Detroit also offered this on some of their engines. My bus's 6V92TAC has a bypass scavenge blower, so some of the turbo's output will bypass the blower's lobes at higher RPMs.

@@icenijohn2 Yes they sure did, 92 series in high output spec had it. Old Detroits were amazing engines, the factory performance options would easily double the power output of a standard Natural engine. Just keep bolting on bigger injectors, charge air inter and after coolers, fuel coolers, high speed blower drives, bigger turbos. The most efficient engine ever developed for turning diesel fuel into noise.

Funny enough the whole reason I just watched this was because I had the question of valve timing. This makes a lot of sense.

True - an advantage of using cam-driven valves in a 2-stroke (instead of the simpler piston-controlled port) is the ability to offset the exhaust timing from the intake timing, without resorting to opposed pistons running out of phase. Another advantage of handling one side (normally exhaust) with valves is that it provides uniflow scavenging... again without resorting to opposed pistons.

No, they were all externally scavenged (not supercharged) with a mechanical blowrer, and some were also turbocharged.

You only have to compare the Deltic with the Class 37 locomotive (Both built by English Electric) Class 37 1750hp, V12, 4-stroke, 850rpm Class 55, 3300hp, Two 18 cylinder Napier Deltic engines, 1500rpm Both weigh about the same Another interesting point, on fast patrol boats, Deltics replaced RR Merlin engines

@@g8ymw IIRC the Deltic and related opposed-piston multi-banks were developed for motor torpedo boats and other light craft, being thin-skinned the difference in fire risk between German-manufactured E boats using diesel powerplants and petrol powerplants used by British equivalents was significant, ironically the Deltic was developed from Junkers Jumo 204 licensed produced by Napier as the Culverin. What I didn't previously know was that Napier continued their R&D into stupendously powerful turbo-compounds after the Nomad was dropped and mated a Deltic to an axial compressor and gas turbine as a gas generator to produce some ridiculous >5000bhp figure before failing, though it didn't have the fearsome gnashing gearbox linking the gas turbine to the piston pack.

They started with stationary engines, and made engines for much more than locomotives... but yes, they were known for their opposed-piston diesels.

They had/have a pretty unique turbo that was driven by the crankshaft at low RPMs, but when the flow of the engine was sufficient, the exhaust takes over and runs it like a normal turbo rather than a supercharger or procharger as they are known. They have what's called an overrunning clutch made into them to decouple from the crankshaft at the required RPMs and exhaust flow. Hope that helps.

@@robertschemonia5617 Thank you, and I already heard about that but I forgot so thanks anyway.

At low rpm the turbo wouldn't spin fast enough to supply air to the cylinder and it would choke itself out.

Yes, electrically powering a turbocharger as a blower would work, if the speed were controlled appropriately, and if you were willing and able to continue to power it until a high enough engine speed and load is reached... not just for starting.

This is how is done in reality. The electric powered blower (or scavenge pump) operates at start-up and when manoeuvring in port to supplement the turbocharger. At full away on passage, the electric blower is stopped.

True

But cushioned at the top of stroke every time.

@@partymanauright, it’s why I write « mean speed ».

Solidworks

It is the same... and Detroit Diesel was far from the only company to use that design.

The cylinder in the 2-stroke diesel pulls almost no vacuum, so the air needs to be pumped in. On the conventional 2-stroke petrol engine, the sealed crankcase is used as the “pump” to draw the charge from the intake and then push it into the cylinder.

@@Clyde-2055 I see, thank you for the explanation. The intake port is too low for effective suction to occur on the downstroke (after the piston passes by the port and uncovers it) and if the port is moved upwards any valve we could put there will be influenced by the hot gases during the power stroke. Guess there is no free lunch after all.

This sunday will be uploaded.

Look at some of the designs used by Japanese on their big stroker bike engines before the Greenies killed em off. Angled ports, windows in piston skirts, oil recirculation. A whole bunch of tricks forgotten over the years.

Need? No. Is it beneficial? Yes Port timing is the same on opening and closing, but a cam-controlled valve can have any timing desired. Uniflow scavenging is certainly better than loop scavenging.

Back in the 60's, 70's and 80's every second truck was running General Motors 2 stroke engines. Known as Jimmys, or bird scarers. The most efficient engine ever developed for turning diesel fuel into noise.

Good point, 2-stroke Diesel engines aren't very common nowadays so of course no one can entirely understand it.

The lower item shown from 4:38 to 4:54 is a cross head, not a piston, and it is explained in the video narration.

​@@fexploder3281they're still common... just not in trucks.

@@brianb-p6586True, they are still used in large ships and some locomotives today.

The diesel engine shown in this model has, like every other diesel, a fuel injector... not a spark plug.

Google automatic translate.

Timing and uniflow scavenge

So they can fit in a regular truck chassis

?>@@markfairhall3671

@@markfairhall3671 But what does that have to do with anything in this case?

This allows for "uniflow scavenging (which is mentioned in the video) which is more efficient that "loop scavenging".

@@carstennobody7047 Yep, OLD high powered engines have INSANE maintenance schedules.

That would be the Scuderi cycle engine.

Yes,@@sockmonkey6666, but there are other designs as well, using piston-controlled ports instead of vavles.

When the compressor spins faster, it pushes more air, but the engine also consumes more air at higher rpm.

Positive displacement pumps, not centrifugal.

To use a positive displacement blower at full power it would need to be huge. A smaller blower is used at start-up and low RPM and a turbocharger at full power. Turbos are better for high flow rates.

When large ships are stopped in port the big propulsion engines are off. These engines are directly coupled to the propeller so when the ship is stopped so is the engine. These ship frequently plug in for electrical power so generator emissions are greatly reduced.

@@jamesmurney1374 they are also required to switch fuels and burn bunker fuel while out in the ocean and burn cleaner low sulfur diesel closer to shore.

A lot of ports will have steam and power provisions for vessels, it's usually preferable because sitting around in port with the engines running builds maintenance and lifetime hours on the machinery, the Russian carrier/carrier-cruiser Admiral Kuznetsov often didn't have sufficient steam or electrical umbilical provisions available to power the vessel so the engines racked up tens of thousands of hours and it shows- the powerplant and a lot of other machinery is sometimes thousands of hours beyond it's useful working lifespan and it never leaves port without a fleet of tugs in case it inevitably suffers a breakdown, and given that it is exclusively mazut/bunker oil fuelled and the poor powerplant tuning it tends to identify it's presence by belching great gouts of sooty particulates On the side, there was a paper released recently that described the effects of the disappearance of so-called ship trails, the clouds left behind vessels fuelled with high sulphur bunker oils as a result of the sulphur aerosols (in the form of sulphur dioxide and sulphuric acid produced when the former interacts with water) seeding clouds, legislation made in 2020 or 2021 changed the regulations on the limits of sulphur content in bunker oils and the net result of this was significant reductions in those trails of seeded clouds, and a proportional increase in the amount of sunlight and thus warming of the atlantic and other areas with particularly dense shipping lanes which would otherwise be scattered out into space again, as measured by arrays of satellite images and oceanographic sensor data. The concept of deliberately deploying sulphur aerosols from aircraft to produce reflective clouds or relax sulphur content limitations on commercial aviation fuels to produce thicker condensation trails has been tossed around as a method of geoengineering

That's the split-single engine... a horrible and antiquated design.

which part?

@@repairman22 two stroke diesels burn oil when new

Sure!!!! If you want to live in a lie do it. Nobody stops you.

the blower is running ok. check it.

@@repairman22 It's pulling the air OUT of the cylinder. I work on screw blowers. This one is running backwards.

as I said... Google it. Look for more videos in youtube if you don't trust me. Share me a video if you find one... thank you.

​@@TheOwlGuy777This isn't a screw type, it's a roots and the air travels around the outside of the blower lobes.

No. its correct.

Saying that something is wrong without saying what means that the video is perfectly correct. Thank you.

There is much, much more to it than that

Well actually it does let out more particles that would hurt air quality in a more concrete way than regular diesels, and logistically speaking it would require more oil to be sold which could also potentially increase emissions indirectly. 2-strokes also have a distinct powerband that doesn't fit all use cases.

Right. “Green” technologies don’t reveal anything “dirty” looking to the end user, so suckers can “feel” that electric, etc. is clean.

In short: Yes _and_ no. It is more environmentally friendly in the sense it uses less fuel for the same energy outtake due to better efficiency. But in the sense of particulates, NOx etc. it is worse, but it is ideal for marine operation where the need for additional washing of the exhaust is less necessary.

Not necessairly because the thing is although 2-stroke engines can be improved in terms of things like emissions and efficiency, nobody wants to let the 2-stroke engine take over since the 4-stroke engine had many years of development and the 2-stroke never had time to be trusted due to being killed by things such as emissions and efficiency as I said.