EFI manifolds vs headers
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
A single out usually works really well. 2 1/4" or 2 1/2" is what's normally suggested.
Always keep in mind with exhaust sizes that it's the AREA that matters, and not the diameter. The area of the exhaust increases exponentially to the diameter.
Area = (diameter / 2)^2 * pi
1.50" = 1.77 sq/in.
2.00" = 3.14 sq/in.
2.50" = 4.90 sq/in.
3.00" = 7.07 sq/in.
Always keep in mind with exhaust sizes that it's the AREA that matters, and not the diameter. The area of the exhaust increases exponentially to the diameter.
Area = (diameter / 2)^2 * pi
1.50" = 1.77 sq/in.
2.00" = 3.14 sq/in.
2.50" = 4.90 sq/in.
3.00" = 7.07 sq/in.
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
The 300 loves 2 1/4" dual piping with headers. Next year I'll build a no loss exhaust system for the truck because I'll be hopping up the engine a bit, but right now my BMW is the priority project.
Back pressure explained.
Once your engine is about performance and not low end torque, you don't want back pressure. You want the exhaust flowing as high as possible to allow for the best fifth cycle possible, but there is a lot of math to it.
No loss exhaust system explained.
Back pressure explained.
Once your engine is about performance and not low end torque, you don't want back pressure. You want the exhaust flowing as high as possible to allow for the best fifth cycle possible, but there is a lot of math to it.
No loss exhaust system explained.
Lead Driver
Joined: Mar 2008
Posts: 7,182
Likes: 380
From: Near Los Angeles
Raven: Back pressure is a myth. That theory has been disproved many many times and buried.
I know I'll take crap for this, but I would also venture to say that needing backpressure is like using a DP intake. We do everything to allow our engines to breathe, cam, 4v carb, header, porting, and then we bolt on a DP that restricts the intake to 1/3 of what a log intake flows. Go figure.
I know I'll take crap for this, but I would also venture to say that needing backpressure is like using a DP intake. We do everything to allow our engines to breathe, cam, 4v carb, header, porting, and then we bolt on a DP that restricts the intake to 1/3 of what a log intake flows. Go figure.
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suthernford
Ford Inline Six, 200, 250, 4.9L / 300
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Sep 26, 2004 07:20 PM
