Bruce Amacker Posted May 29, 2011 Share Posted May 29, 2011 How many catalytic convertors are there on a 6.7 F250? Quote Link to comment Share on other sites More sharing options...
Cetane Posted May 29, 2011 Share Posted May 29, 2011 There is probably something I am forgetting, but I vote for 5. Quote Link to comment Share on other sites More sharing options...
mchan68 Posted May 29, 2011 Share Posted May 29, 2011 One. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 29, 2011 Share Posted May 29, 2011 Now that you ask I am afraid to answer. Am I right in thinking that Mr. Amacker has discovered something that is not documented (at least not where I am looking) in the process of making his 6.7L cutaway engine? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted May 29, 2011 Author Share Posted May 29, 2011 Cetane has it right, five if you include the DPF. I don't remember these dual cats in any of the service or training info. I love cutting stuff open to find out what's inside! 1 Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 29, 2011 Share Posted May 29, 2011 We need to remember that the DPF and the SCR ARE catalysts. Quote Link to comment Share on other sites More sharing options...
mchan68 Posted May 29, 2011 Share Posted May 29, 2011 We need to remember that the DPF and the SCR ARE catalysts.THANK YOU for the clarification. I always love learning something new. KNOWLEDGE is the one thing that NOBODY can ever take away from you. Quote Link to comment Share on other sites More sharing options...
Matt Saunoras Posted May 30, 2011 Share Posted May 30, 2011 any EGR doc on these engines? it's been so long since i was in 6.7 class I can't remember Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 30, 2011 Share Posted May 30, 2011 any EGR doc on these engines? it's been so long since i was in 6.7 class I can't remember That is what I was thinking but I too did not remember there being one. I was looking in my Coffee Table Book... Then who would have though that the DOC and the DPF were not constructed with a single substrate as evidenced by Bruce's picture of the halved assembly. In a way Bruce's question is almost a trick question. A fun one I might add. So this makes me ask why? Are the separate catalyst substrates different for any chemical reason or are the two smaller catalysts less likely to break up physically and fail as opposed to one larger piece of substrate? Originally Posted By: Bruce Amacker I don't remember these dual cats in any of the service or training info. I love cutting stuff open to find out what's inside! And I love the fact that you cut things apart! Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted June 1, 2011 Author Share Posted June 1, 2011 Nope, no EGR DOC on a 6.7. Quote Link to comment Share on other sites More sharing options...
GregH Posted June 1, 2011 Share Posted June 1, 2011 I'd like to argue the semantics of classifying the DPF as a catalyst. The DOC and the SCR are made of materials that participate in the chemical reactions the exhaust gasses go through. While not being consumed, they provide an environment that allows the reaction to continue. The material they are made of is very important. This fits the definition of a catalyst. Once the gasses make it to the DPF, the breakdown reactions are complete. The DPF simply screens out particles bigger than a certain size and hold onto them. Later, during regen, it holds onto the soot as it burns and contains the ash that results. The DPF remains chemically inert the whole time. The material the DPF is made of is chemically irrelevant - as long as it can be made with sufficiently small holes and can withstand the temperature and vibration. So, the DOC and SCR are catalysts, of which there are two each. The DPF is a filter, not a catalyst. Final count is four. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 1, 2011 Share Posted June 1, 2011 The Workshop Manual describes a DPF as "The DPF is a highly engineered silicon carbide wall-flow catalyst that traps particulates." Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted June 1, 2011 Author Share Posted June 1, 2011 The WSM disagrees with you, Greg. In section 309-00 the system operation guide clearly calls out the DPF to be a catalytic convertor. "The DPF is a highly engineered silicon carbide wall-flow catalyst that traps particulates." Generic DPF info: Made of a porous ceramic material, silicon carbide, or cordierite, and commonly coated with platinum. A picture from my Diesel Emissions Book: Have fun! Edit: I was typing while Keith was posting. He types faster than I do. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 1, 2011 Share Posted June 1, 2011 I thought I had read somewhere that the DPF is impregnated with something to cause a chemical change... don't remember where but it was similar to what Bruce posted above. If we want to dumb this down and be semantic about it as well, we can apply another definition of a "catalyst" to the DPF in that it changes the composition of the exhaust gasses by physical removing the particulates and then converting the hydrocarbons in particulates into ash. catalyst n 1. (Chemistry) a substance that increases the rate of a chemical reaction without itself suffering any permanent chemical change 2. a person or thing that causes a change One thing I wish Ford would do is offer a better description of these components, even if it means baffling us with chemistry and engineering babble. Quote Link to comment Share on other sites More sharing options...
GregH Posted June 1, 2011 Share Posted June 1, 2011 I think that if we consider the removal of particulate matter from the exhaust stream by the DPF enough to classify it as a catalyst, then I concede. However, I don't think mechanically removing particles suspended in the exhaust stream should qualify. The DPF on the 6.7 is made of silicon carbide, per the workshop manual, as both Bruce and Keith stated. I also see where the workshop manual specifically calls the DPF a catalyst. However, I don't see where the DPF is assisting in a chemical change in the exhaust stream. Silicon carbide is used in a variety of applications. One of those applications is in catalytic converters, as a Catalyst Support. In this case, the only requirements of the material is that it be inert, thermally stable, and mechanically robust. From wikipedia, the characteristics of a silicon carbide wall-flow filter are as follows: The characteristics of the wall flow diesel Particulate filter substrate are as follows: Broad band filtration (the diameters of the filtered particles are 0.2-150 μm); High filtration efficiency (can be up to 95%); High refractory; High mechanical properties. High boiling point. No mention of catalyst action. However, of interest to me is the diagram of material into and out of a DPF. Hydrocarbons, PAH (is this redundant?) and particulate matter are stopped by the filter, as expected. CO, however, is also stopped - I didn't expect to see that. CO, as a relatively inert gas, should continue through the filter as if nothing has happened. It could combine with oxygen in the presence of sufficient heat (such as during regen) to make CO2, but the diagram doesn't make that connection. The Edmonton Trolley Coalition has an article about DPF that also mentions the CO to CO2 conversion, but does not describe the actual mechanism. If the DPF is actually a catalyst, then all I can see is that it catalyzes carbon monoxide into carbon dioxide... Quote Link to comment Share on other sites More sharing options...
Cetane Posted June 2, 2011 Share Posted June 2, 2011 The 2011 DPF is a catalyst, meeting Greg's definition. Unfortunately thats about all I can say. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 2, 2011 Share Posted June 2, 2011 I think that if we consider the removal of particulate matter from the exhaust stream by the DPF enough to classify it as a catalyst, then I concede. However, I don't think mechanically removing particles suspended in the exhaust stream should qualify. The DPF on the 6.7 is made of silicon carbide, per the workshop manual, as both Bruce and Keith stated. I also see where the workshop manual specifically calls the DPF a catalyst. However, I don't see where the DPF is assisting in a chemical change in the exhaust stream. I agree on all points. However there seems to be hints that indicate that there IS something going on in the DPF beyond filtration. Like I said, I wish FORD would expand on this in the literature, but in reality I guess "we" don't need to know. I will say that when you look at the entire system it is amazing how clean the result is. Could you have imagined this 20 years ago? AND, there is no need to concede my friend, this is a discussion, not an argument. Quote Link to comment Share on other sites More sharing options...
GregH Posted June 2, 2011 Share Posted June 2, 2011 The 2011 DPF is a catalyst, meeting Greg's definition. Unfortunately thats about all I can say. Enigmatic.. Intriguing... What compounds are the DPF designed to deal with? Is Bruce's diagram correct with the CO conversion? Is the silicon carbide coated or doped with something? Is this above our pay grade? Quote Link to comment Share on other sites More sharing options...
GregH Posted June 2, 2011 Share Posted June 2, 2011 Could you have imagined this 20 years ago? 10 years ago we didn't even have catalytic converters on diesels... Black pipes, bed sides and rear bumpers... We've been cleaning the air in some parts of the country since the 6.4... Where will we be in another 10 years? Quote Link to comment Share on other sites More sharing options...
Cetane Posted June 2, 2011 Share Posted June 2, 2011 If you google "coated DPF" you might find some articles describing the main reason for having the coating. There are some secondary benefits as well that I can't/won't describe. This is really the reason I don't participate in the forums much anymore. I cant say a whole lot more than you already know. Sorry. It is probably more frustrating to me than to you that you guys are left in the dark about a lot of the inner working of the systems you are expected to fix, but that is a topic for another thread. Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted June 3, 2011 Share Posted June 3, 2011 Originally Posted By: Keith Browning Could you have imagined this 20 years ago? 10 years ago we didn't even have catalytic converters on diesels... Black pipes, bed sides and rear bumpers... We've been cleaning the air in some parts of the country since the 6.4... Where will we be in another 10 years? Um, didn't the 1995+ 7.3 have a cat bolted to the flange at the end of the down pipe? I think they did until 2001-ish or about then. In 10 years, if the current gov't has their way, we'll all be range limited in electric golf carts. They'll just tax us to death if we try to drive anything that uses an ICE. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 3, 2011 Share Posted June 3, 2011 Yep, they did. But your math is fuzzy. 1995 was only 16 years ago! (sorry, couldn't resist) Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted June 4, 2011 Share Posted June 4, 2011 Well, he did say that 10 yrs ago there were no cats on diesels, so I went a little farther back. I still can't believe '95 is 16 years ago...... I still remember seeing the first 94.5 7.3 DIT and thinking, wow, does that thing look hard to work on! Ah, the good old days! where has the time gone? We got a throwback, a farmer's 1984 6.9 C6 pickup, locked up tight, every time it rains, as the hood/cowl seal was bad, and the water would fill the top of the air cleaner cover and run in the little vent cap. Enough water to bend 2 rods and break the nose clean off the big delco starter. It still runs, albeit a bit knocky, after pulling glow plugs and pumping out the water. Now that thing STINKS when it runs... I wanna puke. Makes a 6.0 idling smell like roses, well, almost. The farmer's still gonna keep using it. Quote Link to comment Share on other sites More sharing options...
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