[Gramp34]

Originally Posted by Omatako

And of course, CAT 3406 are commonly found on yachts. Look long enough and you'll always find a spec sheet that will suit your argument.

Fair enough. One spec sheet isn't enough?

Every single Caterpillar marine engine with charge air cooling is aftercooled.

Every single John Deere marine engine with charge air cooling is aftercooled.

Every single Cummins marine engine with charge air cooling is aftercooled.

Maybe you could let us know how many of their engines are intercooled and don't use that "quite rare" aftercooling?

Your earlier view said "Turbocharging works off the heat in the exhaust". Clearly you have been doing some more reading and now you're saying pretty much what I did. Well done, you're heading in the right direction.

I'm still saying turbocharging works off the heat in the exhaust. The heat is the source of power that drives the compressor. You, on the other hand, said "It has nothing to do with heat." when describing how a turbocharger works. I'm afraid I'm saying nothing like what you did.

No, not really. But the engine is probably developing 1400hp from an original design output of 180. And it is running at max power, full throttle for 100% of the time. Nobody worries too much about the power it takes to turn the supercharger. Oh no, sorry, you do.

Funny, you're no longer insisting a supercharged engine is more efficient.

No I'm not trolling, I try to give info in my posts that I know something about and stay away from those posts I know nothing about. You should consider that as an option.

Uh-huh.

But, back to the original problem.

Capnblu: If you can match up the supercharger to the original application, compare the displacement of your engine to the engine the unit came from, and the pulley drive ratio.

The boost on an automotive gas engine will be fairly mild, and would probably make a good starting point for boost on your Perkins diesel.

If the original engine displacement was more than the Perkins, you'll need to drive the supercharger more slowly, and in proportion to the difference in displacment, and vice-versa.

This is assuming you've got a Roots blower type supercharger (with lobed rotors). Their output will be proportional to speed, so double speed gives double the airflow.

If you've got a centrifugal blower, like the Paxton, its output increases with the square of the speed. Doubling the speed quadruples the airflow. You'd have to run it so it doesn't overboost the engine at high speed, but then it won't provide much boost at low speed. The Merlin engines used in Mustangs and Spitfires in WWII had two speed centrifugal superchargers, but that's probably overkill.

Have fun,

Tim