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2.5' crush bent vs.2.25'mandrel bent

Old 21-Jul-2006, 01:30 PM
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2.5' crush bent vs.2.25'mandrel bent

In terms of flow, which would flow better? My guess is that crush bent would flow better because the loss in diameter at the bends is probably around 2.25? so it would flow little better relative to the 2.5', if so,large difference?
Answers/input should be based on the assumption that I will have the setup that requires between 2.25-2.5 piping. Also, my collector would be 2.5', as well the cat, but the option remains between 2.25 mandrel or 2.5 crush.
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Old 21-Jul-2006, 01:57 PM
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Exhaust flow is measured at the narrowest passage, so if the crush bend diameter and the mandrel bend diameter are the same, then there will not be much of a difference.
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Old 21-Jul-2006, 03:09 PM
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charles, I knew i could rely on you for exhaust tips,lol.
Any idea of what the diameter is of the bends of 2.5' crush bends?
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Old 21-Jul-2006, 03:10 PM
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edited for double post.
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Old 21-Jul-2006, 06:35 PM
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doesnt mandrel bending keep the diameter the same throughout.
isn't that the purpose of mandrel bending???
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Old 21-Jul-2006, 07:00 PM
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^ yes it does

theres lots of arguments about crush vs mandrel but its been proven that mandrel is a waste of money for most people
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Old 22-Jul-2006, 12:21 AM
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why not 2.5" mandrel?
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Old 22-Jul-2006, 01:38 AM
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Rob, the only thing really holding me back from that is $.
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Old 22-Jul-2006, 08:05 PM
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mandrel is expensive anjd it can only be done with certain metals
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Old 22-Jul-2006, 11:01 PM
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go to an exhaust shop and ask em if u can measure some of there 2.5 inch crushbends
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Old 23-Jul-2006, 12:09 AM
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you won't notice the different if the engine are not force induction. I will say mandrel bend will be better then the crush bend (smoother flow)
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Old 23-Jul-2006, 12:21 AM
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Originally posted by Nanase
you won't notice the different if the engine are not force induction. I will say mandrel bend will be better then the crush bend (smoother flow)
what if its a high compression motor?

you would notice it.
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Old 23-Jul-2006, 05:52 PM
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Question

Originally posted by chris_si98


what if its a high compression motor?

you would notice it.
what consider as high compression motor? is it anything above 10:1?
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Old 24-Jul-2006, 09:15 AM
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Taken from a website:

All of this has been specific to mandrel bent pipe. Squeeze bent pipe looses 1/3 of its interior cross sectional area in a right angle bend. There are three right angle bends in the exhaust system of both the Storm and the I-Mark.
Mandrel pipe bending keeps a consistent inside diameter of the pipe through right angle and even U bends.
2 1/2 inch diameter squeeze bent pipe will flow the equivalent of 1.6 inch diameter pipe at each of those squeeze bends. The entire exhaust system will flow only as much as the tightest constriction in flow, meaning that all of the 2 1/2 inch pipe has been a waste, the total system will flow the same as a 1.6 inch diameter mandrel bent exhaust system.
To build a 2 1/2 inch diameter system using squeeze bent pipe, every bend would have to be made using 3 1/2 inch diameter pipe to compensate for the inside space lost from the squeeze bend. This means that the straight sections of pipe would be 2 1/2 inch pipe, then expanded to 3 1/2 inch bends for each and every curve, and then turned back down to 2 1/2 inch pipe for the straight pipe until the next bend.
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Old 24-Jul-2006, 09:40 AM
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2.25 would be good IMO if you want something that works... but 2.5" would flow much better.. you may lose a little power down low, but up top... there is a noticeable difference from what i've seen before.
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Old 24-Jul-2006, 10:56 AM
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I have 2.5" mandrel. It's a bit more expensive but worth it in the long run if you plan on going mod happy. Do it once and do it right.....


as for the 2.5", ya, you notice a little low end power loss, but at a certain point in mid powerband, the car picks up nicer.
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Old 24-Jul-2006, 12:13 PM
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Originally posted by B18C5er
I have 2.5" mandrel. It's a bit more expensive but worth it in the long run if you plan on going mod happy. Do it once and do it right.....


as for the 2.5", ya, you notice a little low end power loss, but at a certain point in mid powerband, the car picks up nicer.




i am running 2.5" mandrel bent straight pipe with a test pipe on my b18c1... you lose the low end, but when you watch that speedo sail 70km/hr....80..90.100... it makes a big difference in my experience.
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Old 25-Jul-2006, 03:04 AM
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Originally posted by Nova_Dust
Taken from a website:

All of this has been specific to mandrel bent pipe. Squeeze bent pipe looses 1/3 of its interior cross sectional area in a right angle bend. There are three right angle bends in the exhaust system of both the Storm and the I-Mark.
Mandrel pipe bending keeps a consistent inside diameter of the pipe through right angle and even U bends.
2 1/2 inch diameter squeeze bent pipe will flow the equivalent of 1.6 inch diameter pipe at each of those squeeze bends. The entire exhaust system will flow only as much as the tightest constriction in flow, meaning that all of the 2 1/2 inch pipe has been a waste, the total system will flow the same as a 1.6 inch diameter mandrel bent exhaust system.
To build a 2 1/2 inch diameter system using squeeze bent pipe, every bend would have to be made using 3 1/2 inch diameter pipe to compensate for the inside space lost from the squeeze bend. This means that the straight sections of pipe would be 2 1/2 inch pipe, then expanded to 3 1/2 inch bends for each and every curve, and then turned back down to 2 1/2 inch pipe for the straight pipe until the next bend.
that is gold Charles
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