Twin 2.25 Exhaust Flow

[WARLORD]

would any one have a clear idea if this twin 2.25 inch exhaust will flow close to 350kw or not ive had conflicting advice and am trying to get a clear picture or if a 3.5 inch is better.

pic of the exhaust

[JonnoHR31]

by my rough calculations a single 3.5" will flow around 25% more than twin 2.25"

[WARLORD]

by my rough calculations a single 3.5" will flow around 25% more than twin 2.25"

would that 25% all round or at top end

so would twin 2.5 be on par with a 3.5

Edited June 18, 2011 by WARLORD

[R31Nismoid]

25% all around

[Owgasm]

Would it not come down to the actual shape/straight nature of both?

Could I hijack for a similar question?

Twin 2.5", splitting from the cat, has bends here and there, could be restrictive. Compared to a 3" very straight looking titanium?

[KiwiRS4T]

Yep twin 2.5in would be similar to single 3.5in but twice as expensive to make!!

[TiTAN]

Yep twin 2.5in would be similar to single 3.5in but twice as expensive to make!!

2.5" is a lot more common pipe size so the materials would be cheaper.

[88cameron88]

yeah 3.5inch isnt that common, harder to work with.

you would be able to get your power goal with a twin 2.5 imo

[SKiT_R31]

If both mandrel, 2 x 2.25 inches is equivalent to 3.1 inches (4926mm2 vs. 4536mm2 of the 3.0") and 2 x 2.5 inches is equivalent to 3.55 inches (6434mm2 vs. 6082mm2 of the 3.5")

So in both cases they are slightly larger than the single pipe (providing you keep them mandrel and not press bent), but could cost more and weigh more so probably only useful if you want to have twin side pipes or are after the different sound .

[simpletool]

would any one have a clear idea if this twin 2.25 inch exhaust will flow close to 350kw or not ive had conflicting advice and am trying to get a clear picture or if a 3.5 inch is better. pic of the exhaust

Yes it will flow 350kw, what you want to know is how much restriction it makes at that power level - or efficiency.

A twin 2.25" could flow enough for 450kw, but the back pressure will be higher than you want and so it will be inefficient.

True but twin pipes also have higher surface area per volume, so I would imagine they allow for more volume attenuation. Then again, you could just run longer muffler on a single pipe.....meh.

Yep twin 2.25 is a touch bigger than 3" for flow.

twin 2.5" is a 3.5"

[R31Nismoid]

350rwkw = 3.5" minimum.

[WARLORD]

thanks everyone for your input i hope this helps others as well.

[MrStabby]

If both mandrel, 2 x 2.25 inches is equivalent to 3.1 inches (4926mm2 vs. 4536mm2 of the 3.0") and 2 x 2.5 inches is equivalent to 3.55 inches (6434mm2 vs. 6082mm2 of the 3.5")

I *think* going on cross sectional area is oversimplifying the question due to boundary layer effects. My guess is that a single 3.5 will flow better than twin 2.5, due to extra drag against the pipe wall that the twin 2.5 will face.

Is there a mech eng in the house to clarify?

[JonnoHR31]

I *think* going on cross sectional area is oversimplifying the question due to boundary layer effects. My guess is that a single 3.5 will flow better than twin 2.5, due to extra drag against the pipe wall that the twin 2.5 will face.

Is there a mech eng in the house to clarify?

yer boundary gasses would make the single 3.5" a better flowing option hence why i originally said roughly 25% as i have no idea how to figure it out exactly