300TDi turbine exhaust housing size Q

Stolen from another forum, quicker than me typing:

It's a ratio of area/radius. The area is a cross-section measurement of a spot in the "snail" of the compressor/turbine housing, the radius is the distance from the center of that cross-section to the center of the turbine shaft.

Smaller a/r's mean higher velocity and more restriction on either the turbine or compressor side. In general though a higher number on the compressor side is sought. The ratios are not comparable between series of turbos, a .80 t3 compressor housing has the same ratio as a t4 .80, but is nowhere near the same physical size.

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Originally Posted by Dougal

I think Bush65 has a GT2256V (brazillian) on one. Functionally it seems the same spec as the GT2256V I have here from a 2.7l mercedes diesel. But the mercedes housings and flanges are different.

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Here is a pic showing the A/R for the turbine housing.

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Originally Posted by up2nogood

Given the higher compression of the diesel, I wonder if there is any greater exhaust pulse being pushed through the exhaust housing than would be the case on a 2.2 petrol?

If there is, then that might compensate for the fact that the turbo only really provided boost from 3000rpm and up on the petrol.

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It's the temperature that has the biggest effect. Since diesels run cooler they normally need a smaller A/R exhaust housing to drive the same size compressor on a petrol engine.

In a nutshell, a smaller A/R exhaust housing will make the turbo start working earlier in the rev range but will sacrifice some top end power. Bigger A/R housings sacrifice low rpm function for more top end power.
The others defined it well too.

Alrighty then, if the MB Garrett has an exhaust housing AR of .64, then I'm going to be fine with my one.

The internals are just T25, so the right 'size' for this engine, the inlet AR is the same so that was the last piece of the puzzle.

There should be absolutely no need to run a wastegate on these? I have not looked at the sprinter/Brazilian turbo set ups. I know the factory fitted VNT 25 (mine) was restricted in boost by the controller and the restrictive standard exhaust system.

The controller on the VNT25 is fully extended at 10PSI. So I might need to graft a controller off the 300TDi one or a MB Sprinter.

What do you guys think?

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Originally Posted by up2nogood

What do you guys think?

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I think you should hurry up.:D

Ha!
The amount of things I've done to this car has taken the last year and a bit, I imaging building the manifold part time will take me a couple of months (wife seems to want me to paint some things and knock down some walls) and I'm just in the middle of rebuilding my heads for the 4.6 conversion into the Disco. Still have to fit auto conversion and rebuild t-case and fit all LPG gear after tossing all EFI off it. Just to make sure I didn't change my mind, I cut the wiring loom off!!

So the diesel Bushy will be getting done a little bit here and there. The only thing I'm sure of is that it's going to Cape York next year, camper in tow.

Quote:

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Originally Posted by up2nogood

Alrighty then, if the MB Garrett has an exhaust housing AR of .64, then I'm going to be fine with my one.

The internals are just T25, so the right 'size' for this engine, the inlet AR is the same so that was the last piece of the puzzle.

There should be absolutely no need to run a wastegate on these? I have not looked at the sprinter/Brazilian turbo set ups. I know the factory fitted VNT 25 (mine) was restricted in boost by the controller and the restrictive standard exhaust system.

The controller on the VNT25 is fully extended at 10PSI. So I might need to graft a controller off the 300TDi one or a MB Sprinter.

What do you guys think?

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This pic shows the A/R of the compressor. Also shows the boost pressure operated actuator for the variable nozzle vanes.

No wastegate required.

Thanks John! Compressor housing is a wee bit larger. But then the TGV is 300cc bigger too.

So off to make a manifold........

OK, you have me intrigued, what's the model # of the MB Sprinter one ?? :D