Turbo V-band & Inlet Bend Welding

[Hek]

Hi all,
Am going to be making a 3" downpipe and 2.5" exhaust for my Saab 9-5 Aero
However I've had a turbo for one kicking around for a while, and the turbo outlet looks horribly restrictive.
As an obsessive tinkerer, I believe this could be improved by machining out and welding a V-band directly to the outlet.
However I've read loads on welding on stainless V-Bands, with varying success, and wondered why mild steel isn't used?
Availability?
I can probably get one machined in steel
What filler would be most ideal?

Also would like to directly weld a cast elbow onto the inlet
(saab use a weird cast S-bend, which is a known restriction. The newer revision requires machining the inlet back anyway, so why not re-profile for better flow, as well as allowing better flow through the bend?)

section view badly showing what I'm on about.

However, I've never TIG'd aluminium before.
Should I just ask someone who knows what they're doing?
I have no idea what I'm doing, although should learn it...

 

[BrokenBiker]

when you say a cast bend, do you mean cast iron or cast aluminium? the way i read it you are planning on welding mild steel to cast aluminium? if so this just flat out will not work. its not possibleto join the 2 materials with a tig welder due to the composition of the 2 materials being so different.

the reason i have taken this assumption is becasue before the picture you talk only about steel and then after the picture you mention tig welding ali.

 

[Richard.]

How urgent is it that its done because you've got quite a way to learn before taking that on.
Clean pure grade Alu in the flat position takes a bit of time and practice from starting out
Cast Alu is a different breed and depending on whether your lucky or not it will either weld nicely or you'll fight with it from start to finish. It's cylindrical a swell which again isn't the easiest to do if you've not had a torch in your hand. I'd put it to one side and get practicing or give the job out and still get practicing.

 

[Hek]

sorry, cast aluminium on the intake side
Yeah I think that was a bit of wishful thinking, i'll concentrate on the porting of the exhaust side

I'm about hobby-competent at TIG welding though, done 316 and mild in work

Mixing together both ends of the turbo confused things!

 

[Lee Dabbs]

Hek what turbo is on the Saab I do fab work on a lot of Saab turbo astra vans and Saab turbo corsa

 

[Hek]

Just standard TD04HL-15T
I had a 9-5 LPT, bought the (aero HOT) turbo to put on there with a remap for 275hp.
Bought an Aero estate so now have a surplus turbo!

Did take pictures, will upload this evening if I remember

 

[Richard.]

Whether you take the job on or not it's always worth learning the skill.

 

[Lee Dabbs]

So what are you trying to do make the flow better on the inlet or exhaust