circular base flange at end of exhaust?

rreegg

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Was passing through Astoria, OR last weekend and while walking around saw an idi bricknose f250 parked at/by a church. Was just admiring it for a bit and noticed the end of the exhaust pipe had what looks like a base flange (wasn't able to take a photo but linked the basic concept from mcmaster below) - it was circular and had like 6 holes around.

Does anyone know the purpose of this if there is one? I've never seen anything like it before but also know little about exhaust systems/design. Is it for bolting on/extending the exhaust tip? Thought exhausts were usually welded or would just use an oval/two bolt flange for joints.

The truck seemed to be really well maintained all around and is probably owned by an Organization rather than individual - just to say it seems intentional rather than something slapped together.

 

Nero

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If it's what I'm thinking it is, lots of newer semis use them on their exhaust dumps that are near the ground, it creates an air vortex to suck in cold air through the holes to cool the exhaust down faster
 

Jesus Freak

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If it's what I'm thinking it is, lots of newer semis use them on their exhaust dumps that are near the ground, it creates an air vortex to suck in cold air through the holes to cool the exhaust down faster
....huh?..... did Elon musk invent this?...
 

rreegg

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Dang that's a fascinating concept, not sure if this truck was turbo but maybe it was upgraded since there were also suspension air bags... didn't see any gauges. From some more searching it seems to resemble an exhaust "trim ring/bezel" even though it wasn't used for that. Oh well would be curious what considerations would make them need/want extra exhaust cooling especially if NA
 

KansasIDI

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Photo 1 is what my brain thinks

Photo 2 is probably more along the lines of what it looks like
 

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KansasIDI

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The tip in the second photo is called an intercooled tip, it creates a vacuum on the exhaust when air moves through the fins, cooling the air as it exits the tip, and scavenging the gases outward. It is commonly used on trucks with DPF, the 6.4 and 6.7 powerstroke exhaust tips use this kind of tip, but it of course varies slightly in looks. Duramax trucks from the LMM series to present also use this style tip stock, and the GM tips are called ‘UFOs’ by some people. Dodge doesn’t use them, and most DPF-back exhaust kits do not use these tips, I don’t think they are really necessary, but cool concept. They supposedly lower EGTs, marginally, by supposedly getting the exhaust out faster. Atmospheric pressure will affect this more than these tips, from what I have seen with them

Some high performance cars and some exhaust kits for said cars also use these tips
 

Jesus Freak

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What about the exhaust tips that have like bendy tabs a few inches back inside them? Do thay do the exhaust cooling thing? Why would you cool your exhaust? Is it the make the air cooler for the guy behind you with a cold air intake?
 

KansasIDI

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What about the exhaust tips that have like bendy tabs a few inches back inside them? Do thay do the exhaust cooling thing? Why would you cool your exhaust? Is it the make the air cooler for the guy behind you with a cold air intake?
Bendy tabs? My mind kinda just goes blank, either I’ve never seen such a thing or my feeble mind simply does not register… I do believe the intercooled tips are yet another scam by our beloved government to ‘save the environment’. Best way to save the environment is keep trash picked up and go to work and keep the world spinning round… but in D.C. they think saving the environment is turning diesel smoke into butterfly farts and protesting about how the seals and fish ate some plastic… if your worried about animals eating trash then go pick up trash instead of protest, make a difference, not a scene.

Sorry for the rant
 

Nero

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The cooling bit is exactly what it does. I have a shop air blow gun that does the same thing, creates a negative vacuum around the tip, causing more air flow, thus more blowing ability. Gets pretty cold, same concept is used on the exhaust.
As for cooling, definitely for exhaust cooling, as dpf regen temps can exceed 1300F. What's also fun is when CNG trucks run them too, they have 3 catalytic converters, so they be piping hot exhaust too.
 

u2slow

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I've wondered, in addition to cooling, that those tips may help disperse sooty black exhaust quicker?
 

Nero

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I've only ever seen them used on vehicles that have aftertreatment. I would imagine it would just act like an air pump, adding extra clean air to the black exhaust to thin it out, but there's no real point in doing that. Black exhaust shouldn't be a thing anyways.
 

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