Turbocharging vs. Supercharging

[Anonymous]

Boy you all stole my glory. Being an ex-machinist I couldn't have said it better myself.

[Anonymous]

Bronco, the BNSF has been down grading some of their SD40s to SD38s. What they are doing is removing the turbo and putting a roots on. Then the locomotive is used mostly in the yard. There is no advantage to having a turbo on a yard engine. It always appeared to me yard work tended clog up the turbo and increase maintenance.

EMDs SD 90s has the new H Block diesel it is a 4 stroke engine and has two true turbos. No gear drive at low RPMs.

[Anonymous]

Non-turbocharged EMD diesel engines use two Roots-type blowers, gear driven off the crankshaft (only one is provided for the the 6-cylinder engine). The blower is necessary to scavenge exhaust gases from the cylinder: it supplies a large volume of air at a low pressure, about 4 psi. It's not enough pressure to provide a horsepower increase, and these are considered normally-aspirated engines, not supercharged in the sense you would find on a automobile.

If an EMD engine is turbocharged, it has no Roots blowers. The turbocharger supplies air at about 15-18 psi, increasing horsepower by 50% in the same displacement. The turbocharger is gear driven at low rpms; once exhaust flow builds to sufficient volume a clutch disengages the gear train and the turbo is freewheeling.

Alco and GE turbochargers run in the 18-26 psi range, as far as I know.

[wabash1]

super charge a sd70? OH YEA i can see it now. 75 cars of grain Im leaving a siding go to notch 8 ...200mph in 5.3secs conductor loses mirror ( again) railroading at its finest.

same thing only a ge engine put it in the 8th notch fire comes out of the stack 3miles down the road and 5mph. somethings never change

[broncoman]

Question, I work with baby GM diesels (6V-92 & 8V-92s), in the forums I notice people saying that turbos are removed and roots chargers are put on instead, my question is do the bigger GM 2 strokes not need the roots charger when they have a turbo. I thought that they had to have the roots charger even if they have a turbo, it just blows through.

Thanks for the info.