Recently my S4 TII engine gave up the ghost. I am out of town and pressed for time so a rebuild is not an option. My solution is to source a good condition n/a block (picked up yesterday) and swap over all the turbo accessories/manifolds.

I've done my research and I'm comfortable with most everything that needs to be done. The exception being the routing of the coolant to the stock turbo. Everyone seems to either use the nipple for the TB thermowax, the heater lines or drill and tap the back of the WP housing. I have a functioning thermowax, would rather not run awkward lines all the way across the engine bay, and don't have my tap and die set available.

My question is why does no one ever just drill out the stock coolant passage in the rear rotor housing and use the stock coolant passage/ lines for the turbo LIM. It seems like this would be a much cleaner and easier solution than the work arounds that are so popular for this conversion.....

 

subscribed. i am turboing my NA block and am still trying to figure out where the easiest place to get coolant and oil from.

 

The "easiest" place would be the stock place.

However I suspect that its a case of monkey see, monkey do. Arron Cake was one of the early pioneers of the 6 port turbo and he actually kept the n/a LIM thus using the stock coolant passage wasn't an option. Most subsequent builds probably relied heavily on his writeup and thus used his coolant routing ideas even if they adopted a TII LIM instead of the n/a version.

But I could be wrong, so that is what this thread is trying to ascertain....

 

Mine goes from the back coolant passage on the block to the turbo out to the waterpump housing. That works for me but I dont have a thermowax.

 

Hiroichi: Are you running a mondified Turbo LIM or are you using the N/A LIM?

I DO have the thermo wax, I also have the lower banjo bolt/ coolant return pipe for the turbo which plumbs back into the WP housing, so coolant return is not an issure.

 

the hard part is that the rotor housing has to seal against the intake manifold, on a T2 housing, there is a second cut, that gives a place for an o ring to sit, the NA doesn't have this cut.

so its not really easy/simple

 

I see 2 issues:
Metal shavings falling into the coolant passage.
Machining the o-ring groove into the housing to seal against the lower intake. It'll be difficult to do by hand. Maybe it doesn't need to be that accurate?

 

NOt worried about metal shavings, The block has coolant in it, and the coolant will want to get out more than the metal shavings want to get in. I'll have to take a closer look at the grove once I get the old engine out and see how deep (important) it really is.

Hmmm....perhaps not.
I replaced that infernal O-ring on the turbo engine that just blew about 2 years ago. I wonder if the second cut is really crucial to sealing or if it is primarily to hold the O-ring in place during assembly?

 

those were the reasons i didnt attempt that when i did 6 port turbo.

instead of using the thermo wax line line ,
i bought some T fittings, and taped intot he heater inlet hose and heater outlet hoses. ( this was using a non t2 water pump housing as well.) heater sill blew plenty hot.

 

Personally, I'm not into coolant facials.

IIRC, the lower intake flange is flat, so the o-ring actually sits in housing recess. I'd guess the rubber ring is there because the stock paper gasket doesn't resist coolant. So just a straight hole with gasket probably won't work.

 

1. the intake gasket will not hold coolant.

2. the intake sits flush with the rotor housing, so there is no place for the o ring, which is why they have the cut. i don't think the cut has to be super precise, but there needs to be SOMEPLACE for the oring to go...

 

just tee off the nipple on the rear iron and cut the flang off the line to the turbo to run the hose to it

 

I was trying to avoid cutting the stock coolant pipe since this engine is a temporary solution But I suppose I could get an aftermarket flange later on down the road.

It seems it would be easier to run the hose to the turbo post TB (instead of to the nipple on the WP) and cap the WP nipple.

 

it is easy... if you have the tools. But since I know you do not have access to the correct machines, heres another way.

1. Drill small pilot hole in coolant passage.
2. Buy a counter bore tool with same size pretruding stub to fit your pilot hole.
* This counter bore tool will look like and endmill that would normally go on a milling machine. But it will have either a hole in the center of it to place a drill or steel rod to position itself. Or have a rod/drill already built into it.
3. counter bore o-ring groove.

Google counter bore tool. Get one, you will use it much more after you have it. Best investments are tools, not parts...

 

Just throwing this out there, why not just pick up a turbo that's only oil cooled? Or are you running the stock turbo?

 

Gotcha, so it would be easy if I were Sen2two...lol. I see your point and have decided to simply do the following path:

nipple on rear iron --> TB --> Turbo --> Return nipple on WP housing. The Return nipple on the thermostat housing will be capped.

I'd prefer to run a hardline (or at least SS) since the coolant port on the turbo is in such a high heat area. But I'm on a tight time schedule so I'll have to come up with a better solution later.

Coolant and water cooled turbos are superior to oil only turbos. I wouldn't forsake that benefit due to laziness.

Thanks all.

 

Since the intake manifold will already be off, you could have the o ring seat machined into the intake manifold. Same result.

 

Touche' salesman......touche'.

If the cost is less than the hose and banjo fitting I would need to run to the TB then I might just have to do that.

 

You'll just have to replace the lower intake once you swap a turbo motor back in. O-rings don't like to seal against each other.

 

My 4 port has an s5 LIM and fd upper, so that is a non issue

 

I have always hated the "block" to LIM interface for coolant on my TII as it is just one more place to leak that is super hard to get to if there were a problem and the stupid o-rings always swell and have to be replaced anytime you have the LIM off.

In addition the turbo coolant inlet to LIM flange is attached to a rigid steel line and I have had it keep the flange from being perfectly parallel, leak coolant onto the turbo and catch fire.

Plus those tiny flange studs get so weak by the heat of the turbo they snap easily so I had to put larger stainless studs in.

All in all I would be happy to be rid of the stock system for the turbo coolant feed and have it off the nipple in the back of the "block" where I can get to it more easily.

I would-

1) cut the flange off the turbo coolant inlet pipe

2) use a stainless Swagelok tube to tube adapter (metric to standard)

3) to a stainless tube bent to route it to the back of the "block"

4) to a stainless Swagelok tube to hose barb fitting

5) to reinforced pressure hose to the "block" nipple (or "T" with the thermowax)