i want to know if any of the vendors out there are planning on creating headers for the ralliart. i know that the ralliart has a decent set already but im tiered of lookin at those rusty things.

i take my car to several shows in the summer and nothing looks better under the hood than a nice set of headers. i geuss i could grind of the bolts that support the heat sheild and take it some where to get ceramic coated or painted but its just not the same.

if theres a reason why no one has made headers for the ra yet because of performance reasons or otherwise , i would also like to know. thanks!

 

so far no as well as in the future...but rpw i think is workin to see wht a race header will do for our cars...otherwise i would just take it some where and have them do wht u want to it...i basicly gave up on the header thing now.

 

check here in this forum - if link does not work the thread is called "Time to modify MYVEC" I think that is what I called it

https://www.evolutionm.net/forums/sh...d.php?t=178672

 

that sucks to hear that no one is planning on making headers for the ra. but thanks for your advice. mabey in time someone would consider it.

 

Sorry what do you mean someone may consider it.... mine will be on my car in the next day or two, these are 4-1 race design tuned length mandrel bent Headers

if you are wanting more info please pm me

 

Hello,I'm from Puerto Rico , and the only headers that we are seing here are press bended. I have a contact who work mandrel bend. Is that a good option?

 

Mandrel bent is the best - because if you go press bent for eg. you might start off with say 2" pipe on the straight but when the bends are put in the pipe will restrict down to 1 3/4" so immediately you have a restriction of air flow ... with mandrel bent you start with 2" pipe bend pipe and the bend will be 2" all the way thru the bend - no restriction in air flow

some ssay or recommend that if you go press bent get the next size up so that on the bent parts the sizing drops down to what it is supposed to for eg. if the car needs a a 2" exhaust and the press bends reduce to 13/4" then you get a 21/4" pipe so that way the press bent bends reduce dow to the required 2" down side of this is that you can lose back pressure due to the rest of the pipe being larger than required

 

basic mechanics laws of engineering tell us from the constant volume of an incompressible(steel is definetly compressible but not here) material like most steels(or whatever the header material is). Even if the tube is collapsed a slight bit in one direction it will expand in the other(like pushing putty on a table). so i doubt the cross sectional area will be any smaller(1 3/4?). it will still be 2". But it may be a question of whether that slight collapse produces turbulent flow that causes friction. its a friction problem not a reduced area problem.

 

That's a different type of compression. That's concerning decreasing the O.D. of the pipe, the wall thickness if you will. When you crush bend you don't change the wall diameter significantly (like you said) but the overall outside diameter of the bent section is reduced in size due to the accordian style ridges on the inside of the radius. That is what constricts the airflow down to 1.75" from an original 2.0" O.D. The air might flow over and under the ridges but it's alot more constricted. Mandrel mends use a "snake" inside the tube to maintain the inside diameter so it doesn't accordian. If there was no difference except for looks.... No one would bother with the CNC maps to mandrel bend entire exhaust systems. It's rather more expensive than crush bending. Hope this explains the difference for you Jvallier.

 

i kind of see what you are saying. I am an engineer for a tube manufacturer, so i mostly do CNC rotary drawn tube bending which would collapse the DOM tube more than mandrel(obviously) but still get no actuall material compression or very little. I use large CRIPPA benders from italy. I am going to maybe try bending a set off headers if i could get right material and dimensions. CNC is so precise especially cause all our tubes are for auto industry. I don't have much experience with material thickness at .25"-.375. mostly light tubing. so your probably right with that. th accordian wrinkes can be reduced though by rotary drawn(cuz it stretches outside of bend vs compressing inside), using a wiper die or the easist but not manufacturable, fill with sand. but again that material is very thick and i don't know how it acts differently. not in a knowledge runoff with you, just sharing personal experience, i take your word.

 

If someone out there could get me a standard material, and dimensions of some headers or approximate distant from cylinders, etc, i could bend some up in no time at all, plus weld flanges. i can change tube bending program in matter of seconds.