display of the Port Air solenoid, Switching solenoid and Relief solenoid while driving and have a fairly good idea what is happening with each of those items when they switch from one state to the other.

slo

iTrader: (1)

I don't disagree with anything you have said.

Your correct as to its function, all I'm saying is that the car will pass smog fine without it. You can easily set the ACV up so that it never goes into port air mode, and all of the air it would be pumping in port air mode gets pushed to the main cat, and it will pass smog every time.

On my own car which is a street legal (refereed for legal engine change in CA) 13B-rew FC, I have a haltech running the engine and smog controls (well some of them).

The only ACTIVE smog control I am using is the air pump (and part of the ACV function), which on the REW (the airpump that is has a clutch like a air conditioning pump. The stock FD turns the Air Pump off at 3500 RPM I believe???

I have it plumbed through the ACV like stock but the port air injection point is blocked off with a gasket and the port air solenoid isn't hooked up to anything, there is a couple other modifications to the ACV system as a whole, can't really remember off hand but basically its pushing all air to cat.

I pass smog just fine, in fact without the air pump even turning on, I just barley failed smog.

The reason I disable port air is because on the haltech I can do open loop O2 feedback control at idle off a wide band O2 sensor, with other tuning this allows for a steady idle as lean as mid to high 13's.