Exhaust pipe size
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Cargo Master
Joined: Jul 2015
Posts: 2,069
Likes: 139
From: tucson
Exhaust pipe size
What do people recommend for pipe size? I'm installing EFI exhaust manifolds and have the pipes that bolt to them. The pipes are 1.75". I'm looking to merge them into a single pipe and run it out the back. Truck is a '66 F100 working truck. Motor is mildly rebuilt with an rv cam and hyper pistons. Thanks.
John
John
Fleet Mechanic
Joined: Sep 2014
Posts: 1,627
Likes: 79
From: NE Texas
If you can lay your hands on a Walker 45166 (think that is the number) Y-pipe both 1.75" merge into a single 2.5" outlet. Believe someone posted here that 2.5" will safely and efficiently handle up to something like 250 hp output. Dual 1.75s would probably do at least as well at a horseback estimate? FF would know better than anyone else here, I think.
FTE Legend
Joined: Nov 2015
Posts: 30,960
Likes: 4,129
From: Angier, NC
Little late on this.
On my 81 F100 Flare Side I am running EFI exh manifolds and think it was the Walker Y pipe.
On any Y pipe look down the pipes to were they are welded. the hole could be really small and defeat going with EFI manifolds.
I did not use the cat that came with the Y pipe, made a short pipe adaptor to fit the Y pipe to the stock mid pipe / muffler / tail pipe.
The mid pipe on back was a little smaller but not by a lot that I was worried about.
I think they say to go with the same year pipes & muffler that the Y pipe comes from as they will be all the lager size.
The mid pipe on back came off my parts truck and was in pretty good shape and wanted to use it.
Dave ----
On my 81 F100 Flare Side I am running EFI exh manifolds and think it was the Walker Y pipe.
On any Y pipe look down the pipes to were they are welded. the hole could be really small and defeat going with EFI manifolds.
I did not use the cat that came with the Y pipe, made a short pipe adaptor to fit the Y pipe to the stock mid pipe / muffler / tail pipe.
The mid pipe on back was a little smaller but not by a lot that I was worried about.
I think they say to go with the same year pipes & muffler that the Y pipe comes from as they will be all the lager size.
The mid pipe on back came off my parts truck and was in pretty good shape and wanted to use it.
Dave ----
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