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Does anyone know the exhaust housing volume for the 150 HP Cummins 4BT. I have checked for air pressure leaks on the intake side and found none. I'm only making about 5 psi of boost at 2000-2100 RPM. I would like to get 10 PSI of boost at the same RPM.

The reason for the needed boost is that when loaded heavy I'm getting a lot of black soot out of the exhaust for both motors.

I want to play with the compressor and exhaust turbine sizes.

Hey Troy,
I don't have an answer for you but good to see you in the sandbox.
I would have to wonder, if your engines are not aftercooled is it possible to run more boost with out exceeding the maximum air intake temperature?
I would also wonder if there is some sort of trade off with spool speed verse maximum volume and the fuel needed to support it. I think the manufacturers of the turbos use compressor wheel efficiency charts based on displacement etc. It's almost like voodoo to me. When I added a turbo to the car they asked for specific engine specs and fuel supply. They wanted to know how much power I wanted to produce and some other variables. They sent a turbo and it did exactly what I wanted it to.

On a side note: Do you still have contact with the guy we got the generators from? I might be in the market for another one if I have to sell it with my house.
Tell D we said hello.
Kevin

You might want to check with seaboard marine SBMAR.COM Tony Athens he is very knowledgeable on All Cummins he might be able to help you.

Troy

Will they still hit the right RPM numbers wide open when fully loaded? How about when you run a normal load? Just wondering if it a propping issue.

Send Bruce a PM, he should be able to help out on this one.

I'm guessing yours are the 150 HP versions?
Adding boost to a marine diesel engine with no other mods is scary. When dealing with a heavy loaded engine, it can be very complex to avoid destruction, exhaust side AR and wheel size.. compressor side AR and wheel size, etc, etc. Turbo experimentation is typically no big deal on vehicles because they are rarely under a load. A marine engine is under a constant load. You can burn holes in a set of pistons in a hurry with too much hot air, on an engine under a load.

The comment about the after cooler (or lack of) is spot on. I have heard it put this way... "you can't add too much air to a diesel engine, but you can add too much hot air". An after-cooler may be a better investment than a bigger turbo, the HP gains can be significant. Cold air is your friend, hot air kills. There is no risk in adding a raw water after cooler, only HP gains from cooling the charge air. With a colder charge, you may be able to go up a bit on the injector size.

If you don't already have EGT gauges (exhaust gas temp) install them first. You may be over loaded now, and on the ragged edge and not know it. Only an EGT gauge can tell you what's going on in those holes.

My $.02

Scott

For that size engine I would go with a fresh water after cooler if it is available. That is what is on my 270 Cummins. Less to maintain and worry about. Also, maybe add a fuel cooler if there is not one now. That will also give you a couple of extra ponies.