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In the past five years or so I have learned so much about the motor…everything it seemed from a 22re to a vg30e…or so I though.
In late 2007, I had purchased a 2003 Yamaha Banshee with a 350cc “two-stroke” engine. I had no idea what that meant at the time and didn’t care other than the fact that I had to mix the fuel with ‘two-stroke’ oil (which mind you, was kind of expensive, especially when I was burning through a can of gas a day at the coast lol), and; that it seemed to have more power at top end vs some of the 4-strokes out there. Some debated me, but I didn’t listen, I just simply nodded, and sped off with a floppy smile ear-to-ear from all the wind blowing into my helmet seconds later. What I did learn about in that time though was that the 2-stroke was being fazed out for some reason and not produced anymore in the recreational/atv world. Again, I didn’t understand, nor cared as I already had what I needed.
Another thing I didnt realize until recently was that 2-strokes come in a diesel option as well. It wasn’t hiding in a Volkswagen Rabbit or Chevy 3500 series, but it was a GM product until 2005. They were in the General Motor’s (now Caterpillar’s) Electro-Motive Division and were actually deisel locomotives! I’m still learning more about them, but I still lack a lot of understanding to these unique movers…
What I’m curious to know are what are the benefits of the 2 and 4-stroke. Why aren’t there any 2 stroke sedans cruising the streets? Are 2-strokes more or less powerful/efficient than a 4 stroke? Yeah, lots of questions and all cover the spectrum of gas variety. I will likely pose more q’s as the forum page fills. I hope this will be a great topic!
Michael
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Two strokes are horrible as far as emissions go because of the oil you mix in the fuel. That is to lubricate to upper cylinder. One good place to see a cutaway view and full explanation of these engines is howstuffworks.com. Instead of a power stroke every other revolution, a 2 stroke fires on a power stroke every revolution. This creates more power. Also, two strokes don’t have the amount of moving parts so they carry less weight, and in something like your quad the lighter it is the faster you can go. They also are able to rev higher without damage.
No two stroke is street legal because of the emissions, which is also a reason some states are trying to get rid of them entirely. This quad isn’t the first one you’ve seen. Weedeaters, chainsaws, Lawn-Boy lawnmowers, any outboard motor, dirt bike or snowmobile that doesn’t specifically say 4 stroke, Mantis tillers all use two strokes. If you’ve got to walk around carrying the things, you’d want the most power for the least weight, right?
Two strokes make the most power on the top end. The manner in which the motor is set up and tuned determine where that powerband is. But they lack low-end torque, and thats what you get on a 4-stroke. They don’t rev up as fast but have power on the low end. Thats why you always run a chainsaw or weedeater at full throttle. The two strokes in locomotives don’t actually drive the train, they turn a massive generator and that turns electric motors in the drive wheels. Same on cruise ships and oil tankers.
Years back a lot of trucks and equipment had 2-stroke diesels. If you hear of a Detroit Diesel engine and the model number is something like 8V71 or 6L92 those were two strokes. I used to work on tugboats that used a bunch of military surplus crate motors that were 8V71. The way they named them made it easy to tell how the engine was setup. The 4, 6, 8 and I’ve heard of 12s before that is the first numeral is the number of cylinders. The letter is either a V or an L and tells you the configuration of the motor. A V is opposing cylinder banks, an L is a longitudinal (like a 22r or a ford 300-6, all cylinders are in a straight line). The last numbers are the cubic inch displacement of each cylinder. So an 8V71 is a V8 motor with 71ci displacement per cylinder, or 568ci total. With diesels, they have to run a supercharger just to even be capable of starting. Otherwise the air will not move through them sufficiently. Many also have a turbo for extra power, but a supercharger driven off the cover gears producing 6psi or so is needed for them no matter what.
Very interesting! Yeah, I knew about the smaller motors for garden tools but didn’t think they would have been used so much in the larger until again recently.
Do the locomotive engines run cleaner than the 4-strokes? Ive seen vids on youtube of 4-strokes clagging up a fierce cloud of black smoke for very long periods of time and even barking flames (these on new locomotives even) and only one do that for a short time in a 2-stroke.
That depends on the condition of the motor. Two strokes by their nature are dirtier but especially on the big ones a lot more emissions controls have been put into place so that its not blowing heavy smoke. They tend to smoke the most when cold like any diesel does.Lot of the you tube vids just show ones in for repair, with major problems, some random guy nearby one that catches a vid with his phone, etc. Their advantage, especially as they get to engines of that size, are that every stroke is a power stroke and they weigh less. When you have something that weighs (and this is a random number for the sake of comparison) 50 tons and to make it a four stroke would add 30% more weight you’d be talking about a weight savings of 30,000 pounds. Thats a lot less you have to build to support it, a lot more weight you can carry, and definitely a lot cheaper engine to build. When you have parts that cost thousands and thousands of dollars for each little component and you don’t have them on your engine, you not only have a lower initial cost to purchase you have removed from the equation a part that can later fail and need to be replaced. On the really big ones they also use water injection to make higher power with lower combustion temps and longer engine life. Realize that an engine in an oil tanker or a cruise liner has a redline of 500-600 rpm. Makes your head spin thinking of that, huh?
That is insane! Then wait….do Indy cars have two-stroke motors or four? They scream at intense pitches (RPM’s yet go a bajillion miles per hour at insanely light weights! Is it due to the technology on the the 4-stroke combustion motors and tons of money thrown at it or are they 2-stroke? I would think that, with the lighter weight and better overall power that emissions wouldn’t be of top concerns to the sponsors/tv companies!
Indy cars are 4 stroke. The engines are super expensive. They run very short stroke length and small cylinder bores but usually more cylinders which is a good combo to allow very high RPM. Even though its hard to think of a race car as fuel efficient it actually is if you look at fuel consumption per cubic inch displacement and horsepower. It achieves more than 1 horsepower per cubic inch of displacement. So it is volumetrically efficient because it makes the most out of what displacement it has. Compare that to the engine of a small economy car going by how many horsepower it makes vs. the displacement.
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