Turbo vs. Non Turbo Diesel


LawnSite Silver Member
We currently have a turbo diesel (cummins 6 cyl) and a non turbo (7.3 liter) and are wondering what the real differences is between the two are. I know everyones going to say the turbos gonna have more power....but that i already know. Thanks Tom

Gravel Rat

LawnSite Fanatic
British Columbia
The first thing the Cummins is a I-6 the 7.3 IDI is a V-8 the Cummins is direct injection (mechanical or Electronic) the 7.3 is In direct injection which means the fuel injector sprays in a precup and the atomized fuel flows out of the precup. The 7.3 IDI has higher compression because it is turboless the IDI is natural aspiration like a gasser. It can only burn so much fuel to how much air it can suck in just from vacuum.

The Cummins has a turbo it also has lower compression so when the turbo spools up there is room for the compressed air to go. With a turbo you can add more fuel because you are adding more air (oxygen).

Both engines are good the IDI is stuck with low power because it has a higher compression so you can't add much boost if you turbo it so your limited on how much fuel you can add before you melt stuff.

The Cummins on the other hand is limited to how strong you can make the head gasket to resist blow out from turbo boost.

Both engines are light medium duty engines both shouldn't be in trucks heavier than a 26,000 gvw essentially a school bus.


LawnSite Silver Member
my main question was just some of the differences..i didnt know how a turbo worked or what it even looked liked so reading that article and thatn post taught me something new