Author Topic: questions about running a cat (reduce smoke?) (Read 3835 times)

the4ork · « **on:** July 09, 2007, 09:54:28 pm »

im considering running a 3" DP to a 3" universal cat and 3" straight piping all the way to the back...

would a cat help reduce some of the smoke? shoulnt hurt performance too much since it would only act like a muffler, and since im running 3" little or no back pressure issues right?

plus it will help reduce SOME sound

jtanguay · « **Reply #1 on:** July 09, 2007, 10:35:00 pm »

hmmm essentially the cat just brings up the exhaust temperatures by using high temp metals such as platinum as far as i know... the gases flowing over these hot metals 'burn' to reduce emissions. not sure if it would get hot enough to do anything about diesel soot though... you're better off tuning your pump like i did. my car has a very light haze when it is hot and humid outside which is okay.

burn_your_money · « **Reply #2 on:** July 10, 2007, 12:52:58 pm »

Well the ECO diesel and post mk2 come with a cat so they must be doing something

bevboyy · « **Reply #3 on:** July 10, 2007, 02:24:46 pm »

The eco's have a special cat, and they can use them as their pumps are missing the lda, which dumps more fuel under boost. More fuel = more soot. The eco and N/a pump can only wick up fuel to a degree, and when in combination with a turbo, they run lean = less soot.

Why put one on if you are building your TD? If it is noise issue, just run two glass packs - one midline as a resonator - the other as a muffler on the tail end. I have this set up on my wifes quantum and it is actually quite civil..

bigblockchev · « **Reply #4 on:** July 10, 2007, 08:45:31 pm »

It is my understanding that diesel cats are quite a different animal than gas engine cats. They are more of a soot trap. It would seem that unless you are planning to use something originally designed for a diesel it will be useless and plug up real fast , universal cats are gas engine only. There are some diesel cats that you could use, my 95 diesel Suburban has a nice big cat but they are quite pricey like $1400 and to the best of my knowledge no aftermarket ones exist, Cheers Dan

clbanman · « **Reply #5 on:** July 11, 2007, 06:29:20 am »

From Wikipedia:
For compression ignition (i.e., Diesel) engines, the most commonly used catalytic converter is the diesel oxidation catalyst. The catalyst uses excess O2 (oxygen) in the exhaust gas stream to oxidize CO (Carbon Monoxide) to CO2 (Carbon Dioxide) and HC (hydrocarbons) to H2O (water) and CO2. These converters often reach 90% effectiveness, virtually eliminating diesel odor and helping to reduce visible particulates (soot), however they are incapable of reducing NOx as chemical reactions always occur in the simplest possible way, and the existing O2 in the exhaust gas stream would react first.

To reduce NOx on a compression ignition engine it is necessary to change the exhaust gas - two main technologies are used for this - selective catalytic reduction (SCR) and NOx (NOx) traps (or NOx Adsorbers).

Another issue for diesel engines is particulate (soot). This can be controlled by a soot trap or diesel particulate filter (DPF), as catalytic converters are unable to affect elemental carbon (however they will remove up to 90% of the soluble organic fraction). A clogging soot filter creates a lot of back pressure decreasing engine performance. However, once clogged, the filter goes through a regeneration cycle where diesel fuel is injected directly into the exhaust stream and the soot is burned off. After the soot has been burned off the regeneration cycle stops and injection of diesel fuel stops. This regeneration cycle will not affect performance of the engine.

All major diesel engine manufacturers in the USA (Ford, Caterpillar, Cummins, Volvo, MMC) starting January 1, 2007 are required to have a catalytic converter and a soot filter inline, as per a new DoT legislation.

http://www.discountconverter.com/diesel/index.htm

http://www.cats-direct-shop.co.uk/volkswagen-diesel-catalytic-converter.php

http://www.azom.com/details.asp?newsID=1955

bigblockchev · « **Reply #6 on:** July 11, 2007, 07:40:37 am »

So thanks for the good info on cats!! They are different than gas cats. It would appear that to install one on a vehicle that did not have one originally one would have to somehow duplicate the regeneration cycle, whatever that is. Since"

Quote

clogging soot filter creates a lot of back pressure decreasing engine performance. However, once clogged, the filter goes through a regeneration cycle where diesel fuel is injected directly into the exhaust stream and the soot is burned off. After the soot has been burned off the regeneration cycle stops and injection of diesel fuel stops. This regeneration cycle will not affect performance of the engine.

" Cheers Dan

clbanman · « **Reply #7 on:** July 13, 2007, 12:22:08 pm »

While I was looking at this I found some information at http://patents1.ic.gc.ca/details?patent_number=2221118 dealing with a patent that a company we buy diesel emissions equipment from that mentions reducing pollutants in combination with a convertor by adding diesel fuel to the fuel in the engine.
I also found some other information on diesel convertors at their site:

http://www.dcl-inc.com/techlib/Predicting%20Diesel%20Particulate%20Filter%20Performance%202%20-%20MDEC%20Oc.pdf
Their url is http://www.dcl-inc.com