does mandrel bent pipe really make a difference?

#1
Iv got a 65 coupe with a 302 and Im gonna replace my exhaust system with some try y's,H pipe,dual mufflers to tips @ the rear valance.Should I buy a mandrel bent pipes for the whole system?I know there's less restriction but my car's not gonna have more than 400hp ever.And is there a big diffrence in the sound of mandrel bent pipes?
The reason I ask this is because I work at an exhaust shop and can build my own pipes for next to nothing.
 
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85_SS_302_Coupe

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#2
Yes. Mandrel bends, like you said, have less restriction, which is good if you're making 50hp or 500hp. They're going to sound more throaty as well.
 

90mustangGT

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#3
Mandrel bent means it doesn't kink in the corners. With regular exaust shop bent pipes when your exaust gasses flow towards a corner, they have to condence down, speed throught the curve then back out into the larger pipe loosing velosity. Hard to explain but basically the bends act as kinks which kills flow and velosity.
 

hbk_136

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#4
easy way to explain it:

2.5" mandrel bent piping stays 2.5" in diameter through every turn, bend, and twist.

Normal piping will get smaller around turns, bends, and twists, which can be quite restrictive. I would strongly recommend mandrel bent.
 

HISSIN50

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#5
it is funny that you are asking since you work at an exhaust shop.

if i did, i would have some crazy exhaust on my cars. :)
 
#7
Well I knew what mandrel bending is I just didnt know if it made that much of a power difference or sound.Im not expecting my car to run super impressive track times or anything but I do want it to sound awsome.I thought that mandrel bending would sound better becaust of the straight through constant pipe diameter.I havent been working in this shop that long and the other guys at my shop are foaming at the mouth to let them rig up an exhaust for my car by bending up a bunch of 2 1/2-3 inch pipe.I dont really trust the guys that much because they have the cheaper is better attitude.
 

HISSIN50

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#8
stephen4785 said:
Well I knew what mandrel bending is I just didnt know if it made that much of a power difference or sound.Im not expecting my car to run super impressive track times or anything but I do want it to sound awsome.I thought that mandrel bending would sound better becaust of the straight through constant pipe diameter.I havent been working in this shop that long and the other guys at my shop are foaming at the mouth to let them rig up an exhaust for my car by bending up a bunch of 2 1/2-3 inch pipe.I dont really trust the guys that much because they have the cheaper is better attitude.
ok, that makes sense (in my first post, i was sorta' curious and a little confused. i would have imagined that we would be asking you. :) )

but i applaud your having asked in here and not blindly takin the word of some guys at work. i dont know much about exhausts, but i would go the mandrel route. you want consistancy and some engineering, not necessarily a sewer-drain-pipe with kinks and ID inconsistancies, that may mess with backpressure, scavenging, and so on.
my two cents. good luck.
 

Michael Yount

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#9
At the HP levels you're contemplating, even non-mandrel bent 2.5" duals will be plenty. Bend it up yourself and you'll be fine. Removing exhaust restrictions with mandrel bent ells only helps if the exhaust size you're running is limiting your abililty to flow - and 400HP through dual 2.5" isn't going to pose a flow restriction. Heck - F-body's with the LS1, and new Dodge and Nissan pickups are all running 320-345HP through SINGLE 2.75"-3" exhaust systems.
 

thumper460

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#10
Mike's right!! bend away with the 2 1/2 pipes!! it is funny to spend 200-300 on a system for a 300 HP car!! I have a killer shop here in Jax do all my exhaust work and when I uncap at the track.. the gain is almost nothing as to capped and thru the system!! have fun and keep the bends to a min!! cool??

Just me.....................................

Thumper
 

Michael Yount

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#11
I just read an article about a stroker LS1 in a late model Firebird - making almost 500 rwhp on spray; he runs long tubes, 2.5" head pipes into a single 3" out to single muffler transversely mounted in back. Car runs consistent high tens. Dual 2.5" pipes even bent on the regular ole bending machine will be fine. As Thumper says, just don't bend it any more than you have to.