I'm going single and making my own manifold. I was just wondering, where should I get the thick-walled mandrel bent piping/tubing from?

Thanks,
Aaron

 

Might try an good exhaust shop.

 

these guys are the best, you can get sch 40 stainless for ~10-20.00 per fitting. Shouldn't cost more than ~100.00 for all you need for a long runner mani. http://www.mcmaster.com/

Look for butt weld X butt weld 2". A 90* is 9.82 each! So let's do some math on those 600.00 plus manifolds. I'd say you could save a dollar or two That said, you need to take your time. I suggest mocking it up in 2" ABS pipe, then copy that onto the stainless. BTW that price is for 316 stainless, I believe that will hold up better than the 304 that most places use. If you are not a great welder, you can cut it up, tape it, and bring it to a good welder. Make sure you are settled on a DP, wastegate, and IC piping so that you can position your turbo properly. An equal length 12-14" main runner with two roughly equal length wastgate runners(merged into a single fitting) is a good design. Something like Chris Roth's set-up, but with a single wastegate would be my choice. If you are going to weld it yourself, do so in an order of assembly that gives you access to the inside of each weld, so that you can grind them smooth. Also, take your time so the entire piece does not get too hot. regards, Carl

 

I will try to do a 16" dual wastegate (depending on available funds) equal length if I can. I will be doing all the welding myself and also fabbing up the dp, and i/c piping so I'll base that off of the turbo location once the manifold is completed. I was almost looking at doing it out of mild steel then coat it since I heard there are cracking problems with the SS ones... Or maybe that is just the 304 ss ones, I haven't heard of 316, but heard good things of 321 which I didn't see there. Thanks for the tips Carl, I'll definately use them.

 

Those pipe/weld el's Carl describes using is anelled (SP?) 316 stainless and is very thick, you most likely will not run into cracking problems. make sure you back purge the pipes as you weld them and use stainless rod so your welds wont turn ugly on you (you could skip the rod filler and just tig fusion weld the pipes together, but I recommend you tig and use rod for the big joints, like at all the flanges and were the wg runners join the primaries). After going through the trouble of finding mild steel thick enough, then pay to have it high temp ceramic coated (nothing else will withstand the heat, so forget about any kind of paint) you could of bought the stainless stuff and be trouble free till your sick of your car or die.

~Mike..............

 

also, make sure to weld BOTH inside and out side of the flanges, you could just fusion weld the insides and use rod filer for the outside, but if you rod both sides you can clean up the welds on the inside nicer if theres more material there to work with.

 

You can use 304L and it will hold up like a champ. Also get schedule 10, not 40 as sch 10 is already 1/8" thick. I have over 5000 miles on my 304L manifold that I made from mcmaster carr fittings, they are good stuff! I fusion welded most of it but did end up using a little rod at the flanges.
Using this material will get you a manifold that will outlast your car

 

Awesome, I thought with the SS being that thick it wouldn't run into the common cracking problems but just wanted to be sure. Yeah I was planning on doing TIG w/ filler rod throughout the manifold and do inside at the flanges, but I'll do some testing prior to and see what works well. Thanks for all the tips guys, keep em coming!

One thing though, at mcmaster, I could only find the 316 ss straight pipe in 6' lengths which equated to about $220 So yeah, maybe I'll just go with the 304 if it has held up fine for you, setzep. Plus its a little cheaper too.

Ooh, I'm getting all excited just thinking about making this mani! It's gonna be so much fun!!

 

AH! I can't get sch. 10 straight 304 in other lengths than 6' either. Hmm, they gotta have shorter lenghts than that...

 

I just ordered some from Mcmaster as well. If you are going to weld stainless to mild steel, please use Nickle 55 rod (55% nickle content), it increases plaibility, important as stainless and mild steel have different heat expansion rates at different temps. Use 304 or higher stainless rod to weld the 304 to 304 (obviously). Just a tip from me to you.

 

Thanks

 

Try http://www.onlinemetals.com.

 

Alternately, we can each pay for ~3', and Aaron can cut it up, and ship it Carl

The Sch 40 allows for a bit more grinding.

 

Well the 6' of 304L sch. 40 is a lot cheaper at only $58.55, but still there's no way I'm gonna need that much right now. How would they even ship that??? I'm definately game for splitting it up

 

Let's find out if 316, or 304 is better for manifold. I know several companies use 321. I'll ask my neighbor, he welds stainless for a living.

 

Aaron,

i built a fairly complex manifold (twin T04s) 2 years ago using mcmaster carr ss and i haven't had one crack in it so you should be fine as far as structual integrity.

the one area that i would caution you on is warpage.

ss goes all over the place when you heat it. do make sure when you weld the flanges to your pipe that the flanges are bolted to a large thick piece of steel to absorb the heat.

always tack weld pipe and flanges at 180 degrees prior to any finish welding. it might be worthwhile to make a jig between the flanges. ss is alot different than mild as to deforming.

finally, grind all your flanges flat after welding as they will bow a bit and you will have exhaust leaks.

overall it is a fun job... as carl suggests, get yourself a bunch of 2 inch abs pipe to mock it up.

you may be aware of all of the above and be a much better welder than i and know all about ss warpage etc... if that's the case consider my post just an attempt to be helpful.

good luck,

howard coleman

 

Howard, what grade stainless did you use? 304? 316? 321?

 

I did know of the heat issues with stainless, but I've never heard of using the steel as a heat sink... It makes perfect sense. All advice is more than welcome and even if not informative to me, I'm sure it will be to somebody else who is someday planning on building one. I say keep the info coming. I've learned a lot in this thread already, more good useable information than you usually find elsewhere on this forum.

 

I've always wondered... how would you shape the pipe to fit a divided T4 flange? I'm only just beginning to learn to work on metals (just completed my first welding class ).

 

I wondered this as well. I'm sure it could be heated up and bent but I dunno if that's ok to do or what?

 

infini4:

ss is surprisingly workable.

as to forming transitions....
make a cardboard mockup. cut pieces from a ss tube. form the pieces by pounding on them over a wider sectioned tube. it is easier than it sounds and can look quite professional if you take your time. (there are numerous manifold pictures posted on the forum that you might take a look at as to guidence.)

stephen, i used 304L ss.

howard coleman

 

Squish it!!!!

 

You can get piping from Burns Stainless and on their website it tells you what grade for what temp. My custom manifold is made from 321, no problems yet.

 

Pipe is measured in I.D. that is what you guys are getting from mcmaster.
tubing is measured in O.D. that is what burns sells.

Big difference.

For most DIY's i would recommend starting out with pipe since it's very cheap, thick so it's easier to weld, and durable.

leave tubing for the experienced. it requires properly bracing the turbo, tough to weld, and very Expensive.

 

Where's the best place to get 4" straight thin walled Aluminum piping? Someone who can post a direct link to Mamaster or anywhere else would be greatly appreciated.