Pollution? Stand behind a city bus for an hour and I'll stand behind my LT and we'll match ratios later.

 

ac has a turbo charged 660 sled, but im not sure if its a 2 stroke or a 4.

 

The whole issue is just an emissions deal. There is technology out there to get a 2 stroke to burn clean.

I know around where I live I'd rather stand behind a city bus than an LT (plus the buses around here mostly have high mounted exhaust). If the bus is pumping out clouds of black smoke it is old. (And some of those old diesel buses were actually 2 strokes.) The new clean burning deisels (in both large and small applications) are much friendlier on the environment. And new low-sulfer diesel fuel is helping to remove the bad smell of diesel. I live in the country's second worst air basin (San Joaquin Valley, California) only behind Los Angeles. I'm all for cleaning up our air.

One only needs to look at all of the 2-strokes starting up first thing in the morning at your favorite riding spot. Most are spewing smoke. When you start up a 4 stroke all you start to see is a water vapor cloud that is condensing because of the cold exhaust system. That vapor cloud dissipates within 2 feet of the tail pipe while the smoke from a 2-stroke rolls through the campgrounds. And most of that comes from having to burn oil with the fuel to lubricate the internals.

I see efficiency in an engine as the entire package. How much power can an engine harness from the fuel. If it can use the least amount of fuel to generate the most amount power, then that's efficiency. And our current internal combustion engines are very inneficient in harnessing all of the energy from their fuel. It's like comparing an incandescent lamp vs. a fluourescnet lamp. Most of the energy used by an incandescent lamp is lost to heat. 14W CF lamp is = to a 60W incandescent in lumen production.

Two-strokes have a power density advantage over a 4-stroke. But they are also using roughly twice the amount of fuel. The Rotary engine fans use the same argument. The only advantage that a 2-stroke has it's its small packaging (as does the Rotary). The last RX-7 turbos that Mazda produced were 1.3L, but were putting out power numbers in the same league as a turbo 3.0L V-6/I-6 (Mitsu. 3000GT VR-4 (Dodge Stealth R/T Turbo)/Nissan 300Z Turbo/Toyota Supra Turbo) but were still using the same amount of fuel. And a Rotary is actually putting force on the crankshaft for 3/4 of a Revolution (2-strokes put power down at 1/2 Revolution[Note: this is assuming a single cylinder.].

If you are igniting fuel twice as much (once per revolution as opposed to .5 per revolution [rotary is 3 times per revolution]) you are dumping at twice the emissions. I would love to see charts and data that shows comparrisons of 2 stroke and 4 stroke engines of comperable size, power, etc. They should show fuel consumption, power output (HP & torque) and emmisions (i.e. like a California Smog Check).

Ok, class dismissed. j/k

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Wow...

Anyways, I think in a 4-stroke, this is what happends with the gas:

30% power
10% friction
the rest is something else heh.

 

Sure am sad to see the 2 strokes go even know there's tons of used ones out there and will be for a very long time.
I think the old brigs i've got on an old lawn mower makes more of a stink then the 2 stroke 400 in my polaris.

 

I believe current internal combustion engines are harnessing a little less than 20%. For some reason 17% is sticking in my head.

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To me it seems like some of the new 2 strokes aren't as bad as the old ones. Is your Polaris oil-injected (it mixes it itself)?

It's kinda like the old diesels vs. the new diesels. The newer stuff is so much cleaner.



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the buses here on campus are less than a few years old, and they spit out all kinds of black smoke. so do most brand new diesel pickups.

 

I rarely see any current generation diesel trucks around here spewing black smoke. But since I live in CA emissions are a huge issue and even diesels have requirements they have to meet. I know that at least one version of the Cummins 5.9 I-6 in Dodge Rams is not available in CA do to emissions. I believe that Ford and GM all use the same version of their motor throughout the US.

The only buses I see around here spewing smoke are Fresno Unified School Dist. And what the deal is, I have no idea. There is also a move to move the Fresno City bus system over to CNG. Though they don't know where they will get the money from.

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ya it is going to be sad to see them go i hope people in the states can still get gas gas quads another thing i was reading a thing by the epa they said that a 2 cyclinder 2 stroke snowmobile puts out as much pollution in seven hours as a car that drove 100,000 miles with mid size engine that is BULL SH$T