Fluxcore for turbo log manifold

Fellow low-buck turbo builders, I am trying to make up a log manifold for my 4age. I have access to a welder that can be either flux or MiG. Currently running flux and it seems to get good penetration, is there any reason I shouldn’t push forward with flux? Will it be weaker in the long run or just ugly?

Not really weaker just uglier with the spatter.  

Technically flux core is better for heavier wall stuff, need less current for good penetration.

Now that I have argon, I want to try dual shield (flux core and gas, at the same time).  It's supposed to be incredible for things like filling drilled holes.  Leaves no occlusions.

I dual shield all the time, flux core and argon, for stuff that I wire feed weld with the flux core, like carbon steel.

If doing a manifold for a turbo, just be real sure to clean the inside out very, very well before you put it on the car.  You don't want any flux or wire or splatter going through the tubo.

You’ll be fine don’t worry about it.

Flux core is great for heavy material. If your angle and stick out length is correct you will not have much if any spatter. The penetration will be superior to mig unless you use a shirlding gas with at least 90 percent argon and run very hot so that you achieve spray transfer. You need about 400 inches per minute and 23 volts to achieve spray transfer with .035 wire. 

When using flux core with gas make certain that you have the proper wire.

Braden

I've been playing a lot with my mig/flux core using flux core wire. I had no prior experience and It seems I can make decently strong welds. Spatter? Yes. Grinder with flapwheel makes the yucky go away. :)

It should be fine.  Flux core tends to burn hotter and be uglier.  My only concern would be the porosity... not for strength reasons, but leak reasons.  As the flux burns inside the weld it leaves bubbles.  If you cut a cross section of a flux core weld, it sometimes looks more like pumice or swiss cheese.

But more than strong enough

As long as you're not trying to weld stainless or cast iron you'll be fine. 

I think really good experienced welders can get good results with flux core.  I’m not particularly good or experienced.  I played with flux core for almost a year; yes, I was able to stick two pieces of steel together.  My welds were porous, ugly, spattery, and generally not good at all.  I finally broke down and got the argon tank, and a regulator off of Amazon for like $20.  I also stepped up and got a nice Lincoln helmet that lets me see my work better.  It is a world of difference- my welds are clean, shiny, great penetration, and even have that cool “stacked dime” look.

I have a welded exhaust manifold on my Miata.  It is essential to have really good welds, they see a ton of heat, vibration, big mechanical stresses.

Crackers said:

As long as you're not trying to weld stainless or cast iron you'll be fine. 

Cast iron would be an issue, but I've welded stainless on an exhaust (both 304 and 409) with mild steel flux core wire and had it work just fine.  Took a couple minutes of practice to get good results (with my minimal welding ability), but the welds were solid when I was done.  No exhaust leaks at the welds either. 

In reply to rslifkin :

I think that would maybe be ok for a non-stressed section like a down pipe or further away from the engine, but between the differing expansion rates between mild and stainless, lack of a back purge, and the weight of the turbo hanging on the manifold you'd be asking for stress cracks. 

It wolnt be pretty and it will be prone to crasking, but you can make it work.  Some advise from personal experiance. 

- Use a really slow feed 

- Use as much amperage as possible

- Go one "puddle" at a time

- Wait 5-10 seconds between each puddle and stack them up.  

IMHO the slower you go, the better your results will be.  

In reply to Crackers :

If you have a tubular manifold  you really should make some way of supporting the turbo besides the manifold.

In reply to Curtis :

It is only porous if you have used an improper angle or the the wrong contact tip to work piece distance.or bad settings on the machine. You need to drag the puddle about10 to15 degrees. The tip needs to be much farther away than when using MIG. Stickout on .035 to .045 wire needs to be .375 to.75 inches, depending upon the voltage and wire speed. Incorrect polarity damn near guarantees porosity. Most flux core runs electrode negative while most solid wire runs electrode positive. Too much voltage without enough wire speed (amperage) or vice versa will also cause porosity. 

In my opinion flux core requires the most skill of the weldor to do properly. When done properly it gives excellent, strong results. I have MIG (GMAW), TIG (GTAW), stick (SMAW) and flux core (FCAW) equipment and I use flux core probably 70% of the time.

In reply to pilotbraden :

10-15 degrees from vertical or horizontal?

In reply to DeadSkunk (Warren) :

Direction of travel. Perpendicular to the joint. Both faces of the weld must be melted equally for proper fusion

In reply to DeadSkunk (Warren) :

This is the angle to shoot for traveling left to right.

This is a cut flux core weld that has been polished and acid etched. It is a dual shield wire that also uses gas for shielding. It has great penetration 

This is a cut MIG weld using the short circuit process. The root did not fuse and it has very little penetration. It probably looks nice.