Manifold piping size & Merge Collector Fab

Afterthought · Post by **Afterthought** » Fri Nov 09, 2018 9:04 am

I’m getting set up to make a manifold or two . I have some weld Ells in 1.5 npd schedule 10 321 stainless. Now that I have them in front of me they look awfully big.
.Wondering if I should be doing 1.25 or 1.5 ID sch 10 pipe for a medium HP I-5 Build .

DE80q · Post by **DE80q** » Fri Nov 09, 2018 10:46 am

That depends on what you are going for. If your looking to squeeze the last bits from the top end of a high reving motor, than stay with the 1.5". If your looking for higher flow, but trying to keep the exhaust vocity up, step down to the 1.25". The manifold that is being made for my 20v is using 1.25" runners.

Afterthought · Post by **Afterthought** » Fri Nov 09, 2018 11:10 am

Nice you are doing a custom one for a 20v ?

Bad ass

DE80q · Post by **DE80q** » Fri Nov 09, 2018 11:53 am

Afterthought wrote:Nice you are doing a custom one for a 20v ?

Bad ass

Kind of, it's a stock location piece. Should have much better flow, and hopefully not crack. I've already repaired my factory one, and it has started to crack again.

Afterthought · Post by **Afterthought** » Fri Nov 09, 2018 1:19 pm

Nice that’s pretty cool . So like the log header but tubular Instead of cast .

I guess regarding my header what I should do is look and see if there is any sort of calculators using like exhaust valve size and port size, desired HP or VE , displacement , no of cylinders etc. but all I can find is for NA

I was curious if there was any sort of accepted size , I’m assuming at some point there’s a volume vs velocity , like 1.25 may spool better but would max out at some point . Don’t know , maybe I’ll measure the exhaust ports . I mean if it’s going into a turbo it’s going through a collector anyways and necks down in size

audifreakjim · Post by **audifreakjim** » Fri Nov 09, 2018 5:11 pm

There was a comparison done at some point. The conclusion was, 1.25" is more than enough. Hank uses 1.25" on all of his headers, that's what I have on mine too. His 1.25" is almost 900 wheel and just trapped 154 in the 1/4. So that should work for ya

Afterthought · Post by **Afterthought** » Fri Nov 09, 2018 6:03 pm

audifreakjim wrote:There was a comparison done at some point. The conclusion was, 1.25" is more than enough. Hank uses 1.25" on all of his headers, that's what I have on mine too. His 1.25" is almost 900 wheel and just trapped 154 in the 1/4. So that should work for ya

10-4 thanks Jim. Holy sh!t he’s almost into the 8’s.
I guess I can use the 1.5 for the non Audi LS project I have .
It looks doable but the OD of that is like 1.9 so it’s a lot of pipe to fit in there
Now I have to figure out how to make a merge collector .
Need to identify and make a paper temple for this that I can overlay and scribe then make these cuts . Will report back in about a month

PRY4SNO · Post by **PRY4SNO** » Fri Nov 09, 2018 9:26 pm

That's where your book of ordinates will pay for itself!

Afterthought · Post by **Afterthought** » Sun Nov 11, 2018 8:24 pm

It’s taken me forever, 2 scrap papers , the Internet , an old book, and probably wasted a lot of time but I think I understand now what I need to do.

If I remove all but 1.8849” of the pipe I will have 1.8849 x 5 which equals a 3” dia circle
So if my math is right (not for sure) I need to remove 1.89.
Which means each cut will be 72 degrees apart .
For he merge angle I think I can go anywhere from like 12-20 deg depending on packaging .
So , now I need this or something similar . Or make a jig using 1/2” square tuning that fits into my bandsaw at a set angle .

Afterthought · Post by **Afterthought** » Sun Nov 11, 2018 8:25 pm

It’s taken me forever, 2 scrap papers , the Internet , an old book, and probably wasted a lot of time but I think I understand now what I need to do.

If I remove all but 1.8849” of the pipe I will have 1.8849 x 5 which equals a 3” dia circle
So if my math is right (not for sure) I need to remove 1.89.
Which means each cut will be 72 degrees apart .
For he merge angle I think I can go anywhere from like 12-20 deg depending on packaging .
So , now I need this or something similar . Or make a jig using 1/2” square tuning that fits into my bandsaw at a set angle .

audifreakjim · Post by **audifreakjim** » Mon Nov 12, 2018 12:07 pm

Hey Pat, when I built my header I did the collector first in PVC. At the end of the day it just took a little trial and error to get it right based on my chop saw I was using. Size doesn't matter, grab something close to it and test away. The angles are the same regardless.

speeding-g60 · Post by **speeding-g60** » Mon Nov 12, 2018 12:45 pm

this was designed just for that work.

https://www.lpsfab.com/product/lps-ccf- ... ng-fixture

Afterthought · Post by **Afterthought** » Mon Nov 12, 2018 1:09 pm

I bought the PVC in 1-1/4 , it’s very close in OD .

That LPS piece is really nice , it says pre-order for 355.00 and ships this month .
Before I order I am going to experiment a little . Still waiting for the 1-1/4 pipe to show up so all I have now is 1.5” .

Wondering about the difference in spool between the two. Looking at header applications I see a lot of people using both , it certainly appears that 1.25 is enough and won’t be limiting .
Also working on drawing up some intake and exhaust flanges in Fusion360.

This will open up a lot of possibilities

PRY4SNO · Post by **PRY4SNO** » Mon Nov 12, 2018 1:58 pm

Pat, don't forget it's 1.25 x 5. Most people opt for a 3" turbo back exhaust. 1.25 ought to be plenty.

dougkehl · Post by **dougkehl** » Mon Nov 12, 2018 6:22 pm

Fushion360 is a great program. I actually have the base flange for the flange for the intake drawn out on 360.

Anyway, 1.25" pipe as others have said ought to be enough. Especially considering 1.25" schedule 10 pipe has an ID of like 1.44" which is not limiting at all!

Afterthought · Post by **Afterthought** » Mon Nov 12, 2018 7:03 pm

dougkehl wrote:Fushion360 is a great program. I actually have the base flange for the flange for the intake drawn out on 360.

Anyway, 1.25" pipe as others have said ought to be enough. Especially considering 1.25" schedule 10 pipe has an ID of like 1.44" which is not limiting at all!

I have a good start on some stuff but it’s a really steep learning curve . I mean when I get stuck on one tiny little thing I realllllly get suck.
I tried drawing the pipe intersection too which took forever but it’s all just practice.

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FFF · Post by **FFF** » Wed Nov 21, 2018 7:01 am

I’m going to have to wait until I retire to even think about trying something like this!!

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Afterthought · Post by **Afterthought** » Sat Nov 24, 2018 9:14 pm

I gave up on the math and just started with the PVC pipe but so far I haven’t had any luck making a fixture that works well.

I’m trying to adjust the merge angle to get it right and haven’t been able to figure it out yet . I think it’s going to end up being around 13 degree cut I need to make .

The issue with the fixture is that the way it clamps the pipe there is too much variation (few degrees) in the way that it holds the pipe to be able to replicate 10 or even just a few identical cuts . I may have to go to something like Speeding-G60 sent me .
This is rev.0 of the fixture

It works but 16 degrees was too much.

Revision 1 , I made it adjustable . But I need to add something to it to make it hold each pipe tight and guarantee it doesn’t move

So back to the drawing board on that .

I did get this setup for the welder though

Afterthought · Post by **Afterthought** » Tue Dec 11, 2018 7:34 pm

So after all the math and everything it didn’t work . I threw all that out , bought 20’ of PVC and just kept making pieces until it came out right .
He amount I need to rotate the pipe between cuts is no where remotely close to what I calculated .
It’s not perfect but getting really close . I’m guessing this is within like 1 degree of what I will end up with for a final.

I also started messing with the settings on the welder , to figure out what I would want for welding pipe . This is all guesswork for me . Here is a test piece .
Stainless pipe
308 filler .045”
roughly 60 amps .

Tried going up to 3/32” filler and that did not work . It may work but I think I need to turn up the amps with it

Also tried messing with the pulse settings which I’ve never done . With it on pulse mode it does keep it really cool (too cool maybe) but I don’t have the coordination down.

Afterthought · Post by **Afterthought** » Thu Dec 13, 2018 10:17 pm

Here she is ... not perfect but I’m happy with it for the first one .
I was able to practice enough on the PVC that I didn’t waste a single stainless pipe which is a feat in itself .

Far right is after I bought a new saw blade .

I already have some ideas for how to improve it. Due to some inconsistencies with my band saw (blade walk I guess) I plan to cut the next one with the band saw but slightly long then use the lathe to get a perfect 90 deg angle and then bevel the edge .
I also may need to try a different torch . I have never used any other torch than this #17 Miller or whatever it is . I may try a flexible or pencil torch and considering trying a #9 torch size .

FFF · Post by **FFF** » Fri Dec 14, 2018 4:57 pm

That is looking great for a first attempt - good idea on using the pvc for mock up.

PRY4SNO · Post by **PRY4SNO** » Fri Dec 14, 2018 5:28 pm

New blade sure made a difference. I would have just used a grinder myself, but that takes a lot of practice to make consistent (and I never had to pay for material either lol).

Afterthought · Post by **Afterthought** » Fri Dec 14, 2018 6:29 pm

New blade will make a huge difference, I’m not steady enough with a grinder I don’t think to make a good cut where I won’t have to sand a bunch . I’m excited to try another with a better blade

I need to still practice some on the welds and figure out the proper amperage for this manifold I want to make , and whether or not to do T4 or good ‘ol V-band ..
When I get a change to go to the shop for an hour or so I’ll practice on stuff but I don’t have any scrap stainless pipes besides the small “coupons” I’m cutting away for the collector .
This is all practice stuff. Stainless sheet metal scraps ,

Aluminum

audifreakjim · Post by **audifreakjim** » Mon Dec 17, 2018 11:52 am

Looking better and better!

speeding-g60 · Post by **speeding-g60** » Wed Dec 19, 2018 9:30 pm

welds are definitely looking better.

too bad you werent down here, i would give you all the stainless you could want for practice. Sch 5 thru 80 even.