Originally Posted by
Chimbu chuckles
Andy RR your faith in catilytic converters is somewhat missplaced I think.
The only difference between 'leaded' fuels and 'unleaded' fuels is the addition of a
VERY small amount of TEL...it is very small because for decades now they have been putting toluene and all sorts of other carcinogens in all fuels so they could minimise TEL...even avgas has these ring compounds in
almost the same amounts as ULP
Seeing as how cat converters are so innefficient and, indeed, stop working after a relatively short time from new (a year or two-20 to 50000kms) I hardly think it is reasonable to suggest they are responsible, alone, for our cleaner air.
They are (or were), apparently, not mandated in NZ...and their air is at least as clean as ours.
Yet another example of single issue advocasy and political correctness robbing society of an informed decision I feel.
Sorry CC, I make my living out of engineering emissions control systems in cars etc. I know pretty much how catalyst systems work and what effect they are having. I know that a well designed and reasonably maintained car will meet its emissions standards for years and a hundred thousand miles at least.
As for catalysts being inefficient, does a 99.8% efficiency not do enough for you? An EU stage 4 car will have a catalyst efficiency of better than 95% on HC and more than 99% on CO from a cold start. That's at the very least 20 times less emissions than anything uncatalyzed and probably more, since non-cat cars tend to be made to run slightly rich.
An aero engine full rich at sea level will probably be belching out CO at an exhaust concentration of 10% or more. A catalyzed car will generate it at 0.5%
before the cat and it will be more-or-less unmeasureable after when the cat is above 250-300 degrees C
BTW, I agree with you on Ethanol - it is so far from carbon-neutral its not funny
But NZ hasn't got enough people to pollute itself to death. California is the best example of what emissions controls have done (and needed to do)
A