A whole new world

[hal stclair]

Most of the two strokes in busses had a real hard time staying cool. Water misters were practically standard issue and they tended to coat the
radiators which reduced the cooling efficiency the more they were used. All you really need to do to make power in a two stroke is add fuel, which
adds lots of heat. Big HP busses were always fighting cooling issues. Having to pull the air through the side was never a great method to cool those
things. The four strokes were better but when they went to EGR things went backward. Prevost had to re engineer the frame in back to accommodate the
larger cooling package when EGR became mandatory. Front mounted cooling is a much easier hurdle to overcome.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1974 Eagle Bus 45',w/slideout

 

[Jim Hupy]

Horsepower is heat. Lots of heat. The 2 strokes fire for 90° of the power
stroke at least, every time the piston comes to the top. No rest like 4
strokes. Cooling is most always a problem except in boats where you have
the whole river to cool them. Just the nature of the beast, I guess.
Jim Hupy

> Most of the two strokes in busses had a real hard time staying cool. Water
> misters were practically standard issue and they tended to coat the
> radiators which reduced the cooling efficiency the more they were used.
> All you really need to do to make power in a two stroke is add fuel, which
> adds lots of heat. Big HP busses were always fighting cooling issues.
> Having to pull the air through the side was never a great method to cool
> those
> things. The four strokes were better but when they went to EGR things went
> backward. Prevost had to re engineer the frame in back to accommodate the
> larger cooling package when EGR became mandatory. Front mounted cooling is
> a much easier hurdle to overcome.
> Hal
> --
> 1977 Royale 101348,
>
> 1977 Royale 101586, Diesel powered,
>
> 1974 Eagle Bus 45',w/slideout
>
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[Matt Colie]

The cooling problem common to all 2-stroke diesels is really easy to understand whether the engine runs at 2800, 800 or 100 RPM, it is the same.
There is no slack stroke to cool the cylinder head. This is even worse in the uni-flow 2-strokes because the exhaust valve(s) are in the head and the
intake is down in the liner. So, the cylinder liners stay cool and the head(s) cook.

GM 2-strokes were a special case for lube oil consumption. Even if you stop all the leaks (not a small feat), they have to use so much lube oil to
cool the piston that it ends up running into the airbox and get sucked in with the charge air. DD spent a lot of money trying to fix this before they
introduced the Series 60. We could reduce it in an in-line package, but with the Vs there was just no hope.

This was true of all of them, 53, 71, 92 & 149. I was told that the same was true of the 567, 645 & 710 EMDs, and while did some run some of each, I
never had them in a test lab.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit