Turbocharger doubt


Thanks for the hint, KPChief. I had to use Wikipedia to enhance my knowledge. Always open to learn…
By the way, under todays economical pressures inventions like that wouldn’t have chances,
would they ?


And, of course, there are the non turbo EMDs (hardly naturally aspirated, though) fitted with roots blowers and NO turbos. Limited to the 16 cylinder or less models.


Please provide a link to an example of such a system installed on a functioning marine diesel engine outside some inventor’s prototype shop. “Mostly” implies that such systems are routinely fitted to marine diesel generators. Please provide a citation to support that statement.

See above … If these mystical devices are fitted to generators, they are already operating at their “service speed” long before being connected to the bus, any generator that requires 30 to 60 seconds to respond to a load increase will no longer be online.

What you read on Google Patents is not necessarily what a marine engineer might find on a ship.

I think there is a great deal of smoke blowing around.


"…fixed and fitted and deliver due to more or less constant revolutions … "

“… varying revolutions thus producing various amounts of exhaust gas resulting in different turbocharger speeds …”

Turbocharger rpm is related to engine load, the statements above are so far from reality and a knowledge of turbocharger operation as to bring the source of those statements into question. The most glaring discrepancies are the statements made in the quoted post (and one other) regarding diesel generator operation.

I smell a rat … or a an internet fake here.



We used this at Wärtsilä engines in the nineties. Sorry, no pics.


We’ve got MAN 6L23/30’s on the ship I’m on now and they have this air assist to the T/C on startup. MAN calls it “jet assist”. It REALLY winds the turbo up fast on startup. Part of the emissions package to meet whatever Tier standards these engines are rated for.



Thanks to support me with your experience. I encountered this contrivance many years ago and mentioned it just out of remembrance. I did not know at that time that a mastermind will question this 20 years later otherwise I would have collected evidence. Frankly, at that time we didn’t care much about environmental behaviour and I am surprised that this jet assist still exists


The jet assist does the same thing that aux blowers do on large 2 stroke engines provide low revs boost, minimising smoke and tier II emissions


Not sure the purpose is the same. Jet assist is only used during startup and large, rapid load changes. It shouldn’t be active in any steady state condition. Aux blowers are required continuously for a 2 stroke engine to operate at low RPM/load conditions (MAN B&W’s anyway).


I agree. The only time I’ve seen this type of set up is on large 4 stroke gen sets that when large load change was encountered, a jet of compressed (not charge) air was sent to the gen set turbine wheel.

Works a treat.


Hi, you are correct re: jet assist, I realised the error last night. Re: Tier… we are at Tier II with Tier III coming I think in 2019 but stand to be corrected on that.

Re: as you say auxy blowers are used continuously at slow speed which on our MAN KSZ’s was 90RPM and below. This of course gives you a problem if at sea speed and there is a slow down (or some numpty on the bridge ‘eases back’ without informing the duty engineer), which causes the aux blowers to kick in. Our gensets were ‘matched’ to sea load minus aux blowers; the result, blackout.