BENSV8

Just a quick question tonight before I go and dream of an LTD with 300-odd kW at the treads...

True or False (and why/why not): A street car that runs purely on LPG (petrol tank replaced with gas keg) has no need for a catalytic converter and can thus operate without one (or two) fitted.

RaceCraft

true, legally you can remove the cat convertor... the emmisions LPG are not considered to be as harmfull as ULP... less Carbon monoxide, bezine and a reduction in the type/volume (not sure which)of hydro-carbons

taximan

Yes but depends on what state you are in.Check with the local authorities.Different states different laws.

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davway

cat cons are only there for the use of petrol so really you dont need them just like you dont need your petrol tank anymore.

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Ghia5L

I did a class on this today :)

Cat converters: (have two parts)

OXIDATION CATALYST 2NO => N2+O2 or 2NO => N[size=1]2 + 2O2

REDUCTION CATALYST 2CO + O2 => 2CO2

I'm assuming a cat converter would be needed for LPG (rich) due to high CO emissions. (Rich LPG however has low NOx, and high hydrocarbons emissions). LPG (lean) could be a different matter, as it has low CO, low NOx, low hydrocarbons.

CO as we know is a no-no for us peoples to inhale. NO however (yes, don't we wish that was N2O) is very reactive with other atmospheric molecules. In a perfect environment with no pollutants -- freeradical organic molecules and hydrocarbons in particular -- NO reacts with ozone to make N2 and O2. This is a good process however, because it is ozone that is close to the earth's surface which it reacts with. This ozone is actually bad for us due to the fact that we can breathe this stuff in (it's toxic, + an irritant). NO doesn't have time to react with ozone up in the stratosphere, which is the stuff that blocks out UV rays.

EDIT (forgot to add): Because we don't live in a perfect world, there are hydrocarbons & freeradicals floating around. NO "traditionally" reacts with low-altitude O3, but when these pollutants are around, the NO has a choice of what to react with, and it happens to react with these pollutants much more quickly, meaning that O3 levels start to rise rather than remain in equlibrium.

Hope that wasn't too off-topic, I just thought it was good timing for me to reply with this since I learnt this about an hour ago :)

-Dave-

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Casper

Basically, its not even worth it, modern cats are efficient and, even at their worst, might rob a car of less than 5rwkw. Keep them and know your legal and helping the environment.

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Perana XR8

Yes what Shane said.... I have also heard of cars loosing power when the Cat is removed.

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Ben

Ghia5L

And cats generally last around 100,000km before they're basically ineffective. Best left on to keep the defect boys at bay I spose

-Dave-

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tinygumby

i was online to the rta yesterday on the very same subject.They tell me that if a car comes standard with them then they must remain.(dammit).Go to the "myrta" website and ask the technical people in the "contact us" part of the site.

tinygumby

Oh yeah , almost forgot - dont forget to bump up your compression ratio to 12:1 that way your gas is as efficient as petrol(no loss of power or increased consumption)Vrooom