Sup guys,
So I drive a 87 603.960 on a 91 250D.
My turbo just died on me so I really need your guys help to figure out my next turbo. I want to know all your guys opinions as if the car was yours! I would really appreciate it if you guys add what kind of turbo, why, and if its a direct fit or have to be modified to fit...

Thx

The stock turbo is already a very good match. That said, the T3 turbo can be changed to a 55-trim compressor from a 3.5L 603, a 60-trim compressor from a Ford Mustang/Thunderbird or a common T3/T4 hybrid without much trouble.

Going to something big like a Holset wouldn't have much point unless you plan on upgrading the injection pump to get past the 175hp limit. Small ones like an HX/HY30 being the exception.

I am in the same boat, my turbo is having issues and I have been wanting to replace it with a larger one anyhow. I am planning on getting my injector pump rebuilt with some larger Elements so I figure if I am going to have to replace it, I may as well get a larger one and get the air part of my upgrade faster.

What are some good candidates assuming I want to get about 250-300 hp eventually? I would LOVE some input on this

Generic "T3/T4", HY35, HX35, HE341 or a ball bearing GT32 or GT35 with a 71 or 76mm compressor. Any one of them would be a good candidate for wastegated turbos. If you want a VNT, the choices are much more rare for that power range and the common ones are too large for a practical daily driver or too small for your goal.

Finding a manifold from a W140 300SD/S350 is a good starting point so you eliminate the bypass pipe, have more room to work with and start with a standard flange angle.

So an exhaust manifold from one of those will bolt right on and give me more room?

Yes. Here you can see the difference.

W126 and W124

  w126a.jpg (Size: 98.78 KB / Downloads: 230)

W140 3.5L

  W140a.jpg (Size: 109.86 KB / Downloads: 231)

The manifold itself.

  W140_3.5L_manifold1.jpg (Size: 68.94 KB / Downloads: 231)

F.I.

That manifold switch out is definitely next on the schedule!
thanks for posting that up...i'll be on the lookout for that mani

Speaking of upgrading turbos, I am trying to determine if my stock one is shot. It's a 603 engine. I don't have a proper boost gauge yet but hooked up a PSI gauge to the vacuum line nipple on the intake (top right) and it put out a max of about 7 or 8 psi whether revving under no load or while driving and nailing it. Is that enough/normal boost?
The car feels like a not turbo diesel. I'm going to compare the reading on another car tomorrow that has good power and see how it stacks up against it. I was told that high mileage Benzes will tend to stretch the timing chain and this retards the injection pump and kills the power. True? Enough to make mine a dog?
I pulled the upper exhaust pipe and checked to see if the wastegate was leaking pressure. No it's not. The turbo spins freely with no noticeable play. Seems ok.
So what's causing this? Can it be vacuum related? Seems not to me.
Thanks a lot!
Derek

Wow, it seems like a few of us are in the same boat, me included. Im certain my turbo is toast (unless oil from the housing is a good thing). However, what I am looking for is a VNT that can evolve with my modding schedule. Right now im pretty stock with the acception of an alda and full load adjustment. HE341VE? Somthing I can run at low boost until I get the fuel for it.

Stretched timing chain may be the main problem with my turbo spooling problem. I advanced the pump timing as far as it would go and it started running better with more power. Still not where I think it should be performance wise but better. I think I'll change the chain and start seeing what's up with the pump.