Powerhouse

iTrader: (4)

Why don't diesels use superchargers? That way they would have boost at all times?

zippy

The power loss is the reason. In order to run a supercharger at 20psi+ boost levels at 3500rpm and lower you'd have to overdrive it heavily and the parasitic drag would be outstanding compared to running a turbo. Detroit Diesel many years ago ran both a turbo and a supercharger on the same engine

TchargedLS1TA

iTrader: (9)

The main reason is Superchargers arent as efficient as turbos.. You would need to overdrive the hell out of a supercharger to make it as efficient as a turbo. Like Zippy said, Detroit Diesel ran superchargers on all there "V" series engines, most of them still using turbo's in conjunction..
Piers Diesel experimented with a supercharger on a Cummins. It was so overdriven, that it was making 5 psi of boost at idle, and 40 psi at 3000rpms, which eventually led to its demise due to the head unit not being able to support that amount of boost..

nightrunner

iTrader: (4)

a diesel puts out so much more exhaust gas volume than a gas engine it only makes sense to make use of that volume by slapping on a turbo and turbos produce more boost more easily

Powerhouse

iTrader: (4)

Ahh, I see. Well that makes sense. Thanks for the replys

1badsilverado

iTrader: (3)

I still work on those old Detroit's at my work. We rebuild 3-53,4-53, 4-71,4-71ti,6-71,6v-53,6v-71, and 6v-92. They all have roots style superchargers but the 6v-53, 6v-92, and the 4-71ti are turbocharged also.