DeleriousZ
New Member
Hello Grumpy world.
I'm here to share my first attempt at making a downpipe for my 300zx project, and first time on a Mig welder. I did this with pretty basic tools, which are as follows:
Lincoln SP-135 mig welder
4.5" angle grinder w/ zip discs, flapper wheel and grinding disc
square
ruler
pipe clamp
duct tape
sharpie
vice not attached to anything
stump (from a tree)
I started off with getting a flange cut for my off-sized turbo outlet, and picking up a 2.5" to 3" mild steel reducer. I crammed the reducer into the flange as to get a good idea of where to cut (about 1/3 the way thru the expansion) and marked it. I tried cutting with a hacksaw, but it took forever to get into it with the single dull blade I had laying around, so I decided to try the angle grinder, this worked much better.
After some test fitting and tacking I decided to dive into it head on. I have taken a few courses for oxyacetylene and TIG, but nothing for mig. This was what i ended up with:
The inside of the joint still had some of the reducer left hanging in it, so I ran a bead around the inside of the pipe and hit it with a dremel to smooth everything out.
After some research and looking at how others made their downpipes I went a head and dove head first into mine. I took a 90* bend and cut it off at 60*, and angled it slightly towards the engine so it gave ample frame rail clearance.
I found the best method for cutting the pipe for me (with very limited access to tools) was to use an angle grinder with a thin zip cut wheel. For straight pipe I measured from the end of the pipe to my desired length in about 6 positions around the pipe and marked each with a sharpie. Grumpyvette gave me a tip to use an appropriately sized pipe clamp, which worked wonders for running a nice straight line around the circumference of the pipe. After marking my lines, I took some painters tape and put a wrap around the pipe, lining it up as best I could with the line. This gave me a nice straight visible edge to follow when cutting. When cutting, I usually would take about 60* to 90* of the pipe with each cut, making sure to be extremely careful to keep the edge of the wheel even with the edge of the tape. To get a good view, I removed the guard on the grinder. I don't recommend this as the safety guards are there for a reason, but I'm young and therefore invincible
.
After each section of pipe I test fitted how the dp was going to sit, the main pain was the steering column/transmission clearance. I was able to get around this using the remainder of my 90* pipe angled just right. It took some cutting and fitting to get it to go but eventually I got it to sit where I wanted.
Notice the gaps between the pieces are pretty tight, this will help when it comes time to weld out the pipes. For this I'll be using a TIG machine if I can ever find one to rent/borrow/beer, with stainless filler rather than the mild wire that's used for the tacs. I will remove the mild tacs after getting some stainless tacs on there to ensure that the welds are the most corrosion resistant possible. (even a little mild steel mixed in with the stainless will cause strength and cosmetic issues after time)
The pipe exit now sits where I want it to, giving a nice spot for a flange, without getting in the way of both the trans fill point, or anything else.
Hopefully I'll be able to update this sometime soon with the fully welded pipes, but for now I need to concentrate on getting the car back together and getting the coilovers installed.
Any comments, questions or critiques please feel free to ask/scold away!
-Travis.
I'm here to share my first attempt at making a downpipe for my 300zx project, and first time on a Mig welder. I did this with pretty basic tools, which are as follows:
Lincoln SP-135 mig welder
4.5" angle grinder w/ zip discs, flapper wheel and grinding disc
square
ruler
pipe clamp
duct tape
sharpie
vice not attached to anything
stump (from a tree)
I started off with getting a flange cut for my off-sized turbo outlet, and picking up a 2.5" to 3" mild steel reducer. I crammed the reducer into the flange as to get a good idea of where to cut (about 1/3 the way thru the expansion) and marked it. I tried cutting with a hacksaw, but it took forever to get into it with the single dull blade I had laying around, so I decided to try the angle grinder, this worked much better.
After some test fitting and tacking I decided to dive into it head on. I have taken a few courses for oxyacetylene and TIG, but nothing for mig. This was what i ended up with:
The inside of the joint still had some of the reducer left hanging in it, so I ran a bead around the inside of the pipe and hit it with a dremel to smooth everything out.
After some research and looking at how others made their downpipes I went a head and dove head first into mine. I took a 90* bend and cut it off at 60*, and angled it slightly towards the engine so it gave ample frame rail clearance.
I found the best method for cutting the pipe for me (with very limited access to tools) was to use an angle grinder with a thin zip cut wheel. For straight pipe I measured from the end of the pipe to my desired length in about 6 positions around the pipe and marked each with a sharpie. Grumpyvette gave me a tip to use an appropriately sized pipe clamp, which worked wonders for running a nice straight line around the circumference of the pipe. After marking my lines, I took some painters tape and put a wrap around the pipe, lining it up as best I could with the line. This gave me a nice straight visible edge to follow when cutting. When cutting, I usually would take about 60* to 90* of the pipe with each cut, making sure to be extremely careful to keep the edge of the wheel even with the edge of the tape. To get a good view, I removed the guard on the grinder. I don't recommend this as the safety guards are there for a reason, but I'm young and therefore invincible
.
After each section of pipe I test fitted how the dp was going to sit, the main pain was the steering column/transmission clearance. I was able to get around this using the remainder of my 90* pipe angled just right. It took some cutting and fitting to get it to go but eventually I got it to sit where I wanted.
Notice the gaps between the pieces are pretty tight, this will help when it comes time to weld out the pipes. For this I'll be using a TIG machine if I can ever find one to rent/borrow/beer, with stainless filler rather than the mild wire that's used for the tacs. I will remove the mild tacs after getting some stainless tacs on there to ensure that the welds are the most corrosion resistant possible. (even a little mild steel mixed in with the stainless will cause strength and cosmetic issues after time)
The pipe exit now sits where I want it to, giving a nice spot for a flange, without getting in the way of both the trans fill point, or anything else.
Hopefully I'll be able to update this sometime soon with the fully welded pipes, but for now I need to concentrate on getting the car back together and getting the coilovers installed.
Any comments, questions or critiques please feel free to ask/scold away!
-Travis.
