2 Stroke Diesels?
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Senior User
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2 Stroke Diesels?
I have read alittle about them and they seem to be the way to go, yet there seems to be none of them left. Why are they not used in 1 ton trucks? What are there power curves like? Just doesn't make since that they are not used since they have twice the power strokes than a 4 stroke motor.
Posting Guru
Joined: Sep 2004
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From: Sapulpa OK
General Motors has used this engine since about 1940. It is a powerful package in the supercharged form. Main drawbacks are very noisy, Leaks oil and poor fuel economy. Thousands were made for WW2. Mostly to power boats.
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They are called "Detroit Diesels".
Originally, it was General Motors Diesels, or "Jimmy Diesels". Then it became Detroit, then Penske bought it, then Daimler Chrysler bought it.
They now sell 4 stokes because 2 strokes are too dirty, at least the way the old Detroits were made.
By the time you design a 2 stroke to be clean enough, you're into 4 stroke territory parts wise, so I'm not sure you're going to see any 2 strokes in small truck sizes.
Some work has been done to clean up 2 stroke gas motors, but current catalyst technology doesn't work with them.
google "two stroke diesel" for more info, including the largest engine in the world.
For more info on Detroit:
http://www.detroitdiesel.com/Corpora...tory/index.asp
Originally, it was General Motors Diesels, or "Jimmy Diesels". Then it became Detroit, then Penske bought it, then Daimler Chrysler bought it.
They now sell 4 stokes because 2 strokes are too dirty, at least the way the old Detroits were made.
By the time you design a 2 stroke to be clean enough, you're into 4 stroke territory parts wise, so I'm not sure you're going to see any 2 strokes in small truck sizes.
Some work has been done to clean up 2 stroke gas motors, but current catalyst technology doesn't work with them.
google "two stroke diesel" for more info, including the largest engine in the world.
For more info on Detroit:
http://www.detroitdiesel.com/Corpora...tory/index.asp
Postmaster
Joined: Feb 2003
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In general, 2 strokes don't make as much torque as 4 strokes do. Also they tend to rev faster (no valvetrain to limit them). So they end up making their power by reving higher and being geared to run in that rpm range.
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Joined: Jan 2005
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From: Lynchburg Virginia.
Worked on many Detroit Diesels over the years and I never noticed them to be "dirty" emission wise when they were properly maintained. It was however, very hard to control oil leaks due to the crankcase being open to the "air Box". If you stayed with the proper injectors and kept the rails and governor properly adjusted they were very dependable and gave relatively good fuel milage. As with any engine where it is subjected to the average truck driver with an IQ on the negative side it will give trouble due to the "driver" adjustments and modifications.
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Posting Guru
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From: N. Mississippi
All the EMD diesel locomotives are two stroke also. But nothing beats the sound of a GE locomotive with their four stroke diesel under load.
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From: Marengo, Iowa
Originally Posted by oldmaninva
Worked on many Detroit Diesels over the years and I never noticed them to be "dirty" emission wise when they were properly maintained. It was however, very hard to control oil leaks due to the crankcase being open to the "air Box". If you stayed with the proper injectors and kept the rails and governor properly adjusted they were very dependable and gave relatively good fuel milage. As with any engine where it is subjected to the average truck driver with an IQ on the negative side it will give trouble due to the "driver" adjustments and modifications.
Many of the mountain runner truckers loved the 2 stroke for climbing ability, they would just keep on screaming up the hill, and that is the sound, screaming... They were a fgood motor, but had to stay on top of them to keep them in shape. If they could get the turbo or charger seals leaking, they could take off on their own and eventually self destruct if allowed to. I never heard of one doing it on the road, but in tech school it could happen if there was any source of oil to feed it. If it was put together wrong or such, it had to be snuffed with a plate to stop airflow...
Fleet Owner
Joined: Aug 2001
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From: Drummonds, TN USA
Most Ground Support Equipment (GSE) in the military is powered by stuffed 2-stroke Detroits. Get into model planes and stuff, and you are likely going to have a tiny (or maybe not so tiny...) two stroke diesel to play with.
My experience in model planes is that they spit oil all over everything, which is why the covering used on models has to be fuel-proof.
My experience around the GSE divisions was that they always had plenty of stuff to work on (IE: Fix...)
My experience in model planes is that they spit oil all over everything, which is why the covering used on models has to be fuel-proof.
My experience around the GSE divisions was that they always had plenty of stuff to work on (IE: Fix...)
Tuned
Joined: May 2005
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yeah, theyre cool engines! i got one to run BACKWARDS (on accident of course....) Set the air brake and went to get out but it was still in gear. Realized it as the engine started to lug down and i stomped back on the clutch and it kept running but the tach needle was down below 0 knocking on the pin. I thought, thats weird.... put it in first again took of the brake and it went BACKWARDS! Reverse and it went forwards! i even have witnesses!! shut it of and started it again and it was fine.
Postmaster
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Just about any 2 stroke engine will do that. There are no valves to time and control direction of engine spin. The 2 stroke model engines Greywolf mentioned would do that a lot. Had to check the direction of thrust before letting them go. Also those model engines were the picture of simplicity. Only 3 moving parts-- the crank, the rod and the piston.
Tuned
Joined: May 2005
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yup.... new ski-doos have R.E.R.- reverse from the engine running backwards. My dad has an old Field Marshal tractor- single cylinder 2 stroke diesel. You start it with a blank shotgun shell. If the piston was before tdc, you had 5 gears in reverse and 1 forward! I also had a honda odyssey (the dune buggy) and got it to run backwards to.... (on accident, of course). I seem to have that problem a lot... maybe i shouldnt be a small engine mechanic. oops, to late.
p.s.- supposedly the old hit-n-miss engines will also run in reverse?!? even with the valves?
p.s.- supposedly the old hit-n-miss engines will also run in reverse?!? even with the valves?
Postmaster
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That may be on the hit-miss enignes, but aren't the intake valves on those just spring loaded and not cam driven? Then when the piston dropps with the exhause valve closed, it pulls open the intake valve. The exhast valve has to be cam driven. I could understand if that kind of setup would run backwards.
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From: Ardmore
2 stroke Detroit Diesels have exhaust valves, just no intake valves There are ports on the side of the cylinders that that are opened when the piston uncovers them at the bottom of the stroke. All of them are supercharged, the air is forced through these ports add pushes out the exhaust gasses through the exhaust valves. Any diesel engine has the ability to run away with itself if it gets a supply of oil from say a leaking turbo, this is due to the fact a diesel has no throttle plates in the intake to stop the flow of air. The detroit fuel system could stick in full throttle position and run away by itself. this is more likely to happen after service on the fuel system. To combat this most of them had an emergency shut off that consists of a flap in the intake piping that could be closed if the engine ran away.
Last edited by fplorer; Sep 9, 2005 at 01:31 PM.