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Old 08-10-2022, 06:41 PM   #11 (permalink)
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All this talk of ram air makes me wonder if the opposite isn't true at the other end..?

ie: Where's the lowest pressure area at the rear of a car? And why doesn't the exhaust exhaust there..??

Yes it's all about keeping CO low, rather than smothering fellow motorists, but perhaps one of those exhaust valves can be made to work at higher speeds where it will be useful.

Hmm... you'd likely want the exhaust sealed where it goes through the rear panel.
Not so easy..?

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Old 08-10-2022, 07:42 PM   #12 (permalink)
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Bellmouths to maximize the coupling.
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Old 08-10-2022, 08:28 PM   #13 (permalink)
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Bellmouths to maximize the coupling.
LOL!

Ye! Except they exit where the number plate is currently. (I'm guessing that's the lowest pressure area on a Bug?)

(I'd love to hear that thing run! )
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Old 08-10-2022, 08:32 PM   #14 (permalink)
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LOL!

Ye! Except they exit where the number plate is currently. (I'm guessing that's the lowest pressure area on a Bug?)

(I'd love to hear that thing run! )
In the past I've had vehicles where the exhaust would get caught up in the turbulence at the rear of the car, and make its way forward through the cabin vents at the rear, and it would smell like exhaust while driving. Moving the exhaust out of the low pressure zone fixed that, unfortunately.
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Old 08-10-2022, 09:41 PM   #15 (permalink)
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This was a bad idea:

i.pinimg.com/736x/e6/81/40/e68140271117bf2e4d3eb7800d5c3ae3--tear-rear-window.jpg
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Old 08-11-2022, 05:14 AM   #16 (permalink)
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In the past I've had vehicles where the exhaust would get caught up in the turbulence at the rear of the car, and make its way forward through the cabin vents at the rear, and it would smell like exhaust while driving. Moving the exhaust out of the low pressure zone fixed that, unfortunately.
Hmmm ye; one does NOT want that happening!

Strange that it would though, unless the trunk didn't seal properly and there was a negative pressure in the cabin..?
Aerodynamics can do strange things, I know.

Cabin vents are usually situated somewhere high up behind the rear windows aren't they?
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Old 08-11-2022, 06:19 AM   #17 (permalink)
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Quote:
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Hmmm ye; one does NOT want that happening!

Strange that it would though, unless the trunk didn't seal properly and there was a negative pressure in the cabin..?
Aerodynamics can do strange things, I know.

Cabin vents are usually situated somewhere high up behind the rear windows aren't they?
In most Hondas they're behind the rear bumper cover, under the tail lights. They have little rubber flaps that are supposed to only allow air out of the cabin and not back in, but for whatever reason, it seems to happen. Maybe when windows are open and there is some venturi effect going on?
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Old 08-11-2022, 12:15 PM   #18 (permalink)
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lowest pressure

Quote:
Originally Posted by Logic View Post
All this talk of ram air makes me wonder if the opposite isn't true at the other end..?

ie: Where's the lowest pressure area at the rear of a car? And why doesn't the exhaust exhaust there..??

Yes it's all about keeping CO low, rather than smothering fellow motorists, but perhaps one of those exhaust valves can be made to work at higher speeds where it will be useful.

Hmm... you'd likely want the exhaust sealed where it goes through the rear panel.
Not so easy..?
The lowest pressure will occur along the sides of the vehicle, not the rear.
Exhausting to the rear requires that zero leakage occur at the trunklid (boot) seal, and seal between trunk and rear seat/cabin.
It's the reason NASCAR demands side pipes to dilute tailpipe gases which could be inhaled during 'drafting.'
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Old 08-11-2022, 05:47 PM   #19 (permalink)
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Quote:
Originally Posted by Logic View Post
All this talk of ram air makes me wonder if the opposite isn't true at the other end..?

ie: Where's the lowest pressure area at the rear of a car? And why doesn't the exhaust exhaust there..??
I am trying this out, making my exhaust exit at a low pressure area. Air velocity should be high here and pressure low. I should get a bump up in engine efficiency.



Seems to work well. Someday I will put on a slip on tail pipe and extend it past the bumper and do a A B A comparison in gas mileage.
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Old 08-11-2022, 06:31 PM   #20 (permalink)
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duckduckgo.com/?q=Bellflower+pipes

Straight outa Bellflower, CA. The H.A.M.B. can't let go of the pic, but check out www.jalopyjournal.com/forum/threads/bellflower-exhaust.400550/#post-5244862 and especially www.jalopyjournal.com/forum/threads/bellflower-exhaust.400550/#post-5537826

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