Over-thinking exhaust
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Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
Over-thinking exhaust
I spent all day yesterday reading about exhaust. Now I'm move confused than ever. I wonder if some knowledgeable person might add a bit of guidance.
I have a 75 f250. The engine is a 250 hp Inline six with a set of shorty headers that has two collectors at 2.5" each. I had wanted to come off the collectors with 2x2.5" tubes into a Y and a single 2.75" pipe back to the muffler. That would mean a new muffler and trouble finding the bends that size. I also suspect that it may be too large. I know that the hp limit of single 2.5" tube is 238hp, but this is my daily driver. I rarely spin it past 3500 rpm, so I'm wondering if a simple 2 into 1 pipe of 2.5" wouldn't be fine.
I have a 75 f250. The engine is a 250 hp Inline six with a set of shorty headers that has two collectors at 2.5" each. I had wanted to come off the collectors with 2x2.5" tubes into a Y and a single 2.75" pipe back to the muffler. That would mean a new muffler and trouble finding the bends that size. I also suspect that it may be too large. I know that the hp limit of single 2.5" tube is 238hp, but this is my daily driver. I rarely spin it past 3500 rpm, so I'm wondering if a simple 2 into 1 pipe of 2.5" wouldn't be fine.
Hotshot
Joined: Feb 2004
Posts: 10,808
Likes: 2,604
From: The Shenandoah Valley
It'll be fine.
By the time the exhaust gets to the convergence of the two head pipes at the Y and go through the muffler, they will be cooled off a bunch and considerably denser. The single 2.5" tail piping will be a plenty and still keep velocities up.
By the time the exhaust gets to the convergence of the two head pipes at the Y and go through the muffler, they will be cooled off a bunch and considerably denser. The single 2.5" tail piping will be a plenty and still keep velocities up.
Cargo Master
Joined: Nov 2007
Posts: 2,238
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I think you'll be fine. I don't believe 238 is the HP limit for 2.5" pipe, i think it's the most you can make without losing anything to restrictions. You could put a dyno proven 500HP engine on a single 2.5" exhaust if you wanted and it's gonna make way more than 238hp. It won't make 500, but it'll still be up there.
I'd run the head pipes as far back as possible before Y'ing into the muffler. You could even step it up to a 3" Y, muffler and tailpipe if you're worried about flow
I'd run the head pipes as far back as possible before Y'ing into the muffler. You could even step it up to a 3" Y, muffler and tailpipe if you're worried about flow
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teamwizard
1973 - 1979 F-100 & Larger F-Series Trucks
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Apr 3, 2002 10:59 PM
