Straight exhaust.

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lazarat

lazarat

Well-known member
Joined
Feb 7, 2018
Messages
657
So I had noticed the old turbos rattly rusty and one seemed a little louder.

Here is an interesting video (in German, a back pressure exhibition using a SBC 5.0, hit CC for translation: https://www.youtube.com/watch?v=UVenCRGGGRM.

So I cut the turbos out and decided to try straight pipes. I have stock exhaust manifold, where the passenger side slopes back and the driver side drops straight down. both go into two inch pipe which dumps out before back wheels.

Then to help with the 'pop' I cut about an inch tab and folded in to create a slight baffle. Put the tips back on which hides the crime.

Loud inside the cabin, but not too bad outside. Not sure i like it, just an experiment, I am between glaspacs and smaller turbos, would like to eventually get headers but thats going to require all kinds of creativity.

EDIT: Got the Thrush Glaspacs. Sounds a lot better, need to configurate a little more.

.
 
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Interesting video.

Megaphones. [ddd Must answer the question of why the big oval exhaust tips. Besides looking cool of course.
 
Straight exhaust is one of my peeves. I have no use for it on a street vehicle.

In regards to the video, his demonstration only focuses on back pressure but changes the total length of the system considerably which also has an impact. I've seen much better videos that focus on the changes in power production with exhaust diameter and length and actual science. Engine Masters has done a lot of really interesting stuff, but it's on a subscription streaming service.

The summary is that the age-old "engines need backpressure to make power" idea isn't proven through testing. A bigger or more free-flowing exhaust can make more power if the engine needs the flow. After a certain point it doesn't help power production, it just makes it louder. However, open headers can also make an engine lose power because of the pressure wave frequency causing some strange effects. There's a lot of science to it, the guy on the YouTube video barely scratched the surface.
 
05snopro440 said:
Straight exhaust is one of my peeves. I have no use for it on a street vehicle.

In regards to the video, his demonstration only focuses on back pressure but changes the total length of the system considerably which also has an impact. I've seen much better videos that focus on the changes in power production with exhaust diameter and length and actual science. Engine Masters has done a lot of really interesting stuff, but it's on a subscription streaming service.

The summary is that the age-old "engines need backpressure to make power" idea isn't proven through testing. A bigger or more free-flowing exhaust can make more power if the engine needs the flow. After a certain point it doesn't help power production, it just makes it louder. However, open headers can also make an engine lose power because of the pressure wave frequency causing some strange effects. There's a lot of science to it, the guy on the YouTube video barely scratched the surface.
Click to expand...

Well I hated the straight pipe experiment.

I see a lot of open headers on these T's and A's and gassers at the shows. What about the idea of baffling to create back pressure if needed, since glaspacs are basically open exhaust?

I am in mock up mode need to hang, maybe a cut or new bend, etc.
 
It`s in Dutch btw...not German. Anyone remember the muffler for the trike I built...? :rolleyes:

edit; I mean the trike I built, not the muffler :eek:
 
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dutch said:
It`s in Dutch btw...not German. Anyone remember the muffler for the trike I built...? :rolleyes:
Click to expand...

Thought it might be Dutch, Dutch. :)

I had straight pipes on my 65 Norton chopper, crafted by Midas! That was an interesting deal :rolleyes:
 
lazarat said:
Well I hated the straight pipe experiment.

I see a lot of open headers on these T's and A's and gassers at the shows. What about the idea of baffling to create back pressure if needed, since glaspacs are basically open exhaust?

I am in mock up mode need to hang, maybe a cut or new bend, etc.
Click to expand...

Glasspacks do impact flow through the exhaust, so functionally they're not that similar to straight pipe. I'll have to watch the videos again and see if they did a good comparison with glass packs.

If you're just going for looks (open headers on a Model T or A), then 5-25 horsepower lost with your choice of exhaust isn't a big deal.
 

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