my first exhaust build (pie-cut, divorced wastegate, turbo-back 3",v-band)

[91talontsifwd]

Greetings everyone. I have recently finished my first exhaust build with my Hobart Tigmate using 304 stainless. It was my first experience welding stainless, and I chose to do pie-cut because I like the way it looks, and also for the welding practice. (ALOT of welding!) I am really pleased the way it turned out, and it took a long time considering this was done on my daily driver with no second car. So, alot of taking apart and putting it back together for fitment, welding, etc. Just wanted to share with the community just for some ideas and feedback.
I did not have a back-purge set-up for this build, so Solar Flux Type B was used on the inside of the piping throughout. Thanks for the time, long-time member here, hope you enjoy. More pictures to come a bit later today.

 

[black_gst]

looks nice. my only comment would be the recirc entry angle. also from experience i used to have a custom made recirc 02 housing and when i switched from dumped to recirc i had a noticeable change in the ability to control my boost, i started to get boost creep. i would assume this was because of the inability of the WG to vent that extra exhaust due the pressure on the outlet side.
just something to consider, but i have never attempted to recirc WGs after that.

 

[91talontsifwd]

Thank you. Yeah, the wastegate entry angle is not ideal, I do realize that. When I was coming up with the design, I wanted to make sure that I didn't have to drop the downpipe every time I wanted to drop the transfer case. So that put the first v-band in that location, and that was as shallow of an angle I could pull off using just straight section of pipe, it was going to be difficult to incorporate a shallower angle with just using a harbor freight chop saw and a bench grinder.
As far as boost creep, I have not noticed any on the couple pulls that I have done thus far, but I will be keeping a close eye on that. (still dialing in the new VE maps and accel enrichments for driveability) Also, I am only running the 14b at 15psi at the moment for my day-to-day driving. I went with the recirculated route due to the noise while boosting, and to keep things cleaner through the lifespan of the exhaust.

Some more pics. Will upload a few more later in the day.

 

[Mark4g63t]

love the way pie cuts look. Are you planning on wrapping it after its all complete?

 

[91talontsifwd]

I had originally planned to wrap it. I had ordered a roll of wrap with the initial build purchase. I read a bit more on the subject during the build, and decided not to wrap it, just installed it the way you see it. I had heard stories about the wrap trapping moisture during the heating and cooling processes. I have been monitoring the underhood components over the past few weeks, and have not noticed any adverse effects yet.

 

[FIBA M - EC17PSE]

I had originally planned to wrap it. I had ordered a roll of wrap with the initial build purchase. I read a bit more on the subject during the build, and decided not to wrap it, just installed it the way you see it. I had heard stories about the wrap trapping moisture during the heating and cooling processes. I have been monitoring the underhood components over the past few weeks, and have not noticed any adverse effects yet.

You would have been ok on wrapping it if you purged it, but i am assuming you did not dobthat so i say just keep it as it is.

 

[91talontsifwd]

Pics.

 

[FIBA M - EC17PSE]

That does look good, consider having a heat shield between the alt and pipe to try help keep it running for longer

 

[91talontsifwd]

Thank you. I did pick up some stainless sheet to make heatshields in case I needed them. I would assume that it would be most effective if the heat shield was mounted onto the pipe itself and not the alternator, correct? I'll have to look into how I'm going to fab that up. Thanks.

 

[Gamble97]

I like it. How did you come up with length and angles for pie cuts?
And how did you keep the flange from warping?

 

[91talontsifwd]

Thanks. For the length and angle of pie cuts, I went through the arduous task of doing each bend individually and in order of front-to-back, using the equations:

L=[(2*CLR)+D]*[sin(angle)] ; angle=bend angle/(2*N)

CLR=center line radius
D=diameter of tube
L = Length of long side of pie cut - the top of this pie cut -> \____/
Angle = angle to cut pie section width, this angle is measured perpendicular to the length of the tubing
Bend Angle = The angle of the bend
N = number of pie sections to complete bend

....and then it was just a matter of getting a piece of string and measuring the CLR, and estimating the angle, and massaging the metal to make it perfect....time consuming, but I had no previous experience to take any shortcuts.


As far as keeping the flanges from warping....the v-bands were just preassembled with the clamps during welding,and then had a piece of flat metal with some sandpaper and elbow grease to make it somewhat true. (again, didn't have much experience or tooling). The main flange got bolted to some 3/8" flat stock mild steel with some holes drilled, and got the same flat stock with some sandpaper on it to "true" it. Again, not sure of any feasible alternatives..What do fabricators use to true flanges after welding? I was always curious of this...the flat surface and sandpaper was the best I could come up with.

 

[AUTOMODSGST]

very nice!

 

[UofACATS]

Cool project, love the wastegate recirculate.

What do fabricators use to true flanges after welding?

The services of the local machinist. There's always the best sander, at your own risk of course. I haven't done it but some fabricators make it work.

 

[black92_tsi_awd]

I've always used my old Craftsman 6X48" belt sander to true up flanges. Works perfectly.

 

[crash89]

Wow, this turned out great! Superb job OP!!

 

[Doubleot]

I really like this setup! Looks great!

 

[91talontsifwd]

Thanks for the replies everyone. I have since borrowed my neighbors belt sander. I have not had the chance yet to take the exhaust off and see how it goes. I'm currently in the middle of a bilstein/hyperco coilover set-up, so that should be finished here in the next month or so. I'll be starting a build thread on that project also, it's coming together nice.
I'll update this when I get those flanges true, see how that goes...

 

[McD]

Looks nice, and tons of work,
did you do any clean up or grinding on the inside to smooth any welds that may have had too much penetration?

makes me want to get back to my Pie cut intake project.