Comparing four front covers, S4 N/A, S4 Turbo, S5 N/A, and S5 Turbo.

What are the differences aside from OMP mounting (S5 electronic versus S4 mechanical) and water pump housing mounting (Match front cover to water pump housing.)

Do they all have the oil feed for a turbo up near the top sparkplug side, or is that only on turbo models?

If one were to use a Turbo front cover on a N/A car, could they put a bolt in that passage to block it up for later use?

 

you can block that whole if you needed to. and as far as water pumps goes, some grinding down will be required if you don't match the pump housings to front cover plates. You can make them work together if need be.

 

There's a front cover and a Front Side Housiing. Your talking two different items as if they were one. Just FYI

 

Where is the oil source located for the Turbo cars? Front cover or front side housing?

I've only seen one turbo engine up close and personal, and I wasn't working on the oil line at the time, so I never really got a good look.

I have a Series 3 13B (First gen GSL-SE) that's missing a front cover. I'm trying to decide which front cover is going on it.

I will need an FC front cover and FC oil pan because it's going to mount on the FC subframe that's going in my 1st gen. (Stock first gen engines mount using the front cover. The oil pan is different, so can't mount there. When I add the FC subframe, I must remove the 1st gen subframe and I lose the ability to mount to the front cover.)

 

from what it looked like to me the oil feed line was coming a sort of banjo bolt coming out of the front iron?? on the top spark plug side of engine

 

you're right.

but I dont understand why mazda chose such a far oil source for the turbo like that....

 

yeah im in the process of getting the motor ready to pull out of my blown 87 t2 and
i didnt even know there was an oil line running that length !!!
i was like WTF?? maybe its there so its close to the oil pump and so it has more constant pressure iono..... crazy mazda

 

They chose it cause "it was convenient".
Pulling something out of the front cover would mean a more complex front cover design.
Pulling something underneath, via the oil pan, would mean fighting gravity and almost guarantee a longer length of pipe / hose.
Pulling anything close to the turbo itself is asking for trouble due to heat.

So what's most convenient?
The top of the front iron.

Why not the other side of the iron, close to the turbo?
There's no oil passage over there.
To redesign the front iron for just an extra oil passage for the turbo engines would mean more money - and it's useless for the non-turbo engines.
Remembers, the molds for the engine parts are either identical or very similar for turbo versus non-turbo.


-Ted

 

It comes from that banjo bolt on the left of the front side housing and feeds into a metal tube that goes to the turbo,

The oil starts at the pump, goes thru the front cover.....then to the oil cooler,.....then back to the bottom of the rear side housing.......to the oil filter........splits off to feed the bearings on one leg and the other leg goes thru a passage on the upper left of each housing and comes out the previously mentioned banjo bolt and to the turbo. It also splits off before the banjo bolt and feeds the passage thru the front cover to the omp.

There's a picture in the online fsm. Lubrication section.

 

Yeah ted and hailers, I knew all that.

but I just didn't realize how much of a hassle it had to be to find a closer oil passage...

 

Doesn't the oil cooler hook up to the front iron down low as well? Could also provide cold oil.

So it's on the iron. Damn.

Oh well. It's probably NOT a good idea to plan ahead in case I want to turbo it in the future, if I'm using S5 N/A rotors.

Or I could just find a different oil passage.