CRDMiller wrote:
I am not 100% on this but i am fairly sure the "cat/filter/part trap" that we have on our crd's are OXIDATION catalyst converters.
That is, they use Platinum and Palladium to (oxidize) HC's and CO to H2O and CO2.
Other types of converters can be used such as "Reduction Catalyst Converters" witch use Rhodium to turn nox levels down to O and H. but it only works when cyl burns are Stoichiometric (witch aint happening in our crd's) OEM's use dosing (injecting on exhaust stroak or using a injector after turbo before "cat") To get there, again not happening in our crd's.
There are also Nox Adsorbtion (not a typo) Catalysts but those require NAC regen cycles, basically NO oxygen can be in the exhaust (not happening in our crd's) They work pretty well though and drop nox into N2 O2 and H2O These use a pretty interesting selection of base metals to actually "store" NOx's and these are sereiously damage by the presence of SULFUR
So, running LSD or normal D2 is fine for us, but it can produce more "ash" and clog our oxidation converters (i don't have one, it fell off) it can not permanently damage our systems. in comparison to NAC's witch can be permanently damaged with as little as 40 miles on normal d2 and again with as few as 100 miles on LSD.
There are only 3 ways for Sulfur to get into our engiens, intake, oil (burnt) and fuel. If there is sulfur in our oil and it gets combusted off the cyl walls on the power stroke because it was not removed by the oil control ring, it can introduce sulfur in to the exhaust an destroy things .(NAC's) This is the reason why we have new oils (cj-4) and fuels (ulsd)
All of this was to reduce NOx emissions from diesel engiens. The side effect is we get less sulfur oxides in the atmosphere which is Great for us, bad for out IP's.
Some of the fractions of diesel oil that provide lubricity are lost during the process that removes sulfur from our fuel, it is added later as an additive package, it also reduces the CN (Cetane Number) of our fuel, witch measures IGNITION quality, and nothing else. The fractions of diesel oil that control the CN (non addative) are pretty volatile and easily "boil" off during storage due to heat
Why you would get better economy is simply because ulsd has a lower specific gravity which equates to loss in btu in any given volume, but were only talking 2-5 %.
There are no trapping or filtering functions with out CATs. They are the straight forward oxidation type, with fairly large honeycomb passages.
Reduction Catalyst Converters do not produce O and H from NOx (H2O is however produced by RCCs from unburnt HCs), they form N2 and O2.
Sulfur is not one of the ash producing components in diesel or motor oil. The new formulation low ash oils have had much of the Ca Mo and Zn (the actual ash producing elements) removed in order to protect Cat converters and DPFs. Engine oil has never really had any appreciable amounts of Sulfur in it.
Sulfur in the fuel will
NOT clog or "poison" the cat under normal operating conditions because a Diesel's cat reaches such high temps with an abundance of O2, and burns off any sulfur accumulations. The catalyst can be deactivated by prolonged idling with HSD, but is easily restored by a 10 minute hard drive. The extra sulfur will cause the catalyst to reach the end of it's usable life sooner than ULSD, but we are talking >100000 miles.
I have decided that I don't care about the amount of Sulfur coming out of my tail pipe, since more Sulfur is produced in nature by one single volcano, than by all of the trucks in existence.
None of this business about plugging cats with S0x applies to me anyway, since like you my CAT has spilled it's guts.
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