Advice needed on ss airpipe fabrication.

[welkman]

Hello all,

Having got the hang of my mig welder on a few workshop based projects I have decided that I would like to fabricate a snorkel for my landrover that connects straight up to the airbox. Can I get away with using my standard mig gas on stainless for this kind of job? Are there any companies that provide pre cut pie segments for curves? My reason for doing this is that none of the aftermarket snorkels seal properly for wading.

 

[Matthew76]

Following as I'd like to make One for mine as well.

 

[Brad93]

Normal mig gas will result in horrible black welds in my limited experience of normal mig with stainless wire.

 

[Nick67GT]

These things are more carefully engineered than you might think.

The effective length of the 'tube assembly' can affect engine performance to quite a degree in the form of flat spots.

It's all to do with standing waves which occur as part of the natural characteristics of the pipe and how they're chopped up by the inlet valves opening and closing at various engine speeds.

Same goes for compressors with extended inlet arrangements.

But nevertheless, I assume you're probably going to copy - sorry - look at existing installations for inspiration.

 

[welkman]

I take your point but by the time you have bolted a giant snorkel to the air intake careful engineering must be out the window ? I have not felt any real difference but did spot some weird 'dead ends' in the factory tubing which may well be there to damp any waves.

 

[pedrobedro]

These things are more carefully engineered than you might think.

The effective length of the 'tube assembly' can affect engine performance to quite a degree in the form of flat spots.

You do realise he's on about a Land Rover don't you ? I assume he's going to bung a pipe on to get it up in the air then work some bends out to make it join to the air filter and seal it with mastic. It will weld with ordinary gas but the welds look brown as they get carbon from the CO2, look at a stainless exhaust they are mostly welded with mix gas and last for years.

 

[Nick67GT]

It's not a question of 'damping' the waves it's all about maintaining optimum air flow as far as possible across all inlet conditions.

The standing waves can seriously affect this according to the nodes / anti-nodes set up by the natural harmonics of the tube itself and where they occur.

That's why they have built in 'dead ends' and other features to minimise or eliminate these effects on performance.

I take the point about it only being a LR though.....

 

[hotrodder]

Your normal mild steel gas mix will physically work fine but as said cosmetically it won't be as good as it could be and neither will corrosion resistance but that won't be a major deal

I never took any photos of it but made an ally snorkel for a mates sons LR the other year. As with stainless it's a case of buying a mandrel bend or two and cutting whatever angles you need out of it. Probably teaching you to suck eggs but remember when cutting sections out of a tube bend to make the cuts perpendicular to the tangent like the dotted lines

If you need to 'cheat' the radius (shown by the exaggerated red line) for whatever reason then need to cheat it by the same amount on both pieces or you end up with two ellipses with different circumferences

Obviously there are exceptions but many production engines are usually designed to avoid pulse tuning because gains at X rpm usually come with losses at Y rpm [/gross generalisation]. In my case the owner had experimented with plastic pipe and glue so we already knew the change in induction length didn't induce any nasty flat spots or horrible induction noise although changing material can change the later due to resonance

Obviously depends where they're located but 'dead ends' could also be water traps for any rain/splashes that make it past the air/water seperator at the inlet end?

 

[colnerov]

Hi, All the above is true for exhaust manifolds and systems and some of them are far from perfect.

Colin

 

[welkman]

Just as an aside, when teaching standing waves you have to be very careful about the pronunciation of 'kundt's tube' which is a classic experiment. There are several good videos on you tube showing this, some with fire!

Any tips of mig wire for stainless?