740 & 760 Turbo question - which one?

So the situation is this.
I am about to start a turbo addition to a B230K (long story on the "k") and have noticed the turbo I have is an 850 T5 turbo on a 940 '90+ manifold. Not a 940 SE turbo - which is what I was told it was.
Some ugly though effective mods have been done to the 850 turbo on the 940 manifold so the wastegate actuator will work. Dead ugly, though can be cleaned up later.

There is also a 90+ 740 manifold and turbo there on the shelf. It is a TD05-12B off a Japanese import car/engine.

Onto a stocker B230 I am looking for a daily drive engine that will spin up quickly, not really fussed about high horsepower or big numbers. Just want it to move swiftly off the mark.

What are opinions and thoughts on which would spin up quicker? The 850 turbo has a much bigger output from the turbine housing, which is encouraging, though not sure if the actual turbo is also much bigger and will require more exhaust to spin it up.
The other complexity is that if from an 850 it is designed for a 2 litre engine, so simple theory is that the 2.3 litre engine should spin it up quicker.


No rush, the plugs to block off the EGR/air recirculation have disappeared so the project has stalled at the parts gathering stage. Still looking...


  • Manual or auto?
    Willing to invest in a cam to go with the turbo?
    I think you need to add i was in an s80 with three wheels getting pulled backwards and was told to "hold on shit is about to get real".
  • 850 T5 engine is 2.3L
    I would lean towards the newer turbo
    I fitted a 16t to a mates stock 740 auto and it spools nice and early and at 10psi he's making about 115kw atw
    Stock fuel system will support it to about 15psi

    If it's still got the 850 conical exhaust housing and you need to fab a downpipe I would recommend changing it for the later straight housing though
  • re: cam, I have a cam from the 740 B230FT, was planning to use that. Have shims ready to go for fitting. And it is a manual, as it should be.
    Did not know the 850 was a 2.3 l. Guess I just associate it with the 2l touring cars of the day.

    There is a 740 turbo downpipe ready to go, and though the output is in a slightly different position it looks like it will work so that is the plan.

    If they are both 2.3l engines then the decision is pretty clear. The newer one.

    Thanks for assistance.
  • DauntlessDauntless (@Dauntless) Central West NSW
    edited January 7
    The TD04-15Gs are nice, I'd use that. The TD05-12B would be from a Volvo too, I think around 1985 from memory.

    What cam is in your current engine? If it's an X cam, the specs on paper look better than a T cam from a B230FT.
  • If manual then the newer 15g from the 850 and a kg2t cam or ipd turbo cam will wake it up very nicely
    Run at 12psi if running the stock IC
  • Vee_QueVee_Que (@Vee_Que) South Eastern suburbs Melbourne.
    If it's the car I think it is, it has a rebuilt 16t fitted. Leave it as it's better than anything else you have mentioned.
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