Re: A Dumb Question

Dw: I saw a similar thing happen when i was younger. A gentleman had a "smoke-blower" turbocharger added to an old Cummins 220HP (743 cid) motor. He idled out to the gate, then 'romped' on it...you could hear the turbo start to scream, then silence followed by tons of smoke from the exhaust. Brought back into the shop, and pulled off the exhaust side of the turbocharger. When the turbo failed, it was spinning so fast and stopped almost instantly when it failed,(spinning somewhere around 12,000 rpm!) it spun the nut off the exhaust impeller(torqued on at like 1250 ft lbs), and it was laying there in the housing. This was a old style water cooled T-590 turbo, had a huge exhaust side,basically acted as a scavenging blower, no real hp advantage other than to clear up smoke issues on the older model Cummins engines. To Phil's point on the GE's with the Cat's, the turbo's added later after the removal of the Roots blower act in a similar manner, they just help push air thru the engine with out any real HP gain.However, with Roots (any "diesel" equipped with one) has to be de-rated for higher altitude, as the Roots blower only adds air to the system to "flush" it, so as you gain altitude, and loose air density, you get more black smoke.Turbo's can compensate for altitude as stated earlier, as they spin free, determined by how much exhaust volume is created. And Turbo-compound is the word i was searching for in my earlier post...thanks! Lastly, wastegates serve two purposes, one to control exhaust flow to the impeller driving the turbo, and secondly to control the total amount of air provided to the engine for combustion purposes. To much air can cause overheating of the cylinders, as air becomes heated as it is compressed, causing cylinder wall oil to be burned off. Carbonized rings anyone?
Thanks to all for letting me share...