fabricating an exhaust

[Filmjay]

Using segmented sections is used to tune the exhaust system in specific lengths. But, it's usually done from a custom header on each individual pipe and involves complex physics.

 

A segmented, tuned exhaust system can net more HP than a normal mandrel bent or cat-back system. A correctly tuned system can increase chamber scavenging, increase the fuel charge in the combustion chamber, as well as increase exhaust flow OUT of the chamber.

 

To get the best gains each pipe MUST be separate with no shared chambers. (resonators, collectors, mufflers, etc...)

 

Because pressure waves move at approx. the speed of sound....assuming you know the temperatures of the exhaust gasses....a rough calculation can be made by measuring the time that it takes for the pressure wave to move from the exhaust valve to the end of the pipe, and back again...

 

Here's a good online calculator I found, in case anyone's interested....otherwise you gotta bust out the calculator, or worse...think about it.. LOL!

 

http://www.mez.co.uk/mezporting/exhaust_length.html

[amorfin]

Is there a welder that you guys with experience would recommend for someone that wants to learn how to weld exhausts and other stuff? Something with decent quality maybe, in a low price range.

[grumpyvette]

http://www.welders-direct.com/merchant2/merchant.mv?Screen=PROD&Store_Code=WD&Product_Code=907335

 

if your limiting your work to stuff like floor pans, fenders and exhaust systems theres no reason this 110 volt mig won,t work reasonably well

 

but ID consider this 220volt mig the minimal over all shop welder

 

http://www.welders-direct.com/merchant2/merchant.mv?Screen=PROD&Store_Code=WD&Product_Code=907312

 

and an oxy-acetolene torch, is an option that can do a great deal in skilled hands (youll need to rent tanks)

 

http://www.welders-direct.com/merchant2/merchant.mv?Screen=PROD&Store_Code=WD&Product_Code=MD-510T

[Filmjay]

What Grumpy said....

 

I'm not a great welder, but my dad's a master welder and certified instructor. Here's what he told me when I asked him the same thing recently... a basic 110 volt MIG is good for up to 3/16" mild steel. (body panels, exhaust tubing, etc...) but, you'll want to get into TIG, or even stick welding for anything thicker...and that's where the real money and skill comes in.

 

For basic use and learning purposes, you can pick up a Lincoln, Miller, or Hobart 110-volt MIG machine for a little over $100 on ebay. They're not the most powerful or versatile, but for learning they're good. You're not gonna be welding nuclear reactors on aircraft carriers any time soon, but it's plenty to replace rocker panels and floor pans.

[weirtech]

I don't know if I am off topic,

 

I plan to mig weld SS exhaust with Argon/co2, do I have to backpurge, if so with what? I have read on other website that I should be fine with the Gas and without backpurging. Please correct me,

 

Thanks

Dayz

 

it is recommended to back purge if you are getting 100% penetration. if you can, get straight argon instead of a mix gas when welding stainless.

 

Using segmented sections is used to tune the exhaust system in specific lengths. But, it's usually done from a custom header on each individual pipe and involves complex physics.

 

A segmented, tuned exhaust system can net more HP than a normal mandrel bent or cat-back system. A correctly tuned system can increase chamber scavenging, increase the fuel charge in the combustion chamber, as well as increase exhaust flow OUT of the chamber.

 

i hope you don't mean pie cuts with this statement. i'd have to argue against that. in no way do pie cuts/segmented welded bends outflow a mandrel bent tube. that is just simple common sense.

[Filmjay]

i hope you don't mean pie cuts with this statement. i'd have to argue against that. in no way do pie cuts/segmented welded bends outflow a mandrel bent tube. that is just simple common sense.

 

No sir. Any required bends should be within the segment.

[Tony D]

The 'thing' about SS is more on the heat transfer side of it. Sure, it corrodes less than mild steel piping (chlorides will attack stainless, but that's another story...) but it retains heat IN the exhaust pipes, radiating much less.

 

Ever stick your hands under the hood of a N/A car with SS headers versus one with a mild steel header and you will see the difference.

 

Sure, it doesn't corrode, but it also helps with keeping stuff around the exhaust cooler due to less heat emission.

 

And if you get the hair...it polishes up real nice, too for that bling bling 'thing'!

[johnc]

You can also use a thinner wall tube with stainless to save some weight.

[joker120]

I don't know if I am off topic,

 

I plan to mig weld SS exhaust with Argon/co2, do I have to backpurge, if so with what? I have read on other website that I should be fine with the Gas and without backpurging. Please correct me,

 

Thanks

Dayz

 

Dayz I have the answer to your question. Before I give the answer I will tell you that I am a pipe-fitter by trade and work in a milk plant that has hundreds of miles of only SS tubing. SS is what I do everyday for a long time. Those welds HAVE to be purged if you wouldnt like the whole weld to"sugar" on the inside that the rookies can't see. I strongly recommend that you dont MIG this, try Tig you'll love it. Just rent one for the day. Get your exaust "fit out", and you can tack w/ Mig but I would strongly recommend tig, because if you make good cuts and file them with a SS only file BTW, you will use much less filler wire. On filler wire use prob ER308L, someone correct me if im wrong but im pretty sure thats the most common for SS tube...

 

If you have to use a mig your going to purge with TRIMIX, look it up or you can just go rent a bottle n tell that to the supplier, they'll know.

 

Used with a tig....

 

Don't purge SS with anything other than pure Argon, also SS should be Tig welded IMHO. Anything less has forfeiture of control and once you practice an hour on a tig you'll get it enough to practice on your tube, just buy a little extra. Anymore q's feel free to PM, home after 1600 Central. Good luck!!!

 

RK

[cjames]

+1 on tig with argon purge, save the mig for body work.

[Dayz]

Thanks Joker,

 

I am not a pro welder, that is for sure. I can Tig/mig pretty well, Oxy/ace...I would need more practice. I only have a Mig at the moment and from what I read I should be fine. Can you please elaborate on the Mig welding process, I would be very interested to know.

 

On another note, why is Mig welding Stainless in now approved in the aviation industry, for welding Headers...Is there a way not to "sugar" the welds with a mig?

 

I really appreciate inputs on this one...Maybe I should starts another thread?

[joker120]

^^^ No prob Dayz Im glad I could finally contribute something to the site instead of all the questions I have!!! Your on your own on the Mig, I never went to trade school and received OTJT with Tig only. I can tell you that the reason they are using a mig and there may be 2. First a Mig is very fast and suits medium to large scale production apps because of the afore mentioned effeciency in moving out product. Number two would be the possibilty of using robotic welders wich are Mig only on the most part...

 

I can tell you that if Mig was better for doing SS tube I could tell you about that, but we only use Tig for a reason and thats control over your work. You just have so many more options and it is what the pros use. Come to the dark side Dayz, rent a Tig for the day and you wont turn back. Got ahead in fit it out and make your tacks and take your time on the fit, Im sure you will do fine either way you go and if you do go Mig remember to use trimix and another hint in purging is to have flow only NOT PRESSURE!! On the end of your tubing pplace masking tape over the end and leave about the size of a pushpin open for your purge flow. On 2-1/2 or 3" set your regulator on about 20-25, hope this helps a little and have fun Sir and take your time for best results

 

RK

[weirtech]

dayz, if you want a quick tig lesson, i'll provide one. i have a spare helmet at my shop, which i'll be at all day on sunday. it is in burlington just at appleby and north service... although i'll be working on my own car most of the day. you are more than welcome to drop by any time.

 

aaron

905-02-4703

[Careless]

man, i'd love to come hang out and have a lesson too, but my car is not on the road

[Dayz]

Thanks Aaron for inviting me to the shop. It was very nice, hope I didn't chat too much with everyone and made you lose some time! Very nice shop and great too see a quality person oriented.

 

I posted public thanks here:http://forums.hybridz.org/showthread.php?t=141206

 

You could post picture of your work there!

Dayz