Fabulous Fabrication Post all your custom fabrication projects here; impress all your friends.
Sponsored by:
Sponsored by:

DIY Greddy downpipe for a first-timer.

 
Old 11-17-2014, 08:00 AM
  #1  
Newb
Thread Starter
 
Join Date: Nov 2010
Location: Yorkshire, UK
Posts: 36
Total Cats: 13
Default DIY Greddy downpipe for a first-timer.

I want to replace my stock Greddy downpipe with something custom. You all know how restrictive it is.

Stock looks like this - (photo stolen from Hornetball - no your not the last one left if you count the UK!)

Name:  IMG00014-20110219-2226.jpg
Views: 280
Size:  35.4 KB

And I'm looking to change it to 2.5" , to match the rest of the system, something like this infamous tony DP -




Now I have a MIG. My dad welds well (Mig, tig, arc, braze etc,) and has given me it, to learn with. I can throw sparks and make things stick together. I'll get better.

I have a mild steel flange. I will be putting a flexi in and some way of better supporting it in place of the OEM bell housing bracket. I can get some 2.5" tube and bends easy. I guess I'll need one tight bend to come straight off the flange.

My first bit of proper fabrication. A learning exercise. Where the best way to start?

Remove original stuff. Bolt flange to turbo. Start cutting. Tack first section. Keep going till the ends meet up. Take it all off and weld up properly.

Any advice? Just go for it?

The existing setup is 2 pc - Greddy pipe, stock pipe to the cat. Doing it in one piece is going to make it a lot harder to fit, right? I guess that pictured ^ has to be snaked in from below with the turbo off.

Would it be sensible to tack it up in one piece, then if I wish to split it, just cut and add two flanges?

I'll be sure to post photos once I've started!
snotrag is offline  
Old 11-17-2014, 09:45 AM
  #2  
Senior Member
iTrader: (3)
 
Join Date: Apr 2011
Location: Volo, IL
Posts: 1,246
Total Cats: 140
Default

In for not being the only one dumb enough to do this.

I'm doing the exact same thing starting in a week or so. I can't weld very well, but I have access to a lot of welding equipment and an endless supply of SS pipe. I'll be spending the winter attempting to fab a good downpipe.

There are more of us than you may think, but we tend to hide our Greddy shame from the limelight.
dieselmiata is offline  
Old 11-17-2014, 10:09 AM
  #3  
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 14,388
Total Cats: 1,328
Default

I would search for pictures of the TurboTony greedy replacement downpipe and copy that.
shuiend is offline  
Old 11-17-2014, 10:45 AM
  #4  
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,169
Total Cats: 655
Default

There's also the BEGI SG Greddy DP replacement. A more complicated welding project, but gave nice gains.
hornetball is offline  
Old 11-17-2014, 04:08 PM
  #5  
Newb
Thread Starter
 
Join Date: Nov 2010
Location: Yorkshire, UK
Posts: 36
Total Cats: 13
Default

Cheers guys, I think that one in the 2nd photo is a Tony pipe?

I also looked at the BEGI piece, its still listed on their site, but with import duty etc it would be a small fortune to get one to the UK.

The flange I bought would suit that type - I haven't decided yet, but I can always cut away but can't add material. Sketched it out today ready to scan in to Solidworks at work tomorrow, because... well, because i can.

snotrag is offline  
Old 12-04-2014, 03:46 PM
  #6  
Senior Member
 
Join Date: Apr 2011
Location: Martin, Slovakia
Posts: 508
Total Cats: 71
Default

Simon, I am curious if you considered making a replacement manifold?

The downpipe is comparatively straight forward for the 15g with an axial mount manifold. This is a similar setup I am working on atm

Name:  P1060579_zpsf93f7489.jpg
Views: 214
Size:  101.1 KB
sturovo is offline  
Old 12-05-2014, 06:29 PM
  #7  
Elite Member
 
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,827
Total Cats: 55
Default

When you say axial log, you mean a log specifically with the flange welded directly to the log itself?

Dann
nitrodann is offline  
Old 12-06-2014, 02:36 AM
  #8  
Senior Member
 
Join Date: Apr 2011
Location: Martin, Slovakia
Posts: 508
Total Cats: 71
Default

Yes Dann that is what I meant. Axial doesnt mean too much.
Mid mount would be a better description?
Making a downpipe for the original Greddy top/aft mount manifold is much more difficult than for a mid mount manifold.
I never understood the Greddy turbo placement. Was it re-purposed from another application?
Name:  P1060613_zps0dfe93b5.jpg
Views: 212
Size:  53.5 KB
sturovo is offline  
Old 12-06-2014, 09:04 AM
  #9  
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,762
Total Cats: 676
Default

No idea, but it's ****. Mounted far back and high, so the downpipe always has to be a ? shape. Huge compromises are made everywhere in terms of size, location, bends, heat, etc.

My side mount downpipe looks like a straight piece of pipe compared to my old greddy.
curly is offline  
Old 12-06-2014, 09:58 AM
  #10  
Newb
Thread Starter
 
Join Date: Nov 2010
Location: Yorkshire, UK
Posts: 36
Total Cats: 13
Default

If you look at an engine bay with a 'stock' Greddy setup it makes sense - they designed this way back when to work with the stock cross over pipe (I think?) and also requiring the cast U-bend for the AFM.

Obviously without these limitations, there's better places to put the turbo.


And - please stop putting ideas in my head .

I'll stick with just a down-pipe for now, in the future, who knows...
snotrag is offline  
Old 12-06-2014, 11:31 AM
  #11  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 76,361
Total Cats: 2,294
Default

why does it curl back? to clear the shelf?
Braineack is offline  
Old 12-06-2014, 04:08 PM
  #12  
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,762
Total Cats: 676
Default

Yeah. To make one without curving back would need a L shaped downpipe. Someone here did that and it immediately glowed red due to the turbulence. Levubin or whatever it's called?
curly is offline  
Old 12-06-2014, 09:11 PM
  #13  
Elite Member
iTrader: (8)
 
Join Date: Jun 2008
Location: Colorado Springs
Posts: 1,643
Total Cats: 51
Default

Originally Posted by snotrag View Post
Cheers guys, I think that one in the 2nd photo is a Tony pipe?
Yes it is, in fact the one I sold last month
matthewdesigns is offline  
Old 12-07-2014, 09:32 AM
  #14  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 76,361
Total Cats: 2,294
Default

here's what you do:

bolt a plate on the current outlet. Tap side of manifold. :P
Braineack is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Full_Tilt_Boogie
Build Threads
67
03-16-2019 08:07 PM
StratoBlue1109
Miata parts for sale/trade
21
09-30-2018 01:09 PM
Goldwar
DIY Turbo Discussion
2
09-29-2015 09:20 AM


Thread Tools
Search this Thread
Quick Reply: DIY Greddy downpipe for a first-timer.


Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.