Datsun Roadster Forum-311s.org

notoptoy wrote: Sat Mar 23, 2019 11:23 am Yep, that is a work of art! (Like a Picaso, or a Garfunkel)

This. ^^^

Nice work.

GoldHawg wrote: Sat Mar 09, 2019 5:57 pm But in shortening tube #2, I just built a new one, and as I looked into the new tight bend I was starting from, I saw what looked like rust from the mandrel bending fluid inside. I cleaned it up, but in my bending the entry in the die to go into the header flange, I felt attraction between it and the high powered magnets I was using to hold the die to the vise. It turns out--for this piece only!!--Vibrant used 409 stainless, not 304 as they do in other bends, and the copy only said SS--did not indicate the type. I can't use 409 in the final design as it will turn a different color faster and darker than the 304. But it will allow me to build the jig and optimize my design on the bench.

I may not be in the bad shape I thought I was. Life has been busy and I haven't been able to figure out how to do the tight radius required for tube #2 to form the die (very difficult to work the curved portion of a bend into the oval port shape). Last night while explaining my problem to my better half, she asked the question about the looks of the metal, as even the larger 304 bend had more of the darker look rather than the polish of the straight portion of the tube. I took one of the super strong magnets I have to show her the difference, and....it had attraction too!!! Now I have twice the problem. But I go to a J-bend I have that is a USA sourced clearly marked 304, and it also has a slight attraction in the bend. But when you put the magnet to the straight section, almost nothing. Turns out that working 304 stainless in any process will increase its magnetism. From another web source, "Some austenitic stainless steel grades, particularly 304, are to some degree attracted to a magnet when cold worked, e.g. by bending, forming, drawing or rolling." And given the super tight radius, it had been worked harder, and therefore had the strongest magnetism. Looking at Vibrant's website, it lists the part # I was using (indeed, all their bends) as 304SS. I've got an email into them asking "for sure." But I think I'm ok, and have learned that 304 can also be magnetic stainless in the bends, not just 409. And I have to say that when I was welding the end of it to the other "for sure" 304 SS it flowed really well, and I didn't see anything in the welding to suggest a problem. I expect to use this tight radius after all, but I'll be doing a bit more checking to be sure.
EDIT: Talked w/Vibrant and confirmed the part is 304; they only use 304SS for bends, never 409.

"This part is 100% American 304ss. The reason you are seeing a bit of magnetism in the bend itself and not the straight legs is because cold forming austenitic 304ss puts a great deal of stress on the material and can actually develop a magnetic response when cold worked (mandrel bent). Cold work can transform some austenite to martensite. The rust you are seeing on the inside of the bend is likely from the internal tooling during the bend process. Cross contamination of materials is very common when using the same tool for different materials. It is just on the surface and can be brushed off with a stainless wire brush. If you have any other questions, please let us know. Thank you for choosing Vibrant,"

So...can finish this design now.

Your information is correct. T304 (and many stainless grades) will, to some degree become magnetic when worked. They's usually not as magnetic as cast iron for example but you can expect to see some magnetic attraction and, yes, as the metal is worked, it can often become more magnetic.
Your project is coming along beautifully. Keep at it, you'll get there.
Dan

Do you ever take on a task and wonder if it will ever get done? Seems like it just takes forever to get this header design done. First, the bad news. I built the prototype with the body off the frame, and then I verified fitment by lowering the body onto the frame. I found initial contact on tube #2, but no big deal I can shorten that. Well, I am building the 2nd version now for Shannon, and the other day I used my version to verify clearance again before I made one of his tubes, and I can't install it from the top. I had not yet tried to install the header with the body on the frame. As you can see from the pics, the overall length makes it impossible with the engine in the final location. I removed the water tube and my AC compressor, and I'm still hitting on the combo of Spriso's motor mount and the firewall by the M/C. It actually could be worse as I don't have an MC right now. I ordered one from Amazon and will be here tomorrow (Z-car 7/8 bore) so I can bolt in place. I also ran into some interference down below on a casting boss that I don't need, so off it went with a saw and grinding belt.

I considered other changes to the design and this is a tradeoff I can't compromise. I wanted ~24" of runner length on each tube, I didn't want an up and over view like RC Mike had (just my and Shannon's personal pref on looks) and I wanted a merge collector. So, there is no choice for me but to go with a harder install. I think once in, the header will not be coming out unless the engine is coming out. So for the performance I wanted, the install will be harder. I'm hoping I can simply loosen the mounts and rotate the engine toward the passenger side for more room, and (likely) remove the drivers motor mount just while installing. If that won't cut it, I'll try installing as part of the engine/tranny going in. Bottom line is this is just an incredibly tight place to work on, necessitating tradeoffs that I'd hoped not to make.

But once I ran into that roadblock I decided it was time to finish my merge collector by welding on the v-band and the O2 sensor bung. The V-band was previously tacked, but I needed to finish weld, and I also needed to drill a hole in the collector for the O2 Bung. Drilling thru the Stainless Steel just stinks, but I finally got it! Once I got a pilot hole the Milwaukee step drill bit (made in USA) easily did the job. While my welds aren't a perfect stack of dimes (by no means!) I was generally happy with the result. Certainly the color was nice (I use a large Furick cup for plenty of Argon). On the backside of this, I use the Solar Flux product to prevent sugaring, and this really works for large pieces that I don't want to backside purge with argon.

Finally for today, you've always heard that cleanliness is next to godliness. And that is never more apparent than with SS welding. I love the way a scotchbrite pad can bring out that clean finished look on the stainless, and then its just an acetone wipedown before welding.

impressive. thanks for sharing.

Funny.. I remember when I brought the project to Brandon.. He came up with a price based on the work he thought he was going to be doing, and material cost..

Every day I came back, there was more grumbling. He had the car, the engine in place, and freedom in the back, told him there would be a new exhaust so just leave room for a flex pipe..

I know EXACTLY what you are talking about.. Steering shaft had to come out, etc. etc. etc..

Keep after it. This looks great! and it will be worth it at the end..

I'm hoping to pick up another 10- 15hp with this header so having to unbolt the motor mounts, transmission mounts, lift the engine, and remove the steering column is not a problem. Hopefully I can get it done this summer.

Unfortunately my engine tuner has gone out of business so I'll have to use a different dyno for the before and after testing.

Shannon

Close is never a cigar in this header build. I am almost done with the one I'm building for Shannon (since he's ready to run and I'm a couple of years away), but every time I think I have it, I see another angle. I had four tubes done, and then I realized that I didn't put a place for the frame on my jig, and looking at my prototype on the engine I have only about 5/16" clearance where all the header tubes come up from the merge collector, and what I had for Shannon would have interfered. So back to work on Tubes 3 & 4. I got almost done today but when I built tube #4, that made #3 too long. I took it out and shortened it ever so slightly (cuz these things tend to jump on you with a 1/4" cut taking off much more due to the arc of the header tube). Better, but still too long so I'm quitting for the night. 1st pic doesn't really show it but tube #3 is not in the port (about 1/8" too long). Tight fit up is the key for better tacks, and good cleaning makes for a nice weld.
Shannon you are almost here...

And then we have to see if this fits in the chassis.

Why its often good just to stop and sleep on it. In the middle of the night I wondered if I could rotate the collector slightly to take that distance out. So I pulled tube one out this morning and rotated the collector and was able to get it in, and then I was able to get tube one in also! So all four in.

Progress may be delayed a few days as you heard there was a tornado in Dayton, and I may have the opportunity to be part of cleanup later today and this week. But this is ready to mount in the car to check fitment.

For fitment, I cut the complete lip off the frame (the frame sticks out about 5/8" from the motor mounts back), and I also ended up cutting off one casting boss on the engine that is not needed. Nevertheless, it still is not possible to install the header w/o raising the engine. Fortunately the problem of the SR20 engine tilt toward the driver side means that when you lift you can lift this side w/o really lifting the passenger side much. In the pic below (last one) you can see I had to raise it about an inch to get the header in--and that is with the frame lip cut off. It will probably be a fair bit more (to allow you to push the engine more to the passenger side) if you do not cut that frame lip off. Shannon's fit but ended up being a bit too close to the engine. I could pull the collector out to nicely place it where I wanted, but that did pull the tubes out of the flange slightly (see pic). I don't think that will matter much (although I'm going to consult the folks at stainlessheaders on Monday*) as I've seen other headers where the tube isn't flush with the flange at the inside. I will just have to carefully scribe where each tube is to ensure the finish welding keeps this in a good spot.

So next steps are 1) drill and tack the O2 bung for the 2nd header, 2) redo at least one of the tubes on my prototype based on this finished version and 3)finish weld both headers.

Pictures are unfortunately in reverse order of how the description above goes; wish I could get them in chronologically.
* Edit update--no problem with welding the tube not flush with inside of flange; stainlessheaders.com often does it this way.

Did anyone ever tell you how hard it is to work with stainless steel? Especially top quality USA 16 gauge? I had to drill thru the collector to put in the O2 bung yesterday, and once again it took me almost an hour. Last time I used a very small cobalt drill bit to get a pilot, and I ended up breaking it with the pressure, and it still took me about an hour to get a small hole thru with my hand drill. So today I decided to use the blair rotobroach for this one. Still took me a good hour. Once thru, as before, the step drill made short work of getting to the right size. If I ever do this again, I can now order the O2 bung installed on the collector already now that I know where I want it.

Ready to go to finish weld. Or am I? I redid tube #2 and #4 today on my header, based on what I'd done for Shannon's header, and I have everything in and it fits. Only question now in my mind is if I want to go in and try and redo tube #1 to tuck the top loop in a bit more. It sticks out more on mine that on Shannon's and doesn't quite look as neat. Mine is in the car (and on the jig) in the pics, his is on the box I'll use to ship both to Jet Hot. I'll make a decision tonite; tomorrow I have to be done and deliver to the finish welder (hint--not me!).

Another wrinkle; I tried putting the A/C compressor back in with the header on, and the long bolt in the rear interferes with the header. I shortened Tube #1 about an 3/16" to try to get clearance (and since I wasn't happy that it stuck out noticeably farther than #2), but that couldn't quite get there. I talked to Shannon (both of us have A/C) and we're going to press with the design, as I don't see good options. This just means when and if the compressor goes bad the header will have to come loose to replace it, and obviously install it before the header goes in.(Edit Update: I just cut some of the threads off the bolt and that shortened it enough to get it thru the tight space--still more than enough thread to tighten the compressor down securely) I'm going to take each tube out of my header for a final cleaning with a scotchbrite and then off to the finish welder. Here is how my header fit after the final shortening of tube #1.