Soul Performance

We're proud to back purge out welds as the additional effort yields a superior product. I've been asked to take photos of your systems being built and wanted to highlight part of our process which sets us apart.

Below you see three welds that look very similar on the outside – but inside it’s a very different story! Proper TIG welding technique is not just about achieving a great stack of dimes on the outside of the piping, but more importantly about penetration and preservation – making sure the back of the weld is functionally sound.


Back purging is the process of shielding the inside of the weld with an inert gas to prevent contamination during the welding process, resulting in a stronger weld.

Wikipedia extrapolates on this statement: “Stainless steels, duplex steels, titanium-, nickel- and zirconium- alloys are sensitive to the presence of air, oxygen, hydrogen, water vapour and other vapours and gases that may combine with the hot metal as it is being joined.

Such gases may combine with the metal to form undesirable compounds that may reduce corrosion resistance or may be instrumental in creating cracks or other structural defects in metals.”

The rate of oxidation in metal progresses more rapidly as temperature increases – to a very high level during welding. Back purging prevents this from happening. An inert gas does not undergo chemical reactions and prevents rapid oxidation while the stainless is in a molten state.

Argon, a noble gas, is the most commonly used shielding gas in TIG welding. It offers a very stable arc allowing a skilled fabricator great control over the resulting weld.

As part of the welding process, the welding torch is designed to emit shielding gas to protect the front of the weld. Different cups offer different gas patterns as seen below in a still below from a demonstrative video, but ultimately the goal is to shield the weld from oxidation and the negative effects explained above. This is how you can have a weld that looks great on the outside with the interior of the welding looking much different. To protect the inside of the weld, back purging is necessary – but not always done.




Here’s an example of SOUL using back purging during the fabrication process. Our fabricator has plugged the ends of this 991.2 Carrera Cat Bypass Pipe and Argon gas is being pumped from a gas cylinder at a controlled rate through the inside of the piping. It takes some time to displace the ambient air with the inert gas before the welding can begin.



Now that you’re aware of what back purging is and why it’s done, let’s go over a few examples of different welding scenarios with and without it to give you a better idea of why it is used.

Weld 1: Lack Of Penetration (No Back Purging)

This butt weld shows a lack of full penetration, leaving the root gap exposed. During the welding process this gap can allow for a better, stronger weld. Left unfilled, it can attract moisture and corrode quicker than the rest of the exhaust system. Without full penetration in this butt joint, this is a weak weld with reduced strength – it’s a point of failure. Below is an example of weld that failed from lack of full penetration.



This weld can result from high amp / low duration settings with no back purging. The blackened surface consists of oxides of chrome, iron, and nickel – effectively the rust resistant properties of the stainless steel are being burnt out of it.

Weld 2: Sugaring (No Back Purging)

Sugaring / granulation / contamination is extreme oxidation of the back side of a stainless weld. This weld has penetration but is also heavily oxidized due to lack of a shielding gas. While this weld has full penetration it is not as strong as a back purged weld and is also a point of potential rust and / or failure under stress. To a mild effect sugaring also interrupts exhaust flow.

• Sugaring is often a rejectable defect in medical / food industries as the texture can trap bacteria.

Weld 3: Back Purged Weld

In the end strength, longevity, and minimal impact of flow are the end goals of a back purged weld. This weld was done with the same settings as the weld above but was back purged with Argon. The inert gas prevents burning and contamination for a visibly different weld. There is full penetration with no contamination on the backside. Not only is it beautiful and well done, but it is quite strong.

Here are a few examples of our back purged welds and some other welding highlights on a Race Exhaust System coming through fabrication today:







-Mike

G-forceGT4

The last post was very informative Mike, thanks for posting! The back purging technique yields a more superior result. You guys make awesome stuff & it's great when you share some of the technical aspects of the fabrication process.

UncleDude

Very interesting!

Soul Performance

Thanks for the kind words guys! We enjoy showing the nitty gritty every now and then for those that appreciate it haha

Regards,
John Gaydos

kart125

Awesome welds!! I'll stick to my day job!

lovetoturn

Yah, it is the nitty gritty that makes for an excellent product that lasts. Simplistic form of marketing is just to make it right, stand behind your products, and provide great customer service. Over time everyone figures that out and continues to send their business your way. As a bonus, we at Rennlist are the kind of folks that love to see and hear about the little tid-bits that make vendor's products of the highest quality. Thanks for the detailed photos and explanation of your welding process.

TXshaggy

These go on tomorrow. Excellent quality and support from John at Soul.

Will report back.

UncleDude

^ on point with the colour scheme

Soul Performance

Me too, I've been practicing myself after hours ever now and then and the burn on my elbow still hasn't healed

Thanks for saying that Jeff, it's awesome to hear that these kind of posts are appreciated. Our guys take a lot of pride in their workmanship and the steps we take as a company to ensure the quality exceeds expectations.

Give me a shout directly as well, I'd love to hear your feedback after your get some seat time

It's not often I see yellow, and I'm always surprised how much I like it of a Porsche haha.

Regards,
John

TXshaggy

Got the Soul Over axle pipes installed yesterday and put about 100 miles under throttle.

I’d call it a transformative upgrade; positively shrieks under throttle. Dare I say “supercar” sound?

Construction, fit and finish flawless. Installer backed the threads out without a problem.

Here’s some shots of what came off and a couple from the installer.

Finally, no matter how many YouTube videos you watch it doesn’t capture the sound adequately— it’s so much better. On start up I’m like, oh boy here we go...

Class act from Soul all the way. John personally called to discuss the installer and expectations. Easy recommendation for Soul...

DFW01TT

I had the same experience with John when I put their valved exhaust on my 981. They're a top notch manufacturer, in my experience.

Westcoast

I would like to understand more about your comment "transformative", can you expand on the traits and differences? Also now with just the over axel pipes, are you happy enough to stop or would you say there is some more worth having?

Thanks!

TXshaggy

First, the easy response to “is some more worth having” — for me NO, I’m super satisfied with where the car now is.

I did consider a controller, but I decided to incrementally approach this project. I won’t be getting a controller. Here is how I’d divide my TX Hill Country driving and why it doesn’t make sense for me.

1) Transit/casual. This is around town and highway/interstate driving with speeds up to around 90 MPH...this is TX lol. These environments all occur at below 3700 RPM. I’m happy to have the valves closed during this. Now with the GPF pipe, little more growl which is fine. OBTW, I drive with PSE on *** off every start up. Not an issue for me with *** off, but you’d never want to hear 3 cylinder mode with GPF delete and valves open...so something to consider if you’re an *** on type...so to speak lolz. Finally I’ve read that some that have hard wired valves open experience drone in these RPM regimes.

2) “Canyon carving”. Most of this is PDK manual mode and above 3700. So glorious.

Lastly, while some bemoan the transition as unacceptable; I’m more like meh...it doesn’t bother me. Before or after pipe install.

Sound and volume. Volume is easy, turn it up to 11...haha! Based on the online videos I wasn’t expecting such a large shift. Frankly some before/after are hard to discern if the expense is worth it. Anyway to me, I find it significant.

OK, now on to the hard part...sound. The easy analogy is when wearing NC headphones/muffs and taking them off; increase and depth of frequencies.

My experience is with a 3.4 PSE Spyder; yes this is completely different. I’d describe the 3.4 as sonorous and above 6000 starting to howl to RL all at a higher monotone pitch. Frankly I loved it...believe the 3.8 was similar.

This 4.0 is different. Perhaps some is induction noise. There is more going on. When it gets going it’s more guttural if that makes sense. The GPF pipes won’t change the characteristics, just unmuffle what’s there.

I’ve read where folks are chasing “that flat 6 sound”; perhaps better stated would be that 3.4/3.8 PSE sound. That’s not for me; I’m not backward looking like that. I’ll celebrate the 4.0!

Lastly, maybe wishful thinking but feel more thrust now uncorked. Rear has stepped out a couple of times...that never happened before. Same temps 70s and throttle commands...I dunno.

Bottomline, I’d recommend getting the GPF and go from there. Many, including John from Soul say best bang for the buck—I agree.

Hope this helps.

Shaggy

Rennolazine

Thanks for the detailed writeup. How would you say the noise is below 3700 rpm? Can you tell its not stock, how much more volume would you say you have gained?

UncleDude

I've been waiting for someone to say this.