I'm very ignorant when it comes to diesels, please keep this in mind. My question is, why aren't diesel engines 2 strokes? It seems that diesel fuel is more like an oil than a solvent and I've always heard 2 strokes are more efficient than 4 strokes. I'm just curious.
newbie....just curious
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Diesel engines also come in 2 stroke variety, big diesel generators usually are 2 stroke.
You musta fergot about the screamin demon detroits! 4-53, 6v71,6v92,8v71,8v92, 12v92 etc.
These were very popular engines in their day. Tighter emisions regulations and the need for better fuel economy put an end to the 2-stroke engines in big trucks.
These were very popular engines in their day. Tighter emisions regulations and the need for better fuel economy put an end to the 2-stroke engines in big trucks.
I think 2 stroke Diesels always have a Blower,
one interesting Light commercal 2 stroke Diesel in the U.K. was the 'Commer Knocker', it had 3cyl and 6 pistons!
one interesting Light commercal 2 stroke Diesel in the U.K. was the 'Commer Knocker', it had 3cyl and 6 pistons!
Huh?
Confused huh? I don't know that engine specifically but it most likely is what is called Opposed piston engine. An opposed piston engine has two cranks, one above and one below with 2 pistons sharing one cylinder. The pistons achieve compression by driving towards each other and just short of crashing together. My personal experience is of the Fairbanks Morse Diesel Generater on U.S. Navy Submarines where it is also of the opposed piston type. The top crankshaft on this diesel drives the giant blower and the bottom crankshaft drives the generater.quote:
Originally posted by 55:
Huh?
Hammer
On the Commer the opposed pistons drive bell cranks that connect to the crankshaft that runs centraly in the engine.
Another common opposed 2 stroke was the Deltic, 36 pistons in 6 groups of 3 cyls set in a triangular pattern, the Blower was in the middle of the triangle. it was used on fast boats and the first British Diesel Trains, the noise it made sounded like a never ending ****
Another common opposed 2 stroke was the Deltic, 36 pistons in 6 groups of 3 cyls set in a triangular pattern, the Blower was in the middle of the triangle. it was used on fast boats and the first British Diesel Trains, the noise it made sounded like a never ending ****
I tried to use the 'F' word that means Passing wind, Looks like I got Censored
There are some cutting edge diesels that are 2 stroke, direct injection, and are scavenged by the use of turbos.
Started on compressed air, and when they are running, the difference between the exhaust pressure, and the boosted intake pressure scavenges the thing.
I think that they are an engine of the future.
With hybrid designs, power density is what is required, and strokers offer that.
Started on compressed air, and when they are running, the difference between the exhaust pressure, and the boosted intake pressure scavenges the thing.
I think that they are an engine of the future.
With hybrid designs, power density is what is required, and strokers offer that.
There are parbably about 50 Detroit Diesels In Bolivia, none very popular. Detroit recommends against the use of multigrade oils for shear, and says to plug them in in cold whether. When you are driving where there is no electricity for two or three days, with temperatures below 0, there is no way to plug it in, so they end up building fires under the oil pan to heat the oil in the morning or have extremely short engine lives.
The 2 stroke diesels have a crankcase like a 4 stroke but has inlet ports like a 2 stroke but doesn't use the crankcase as the compressor it uses a roots type blower to scavenage the exhaust through the cyl heads like a 4 stroke motor.
The 92 seris Detroit diesela used the blower to start and run at low rpm and at higher rpm the turbo put enough air flow to run the engine that allowed a large increase is power due to less power required to run the blower at a higher speed.
Oilguy,
Two stroke diesel engines, generally, are smaller, lighter, cheaper for the same hp compared to a four stroke. The two stroke engines burned more fuel, much more lube oil, and has high levels of exhaust emissions.
The largest diesels remain two strokes. These are the ship propulsion and power plant engines with horsepower up to 7500 hp per cylinder with a straight 14 the largest engine available.
Ken
Two stroke diesel engines, generally, are smaller, lighter, cheaper for the same hp compared to a four stroke. The two stroke engines burned more fuel, much more lube oil, and has high levels of exhaust emissions.
The largest diesels remain two strokes. These are the ship propulsion and power plant engines with horsepower up to 7500 hp per cylinder with a straight 14 the largest engine available.
Ken
In the 92 series the roots blower still runs at high speed, but there are bypass valves to allow the turbo to blow around it.
On a high performance 6V-92 the bypass was worth about 40 hp on the top end. 40 more hp with the same amount of fuel!
I had a few prototype 6V-92s rated at 580 hp, but they all put out 600 to 620 hp on the dyno. After some mods, that version went on to be one of their high performance marine engines. IIRC, it was rated at 620 hp.
6V-92 = 552 cubic inches. 1.12 hp/in^3 at 2200 rpm from a production diesel. IIRC, they ran about 36 psi boost.
xs650,I always thought the blower speed was less due to the lower noise. Were the high output engines for marine use?
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