Why would a 2-stroke need valves?

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

What I got out of it was that the cylinder next to it added the atmosphere mix which causes the exhaust to be pushed out via the exhaust valve.

Because they don't use the crankcase as a mixer/supercharger like a 2stroke gas engine does.
There are slats in the bottom of the cylinder walls, when the piston is at BDC the supercharger/turbo blows the exhaust out of the exhaust valve, the valve closes and the cylinder is pressurized. Then the piston moves up an does a typical compression/ignition. When the piston goes down the exhaust valve opes and the process of blowing out the exhaust, then charging the cylinder happens again.
This is the reason that detroit diesels need a supercharger to work.

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1984 300TD -- summer daily driver
Many others that aren't Mercedes...

Chris tree'd me. He's 'zakly right. A trick question at a gathering of Diesel fans - "How many HP does a Detroit 2-stroke make without a supercharger?" The answer is "zero" - They won't run. Most Diesel fans haven't messed with a DDA (Detroit Diesel Allison, the name of the company when they were making these) and so folks haven't any experience with them. We ran one on the dyno and it made a ton of lb/ft but was, as noted, VERY high in emissions.

Another Diesel trivia question though my info is a bit dated: Last I heard, Penske owned Detroit Diesel and was making them in MI. I did a tour of their emissions facility as we looked for a correlation offset between their lab and ours though I can't remember for the life of me what we finally determined.

Dan

Daimler owns Detroit Diesel, makes a range of engines DD(displacement) for trucks, the largest I believe is the DD16.

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Gone to the dark side

- Jeff

In the 1930s the design was bought from Gray Marine.

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84 300D, 82 Volvo 244Gl Diesel

If someone has not mentioned it Detroit Diesel Engines have Exhaust Valves. Detroit Diesels also use the (The engine is uniflow-scavenged by way of exhaust valves) Uniflow type scavenging.

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84 300D, 82 Volvo 244Gl Diesel

When you get to large engines, you see many unusual combinations. Also, parts are so large that things like the crank may be constructed from multiple components. Decades ago, I designed controls for large stationary natural gas pumping engines. They ran on the natural gas from the pipeline, were 2 stroke, but had valves, plus ports in the cylinder walls. I vaguely recall the ports were for intake (after a compressor & throttle) and the valves for exhaust. Don't recall if the compressor was turbo or crank driven). Even the connecting rods were different, with one attaching to the crank and its V neighbor attaching to it above the crank. It was spark ignited, but was controlled more like a diesel by adjusting fuel flow, w/ the throttle usually wide-open. They can do this because natural gas has a much wider flammability limit than gasoline, so can still ignite when very lean.

BTW, people get confused in numbering V engine cylinders. They should be numbered front to back in the order they attach to the crank (recall Ford doesn't do so). But, in this engine the V cylinders were directly opposite each other.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans