Random question on emissions

Pathfinder100 · 2024-07-07 17:21:25

So this has been bugging me for a while (and as much as I search on google I can't find any definitive answer).

Is there any benefit to running a second inline catalytic converter to reduce emissions further? So on our vans, if you removed the back box and replaced it with a secondary cat, would that do anything for the emissions, or are most of the emissions cleaned at the first stage offering little benefit to a second stage filtration?

Anyone have an answer, even if not definitive?

AlvyLad · 2024-07-07 19:14:14

Depending of factory set up Cats are meant to operate at higher or lower temps (own specific + and -)
Adding a second Cat, might be beneficial, if your emissions are trully bad (to not to pass Euro3), your engine must be really knackered in some or the other ways

2.0 HDI models (Euro 4 emissions)... I'm not gonna get involved with, just saying as power and sophistication on my Pug 5008 is amazing, but FAP and amount of electrics/electronics, I'd rather never needed to learn about.

Bottom line, you can fit lower operating temp additional Cat to get through MOT, so be it, but power restraint at any higher revs will be very noticeable, to "cut it back out" straight after

Last edited by AlvyLad (2024-07-07 19:17:51)

Pathfinder100 · 2024-07-08 01:52:15

Actually not specific to my van. I have never had a fail on emissions. I was just musing over things like the use of Ad Blue on Euro 6's and DPF on Euro 5's. I just wondered if adding a second inline cat would drop the emissions lower on older vehicles. But on my van I always get comments from the garage that the emissions test was super low. This is namely due to the fact i swap the oil and air filters, swap the oil and put 10-15L of High Octane diesel in the tank with a couple of caps of redex, prior to MOT. Been doing it that way for 30 years and never had an emissions fail on a diesel. Had a petrol fail once, but did a few things to tune it up and it passed.

AlvyLad · 2024-07-09 01:00:16

Cat elimination on my bike gained extra 7HP, especially on higher revs (on a 1100 CC , 100 HP bike)

Considering exhaust piping on our vans being more or less same size, despite being double CC capacity (but half of the revs, than petrol engines), doubling up CAT would build back pressure even more, so, if to say they realistically have 60 HP - ~10% =~54HP would be noticed fast enough
Whilst cutting all/any out, I highly doubt, if would make a gain more than +2% (~+ 1.3HP)
IMO wink

Last edited by AlvyLad (2024-07-09 09:39:15)

AlvyLad · 2024-07-09 17:05:12

Bit about "on the topic" about how cats work
https://youtu.be/lJiznlz5buc?si=WXjyTcbK5txSBVqJ

Exhaust gases are miles ahead in "purity", compared to prior to cats and miles behind current emission compliant engines

Casper · 2024-07-13 01:03:12

Just noticed two weeks ago that a previous owner has cut out the CAT on my bus and replace it with a bit pipe. That is three MOT's now with no emissions comments. Are you looking to get your van into a LEZ or just reduce your carbon footprint??

Pathfinder100 · 2024-07-19 21:58:38

Neither, just wondering if anyone had any ideas, links to resources or insight, on a theoretical question. i did think about it for my van a while back, but it's never failed an emissions test, so it's kinda moot.

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#1 2024-07-07 17:21:25

Random question on emissions

#2 2024-07-07 19:14:14

Re: Random question on emissions

#3 2024-07-08 01:52:15

Re: Random question on emissions

#4 2024-07-09 01:00:16

Re: Random question on emissions

#5 2024-07-09 17:05:12

Re: Random question on emissions

#6 2024-07-13 01:03:12

Re: Random question on emissions

#7 2024-07-19 21:58:38

Re: Random question on emissions

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