Tips, tricks, ideas, advice before jumping into first turbo manifold project?

[sniper]

I am about to start on my first header/manifold project and just wanted to get some advice on how to start. First off, im trying to make something say about like this..

I am starting with 1.5 inch U Mild steel bends, 10 of them in fact, and i am going to use a T3 turbo flange and i may have to set it up for an external wastegate. Any tips on the part of the manifold where all the pipes merg into one? any links to articals anyone might know off hand that may help with this project? I am using a MIG welder with steel wire and a 75/25 mix and I have a chop saw and grinder. Might be a file or two lying around too, but thats about it...

 

[BigKriss]

Sniper,My humble opion on this..

Cast iron manifolds-first prize.
Cast steel steam pipe bends-second prize.
Stainless grade 258MA-third prize.
Stainless grade 321-fourth prize.
Mild steel-dont bother,it will crack.

I am now using the cast steel steam pipe bends and with some expansion engineering in the design,theyre pretty reliable.

Nothing is bulletproof unfortunately.
I do a small production of Alfa Romeo turbos for guys all over.Ive cast my own log type turbo manifolds,use a single turbo setup,(Cost factors and correctly done,no advantage with twins..)

Hope this is of value to you..

 

[speedsex]

are you going to be using the manifolds in your 240 ? if you are going twin turbo ill send you some pics of my setup

 

[mdcmotorsports]

You can start with mild steel, but as stated it will crack in time. You can prolong its life with a ceramic coating.

Remember to measure 4 times, cut once. Take your time. Clean every thing! (Welds like clean metal to start with) Have some poster paper board around as its great for cutting out patters before you cut metal.

 

[Toysrme]

merges are pretty easy. if tigging you're just going to walk the cup all the way down the seams.
have a horizontal bandsaw, with a bi-metal blade (in the correct tpi range) and use a coolant setup if-possible, or atleast run a candle along the blade before every cut.
14" chopsaws can be used, but they're not as accurate, much more dangerous to cut with & very messy...

Be very careful with heat unput on all of your flanges. otherwise they WILL WARP. ESPECIALLY stainless flanges (whcih is why almost noone uses stainless flanges). Stainless expands at 50% of the rate MS does.







schedule 10
321 if you're rich
304 if you're normal

if you're going to use anything MS or cast use schedule 40 or you run an extremely high risk of cracking over time.

if the turbo & downpipe are very heavy it is adviseable that once built & mounted. youw eld supports in from the main flange to another flange on the manifold, and to fabricate a good bracket support from the turbo flange to the drivetrain of the car to keep swaying at a minimum.









cracking is inevetable regardless of what you do. eventually the manifold will crack as none of these materials (short of 321) are particularly well suited for the high temperatures + the vibration & swaying they are subjected too. N/A, or FI, doesn't matter. anything will crack eventually.



in my experiance the majority of turbo manifold cracking comes from:

1. building a manifold under stress so that it pulls apart
2. incorrect installation
3. poor material choice & combinations
4. weld defects

of those stainless is no more prone to crack than anything else. the problem mostly associated with cracking stainless manifolds would have caused premature cracking of any other manifold.




you MUST NOT build a manifold under stress!!! that can not be said enough! The manifolds will pull apart during heat cycling if they're already warped, bent, or shoved together. FI Stainless manifolds are most commonly made with schedule 10. It's light weight, easily avalible & plenty strong enough. (that's a wall thickness of 0.109") Most mild steel manifold's (T log manifolds, or tubular manifolds) are made of schedule 40 (0.145").

The MS has to be that thick, stianless, when not warped during construction is perfectly fine at schedule-10.