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Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 8:07 pm
by Mito Man
It’s just a conclusion based on the fact that I’ve followed many BMWs crawling in traffic in London and in such instances the valve opens and closes irrelevant of how much throttle is used. They’re usually opening and closing every 10 seconds crawling at 5 mph so it must be doing something to reduce emissions.
Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 8:07 pm
by tim
It isn't. Mito is an idiot. None of this is news.
Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 8:16 pm
by V8Granite
When we run our gas engines through big urea filters we control the back pressure with a big butterfly valve. This is downstream of the cat and filter arrangement. It’s to make the filters more effective but I’m not sure at what point the back
Reassure affects it, ours is load dependant but I’ve not commissioned one yet.
It may be similar in that you need a certain gas flow through the cat to be as effecient as possible.
Dave!
Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 9:04 pm
by Mito Man
tim wrote: Sat Apr 27, 2019 8:07 pm
It isn't. Mito is an idiot. None of this is news.
If I’m an idiot does that make you completely brain dead?
https://www.partinfo.co.uk/articles/28
Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 10:22 pm
by NotoriousREV
Mito Man wrote: Sat Apr 27, 2019 1:12 pm
The only loser on this thread is Mito Boy because he’s spent the whole of his weekend so far googling this shit.
Re: Fake exhaust pipes
Posted: Sat Apr 27, 2019 11:09 pm
by duncs500
Wow. M1t0wn3d.
Re: Fake exhaust pipes
Posted: Sun Apr 28, 2019 7:05 am
by RobYob
McSwede wrote: Sat Apr 27, 2019 4:41 pm
Car starts noisy then quietens after a few seconds as the car is in comfort mode.
Noisy start is probably just the delay in accumulating enough vaccum to close the exhaust valve flap. I think some cars have started fitting small vacuum tanks to enable a "quiet start" mode. That or electric exhaust valves but they're far more expensive and heat sensitive.
As for the valves being used for controlling back pressure that's been happening for a while on dieseasels so it's now affecting petrol too. Higher back pressure gives you more EGR as a guess?
Re: Fake exhaust pipes
Posted: Sun Apr 28, 2019 11:04 am
by ste
McSwede wrote: Sat Apr 27, 2019 7:49 pm
Mito Man wrote: Sat Apr 27, 2019 6:52 pm
The valve opens and closes randomly when crawling through traffic from what I’ve seen, of course it opens fully under harder acceleration to also give more noise but it is definitely being used for emissions purposes too as every dual exhaust BMW seems to have it now regardless of being a sporty model or not.
How can it be anything to do with emissions? All the valve is doing is altering the route the gasses take as they have already been through the cat and PPF.
It's different to the pre-WLTP cars. They open and close constantly to increase back-pressure and heat the cats up more. It looks ridiculous.
Re: Fake exhaust pipes
Posted: Sun Apr 28, 2019 11:36 am
by McSwede
ste wrote: Sun Apr 28, 2019 11:04 am
McSwede wrote: Sat Apr 27, 2019 7:49 pm
Mito Man wrote: Sat Apr 27, 2019 6:52 pm
The valve opens and closes randomly when crawling through traffic from what I’ve seen, of course it opens fully under harder acceleration to also give more noise but it is definitely being used for emissions purposes too as every dual exhaust BMW seems to have it now regardless of being a sporty model or not.
How can it be anything to do with emissions? All the valve is doing is altering the route the gasses take as they have already been through the cat and PPF.
It's different to the pre-WLTP cars. They open and close constantly to increase back-pressure and heat the cats up more. It looks ridiculous.
Ok. I'm glad mine is out of site. I may just unplug it.