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[QUOTE=85e150six4mtod]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.
Wwwaaaaaaayyyyyyy back in time, they were called Grey Marine Diesel Engines. Then I beleive that around WW2, they were sold/given to General Motors for increased war production, but don't hold me to that fact!
But go back to my earlier post with the history of GM Diesel link. No mention of Grey Marine.
As for them running away and running backwards, I've heard guys talk about that also.
One other point: The model airplane engines are not diesel. The are fueled by a nitro-methane, methanol & castor oil mix. They use a glow plug for ignition. At 20,000 rpm the glow plug stays hot enough to light off the charge without power. Some larger engines have spark plug ignition.
the diesel rc engine run on a mix of ether and oil, and does not have a glo-plug
all diesel engines will run backwards,i have had it happen to me with cat, cummins, duetz, detroit 2 stroke, mercedes, and mack engines. but the detroit 2 stroke did it the most.
If you let the clutch out too fast and choke down a 2 cycle Detroit, especially if taking off uphill, it will definitely run backwards. I had this happen a couple times with a 318 I owned back in the seventies.
At one time I owned a 6V92TTA in a single axle and averaged over 6mpg. The 318 usually averaged 4.25-4.5 mpg. My worst was a 350 Cummins that got 3.7 mpg. Didn't keep it long.
I have either owned or driven most 2 cycle Detroits. If you can stand the noise, and keep oil in them, they were not bad engines. I got 700 miles to the gallon in the 318.
The 60 series Detroits are light years ahead in power, fuel mileage, and durability. I have owned a couple of them and averaged between 6.75-7.25 mpg, depending upon idle time. I also got 10,000 miles per gallon of oil.
But, there is nothing like the sound of a 318 with 4 inch pipes and gutted mufflers turning between 2100-2500 rpm. It's a sound that is sweet to hear. You might be going slow, but it sounds like you're flying.
My last boat had a pair of 8V-71 Detroits in it. Leaky, smoky, stinky and noisy, but you just couldn't kill the silly things. They would run in the worst conditions and never miss a beat. Not the best as far as efficiency goes, but the power to weight ratio can't be beaten.
I have seen a detroit come apart, it's not fun. This thing wound up way higher than I ever thought a diesel could run, it didn't have a damper, so they broke the fuel line on it, but it started drawing oil up through the rings, kept running away and came apart at what sounded like 8k. Big chunks of cast iron all around, pieces embedded in the cement under the engine.
I work on GM EMD 567(cid per cyl), 645 12cyl(locomotives use 20cly) and some cleveland diesel 278, 278A, 498.
we use the 2 strokes because of reliabilty. some of our tug boats have sunk and we bring them back up, change oil and inspect power packs and bearings and they are good to go for another 30,000hrs. The old Cleveland diesel have been around since the 1930s. most of the 278s we have were surplus ww2 sub motors.
They puke oil and pump it by the rings because the crankcase is pressurized by the supercharger.
OK now I'm confused. I understand the operation of a chainsaw 2 stroke and the need for an oil/fuel mix. I thougth these detroit diesels had an oil sump and the intake air was supercharged directly into the combustion chamber, not into the crankcase. Anyone know of a cut-away diagram for these things?
ALL two strokes have the fuel/air mix go through the crankcase first. That is why you mix oil with the gas. The oil sump your talking about is probably the "injector" pump- making it an oil injected two stroke. Oil in one tank, gas in another, injector mixes the oil with the gas as it goes into the crankcase. It lubes the bottom end, then its pumped up to the top and burned. check out this website: http://www.keveney.com/twostroke.html. Its got animations of almost any engine ever made. pretty cool stuff.....
on re-reading your post- i guess its possible to supercharge just the top end, but i dont see how that would work- the gas/oil in the crank case wouldnt flow into the cylinders if they were at a higher pressure, unless they compressed it after it was already in there? okay. i've confussed myself enough for one day. i'll go with what he said. anyone got a cutaway?
Last edited by dorkpunch; Sep 14, 2005 at 12:50 PM.