[scrgdk]

Since guilias is calling me a TJ, I'll post my question here.
I need advice on Mandrel bending of exhaust systems.
Is it true that a 50mm mandrel bent exhaust ahs the same restrictive properties as a 57mm conventionally bent exhausts?
I can get a 50mm mandrel or 63mm mandrel bent exhaust and really want to know if I should go for the 50mm. 63 ismm is too big IMO. or do I stick with what I have, the very poorly bent powerflow 50mm into 57mm???

 

[Guili]

why don't you just use this thread since its about exhausts anyway?
You just wasting valuable AO space!

http://www.alfaowner.com/Forum/south-africa/376391-exhaust-advice.html

 

[scrgdk]

why don't you just use this thread since its about exhausts anyway?
You just wasting valuable AO space!

http://www.alfaowner.com/Forum/south-africa/376391-exhaust-advice.html

Someone is looking for a PK I tell you... :tut:

 

[Guili]

Lol

 

[Ian Lusso]

a 57mm pipe bent conventionally decreases in diameter. this is due t the bending process. Not sure if it would decrease to 50mm though. A mandrel bent pipe should not decrease in diameter much, or at all.

http://www.cmperformanceexhaust.com/images/stories/mandrel_bend.jpg

 

[scrgdk]

a 57mm pipe bent conventionally decreases in diameter. this is due t the bending process. Not sure if it would decrease to 50mm though. A mandrel bent pipe should not decrease in diameter much, or at all.

http://www.cmperformanceexhaust.com/images/stories/mandrel_bend.jpg

I figured that, but I'm with the "pulsing" of the gasses from the restriction and expansion WRT the crimps, it will cause the "bad" flowing. (sorry I left my technical dictionary at home today.)
so a "free-flowing" 50mm would, in theory, "flow" better than a 57mm conventional pipe.
Is that wrong?

 

[Ian Lusso]

Hard to say without doing the calcs. You experience pumping losses at the entry, during the restrictive area as well as the exit of the restriction. So depending on the number of bends and the length of the pipe you can determine the pumping loss. In my opinion you lose more through a mandrel bent 50mm pipe than through a normally bent 57mm pipe.

 

[scrgdk]

Thanks Ian, I've got a meeting with the guy who does it and I'm taking Jim K's book with as well, wane see what he can work out for me...