Mike J

You are building a mix chamber similar to what is on Baron's (Knight's) car - in his case the PO cut the ends off the stock cats, joined them with a large tub (4-5" diameter) and then built exits on the bottom side. In your mixing chamber, it would be cool if you mirrored the exit with the entrance, ie. build small ramps to direct the exhaust gases out rather than them hitting directly against the bottom of the chamber. That might reduce the temperature of of the chamber as well because you are getting the hot gases out as quickly as possible.

It's going to be interesting to see how much attenuation you get from the resonators. One idea I was playing with is exactly what you are doing, but have a direct and indirect route controlled by a butterfly valve, essentially building a "sport" exhaust. :-)

You get grey welds instead of the nice rainbow effects. I think the discoloration is oxidation. It is just a matter of the argon shielding envelope leaving the hot metal before it has a chance to cool enough to not oxidize. The good news is the welds will be strong enough anyways (I suspect). I have been running mine for 10 months, including some hard running and a track day, no issues other than that nice shiny stainless is not anymore. :d

Once your are happy with it, we should meet up and compare exhaust notes ... the mixing chamber will really make a nice sound I suspect.

Cheers,

Mike

tacker

Using skill saw and hole saw is a workout. Kudos to your hard work and motivation. I'm interested to hear the results. I need to go back to my exhaust system and try to remove the exhaust drone at 2200 to 2400 rpms it's not terrible but its bothers me. Keep up the good work!

Basal Skull

Thanx guys.
The idea was so that I could change the centre section design/make different centre sections so I could make another set with ramps on both sides. The stock ferrari 360 exhaust is a box with inlet directed at each other and outlets in the same orientation out of the box a few inches away. ? the turbulence decreases the sound. Also someone mentioned that one of our popular modified mufflers are empty cans, so thought this might be okay?
I guess I should try higher argon flow rate? I realized yesterday that I was inadvertently using green tungsten (since I was welding aluminum before and didn't realize pure tungsten was just for aluminum... ), that might have contributed to do with he hot/black welds :roll eyes:

Mike J

I use a 2% lanthaniated tungsten with a gas diffuser lens - I like pyrex cups because I can see better, but they are really brittle and expensive. Most of my stuff is from C K Worldwide, I really like their torches.

As far as a higher flow rate goes, it depends on the cup you are using and in what situation. This is where the hours come into play to get that experience, I certainly do not have it down yet. I use about 15 - 20 CFH, but take it down to 10 if the cup is smaller (like a #4). The gas lens helps a lot too.

What size tungsten and what rough current settings are you using?

Jody on this site is very good - and great if you are learning, he has a lot of good tips and very good video on showing techniques for puddle welding.

http://www.weldingtipsandtricks.com/...ding-tips.html

Cheers,

Mike

Basal Skull

pyrex sounds like a good idea, I switched to 2% ceriated which seem easier to use. I have 2% lanthaniated tungsten but much larger gauge. I think I'm using too low a flow rate as I've been using about 12 cfm, cup size 5, and 6. The cups that came with this welder don't seem as good quality as I've broken them and now am using 7 size cup that came with the miller welder. The tungsten I think is 1/16, it's the thinnest I have. I'm using about 40-45 amps for but welding the ?16 gauge pipe and going up to 60-65 when I'm welding to thicker/flange. I'm going to go look at those web sites you mentioned for tips!

The exhaust is bolted together and making heat shields for the turbos but the tips end up being about 2 cm lower on the drivers side unfortunately which is bothering me. There's absolutely no give on the v type clamps for adjustment. Going to stare at it a bit but I think I'm going to make another centre section and build in ramps on both side as you suggest... I'll get more welding practice and there's lots of time before next track season anyways!

Mike J

General rule of thumb - go one amp per thousand of an inch. Set the maximum current of the welder above that so if you are about 3/4 pedal down, you are at the target current. That gives you room to move.

I tend to use larger cups and burn through more Argon - but I have a 250 sized tank, less trips to the welding shop.

Jody at Welding Tick and Tips is a good guy - loads of good info there. have fun! You have those damn surgeons hands so you will be welding like a pro in no time.

Cheers,

Mike

FlatSix911

Looks good so far ... did you consider using a true X-pipe design?

PelicanParts.com

Very nice! Looking good.

Basal Skull

yup, since I can change the center section, planning on making different sections from center and distally to see what changes it makes to the sound.

I've modified things a little and reworked the center section to make it fit better, a little higher, and tips more level. Plan on working on it some more this weekend. Played hooky over lunch and got some more argon/welding cups/tungsten and a foot pedal for the welder!

Mike J

What did you use for control before, a torch mounted hand switch?

Basal Skull

Yup the current welder only had a hand rotary switch which took a bit to get used to and limited how I could hold the torch. But actually useful when working on pieces and tack welding on the car. Now I have both!

FlatSix911

Here is a photo of my exhaust system design with sport cats

Mike J

Nice but that looks like a fabspeed na system - i found the x-pipe in that system has too small of a cross port to generate the sound that i wanted. Basal skull is building an even larger chamber than i did - its going to be interested to see the differences!

Cheers

Mike

OverBoosted28

I have been told (by a very well respected fabricator) that there's absolutely no gain with X-pipes and merging both banks. With the area of the currently available "X-pipes", I tend to believe that assumption. Talked with Mike about doing this a while ago. He kept at it and made a nice system. Feel that a merge of both banks may yield rewards (if only audibly) when there's enough area in the mix. Maybe Ryojo wants some practice and will sell me one of his creations. :-)
Keep it up!!!!!

Basal Skull

FlatSix your system looks good and clean!

Boosted - there's lots of controversy regarding x pipe/h pipe/prochamber etc as to any benefits.. A lot of current cars do use a merging type system though. I thought at the least, you will have 2 outlets to potentially decrease the back pressure (past the merge) vs 1, so especially if you are going to keep the mufflers, one bank now has 2 mufflers and 2 pipes to exit from, which should decrease the back pressure. Decreasing back pressure may not be as useful for NA cars but theoretically not a bad thing for turbos.
My reasoning anyways.