2-strokes

[9007pinza]

Spotting days in my youth, living just north of Darlington near the ECML, many a nite the Deltic howl could be heard, either powering down to stop at Darlo, or full power scream leaving darlo heading north. Fond memories of those long gone days, when deltics were ` boring`.
My work also got me invloved with other 2-strokes, Foden & Commer & Detroit GM`s, which again all had that distinctive scream or howl.
I know that most where triangulated opposed piston, or flat opposed piston, but the GM,s are a conventional V or inline design.
Correct me if i`m wrong but am i rite in understanding that most `recent` locos mainly from USA, are a 2-stroke design?
It that is the case, where has the howl or scream gone?
perhaps modern design & technology?, and better muffling.?,, any ideas?

 

[Warbonnet]

The howl is still there, its just that it is now fitted with a silencer.
EMD's in America sound pretty hellfire, you just need to know where to look.
Here's a few to get started:
The first one, its the helpers on the rear you need to hear. Those are SD40-2's and are powered by the same engine that resides in our Class 59's but without a silencer.
http://www.youtube.com/watch?v=VPA-SrEFWvw&list=FLMKlE9XhHaMu9-1K0lOp2zA&index=95
Next up is the legendary "Tunnel Motor" of the Southern Pacific. Some of these had a V20 un silenced EMD motor.
http://www.youtube.com/watch?v=I3ubRfejpJ4&list=FLMKlE9XhHaMu9-1K0lOp2zA&index=23
Some more old SP power working hard-
http://www.youtube.com/watch?v=GQJVgY9yprg&list=FLMKlE9XhHaMu9-1K0lOp2zA&index=33
Ofcourse, all these are EMD 2 stroke.

 

[themiller]

The scream you hear from some diesel engines is a function of the engine speed. The deltic engines were a railway version of the engine installed in minesweepers and was very high speed whereas the engines in the likes of class 66s are medium or low speed engines and so have a lower pitch.

 

[DownSouth]

That is not correct, an unsilenced EMD 645 or 710 engine will put a Deltic to shame despite running at only 900 rpm.

 

[fowler9]

I would have thought the scream was from the turbo? Apologies if I am totally wrong.

 

[dubscottie]

There used to be a video on youtube (may still be there but could find it) of an Irish 201 running without its silencer.

Sounded like a 071.

A bit like this but at full whack with 9 Mk3's in tow..

http://www.youtube.com/watch?v=9gjV7WpoyLs

 

[Teaboy1]

2-stroke diesels now a bit thin on ground due to emissions I believe. Exception is the likes of a Detroit deisel as fitted to large earth movers, these are super-charged 2-T engines where high output is needed in a small space....... like those early minesweepers etc. Advantage is that every downward stroke of piston is producing power but at full chat they tend to emit some un-burnt fuel so not super efficient. Good sound .... but not at 3am!!

 

[jopsuk]

2-stroke diesels now a bit thin on ground due to emissions I believe.

big two stroke diesels suffer far less from emissions problems than little petrol ones. Diesel ones are generally fuel injected, avoiding fresh fuel/air mix going out the exhaust and also avoiding having the fuel coming through the crankcase- this avoids needing to have two stroke lubrication oil mixed into the fuel (they're lubricated as for four strokes).

 

[Warbonnet]

That is not correct, an unsilenced EMD 645 or 710 engine will put a Deltic to shame despite running at only 900 rpm.

I agree.
Many times ive heard the un silenced 645 or 710 emit a lot more of that certain pitch racket you only get from a 2 stroke diesel. The old roots blown
'567's are also worthy of the title.

 

[themiller]

That is not correct, an unsilenced EMD 645 or 710 engine will put a Deltic to shame despite running at only 900 rpm.

Sorry, got carried away with memories of a minesweeper engine room with a pair of Deltic engines screaming away compared to a pair of Paxman Ventura diesel alternators. In railway traction terms, I agree that the sound of the turbo-charger can be extremely loud and the pitch of the sound is a function of the speed of the turbo which in turn is determined by the volume of exhaust gas from the engine. Inevitably, an unsilenced engine will be louder than a silenced one so comparisons should be like with like.

 

[Peter Sarf]

Right. I must must know. Does anyone know what an unsilenced Deltic sounds like then ?.

How about a Western btw.

 

[TDK]

All class 66, 67, 68 and re engine class 57's have 2 stroke diesel engines in them, all of them tick over (without ETH) at about 250rpm and at full welt run at about 910 rpm.

 

[Warbonnet]

Right. I must must know. Does anyone know what an unsilenced Deltic sounds like then ?.

How about a Western btw.

The closest you'll get to that is the Baby Deltic engine they've been messing with at Barrow Hill last couple of years. Its a smaller version of the 'big' Deltic engine. The guys there are actually 're creating' a Baby Deltic from a 37's body shell.
There are plenty of clips on YT of it in unsilenced form, sounds abit like a V12 Detroit.
http://www.thebabydelticproject.co.uk/#