straight pipe questions
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New User
Joined: Sep 2013
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straight pipe questions
so i have a 1986 f350 with a 6.9 and i just recently strait piped it and my dad wants me to ask if theres any drawbacks or things that could go wrong with having a strait pipe? from my understanding it helps everything. correct me if I'm wrong.
thanks.
thanks.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
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From: Western Mass
1) You won't be able to hear yourself think
2) Your neighbors and the cops might not be too happy
3) If you have a state that does emissions inspections, you might be in trouble
As far as the engine and performance goes, no problems at all.
2) Your neighbors and the cops might not be too happy
3) If you have a state that does emissions inspections, you might be in trouble
As far as the engine and performance goes, no problems at all.
Mountain Pass
Joined: Feb 2012
Posts: 244
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In all actuality you'll be fine with the neighbors too if you keep the rpms down.
And correct me if I'm wrong here but its my understanding that none of the 7.3 IDIs and the 6.9s had a catalytic converter. Cats were only required on 7.3 powerstrokes and on after 1997. I don't have a source on this though except personal experience
Tuned
Joined: Jan 2011
Posts: 271
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From: Bluffton, IN
My dads power stroke has no muffler and has passed D.O.T safety inspection. I would think if it was illegal he would have been caught.
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Senior User
Joined: Nov 2012
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From: Montana
Not illegal where I live, the majority of diesels run with no muffs, What happens where I live, is most get farm vehicle exemptions and take the mufflers off, also many run red diesel as well, there never any check points, so pretty much normal.
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Post Fiend
Joined: Feb 2009
Posts: 8,005
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From: Ottawa, Ontario
Having it straight piped in terms is suppose to make more power, and better fuel economy (as some have claimed), but I straight piped my van, and seen 0 difference in anything else but sound quality. I purely did it cause I love the sound.
Posting Guru
Joined: Feb 2013
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From what I understand in colorado. You don't need a muffler just some place for the gasses to expand. Like going from 3" to 4" pipe, even 3" to a 4" tip can pass but it's questionable.
idis I've been around are quite even straight piped no worse than a gasser with a glass pack, most of the noise comes from under the hood.
idis I've been around are quite even straight piped no worse than a gasser with a glass pack, most of the noise comes from under the hood.
Post Fiend
Joined: Nov 2005
Posts: 7,437
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From: Charles Town, W bygod Va
That's what I thought.... I have a state inspectors license in WV and you have to have an OEM type muffler. Welded seam mufflers are illegal. I'm not saying it is enforced, but it is not legal.
Senior User
Joined: May 2011
Posts: 497
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From: Morgantown, WV
with how it currently is now, its really loud and I dont really like it cause when I go through a drive through or something, I have to shut the truck off so they can hear me order, haha, which I dont like doing since its hard on the GPs batteries and starter
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
You'll still have to shut down in the drive-through, it's a diesel.
PSDs can get away without mufflers much easier since they are turbocharged. The turbo does quite a bit to muffle the sound, and generally a larger pipe with less restriction will allow faster spooling and lower EGTs. Most of the gain people have seen pulling the muffler off an IDI is from ditching the stock 2 1/4" pipe and restrictive style muffler.
So, the proper solution is to put a 3" or 4" pipe behind a turbo-
PSDs can get away without mufflers much easier since they are turbocharged. The turbo does quite a bit to muffle the sound, and generally a larger pipe with less restriction will allow faster spooling and lower EGTs. Most of the gain people have seen pulling the muffler off an IDI is from ditching the stock 2 1/4" pipe and restrictive style muffler.
So, the proper solution is to put a 3" or 4" pipe behind a turbo-
Senior User
Joined: May 2011
Posts: 497
Likes: 0
From: Morgantown, WV
You'll still have to shut down in the drive-through, it's a diesel.
PSDs can get away without mufflers much easier since they are turbocharged. The turbo does quite a bit to muffle the sound, and generally a larger pipe with less restriction will allow faster spooling and lower EGTs. Most of the gain people have seen pulling the muffler off an IDI is from ditching the stock 2 1/4" pipe and restrictive style muffler.
So, the proper solution is to put a 3" or 4" pipe behind a turbo-
PSDs can get away without mufflers much easier since they are turbocharged. The turbo does quite a bit to muffle the sound, and generally a larger pipe with less restriction will allow faster spooling and lower EGTs. Most of the gain people have seen pulling the muffler off an IDI is from ditching the stock 2 1/4" pipe and restrictive style muffler.
So, the proper solution is to put a 3" or 4" pipe behind a turbo-
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
One of the axle sets I sold went to a guy with a straightpiped turboed IDI in a crew cab on a short frame, it sounded great. The exhaust was all the way to the back, but at idle it had a nice rumble with a little turbo whine. I saw him on the highway a bit later and it sounded louder than stock, but not annoyingly so.