Quote :

"Mythbusters answers which is greener, cars or motorcycles? Using portable emissions equipment, a wide sampling of cars and bikes from the 1980s, 1990s and 2000s and with the help of Dr. Kent Johnson of UC Riverside, the Mythbusters team claims they proved motorcycles are dirtier than cars. Doing so meant gathering data in real-world driving conditions along a 75-percent freeway, 25-percent city driving loop in and on the vehicles from different eras. The results of that test proved one thing that everyone should already know: motorcycles use less fuel than cars. They also produce less carbon dioxide than cars, which accounts for 90 percent of a vehicle's emissions. Where cars pull ahead, though, is in the amount of other noxious gases they produce. The Mythbusters found that bikes produce tons more hydrocarbons, which are carcinogenic; nitrogen oxides, which cause acid rain; and carbon monoxide, everyone's favorite odorless deadly gas. Astoundingly, the 'busters claim bikes produce up to 8,000 percent more carbon monoxide than cars. Yes, 8,000 percent. A controlled test on a track using a small displacement, fuel injected modern bike didn't give two wheelers the help the 'busters thought it would.To give bikes another chance, Jamie and Adam built an aerodynamic frame to make the modern bike sip even more gently through the wind. The result, predictably, was that the emissions got a little better, but were still worse than the car's"

I've always assumed that most (if not all) motorcycles are devoid of a catalytic converter so these results aren't really much of a surprise. Nonetheless I'd imagine that an uninformed "green" enthusiast still thinks he's doing his duty b/c CO2 emissions are so much lower...and ignoring the increased emissions of gases that are actually harmful to plants and animals.

http://www.autoblog.com/2011/10/03/mythbusters-answers-which-is-greener-cars-or-motorcycl/

10/4/2011 1:19:31 PM

they tested a motorcycle with a catalytic converter

10/4/2011 1:23:16 PM

I saw this episode and was surprised.

10/4/2011 2:09:34 PM

well the government can give me cash for my harley then.

10/4/2011 2:12:36 PM

^^^my mistake! (also I didn't watch the episode). Interesting indeed then.

10/4/2011 2:18:54 PM

And lawn tractors are dirtier than motorcycles, and weed eaters are dirtier than lawn tractors.

10/4/2011 2:25:33 PM

Modern motorcycles have catalytic converters, but they're still not as efficient as ones on cars because it's neither industry required nor consumer demanded. The cat's are just efficient enough to pass noise and emissions tests, which is why the engine is able to breathe so well and be so efficient otherwise. If they filtered crap as well as the smothering cat's on cars, they would just be grossly fuel inefficient as well.

Motorcycle engines in general have not even seen a fraction of the efficiency improvements that auto motors have had in the last couple of decades. Overall, rudimentary catalytic converters, fuel injection, and evaporative recovery systems (in Cali only) are the only major things that have contributed to efficiency and emissions controls. Every improvement in fuel efficiency is offset by a hit from increased emissions controls, and the primary goal of motorcycling is high-performance and having fun, not being "green".

10/4/2011 2:27:17 PM

Yea. This is common sense.

10/4/2011 2:59:41 PM

I'm not saying this is entirely incorrect

But lol @ citing Mythbusters

10/4/2011 3:50:51 PM

Coming up next: Mythbusters investigate which are louder, cars or motorcycles?

10/4/2011 4:13:11 PM

^^go back to sports talk

10/4/2011 4:28:25 PM

I'm certainly not surprised. My bike doesn't even have a catalytic converter, and the AIS system is only required for CA emissions, so I can just take it off, meaning everything from my cylinders goes through a pipe into the atmosphere with zero treatment.

As said above, engine technology is good on bikes performance-wise, but certainly behind cars in terms of eco-friendly capabilities. Of course, it's only a matter of time until that changes

[Edited on October 4, 2011 at 7:37 PM. Reason : :]

10/4/2011 7:37:01 PM

Gee... motorbikes produce more toxins than cars... yet cars outnumber bikes 250,000:1. or whatever arbitrary number it is.

10/4/2011 8:33:04 PM

yeah but some people convert to vespa's and shit to "go green" i'd like to see how they compare...
(especially since most of the 49cc setups are 2 stroke)

10/4/2011 8:38:56 PM

and everyone of them sucka's burns oil like no tomorrow... yes i know oil in gas, but still... Its pretty crazy how many fuckers are on scooters now days, and they still don't know how to drive properly, but this time they have expanded their territory to include sidewalks and other pedestrian only areas.

10/5/2011 12:33:38 AM

Modern Cars produce basically zero emissions (except CO2) when they are driving around with an engine that has been warmed up.

Evaporative emissions systems prevent HC vapors from escaping to the atmosphere, especially during hot start. During cold start the biggest thing is to get the catalytic converter warmed up as fast as possible; there are all sorts of ways to do this. Without strict emissions laws the bike manufacturers have little incentive to incorporate them

Also, short stroke/high revving engines tend to have poorer fuel economy in general.

10/5/2011 10:01:03 AM

http://www.youtube.com/watch?v=-U7Lqwl3Vzk&feature=related

10/5/2011 11:07:15 AM

how hot does the cat converter get?

10/5/2011 1:25:04 PM

Quote :

"The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F. The normal operating temperature can range up to 1,200 to 1,600 degrees F. But as the amount of pollutants in the exhaust go up, so does the converter's operating temperature. If the temperature gets up around 2,000 degrees F or higher, several things happen. The aluminum oxide honeycomb begins to degrade and weaken. The platinum and palladium coating on the honeycomb also starts to melt and sink into the ceramic substrate reducing its effect on the exhaust. This accelerates the aging process and causes the converter to lose efficiency."

Found this here: http://www.aa1car.com/library/converter.htm

According to that article, modern cats have a negligible rise in temp across the converter due to how clean the engines are (maybe 30F or so), but if you end up with unburnt fuel in the exhaust for whatever reason, you can see a rise of 500F or more across it.

[Edited on October 5, 2011 at 1:35 PM. Reason : ]

10/5/2011 1:34:35 PM

Precats (closer to the exhaust manifold, not on every engine) and main cats operate at different temperature ranges. The catalyst efficiency on a conventional port-injected gasoline is calculated by comparing the oxygen sensor signals in front of and behind the converter.

10/5/2011 3:28:59 PM

whats the impact to the environment from the production of gasoline? that bike in mythbusters got like 70 mpg. i wonder how that would factor in.

10/5/2011 4:38:15 PM

Quote :

"Modern motorcycles have catalytic converters, but they're still not as efficient as ones on cars because it's neither industry required nor consumer demanded. The cat's are just efficient enough to pass noise and emissions tests, which is why the engine is able to breathe so well and be so efficient otherwise. If they filtered crap as well as the smothering cat's on cars, they would just be grossly fuel inefficient as well."

i am not at all surprised by the OP's post, but i'm curious as to why what you said is true...i realize i'll probably catch flak for posting about a scooter in a motorcycle thread, but why would motorcycles take a hit?

my scooter surpasses Euro 6 emission standards for passenger cars (which, if i'm not mistaken, is more stringent than US standards), gets 100-110mpg on average, and tops out at 65mph...granted, i only gradually get up to speed (rather than going full throttle from a stop), but i frequently go all out on 4-lane roads

i realize that a scooter is a different animal than a motorcycle and the smaller engine (mine's 110cc) makes it more efficient than the "average" 650cc motorcycle...but my scooter is smaller, has all the crap to make it cleaner, and it's downright efficient...surely they could implement these same standards on motorcycle without significantly hurting fuel economy

10/6/2011 8:27:33 AM

^ Euro 6 is no joke for a small engine. I'm surprised, but if that is a world-market product it makes sense. Scooters are used all over the world in urban areas.

Catalytic converter design is not a simple thing. I'll put it to you this way: the more efficient you can reduce the engine-out emissions (the exhaust entering the converter), the less restrictive the converter will need to be. Besides, there's a heck of a lot more to emissions tests and emissions standards than converters.



Here is the most common/basic EPA test cycle. With modern emissions technology the biggest deal is warming up the converter for the cold start phase and reducing vapor emissions for the hot start phase. Warming up the converter can be done in a number of ways--the more sophisticated the fuel and emissions system, the easier it is to do. Without a strong regulating hand there's limited incentive to use this technology on small engines. You're more likely to get incremental changes on old designs, like GM and Ford were doing back in the 90s when they still had engines designed in the 70s in production.

10/6/2011 9:18:14 AM

Quote :

"i am not at all surprised by the OP's post, but i'm curious as to why what you said is true...i realize i'll probably catch flak for posting about a scooter in a motorcycle thread, but why would motorcycles take a hit?"

RAWR RAWR RAWR, I hate the environment I said it b/c it's pretty clear that most motorcycles don't have as advanced emissions equipment as cars. Now excuse me while I go produce more plant food.

10/6/2011 9:32:41 AM

^ uh...what's your issue? i didn't criticize anything...calm down, kiddo

^^ thanks for the info...i'm always up for a little learning

10/6/2011 11:34:08 AM

lol, oh sorry I read your comment as to say you weren't surprised to my remarks to the article.

10/6/2011 12:55:44 PM

wouldn't motorcycles in Europe also have to pass Euro 6 rules?

I'll stick with my earth hating wheelie machine with the loud straight pipe. God knows that I can only stand 20 mins of it at a time anyhow, negating any real environmental impacts. lol

10/6/2011 1:54:37 PM

^^ in retrospect, my post was somewhat unclear

^ i have no idea...a quick google search makes me think that Euro 5 and 6 standards are only for passenger and commercials vehicles and that other vehicles (motorcycles, large delivery, etc) are held to prior standards (motorcycles might only have to conform to Euro 3 or 4)...i'm far from an expert, though, and i may not be reading it right

[Edited on October 6, 2011 at 3:36 PM. Reason : 3456]

10/6/2011 3:35:17 PM

Quote :

"The average light off temperature at which the catalytic converter begins to function ranges from 400 to 600 degrees F. The normal operating temperature can range up to 1,200 to 1,600 degrees F. But as the amount of pollutants in the exhaust go up, so does the converter's operating temperature. If the temperature gets up around 2,000 degrees F or higher, several things happen. The aluminum oxide honeycomb begins to degrade and weaken. The platinum and palladium coating on the honeycomb also starts to melt and sink into the ceramic substrate reducing its effect on the exhaust. This accelerates the aging process and causes the converter to lose efficiency."

+20 psi = mysteriously disappearing cat innards

10/6/2011 9:10:59 PM