The later M104 inline 6 has fabricated double wall stainless exhaust manifolds that look like a good candidate for cut weld. Any one try this yet?

I've always been leery of one piece inline 6 manifolds turbo manifolds in terms of cracking , exhaust gasket life. MB and industrial diesels have slip joints to take care of expansion.

I haven't tried yet but that is the avenue that I was thinking I would take when I'm ready to turbo my coupe (104.980) I'm not sure if I'm going to cut up the later stainless manifolds or the early cast ones. I like the ease of working with stainless but the cast would likely give a better service life.

FWIW I've been tossing around the idea of two smaller VNT turbos on my104 for around 500HP.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Just buy a turbo bandit manifold and save the headache. $1300 isn't THAT expensive. Better than anything most people could make.

I tried cutting them apart but honestly it was taking forever to grind through the welds in the ports and clean them up and I just decided that it was silly.
I have flanges still if anyone is interested. I have 3 extra sets. I am just asking 200.00 for a set. I think that is less than it cost me to make them.

Cast is a mess to weld, I'd think that SS would be just fine. And besides, if you make a jig once the prototype is finished, you can replicate the manifold in a few hours.

There are a couple of threads that I've posted to in this section about VNT Volvo turbos.


I wasn't suggesting that the flanges be cut off and reused, I was suggesting that the outlet pipe flange be cut off then an upward facing turbo pipe / flange be welded on and the entire manifold be used.

That would be pretty hard to do. The double wall is fairly hard to deal with and the ports are aiming the wrong direction. If you wanted to do something simple then just do a short backwards version of the stock manifolds pointing up and forward. But they cannot be flipped. You could maybe build a y pipe to the stock manifolds and bring that back around to the front for a turbo just leaving the stock manifolds alone. You would probably have to undermount the turbo to get the exhaust back out. But honestly that is the problem that is hardest to deal with is getting the exhaust out through where the manifolds are.
Just easier to make something new that is going to work.

I was thinking of 2 small turbos like the Turbo Techniques kits. I don't see double wall to be an issue, just cut away the outer shell as needed.

It would be really great if someone had a dimensional drawing of the TT manifolds for a pattern.

You should chop one apart. They are really a mess. I am not saying it cannot be done but it would be a pain and about the worse design you could come up with from a flow standpoint. If you are looking for easy and cheap just make a log manifold. There is no reason for twin turbos with today's turbos. A good sized single will spin up really well.
For instance we are running a B/W S366 on a om606 diesel project I am working on and it is huge. With a 1.0A/R. And it still hits at around 3k RPM. If we drop the A/R down we could get it spooling at around 2500 rpm. You could use half the turbo to make 4-500 hp. And it would probably spool earlier on a gas engine as well.

whipplem104, Do you still have those exhaust flanges? I'm headed up to seattle this weekend for work and would like to pick up a set if you still have them. I'm about to start the epic quest of building a turbo manifold for my m104

yes