diy exhaust project
09-19-2015, 02:38 AM
#1
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diy exhaust project
Traditionally, I think we've been posting about our projects after we finish but I thought I might start posting as I go this time. The only problem is that there is a risk that I might not be able to finish for one reason or another, and would expose myself to possible banter...
Catalyst for this project was Mike J's and Tasker's previous post on exhausts.
I don't mind much about sound, but do care about weight loss / performance and too much noise.
I wanted to get rid of the mufflers for weight. Have and continue to read about exhaust/muffler theories/noise equations/papers on theories and experimental muffler design. Crossover/H- pipe/prochamber/expansion chambers etc. Taking into account firing order of our engines.. Have looked at pictures of 100's of mufflers.
Anyhoo, I think with the elbows I found, I can fit 2x 12" resonators on each side behind the bumper with a cross over/expansion chamber in between connected with v-clamps so I can easily change out and vary the cross over design. Initially thought of just keeping each side separate with 180 u bends, but realized that using a cross over design with our firing order, the cross over essentially allows one bank to exit out of 2 exhaust/tips which probably decreases back pressure (vs keeping sides separate). All this will be more clearer as I put it together over the next few weeks or months (depending on how much free time I have).
Using 3" pipe 304 stainless thought, spacers for O2 sensors, making flanges etc by hand. Was hoping Santa might be bringing a plasma cutter for xmas but apparently no such luck (I will continue to ask in hopes to change her mind). Local auto parts store was helpful with parts (Mopac) and metalsupermarkets.com happen to have a store outlet close by for raw materials. Aluminum intake pipe for heater duct.
Also thinking about minor mods to bumper cover, strengthening supports in aluminum (after removing muffler) and removing bumperettes/some shielding for better venting...
Catalyst for this project was Mike J's and Tasker's previous post on exhausts.
I don't mind much about sound, but do care about weight loss / performance and too much noise.
I wanted to get rid of the mufflers for weight. Have and continue to read about exhaust/muffler theories/noise equations/papers on theories and experimental muffler design. Crossover/H- pipe/prochamber/expansion chambers etc. Taking into account firing order of our engines.. Have looked at pictures of 100's of mufflers.
Anyhoo, I think with the elbows I found, I can fit 2x 12" resonators on each side behind the bumper with a cross over/expansion chamber in between connected with v-clamps so I can easily change out and vary the cross over design. Initially thought of just keeping each side separate with 180 u bends, but realized that using a cross over design with our firing order, the cross over essentially allows one bank to exit out of 2 exhaust/tips which probably decreases back pressure (vs keeping sides separate). All this will be more clearer as I put it together over the next few weeks or months (depending on how much free time I have).
Using 3" pipe 304 stainless thought, spacers for O2 sensors, making flanges etc by hand. Was hoping Santa might be bringing a plasma cutter for xmas but apparently no such luck (I will continue to ask in hopes to change her mind). Local auto parts store was helpful with parts (Mopac) and metalsupermarkets.com happen to have a store outlet close by for raw materials. Aluminum intake pipe for heater duct.
Also thinking about minor mods to bumper cover, strengthening supports in aluminum (after removing muffler) and removing bumperettes/some shielding for better venting...
09-19-2015, 02:47 AM
#5
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took a few mins each day for a week (could only stand the noise for a few minutes each day) for each flange to cut the hole using a hole saw and my old drill press. Cutting stainless with a hole saw is not very efficient, I went through 2 saws for each side.. 
09-19-2015, 02:50 AM
#6
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cutting with a metal cutting disc on a skill saw is noisy and takes a long time too (boy I wish santa would okay a plasma cutter 
)
tuned out reasonably pretty.
)tuned out reasonably pretty.
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09-19-2015, 03:37 AM
#8
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Nice work!!
Hey, let me know if you need to cut with a plasma cutter, I have one. Takes some practice to make an nice cut, but it works. It's too bad we are far apart, I am in North Burnaby so its a good 40 minutes across town.
I cut out my own flanges too, but had the advantage of a metal lathe as well to turn the outside etc. I used a 4 jaw chuck to hold the piece, and then cut the hole with a hole saw like you did, but on the lathe I have much more power and can lubricate the cutter. If you want to turn the outsides of those flanges, you can certainly come over and we can give it a try. SS is challenging to cut at times. Next time I do this, I would just buy a water jet cut flange off a supplier .. :-)
When I was fabbing, I took some of the tubing down to a local exhaust shop and had them expand the piping so I could use slip joints - its much easier to fiddle with the angles etc with those sort of joints, and once everything is lined up, I can then put in better joints (like quick disconnects, etc.).
I also can get great deals on 3" local SS tubing because of my wife's contacts - but need to buy 20' at a time, worked out much cheaper than the US. I have some piping around if you need some more. I also bought some mandrel bent piece like you - who was your supplier?
I cut a lot of the piping with a 14" abrasive metal cut-off saw. I also used a metal cutting bandsaw for finer work, and then used a die grinder with a carbide bit to clean up all the joints. I found the cut-off saw worked best since you need a very flat face on the cut in order to get a good joint for TIG welding, especially on the thinner gauge stainless.
This winter will be stage 2 of my design, since I am happy with the exhaust to past the X-pipe, now it's time to build the rest, including new mufflers. I want a two stage system since I need to be able to bring the car home late a night with it running in quiet mode, then use vacuum controlled bypasses to open up the system. I found a used 991S muffler that I got cheap and stripped the valves off of that, but also plan like you to make it all 3" pipe including new tips.
Let keep exchanging info, lots of fun!
Cheers,
Mike
Hey, let me know if you need to cut with a plasma cutter, I have one. Takes some practice to make an nice cut, but it works. It's too bad we are far apart, I am in North Burnaby so its a good 40 minutes across town.
I cut out my own flanges too, but had the advantage of a metal lathe as well to turn the outside etc. I used a 4 jaw chuck to hold the piece, and then cut the hole with a hole saw like you did, but on the lathe I have much more power and can lubricate the cutter. If you want to turn the outsides of those flanges, you can certainly come over and we can give it a try. SS is challenging to cut at times. Next time I do this, I would just buy a water jet cut flange off a supplier .. :-)
When I was fabbing, I took some of the tubing down to a local exhaust shop and had them expand the piping so I could use slip joints - its much easier to fiddle with the angles etc with those sort of joints, and once everything is lined up, I can then put in better joints (like quick disconnects, etc.).
I also can get great deals on 3" local SS tubing because of my wife's contacts - but need to buy 20' at a time, worked out much cheaper than the US. I have some piping around if you need some more. I also bought some mandrel bent piece like you - who was your supplier?
I cut a lot of the piping with a 14" abrasive metal cut-off saw. I also used a metal cutting bandsaw for finer work, and then used a die grinder with a carbide bit to clean up all the joints. I found the cut-off saw worked best since you need a very flat face on the cut in order to get a good joint for TIG welding, especially on the thinner gauge stainless.
This winter will be stage 2 of my design, since I am happy with the exhaust to past the X-pipe, now it's time to build the rest, including new mufflers. I want a two stage system since I need to be able to bring the car home late a night with it running in quiet mode, then use vacuum controlled bypasses to open up the system. I found a used 991S muffler that I got cheap and stripped the valves off of that, but also plan like you to make it all 3" pipe including new tips.
Let keep exchanging info, lots of fun!
Cheers,
Mike
09-19-2015, 12:14 PM
#9
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thanx for the offer to use your plasma cutter Mike!
SS is a pain to cut vs other metals, although I have secret lubricant that works really well, i'll have to give you some next time (you won't believe how well it works).
The resonators I'm using have 3" ID so the 3" OD pipes slip on and was relying on that for some of my 'adjustable' joints. Also going to weld 3" ID pipe on those flanges so there's some adjustability there (planning on doing this after mock up since I may be able to angle it up higher into the bumper).
Mopac in Langley (grew up in the area) usually has most things in stock. I bought Vibrant SS pieces/pipe, they have sharper angles (which may not be as good for flow but good for the tight space).
I don't want things too loud either, and anxious to see how loud things are with 2 resonators per side. I thought it was too loud with muffler bypass and sport cats, muffler bypass and stock cats were ok. So I'm hoping the resonators will do the trick. I'm also going to incorporate expansion chambers to the cross over so the centre section may act somewhat as a muffler. I was going to attach this part with the v clamps so I could remove and modify the cross over depending on the sound easily.
I'm going to try to make most of my pieces before taking the exhaust off so next will be welding the v clamps onto one ends of the resonators.
Lots of fun is right! Off to the gym and then KMS tools to get another tank of Argon and more welding supplies today.
SS is a pain to cut vs other metals, although I have secret lubricant that works really well, i'll have to give you some next time (you won't believe how well it works).
The resonators I'm using have 3" ID so the 3" OD pipes slip on and was relying on that for some of my 'adjustable' joints. Also going to weld 3" ID pipe on those flanges so there's some adjustability there (planning on doing this after mock up since I may be able to angle it up higher into the bumper).
Mopac in Langley (grew up in the area) usually has most things in stock. I bought Vibrant SS pieces/pipe, they have sharper angles (which may not be as good for flow but good for the tight space).
I don't want things too loud either, and anxious to see how loud things are with 2 resonators per side. I thought it was too loud with muffler bypass and sport cats, muffler bypass and stock cats were ok. So I'm hoping the resonators will do the trick. I'm also going to incorporate expansion chambers to the cross over so the centre section may act somewhat as a muffler. I was going to attach this part with the v clamps so I could remove and modify the cross over depending on the sound easily.
I'm going to try to make most of my pieces before taking the exhaust off so next will be welding the v clamps onto one ends of the resonators.
Lots of fun is right! Off to the gym and then KMS tools to get another tank of Argon and more welding supplies today.
09-25-2015, 04:32 PM
#11
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Will get more done this week end (just started some welding) and will post pics. Was thinking of holes in the bumper cover like your 930 but don't think I can bring myself to do any cutting of my cover. I'll see if leaving the bumpettes off looks to be useful.
10-05-2015, 01:19 AM
#12
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well, this is going to take a bit of time and effort...
I hate running out of Argon during a project so bought another tank. So I have lots of gas but then my tig welder broke this weekend (second time); last time it took about a month to fix and good luck finding time off work during regular business hours to take it to a shop, so bought another tig welder
The heat shields around the turbo are rusted so will fab those. Made little spacers to use the hangers the cats attached to like Mike J. Was planning on using sliding joints but I don't have the space using these resonators, so just going to build things out from the Turbos to the centre and build in the centre piece in place using v joints (wish me luck). Takes a little bit of practice to be able to weld the tubing onto the flanges without blowing a hole through the tubing
I hate running out of Argon during a project so bought another tank. So I have lots of gas but then my tig welder broke this weekend (second time); last time it took about a month to fix and good luck finding time off work during regular business hours to take it to a shop, so bought another tig welder
The heat shields around the turbo are rusted so will fab those. Made little spacers to use the hangers the cats attached to like Mike J. Was planning on using sliding joints but I don't have the space using these resonators, so just going to build things out from the Turbos to the centre and build in the centre piece in place using v joints (wish me luck). Takes a little bit of practice to be able to weld the tubing onto the flanges without blowing a hole through the tubing
10-05-2015, 02:11 AM
#13
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Looks good! - you may want to drop your amps a bit - like me, you are tending to cook the metal/joints a bit and not getting that nice rainbow coloring. . When I TIG, I quickly realize how many hours it takes to get to the level of some of the welding you see on the net - wow.
It will be interesting to see how much noise reduction you get with the resonators, I seem to remember they are good at taking out the higher frequency noises (they will be absorbed by the perforations) but the lows will continue through. I assume you will do the resonators right from the turbos, mix, and then resonators back to the tips, with no cats?
I found going down a size on the tungsten for a smaller bead and less heat, lowering the amps, and sometimes, instead of a DC feed, use the "rule of 33" as a place to start which really helps control the heat any burnthrough.
The rule to 33 pulses per second, 33% pulse time, 33% background current, adjust from there.
Can't wait to see your progress! I am going to do more on my exhaust as well, but likely won't start until Christmas or so so watching closely to see your results.
Cheers,
Mike
. When I TIG, I quickly realize how many hours it takes to get to the level of some of the welding you see on the net - wow. It will be interesting to see how much noise reduction you get with the resonators, I seem to remember they are good at taking out the higher frequency noises (they will be absorbed by the perforations) but the lows will continue through. I assume you will do the resonators right from the turbos, mix, and then resonators back to the tips, with no cats?
I found going down a size on the tungsten for a smaller bead and less heat, lowering the amps, and sometimes, instead of a DC feed, use the "rule of 33" as a place to start which really helps control the heat any burnthrough.
The rule to 33 pulses per second, 33% pulse time, 33% background current, adjust from there.
Can't wait to see your progress! I am going to do more on my exhaust as well, but likely won't start until Christmas or so so watching closely to see your results.
Cheers,
Mike
10-05-2015, 03:04 AM
#14
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Yup going to do the resonator, mix, resonator and tips with no cats. I've seen the innards of ferrari mufflers and the 'free flowing' part of the muffler is just an expansion chamber with two in lets (one from each bank) aimed at each other and two outlets. So I'm going to make something similar with the cross over.
I'll have to read up on the manual to use the pulse settings, and will try your 33 rule. The new tig welder has a thumb wheel you turn instead of the foot pedal, and I keep turning it the wrong way! I also don't seem to be able to adjust max current like I could with my other tig welder. I'm using 1.6mm tungsten. With the miller 180 I just had to select max current and if I'm welding aluminum or stainless/steel. The Firepower 200 I have now has a pulse setting, and I have to learn about all the settings...
I'll have to read up on the manual to use the pulse settings, and will try your 33 rule. The new tig welder has a thumb wheel you turn instead of the foot pedal, and I keep turning it the wrong way! I also don't seem to be able to adjust max current like I could with my other tig welder. I'm using 1.6mm tungsten. With the miller 180 I just had to select max current and if I'm welding aluminum or stainless/steel. The Firepower 200 I have now has a pulse setting, and I have to learn about all the settings...
10-12-2015, 03:22 AM
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I think there's hope I'm going to be able to put this together. Welds aren't pretty but I think it's reasonably solid; hopefully won't have any big leaks and won't crack. Good thing most of it will be covered. Going to use spacers for the distal O2 sensor. Lots of mixing, hopefully it will flow okay? lots of hoping.. having fun anyways which is the main thing, wonder how it will sound. I bet it's going to be loud. 
