Exhaust Pipe Size Vs Area

[Johnny G]

Guys - this is buried in a couple of threads - thought it might be good to post under it's own heading:

Exhaust pipe cross sectional area reference list…... a fast guide.

(Calculated mathematically using Pi. Area = Pi x r^2 assuming Pi to three decimal places. Does not take into account actual inside pipe diameter – reference gauge for accuracy. Remember - with twin systems there will be a minimal double loss due to ID variation. Exhaust gas flows in weird and wonderful ways, and changes it’s flow characteristics with temperature drop and change in direction.)

Single 3” system:

R = 3/2

R^2 = 2.25

Area = 1 x (Pi x 2.25) = 7.069 square inches

Twin 2.25” system:

R = 2.25/2

R^2 = 1.266

Area = 2 x (Pi x 1.266) = 7.955 square inches

Single 3.5” system:

r = 3.5/2

r^2 = 3.0625

Area = 1 x (Pi x 3.0625) = 9.622 square inches

Twin 2.5” system:

r = 2.5/2

r^2 = 1.5625

Area = 2 x (Pi x 1.5625) = 9.818 square inches

Single 4” system:

R = 4/2

R^2 = 4

Area x 1 x (Pi x 4) = 12.568 square inches

[tab]

Good work Johnny...thread pinned

[civillian]

Single 3.5” system:

r = 3.5/2

r^2 = 3.0625

Area = 1 x (Pi x 3.0625) = 9.622 square inches

Twin 2.5” system:

r = 2.5/2

r^2 = 1.5625

Area = 2 x (Pi x 1.5625) = 9.818 square inches

Those 2 look familiar

... assuming Pi to three decimal places. ... reference gauge for accuracy ...

I used Windows calc to come up with those numbers...for best comparison etc... Use scientific mode, find the blue 'pi' button and you'll get Pi as this:

3.1415926535897932384626433832795

Use as many decimal places as you can in the working, then do the 3dp conversion in the final answer.

Well worth sticky

[qik1]

does someone want to have a crack at the twin 3' option. Im looking at the twin manta system would be interesting eo compare to a 4' system

[Johnny G]

Take the single 3" system, and double it. The number is equivalent to the volume of the west chamber of the Jenolan Caves.

Edited 31/10/09 02:25 AM by Johnny G

[sexual harrassment panda]

I love how 4" is getting too small.

John, There is some 5" stainless exhaust pipe at work

twin 3" = 14.138

5" = 19.635 square inches

[qik1]

well that same day we do your cooler we can build an exhaust. you weld I'll pass the stubs. lol.

[ravenhard]

So is 2x2.25" the stock system size?

[Mr Man]

yes Ravenhard it is

[-MIX-]

hey guys there is another factor u gotta think about the frictional area of the pipe

Example one : 2.5" pipe 1 foot long frictional area = 94.24" square

Example two : dual 2.5" 1 foot long frictional area = 188.48" square

Example three: 3.5" pipe 1 foot long frictional area = 131.94" square

if u compare a dual 2.5" (9.818 square inches) agains a single 3.5" (9.622 square inches) system the cross section is nearly the same but in a single 3.5" the exhaust gas got less area to " rub " on compared to the dual 2.5" so it will flow better than a dual 2.5"

Cheers MIX