2.75" vs 3" pipe on supercharged vehicles.

Sh0velMan · 03-04-2013, 11:22 AM

Oh and your figure for 2.5" dual is a little off.

2.5" Dual = 9.817 sq inches
2.75" single = 5.939 sq inches
3" Single = 7.068 sq inches
3" Dual = 14.136 sq inches
3.5" Single = 9.621 sq inches
4" Single = 12.566 sq inches
4.5" Single = 15.904 sq inches

Edit: re-read your post, I see where our numbers are different, you're subtracting wall thickness. Pipe diameters should be ID rather than OD. So subtracting thicknesses should be unnecessary.

Edit 2: And the reason they over-estimate pipe size is because most of the flow is happening at the outside perimeter of the pipe, so a general rule of thumb is to add 10-15% (with the percentage being smaller the larger the pipe diameter) to the pipe size to allow for turbulence losses at the center of the pipe. Sounds silly, but it's been worked out many years ago by folks a lot smarter than us hahaha.

03-04-2013, 11:22 AM	#5 (permalink)
Sh0velMan A True Z Fanatic Join Date: Jan 2012 Location: Dallas/Ft.Worth Posts: 3,349 Drives: Noisily. Rep Power: 21	Oh and your figure for 2.5" dual is a little off. 2.5" Dual = 9.817 sq inches 2.75" single = 5.939 sq inches 3" Single = 7.068 sq inches 3" Dual = 14.136 sq inches 3.5" Single = 9.621 sq inches 4" Single = 12.566 sq inches 4.5" Single = 15.904 sq inches Edit: re-read your post, I see where our numbers are different, you're subtracting wall thickness. Pipe diameters should be ID rather than OD. So subtracting thicknesses should be unnecessary. Edit 2: And the reason they over-estimate pipe size is because most of the flow is happening at the outside perimeter of the pipe, so a general rule of thumb is to add 10-15% (with the percentage being smaller the larger the pipe diameter) to the pipe size to allow for turbulence losses at the center of the pipe. Sounds silly, but it's been worked out many years ago by folks a lot smarter than us hahaha. Jordo!, DarkJak, GaleForce and 2 others like this. __________________ Buy My Car! \| Build Thread Last edited by Sh0velMan; 03-04-2013 at 11:26 AM.

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