# Two Stroke Emissions

Discussion in 'General Questions' started by Tinker1980, Jan 10, 2009.

1. ### Tinker1980Guest

I was looking for information on the emissions of 2 stroke engines, I just can't get my head around the idea that my bitty little 67cc one lunger pollutes a whole lot more per mile than my fullsize chevrolet truck, which for the record has a 350 V8. (Which is 5736.5cc)

I found some info at this site: http://www.bajajusa.com/emissions.htm there they mentioned a 150cc Bajaj scooter that was a 2 stroke, and said it gave off 660-1540 pounds of hydrocarbons per 10,000 miles.

I got to thinking about those numbers, and they don't add up. Lets assume our Bajaj Chetak 150 cc scooter gets only 80 MPG. (I know someone who has one of the 2 strokers, and she gets right at 100 out of it) Assuming that, we could say it burns 1/80th gallon per mile, or about 1.2 ounces by weight per mile. That adds up to 750 pounds of gas to go 10,000 miles. So... How... are we getting 660-1540 pounds of hydrocarbons per 10k miles? That would mean that, on average, the entire mass of gasoline used is emitted in unburned hydrocarbons, so, how is the silly thing even running since you're in effect pouring the gas out on the ground?

Or, more likely... Who's math is wrong? Is this a case of panicky sky-is-falling environmentalism, or are my math skills at 1:48 post meridian (Early morning for me) not up to snuff yet?

-Mark

2. ### bluegoatwoodsWell-Known Member

I think you've made an error when you equated "fluid ounces" with ounces of weight.

Let me do some figuring. I'll be back if I can figure out whether the difference will work in favor of your suspicion or against it.

3. ### Tinker1980Guest

No - I figured out the 1.2 ounces per mile from the six pounds that a gallon of gas weighs, not the 128 fluid ounces in a gallon.

-Mark

You also have not taken into account the weight of the oxygen that is burned at over 10 times the amount of the fuel and is compounded with the fuel during the combustion process to become a component in the so-called greenhouse gases.

5. ### Tinker1980Guest

Actually, yes I have. I'm just talking about Unburned Hydrocarbons. They haven't been burned, so there is no oxygen from the air present. As far as "greenhouse gases", the amount of CO2 produced is directly proportional to how much fuel you burn, so in that case, a little 2 stroke is far cleaner than a car.

-Mark

7. ### Tinker1980Guest

No... I'm only talking about *unburned hydrocarbons*. They are unburned. And hydrocarbons. They are only hydrogen and carbon. They are the bits of gasoline and oil that went through the combustion process without combusting, therefore have not gained any mass from added oxygen. I understand that getting CO2 and CO adds mass because of the added oxygen, but I'm not talking about CO2 or CO.

-Mark

8. ### bluegoatwoodsWell-Known Member

Okay, we're talking about nothing but the fuel and oil that passes through unburnt.
And as a matter of fact, that is what you said in the original post.

At the moment I'm a bit too tired to work with figures without screwing it up.

But I can make one comment; two strokes are on the dirty side but two stroke haters can exaggerate to the point of being kinda dirty themselves.

9. ### RATRODERGuest

Ok here is some numbers,
1gal.=6.3lb
1lb=453.6grams
Now to get close to the numbers the site stats your 2 stroke would be 66% efficient.
So 30grams per mile x 3 =90, 2857.7grams per gal.gas\ 90=31.7 mpg.
Just plane stupid!
And 70grams per mile? louis

P.S. I'm tired of people bashing 2 strokes

10. ### Tinker1980Guest

I wrote an email asking them what was the deal with their math, once I woke up all the way. They haven't responded but it's the weekend, and I imagine they will try the "Oxygen adds mass" argument, which is of course invalid in this case.

On a related note, how big a deal would it be to make a homebuilt catalytic converter? Seems that you could hit up a junkyard, find a honeycomb type catalyst, core it with a pipe and run your exhaust through it.

-Mark

11. ### Skyliner70ccActive Member

Who cares, for crying out loud? How many of the environmentalists on this website own flat screen TVs which use more electricity than traditional TVs? Any idea how much pollution is expelled into our atmosphere as a result? Tons, literally.

Many signs point that our planet may be slowly entering another ice age. If that doesn't get us, then the panic of the Mayan Calendar ending in 2012 will.

You want to save the planet? The biggest impact you can have is not to reproduce; its simple.

12. ### loquinActive Member

The old design, unscavenaged 2-stroke passes 25-30% of the fuel-oil mix straight through the engine, unburned. Newer designs are in the 5% (or lower) range.

If you are getting 80 mpg, then figure (worst case, old engine design) about a third of a gallon of fuel goes into the air in 80 miles. Or, 6.2 pounds spread over about 240 miles.

6.2 lbs * 453 g/lb / 240 miles = 11.7 g/mile

(fyi - current federal standards are apx 3 g/mile for all emissions.)

in 10000 miles, you pass apx. 117000 g of unburnt hc into the air, or about 258 lbs.

Last edited: Jan 12, 2009
13. ### Tinker1980Guest

How true. Less people will always mean less impact, more resources, etc. But there are too many who think it's their right to create more of themselves, and I wonder if any country other than China will have the intestinal fortitude to make laws regarding how many children a couple can have.

About the flatscreens... I thought the whole point was that they used less juice than CRT's? Do the LCD screens still use more?

In the bottom of some if not all flatscreen TV's there is a light bulb, usually fluorescent. In that bulb, and in all bulbs of that type, there is a smal amount of mercury. So... I was wondering... How are the little squiggly light bulbs that cost 20 times as much as normal bulbs cleaner?

-Mark

14. ### Skyliner70ccActive Member

From Yahoo tech column:

Part I: Do Flat-Screen TVs Consume More Power? SHORT ANSWER IS YES
Tue Jan 2, 2007 6:47PM EST

Why is it that there's no such thing as an easy answer to a simple question when it comes to technology? Over the warm holiday weekend we had one of those "green" discussions, as I'm sure so many of you did. The questions posed were simple: Are the new LCD and plasma displays more energy efficient than old CRT screens? And, which is more energy efficient: plasma or LCD? (I'll cover this question in part II of my post.)

The answer depends on many things, including how you use your TV, when you bought it, and—most of all—how TV power consumption is measured today.

First, the question of new flat-screen TVs versus old cathode-ray TVs. Generally speaking, large-screen TVs consume more energy than the smaller-screened CRT-based TVs they replace. And most people are adding TVs. That is, they tend not to replace old TVs with new ones but add a second or third TV. And since TVs consume power even when they're not on, just adding a TV set or two can add dramatically to your power consumption.

A recent report by the BBC found that in the United Kingdom, plasma televisions, which it says are about 50 percent bigger than their cathode-ray-tube equivalents, "consume about four times more energy according to the government-funded Energy Saving Trust." And when looking at the carbon emissions from the power plants, the same group found that old-style TVs produce 100kg of climate-warming C02 per year, while larger, plasma screens will pump out 400kg from the plant. A recent report from Panasonic, makers of both LCD and plasma TVs, said that the new TVs consume more power than older CRTs, but the company is working to get the new TVs to be more energy efficient as fast as it possibly can.
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As for compact flourescent light bulbs. I'm all for them but don't think that big brother should eliminate incandescents and force consumers to use a product that is potentially dangerous if it is shattered (mercury).

I personally use CFC bulbs because they save me money on my monthly electricity bill and if they cut down on pollution from coal fired plants, that ok with me. If they cut down on CO2, that's a bummer cuz we are heading into an ice age and need more green house gasses

15. ### bluegoatwoodsWell-Known Member

I've been watching this thread but not posting because I have no hard info to contribute.

But I'll make one comment; I'm all for CFCs in priciple. But aren't they just the coldest light? I'm gonna miss fluourescents.

16. ### Old BobMember

Those numbers are more in line with reality than what was reported at the baja website.

Can't agree more, some of us voluntarily have elected not to add to our "carbon footprint" by adding to the population of our already over crowded planet.

17. ### BSAGuest

Who cares? I certainly don't.

BSA

18. ### YoungbirdMember

Why worry about it? As long as we have diesels and jet planes why worry about a few 2 stroke mc engines. Its dumb!:jester:

19. ### Old BobMember

Yeah its dumb, but people get on the anti fun bandwagon and outlaw our sports.We have to police ourselves before the government comes in and does it for us.
PWCs have been banned on lakes, snowmobiles from national parks and other areas. Two stroke lawn equipment in various communities across the country have been banned. All because of noise and smoke.

20. ### bluegoatwoodsWell-Known Member

In my last post, did I say that I'd miss fluorescents? (Odd Fruedian slip there)
I meant to say that I'll miss incandescents.

And Old Bob has a good point; when the day comes that these MBs are numerous enough to gain real notice, then someone will try to outlaw them. And they'll likely succeed, barring any powerful counter-arguments such as \$4.50 fuel.

I don't have much to suggest other than that we should be aware of it. Be prepared to lobby on our own behalf (though too early would be almost as useless as too late) and show our best sides to the world.