Bikes dirtier than cars - Mythbusters | GTAMotorcycle.com

Bikes dirtier than cars - Mythbusters

A lawnmower pollutes more in an hr than your car does in a yr.

Of course a non catalyzed, carbed bike pollutes more than a modern Subaru with 5 oxygen sensors and 3 catalytic converters.

However, get a BMW 650 single, fuel injected and catalyzed, then do a comapro. The BMW bike would likely show a much cleaner tailpipe emission than the bike they used.
 
omnivore said:
However, get a BMW 650 single, fuel injected and catalyzed, then do a comapro. The BMW bike would likely show a much cleaner tailpipe emission than the bike they used.
Click to expand...

Awww, not an inline-four SS with the cat removed and an aftermarket pipe to drop weight and increase the horsepower?

Are BMW 650 singles that popular?
 
Baggsy said:
Awww, not an inline-four SS with the cat removed and an aftermarket pipe to drop weight and increase the horsepower?

Are BMW 650 singles that popular?
Click to expand...

First mod almost every turbo subaru owner does is ditch the pre-turbo cat completely and get a catless downpipe or highflow replacement. There are very few 4 wheel drive drive clean facilities so they only need to pass the idle test - off boost, they are pretty clean even without the 3 original cats. On boost is a different story altogether.
 
mma01 said:
First mod almost every turbo subaru owner does is ditch the pre-turbo cat completely and get a catless downpipe or highflow replacement. There are very few 4 wheel drive drive clean facilities so they only need to pass the idle test - off boost, they are pretty clean even without the 3 original cats. On boost is a different story altogether.
Click to expand...

Also, the pre-turbo cat is primarily there to control cold start emissions, while the drive clean test is run at normal operating temperature.
 
I'll back that up about the Subys.... I did my exhaust on a WRX I had within the first year.... 3" HKS from the turbo back. Fun car, but the environment hated it.

I find that a lot of times for the car/bike/truck/airplane mythbusters they seem to choose poor examples that don't accurately represent the average of what is taking place in the real world.
 
I'm not sure what's so shocking about any of this. OEM car companies spend millions in R & D for emissions equipment and research. OEM motorcycle companies probably don't.

I mean, generally speaking, the only reasons motorcycles get better gas mileage than cars is because of weight savings. Motorcycles are not necessarily better for the environment than cars, nor are they more efficient in a thermodynamic/energy conservation way.

Cars are pretty goddamn clean when it comes to emissions; provided that you don't swap out the OEM equipment with a bunch of crap from pacific mall, anyway. ;)
 
Flashmonkey said:
I'm not sure what's so shocking about any of this. OEM car companies spend millions in R & D for emissions equipment and research. OEM motorcycle companies probably don't.

I mean, generally speaking, the only reasons motorcycles get better gas mileage than cars is because of weight savings. Motorcycles are not necessarily better for the environment than cars, nor are they more efficient in a thermodynamic/energy conservation way.

Cars are pretty goddamn clean when it comes to emissions; provided that you don't swap out the OEM equipment with a bunch of crap from pacific mall, anyway. ;)
Click to expand...

Expect this to change soon as I believe Europe is really clamping down on motorcycle emissions. As it is, motorcycle's are far from designed with emissions in mind. Only recently did carb's go out of fashion, and most new bikes still don't have O2 sensors. Cars have been running O2 sensors to adjust air/fuel ratio in real time for over twenty years now.
 
mma01 said:
First mod almost every turbo subaru owner does is ditch the pre-turbo cat completely and get a catless downpipe or highflow replacement. There are very few 4 wheel drive drive clean facilities so they only need to pass the idle test - off boost, they are pretty clean even without the 3 original cats. On boost is a different story altogether.
Click to expand...

Oof a mod I missed, then again I didn't need any more power, and I don't remember seeing a separate AWD drive clean test. Mine passed the normal one at a normal test shop.
 
Baggsy said:
Oof a mod I missed, then again I didn't need any more power, and I don't remember seeing a separate AWD drive clean test. Mine passed the normal one at a normal test shop.
Click to expand...

My only point is that in the real world, they are relatively dirty cars because:
a) they are mod friendly and many owners choose to do so (you are probably in the minority if you have a bone stock turbo subaru)
b) they get a break from the same drive clean standards applied to fwd/rwd cars b/c they cant apply the load testing requirements due to lack of awd dynos.


btw. ditching the pre-turbo cat is for reliability, not power - if pieces of that cat break off, its taking out your turbo and possibly your motor.
 
Last edited:
My wrx gives a nice little puff of black smoke the first time it gets boosted hard during a drive. My bumper is coverd in soot all the time too. One cat is good enough anyway, shows that you kinda care :)

My bike was running an off the shelf map that turned my signal light black in 100km so I'm sure it was way worse than most cars. I'm sure soon enough you'll have to keep a cat on your bike but really what's the big deal if it's not a track/race bike. It's a few extra lbs and a couple hp that you probably didn't need anyway.
 
Last edited:
regder said:
Expect this to change soon as I believe Europe is really clamping down on motorcycle emissions. As it is, motorcycle's are far from designed with emissions in mind. Only recently did carb's go out of fashion, and most new bikes still don't have O2 sensors. Cars have been running O2 sensors to adjust air/fuel ratio in real time for over twenty years now.
Click to expand...

Nice...I can't wait for the days when we have to driveclean our motorcycles.
 
mma01 said:
My only point is that in the real world, they are relatively dirty cars because:
a) they are mod friendly and many owners choose to do so (you are probably in the minority if you have a bone stock turbo subaru)
b) they get a break from the same drive clean standards applied to fwd/rwd cars b/c they cant apply the load testing requirements due to lack of awd dynos.


btw. ditching the pre-turbo cat is for reliability, not power - if pieces of that cat break off, its taking out your turbo and possibly your motor.
Click to expand...

Do you really live in a world where most car owners modify the exhaust on their cars? Cause I'll tell you, there are probably 300 cars inthe parking lot at my office and I can almost guarantee you not one of them has a modified exhaust. (there's probably a Civic hidden in there somewhere...)

Also, in what universe is a Turbo Subaru a common car???
 
Myztyk said:
Also, in what universe is a Turbo Subaru a common car???
Click to expand...

The AWESOME universe!

My 02 WRX has a stock exhaust...well mostly. I got rid of that cat in the up-pipe, but it's all stock afterwards. I'm pretty sure that car is still dirty as hell, though haha.
 
Myztyk said:
Do you really live in a world where most car owners modify the exhaust on their cars? Cause I'll tell you, there are probably 300 cars inthe parking lot at my office and I can almost guarantee you not one of them has a modified exhaust. (there's probably a Civic hidden in there somewhere...)
Click to expand...

I dont live in a world where most car owners modify their exhaust. I do live in a world where most turbo subie owners do, though. Ask how many members on this forum have a completely stock wrx, sti, legacy gt etc.....

Myztyk said:
Also, in what universe is a Turbo Subaru a common car???
Click to expand...

They arent exactly rare...with the exception of the tribeca, I believe every model avail in n.america is available turbocharged (impreza, forester, legacy, outback etc) and the wrx model outsells the normally aspirated 2.5i variant according to global sales figures. In any event, I dont recall making any statement that they are a common car.
 
Last edited:
I actually watched this episode.

For the first part they take old cars and bikes from the 80-00's and analyze their emissions. Not suprisingly, the bikes get better fuel economy, and emit less CO2, but otherwise spew deadly poisons into the atmosphere like there's no tomorrow.

For the second part they take a WR250X, the only fuel injected catalysed bike and fab a canopy for it to reduce drag. It ends up getting over 70MPG, but the emissions are still pretty poor. Still, I wonder if there isn't a better "best-case" bike, the fuel injection on the WR250X is probably pretty simple. The BMW S1000RR has multiple oxygen sensors, but the catalytic converter probably self-destructs pretty quick. Maybe a fancy touring bike, or a Japanese 600SS?
 
Fuel injection and catalytic converters don't guarantee low emissions.

My ZX10R fits that description, and I left it stock for years, and one thing I was never happy about was the dismal fuel consumption. Upon acquiring an air/fuel ratio gauge for general tuning purposes, I fitted it to that bike ... and determined that it was running at 11:1 air/fuel ratio during highway cruise, which is obnoxiously rich and completely unnecessary.

Power Commander here we come, and over some period of time I made up my own map for it that uses "lean cruise" (slightly leaner than stoichiometric throughout the entire part-load regime except at idle because I couldn't get it to idle smoothly when lean - but it's still a lot less pig-rich than it was).

The OEM emission control strategy was to let the engine run rich then squirt air into the exhaust and let the catalytic converter clean up the mess. It is an open-loop system - no oxygen sensor. It's easier for the OEM's to err on the rich side.

The new "lean cruise" strategy probably spews NOx like there's no tomorrow, but it's almost certain to be better in terms of CO and HC - haven't measured it, though. Fuel consumption is much improved - went from 7 - 8 L/100 km to low 5's and that's despite putting dragstrip short gearing on it at around the same time.

The European version of that bike (which had to meet Euro 3) has an O2 sensor and runs in closed loop for some portion of the speed/load range ... but probably only for the minimum region necessary to pass the regulatory test and no more.

My Honda CBR125 uses closed-loop EFI with lambda sensor and 3-way catalyst. It runs at stoichiometric up to quite high load on the engine, provided it is not too cold.

The remaining issue is probably catalyst durability, because there is no durability requirement in the motorcycle emission standards. And the catalyst isn't very big. It's probably the minimum necessary to pass the Euro 3 regulation and no more.
 
Brian P said:
Fuel injection and catalytic converters don't guarantee low emissions.

My ZX10R fits that description, and I left it stock for years, and one thing I was never happy about was the dismal fuel consumption. Upon acquiring an air/fuel ratio gauge for general tuning purposes, I fitted it to that bike ... and determined that it was running at 11:1 air/fuel ratio during highway cruise, which is obnoxiously rich and completely unnecessary.

Power Commander here we come, and over some period of time I made up my own map for it that uses "lean cruise" (slightly leaner than stoichiometric throughout the entire part-load regime except at idle because I couldn't get it to idle smoothly when lean - but it's still a lot less pig-rich than it was).

The OEM emission control strategy was to let the engine run rich then squirt air into the exhaust and let the catalytic converter clean up the mess. It is an open-loop system - no oxygen sensor. It's easier for the OEM's to err on the rich side.

The new "lean cruise" strategy probably spews NOx like there's no tomorrow, but it's almost certain to be better in terms of CO and HC - haven't measured it, though. Fuel consumption is much improved - went from 7 - 8 L/100 km to low 5's and that's despite putting dragstrip short gearing on it at around the same time.

The European version of that bike (which had to meet Euro 3) has an O2 sensor and runs in closed loop for some portion of the speed/load range ... but probably only for the minimum region necessary to pass the regulatory test and no more.

My Honda CBR125 uses closed-loop EFI with lambda sensor and 3-way catalyst. It runs at stoichiometric up to quite high load on the engine, provided it is not too cold.

The remaining issue is probably catalyst durability, because there is no durability requirement in the motorcycle emission standards. And the catalyst isn't very big. It's probably the minimum necessary to pass the Euro 3 regulation and no more.
Click to expand...

Interesting points, I remember reading something along the lines of it being better for the engine to run on the rich side to get the catalytic convertor up to operating temperature quicker and to maintain it. Running the engine leaner than that, or even at stoich may cause premature catalytic convertor wear, not to mention increased emissions. Same reason why your fuel economy gues into the gutter in the winter if you do a lot of cold starts. Effectively burning more gas, but getting cleaner emissions out of the pipe. I could be wrong on the above, but pretty sure it's something along those lines.
 
Are emissions measured as a ratio, or as an absolute amount?

When it is said that the bikes are worse for emissions, even though they have better fuel economy, does that mean that in final amounts (ie: actual weight/volume of polutants put into the atmosphere) they are worse, or only worse per litre of fuel burned?
 
jolomatic said:
Are emissions measured as a ratio, or as an absolute amount?

When it is said that the bikes are worse for emissions, even though they have better fuel economy, does that mean that in final amounts (ie: actual weight/volume of polutants put into the atmosphere) they are worse, or only worse per litre of fuel burned?
Click to expand...

They are measured in ratios. For an example, look here: http://en.wikipedia.org/wiki/European_emission_standards (most bikes are built to target Euro 3)
Forum Sponsor
 
You must log in or register to reply here.

Back
Top Bottom