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-   -   DIY Downpipe to tailpipe *56k Warning* (https://www.miataturbo.net/diy-turbo-discussion-14/diy-downpipe-tailpipe-%2A56k-warning%2A-34647/)

railz 05-05-2009 01:59 PM

That Lathe work is sick!

Joe Perez 05-05-2009 02:10 PM

Very nice looking piece of pipe you've got going there. Indeed, a lathe is a beautiful thing to have. I miss mine...

gospeed81 05-05-2009 04:00 PM

Must have lathe in garage before I get fired for my "saturday projects" at work (I don't even work in the machine shop anymore, but somehow find reasons to go back there when I should be in my "closet").

Super nice build. I'm trying to buy some bends right now, and will probably fab my own (on Saturdays of course). $150 at local muffler shop was cheap, but can't bring myself to live with crush bends. And all the mandrel systems are way out of my budget.

What bends precisely did you need to get around diff and to muffler? (EDIT: The pics are nice, but it's hard to piece it all together in my head)

I know I'll need a 90 on the other side to bumper exit, and I'm guessing I need atleast one "U" and two 45s to get over rear brace and into muffler.

cjernigan 05-05-2009 04:54 PM

Why did you turn down the tubing, guess I missed that part?

SKMetalworks 05-05-2009 07:08 PM


Originally Posted by cjernigan (Post 404709)
Why did you turn down the tubing, guess I missed that part?

See pic 13 on my second set of pics. There was a gap that wouldn't work for connecting the lower and upper downpipe together. So i just turned down some pipe that was a bit too large until it was just right

gospeed81

If you see my build you will notice that im not that far yet. What i plan to do is use 2 45* to limit backpressure. Ive seen some that go 90 up and over and then another 90 out.

1 90* is = to 20ft of straight pipe ( backpressure ) the less bends you use the more your turbo can breathe!

gospeed81 05-05-2009 08:02 PM


Originally Posted by sbkcocker499 (Post 404782)

gospeed81

If you see my build you will notice that im not that far yet. What i plan to do is use 2 45* to limit backpressure. Ive seen some that go 90 up and over and then another 90 out.

1 90* is = to 20ft of straight pipe ( backpressure ) the less bends you use the more your turbo can breathe!


Fluid Mechanics FTMFW!

Took it last semester, got an A, was laughing the whole way through the "coolant reroute" thread.

I'm trying to find the simplest route out too. I noticed y8s has a big 180 on his going into muffler, and I'm trying to avoid this, especially since I'm building in 2.5" (already have 2.5" 200cell/in metal cat and 2.5" muffler). I'm even thinking about putting the muffler in an unconvential spot.

wayne_curr 05-05-2009 08:18 PM

There is some total win in this thread. Good idea getting the lathe involved...very cool.

Cant wait to see all this in person.

cjernigan 05-05-2009 10:18 PM


Originally Posted by gospeed81 (Post 404799)
Fluid Mechanics FTMFW!

Took it last semester, got an A, was laughing the whole way through the "coolant reroute" thread.

I'm trying to find the simplest route out too. I noticed y8s has a big 180 on his going into muffler, and I'm trying to avoid this, especially since I'm building in 2.5" (already have 2.5" 200cell/in metal cat and 2.5" muffler). I'm even thinking about putting the muffler in an unconvential spot.

Look at turbo tims setups he builds, he doesn't use a 180, more like a 45 in and a 45 out.

gospeed81 05-05-2009 10:27 PM


Originally Posted by cjernigan (Post 404853)
Look at turbo tims setups he builds, he doesn't use a 180, more like a 45 in and a 45 out.

That's what I'm talking about!

I feel like I saw that back when I was a newb, and it impressed me. That is badass. I plan to replicate this.

While on the topic, will I be okay without a flex joint? My downpipe has a sleeve joint with a band clamp on it, and there will be one 2 bolt flange before the cat. I plan to weld everything after that.

SKMetalworks 05-05-2009 11:46 PM

9 Attachment(s)
Tonight got some welding done before and after English 101. Since my old welding instructors are so cool they let me use their machine, rod, and GAS!!

1. Flange top side

2. Flange side view

3. Full shot :giggle:

4. Sleeve end ( notice the penetration )

5. Inside flange view. I only got crystals 3 little times from the angle of the tube being to sharp to get my tungsten in there right. I also welded the inside for added strength ( yes im going to sand this down nice and beautiful)
Also notice the penetration on the second joint

6. view of one of the Seperated gases pipe that i welded at the right angle for reintroduction

7. another view

8. close up! damn flash!

9. tried to get the shot of penetration o wells.

gospeed81- The purpose of the flex joint is to reduce stress on your manifold/downpipe. When the motor is experiencing a load it twists side to side. Now your cat back exhaust is held in by hangers that are attached to rubber. This is to give it more sway.

the downside of using a flex pipe is that its more prone to exhaust leaks because its not a solid tube ( go figure ) I decided to use one because its easy for me to cut one out and weld a new one on if it ever does happen.

Will you be okay without one? probably

Should you get one? Up to you

Do i recommend it? Yes

SKMetalworks 05-06-2009 12:07 AM

Fuuck those are blurry sorry for making you squint :facepalm:

99mx5 05-06-2009 12:33 AM

Nice welds!

curly 05-06-2009 01:26 AM

OMG! You turned down a piece of pipe to a slightly smallar diameter! You're a mother f'ing lathe goddess!!!!!!!!!!!!!!!!!11










j/k, as a machinist I had to give ya shit, anything made on that puny lathe that works as intended is impressive, good job so far. NW MT members FTMFW!

SKMetalworks 05-06-2009 01:30 AM


Originally Posted by curly (Post 404949)
OMG! You turned down a piece of pipe to a slightly smallar diameter! You're a mother f'ing lathe goddess!!!!!!!!!!!!!!!!!11

why ya gotta bust balls? :fawk:

wayne_curr 05-06-2009 12:55 PM

English 101 sucks, i'm taking it this quarter too.

I think you've thoroughly convinced me to take a welding class summer quarter. It would be awesome to do welding work on the side while going to school.

SKMetalworks 05-06-2009 08:19 PM


Originally Posted by wayne_curr (Post 405141)
English 101 sucks, i'm taking it this quarter too.

I think you've thoroughly convinced me to take a welding class summer quarter. It would be awesome to do welding work on the side while going to school.

Bellingham technical college has an AMAZING shop. I went their for the annual welding rodeo and it is indeed nice.

wayne_curr 05-06-2009 09:01 PM


Originally Posted by sbkcocker499 (Post 405358)
Bellingham technical college has an AMAZING shop. I went their for the annual welding rodeo and it is indeed nice.

ya its just a bitch to get into the program. I tried this quarter (fairly early too) and it was already full.

SKMetalworks 05-07-2009 12:32 AM

15 Attachment(s)
Tonight i got the first section of my 3 part exhaust done. Turned out better than what i expected although due to the limited space i couldn't route the wastegate port exactly where i wanted it. But hey; for my first time ever building an exhaust it will work.


1. Testing the fitup

2. Another view

3. Marking out the whole of where i need to tap it back in

4. i first started drilling holes around the perimiter

5. Then i rememberd i had 25 pack of dremel cutoff wheels :facepalm:

6. Smoothed out the hole so its nice and clean.

7. Tacked in, Off to the welding classroom!

8. Welded where i tapped back into the main pipe

9. Top side.

10. Faraway shot.

11. Closeup of top side

12. Bottom side

13 Turbo mating side

14. Another view of bottom side. The only part that looks not as good as it should is right on the bottom side where the flange, 2 1/2" and 1 1/2" pipe mate. Absolutely ridiculously impossible to get my tungsten/rod in there even with the stubby :vash:



now onto my english paper :crx:

curly 05-07-2009 12:57 AM

Whoa. Your lack of lathe skill is made up for ten fold by your welding/fabricating skills, that's f'ing gorgeous dude! Nice job.

Could you copy and paste the image locations between your little picture descriptions? That way if we wanna read about what we're looking at, we don't have to scroll up a bunch.

SKMetalworks 05-07-2009 01:03 AM

If i knew how i would of already. Can you teach me? :laugh:


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