Exhaust flex pipe
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Tuned
Joined: Nov 2007
Posts: 386
Likes: 3
From: Whitmore lake Mi
Exhaust flex pipe
I have 2 options for exhaust in my 300 powered FFR kit.
1st EFI manifolds mounted rear = rear/front = rear.
2nd EFI manifolds mounted in the standard positions rear = rear/front = front.
I would like the 1st option as it would point both manifolds exits toward the front to a pipe which would exit out the body cutouts for the sidepipes this would give me smooth transitions and less clutter where I do not have much space but may cause issues with clearance with the alternator. This would mean I would have to modify the rear manifold for the front which means cutting/grinding and welding it which I do not want to pay someone to do and I am not sure if I want to tackle it with my novice welding skills.
The second option would mean less smooth transition more clutter i.e. less access to the starter and maybe heat issues.
Also at this point I am not locked into any configuration except I will be using EFI manifolds and it will have solid engine mounts.
All of this is just as I say "thumballed". The engine and trans are sitting in. I just finished gathering up the intake/exhaust manifolds and studs. I recently acquired my Weber DCOE's. Noting is mounted yet but will be soon.
So with that said could I have some opinions on using flex pipe? Which is easier to work with? What would be the best choice of material? Is it a good Idea or not?
Jim
1st EFI manifolds mounted rear = rear/front = rear.
2nd EFI manifolds mounted in the standard positions rear = rear/front = front.
I would like the 1st option as it would point both manifolds exits toward the front to a pipe which would exit out the body cutouts for the sidepipes this would give me smooth transitions and less clutter where I do not have much space but may cause issues with clearance with the alternator. This would mean I would have to modify the rear manifold for the front which means cutting/grinding and welding it which I do not want to pay someone to do and I am not sure if I want to tackle it with my novice welding skills.
The second option would mean less smooth transition more clutter i.e. less access to the starter and maybe heat issues.
Also at this point I am not locked into any configuration except I will be using EFI manifolds and it will have solid engine mounts.
All of this is just as I say "thumballed". The engine and trans are sitting in. I just finished gathering up the intake/exhaust manifolds and studs. I recently acquired my Weber DCOE's. Noting is mounted yet but will be soon.
So with that said could I have some opinions on using flex pipe? Which is easier to work with? What would be the best choice of material? Is it a good Idea or not?
Jim
Tuned
Joined: Nov 2009
Posts: 407
Likes: 0
From: Rochester
I had the flex exhaust on my truck for awhile while I was debating what I wanted to do. It rust really quick and becomes stiff. I also felt that the ribbed piping restricted flow alittle and the sound wasn't as good as with standard exhaust pipe. I would go with normal exhaust pipe the flex is ok for a temporary job but not anything permanent in my opinion.
Moderator
Joined: Aug 2002
Posts: 6,104
Likes: 384
From: Southern California
I had the flex exhaust on my truck for awhile while I was debating what I wanted to do. It rust really quick and becomes stiff. I also felt that the ribbed piping restricted flow alittle and the sound wasn't as good as with standard exhaust pipe. I would go with normal exhaust pipe the flex is ok for a temporary job but not anything permanent in my opinion.
Lead Driver
Joined: Dec 2000
Posts: 6,298
Likes: 47
From: South central, Minnesota
In my opinion the only thing that flex pipe is good for is emergency exhaust repairs in a parking lot!
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Tuned
Joined: Nov 2007
Posts: 386
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From: Whitmore lake Mi
I guess I should have mentioned if I do use it it will be semitemporay 
just to get it running. My plans are to add turbo in the future and since I can not find exact data on a 309 inline truck motor with 3x2 Webers and an AODE I need to learn/tweak that system before I add the turbo. Once that is done I would like to do it all in SS.
Jim
just to get it running. My plans are to add turbo in the future and since I can not find exact data on a 309 inline truck motor with 3x2 Webers and an AODE I need to learn/tweak that system before I add the turbo. Once that is done I would like to do it all in SS.Jim
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Lead Driver
Joined: Dec 2000
Posts: 6,298
Likes: 47
From: South central, Minnesota
I guess I should have mentioned if I do use it it will be semitemporay just to get it running. My plans are to add turbo in the future and since I can not find exact data on a 309 inline truck motor with 3x2 Webers and an AODE I need to learn/tweak that system before I add the turbo. Once that is done I would like to do it all in SS.
Jim
just to get it running. My plans are to add turbo in the future and since I can not find exact data on a 309 inline truck motor with 3x2 Webers and an AODE I need to learn/tweak that system before I add the turbo. Once that is done I would like to do it all in SS.Jim
If it was me I'd just build a pair of headers to get it to exit where I want.
And for the system I would just buy some mandrel U-bends to make the connections
Moderator
Joined: Aug 2002
Posts: 6,104
Likes: 384
From: Southern California
Code of Federal Regulations, each state adopts under a different cite (such as california vehicle Code, etc.) but flexible exhust pipes are prohibited in all 50 states.
Post Fiend
Joined: Jan 2005
Posts: 26,337
Likes: 12
From: Paradise Found!
Prove it! I just looked and can find NO federal law that prohibits it: Exhaust systems. - Federal Motor Carrier Safety Administration
I can also list at least a half dozen car and motorcycle manufacturers that use it from the factory!
I can also list at least a half dozen car and motorcycle manufacturers that use it from the factory!
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
This is what I am most familiar with:
Federal Motor Vehicle Safety Standards and Regulations
I cannot find a single occurrence of the word "exhaust" anywhere in it.
Forums like this are often a great venue for spreading BS & hearsay but presented as fact.
I personally hate that, and don't like to see FTE contributing to it.
Hence, since you're making a Statement of Fact, we're asking you to back that up with credible & verifiable sources.
Just as if you were turning in a Research Paper to the college prof; at the end, you have the Bibliography in which you list your sources of information presented in your paper.
Telling the prof to go look up & verify those claims himself will get you a big, fat F on the paper.
Federal Motor Vehicle Safety Standards and Regulations
I cannot find a single occurrence of the word "exhaust" anywhere in it.
Forums like this are often a great venue for spreading BS & hearsay but presented as fact.
I personally hate that, and don't like to see FTE contributing to it.
Hence, since you're making a Statement of Fact, we're asking you to back that up with credible & verifiable sources.
Just as if you were turning in a Research Paper to the college prof; at the end, you have the Bibliography in which you list your sources of information presented in your paper.
Telling the prof to go look up & verify those claims himself will get you a big, fat F on the paper.
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
I searched a bit more on fabman's listed site, found some more stuff about exhaust but absolutely no mention of anything regarding flexible pipe:
Exhaust systems. - Federal Motor Carrier Safety Administration
Exhaust systems. - Federal Motor Carrier Safety Administration
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
Class 8 trucks come from the factory with flex pipe connections in the exhaust system. They are the weak link in the system and have to be replaced as they rust out before the piping in the rest of the system. It's something DOT inspectors look for when doing safety inspections.
Moderator
Joined: Aug 2002
Posts: 6,104
Likes: 384
From: Southern California
California Vehicle Code Division 12 Chapter 5 Article 2, then read the appedices & supporting references.....
This also isn't something new, I can remember being taught this back when I was a jr in High school in Drivers ed....yes, they use to teach drivers ed in high school & it was part of the Hygiene requirement!
This also isn't something new, I can remember being taught this back when I was a jr in High school in Drivers ed....yes, they use to teach drivers ed in high school & it was part of the Hygiene requirement!