i dunno if this is a stupid question, but

how come there never is any supercharged diesels, vs. turbocharged? is it something to do with exhaust backpressure?

 

2-Stroke detroit diesels had them. Thats where all the current roots blower desinations came from, ie. 6-71 - 6 cly at 71 cid per cly, 8-71, 12-71

 

Diesels don't lose power from exhaust pressure nearly as much as gassers do, we just run hot. A supercharger sucks a lot (30 to 2000 if you run a top fuel motor) of horsepower, so they are not as efficient as a turbo. There is a twin turbo, centrifugal supercharged 12v Ranger in diesel power this month, take a look at the website, its the craziest plumbing I've ever seen.

 

The only reason a Detroit uses a blower is because its a 2 stroke and through design will not run without one. The main advantage with a turbo is...free power. When you burn a gallon of fuel, you only use about a 1/3 of the energy within that gallon, the rest of the energy goes out the exhust and is transfered into the cooling system. The turbocharger converts some of that lost energy to boost. The only real downside to a turbo is that is acts like a cork until the unit "spools up" so you get some lag. A blower will give you GREAT response, but it will cost power to make less power than a turbo can make for free. Now using a small blower to light up a huge turbo