What flows more air? 2.5 mandrel bent or 2.75 not mandrel bent

[BigED]

Are they equivalent? I think the v8s are 2.75 not mandrel. So if I got a 2.5 mandrel, would that be about equivalent?

I'm trying to find a happy medium between our stock 2.25 and the wide open 3.0 mandrel bent catbacks.

[HAZ-Matt]

"This looks like a job for Fluid Dynamics Man!"

[Cale]

mandrel doesn't do much other than a couple horsies at most in a high-horsie application situation.

[WickEdSix9838]

the 2.75" from the factory on the v8's is a half-a$$ mandrel bent...its a lot better than the non-mandrel that the exhasut shops make

[BigED]

So is it worth going to 2.5 inch mandrel, or should I just go to 2.75 mandrel?

[Aaron Thomas]

the mandrel bends will just make the exhaust flow better, the larger diameter will flow more, so if you have a large pipe and no mandrel bends you will flow more but the gas in the pipe will be more chaotic, thus causing more backpressure, the smaller pipe will flow less gas, but will flow it in more of a streamlined flow. with the mods you have listed i do not think that the mandrel bends will make much of a difference, however i think mandrel bent exhaust sounds better, so your call

-ATL

[Loochy88]

<blockquote>quote:</font><hr>Originally posted by BigED:
Are they equivalent? I think the v8s are 2.75 not mandrel. So if I got a 2.5 mandrel, would that be about equivalent?

I'm trying to find a happy medium between our stock 2.25 and the wide open 3.0 mandrel bent catbacks.<hr></blockquote>

im wondering the same thing. 3" seems too wide open to me. i was wondering also if s.75 nonmandrel would be the same as 2.5 mandrel. and if getting a 2.5 nonmandrel would be any improvement over our 2.25

[AZ3.8Camaro]

According to Magnaflow, not mandrel bending causes a 20% loss in flow. So a non-mandrel bent 3 inch pipe flows like a 2.4 inch mandrel bent pipe. To get the flow of a 2.5 inch mandrel bent pipe, you would have to have about a 3.2 inch non mandrel bent pipe.

[shortdog273]

<blockquote>quote:</font><hr>Originally posted by BigED:
I think the v8s are 2.75 not mandrel.<hr></blockquote>

Naw, they ARE mandrel bent. That would be your best bet.

[BigED]

Ok, I worked out the math, assuming a 20% loss without mandrel bending:

(A = r^2 * pi)
(Multiply by .8 to lose 20%)
(For diameter of 2.25, r = 1.125)

2.25 Non mandrel
1.125 * 1.125 * .8 = 1.0125

2.25 Mandrel
1.125 * 1.125 = 1.265

2.5 Non mandrel
1.25 * 1.25 * .8 = 1.25

2.5 Mandrel
1.25 * 1.25 = 1.5625

2.75 Non mandrel
1.375 * 1.375 * .8 = 1.513

2.75 Mandrel
1.375 * 1.375 = 1.891

3.0 Non mandrel
1.5 * 1.5 * .8 = 1.8

3.0 Mandrel
1.5 * 1.5 = 2.25

According to this (assuming that the 20% is correct, mandrel bending is like having a pipe that is .25 inches thicker.

ie:
2.5 non mandrel = 2.25 mandrel
2.75 non mandrel = 2.5 mandrel
3.0 non mandrel = 2.75 mandrel


You guys can check my math if you want, but it should be right.

This being correct, I guess that I should either get a 2.75 non mandrel or a 2.5 mandrel - they should be the same. I'm think 2.75 mandrel might lose me too much low end torque. Anyone agree with this?

[Aaron Thomas]

just something to think about, does magnaflow make non mandrel bent pipes? so if they dont wouldnt they want to make their pipes look better by maybe saying that they flow better........ i have nothing to back this up with but a little thing to maybe think about

-ATL

[Birdie2000]

You, uh, never multiplied by pi. Might change results a little.

[BigED]

No I didn't but its a constant so the ratio between each calculation doesn't change. Just take each result and multiply by pi to find the real result.

[nova]

I could ask my astrodynamics, propulsion and structures professor next week. He's an expert in computational fluid dynamics and could probably run the equations in his head.