alternate fuels

[dieselsmoke]

Hello

I was just curious, were there ever cases where EMD engines were converted to use alternate fuels, such as heavy fuel oils, and similar (anything other than diesel).

thanks

[Allen Hazen]

Very verry vaguely I recall (so this is going to be useful only in jogging someone else's memory) that some railroad-- Union Pacifc? -- in the 1950s experimented with two fuel tanks: a tank of diesel for starting the engine with, and then a tank of some heavier oil to run it on once it was hot. On, maybe, something like a GP-9.
Burlington Northern, in the 1970s or 1980s, experimented with gas: maybe propane? maybe LNG? My recollection was that two units-- SD40-2 or similar-- were modified to take this fuel, and ran for a while with a tank-car as a gas tender coupled between them.

[dieselsmoke]

I've read a bit about this since I posted the question, and found two cases. UP and SP. UP had their GP9's converted to Bunker C, and I think they ordered some GP24's to burn that oil from factory.

SP also converted some GP9's to Bunker C, or was it "oil number 5", don't recall.


Anyway, I was just wondering, I assume one of the modifications would involve increasing compression. Would that make the engine louder in theory?

[FarmallBob]

Anyway, I was just wondering, I assume one of the modifications would involve increasing compression. Would that make the engine louder in theory?

Depending on the cetane rating of the fuel, if compression ratio were changed at all it would most likely be REDUCED slightly.

But somewhat counterintuitively reducing the CR on a diesel engine - while reducing internal engine racket - CAN make the exhaust note a bit louder. (Lower comp ratio = lower expansion ratio = higher residual pressure at the end of the power stroke = more noise when the exhaust valve begins to open.....in theory anyway...).

More signficant engine modifications to successfully burn bunker oil would include provisions for preheating the fuel; injector mods (higher injection pressures, spray pattern changes, timing/rate of injection changes); possibly modifications to the combustion chamber shape; "dual fuel" plumbing mod's so the engine can be cold started on regular diesel, etc.

[dieselsmoke]

You are right, I forgot the fact that compression ratio is altered by changing "initial" pressure in the cylinder.
If the pressure of fully "opened" cylinder is higher (and exhaust pressure with that too) then the compression ratio is actually lower, not higher

So, you are right, the exhaust would be even louder than it is, and the engine beats from the block would be even quieter

thanks for clearing that out