waped exhaust manifold - Alfa Romeo Forum
You are currently unregistered, register for more features.    
Tuning & Upgrades Discuss performance enhancements for your Alfa Romeo

 
Thread Tools
(Post Link) post #1 of 12 Old 08-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
waped exhaust manifold

Broken 4 studs in cylinder 1 and 5. Itīs not to much warped (+ - 2mm).
Does some one know what class\grade studs are used from standard? Iīm thinking of using grade 8\class 10.9 studs with proper washers (donīt know why Alfa didnīt use any ) and copper lock nuts.
Upgraded studs is enough or go for M10 instead of standard M8? Since iīm going to drill them out, M10 in the cylinder 1 and 5 should keep it in place, with proper tightening torque off course.
Xinoka is offline  
Sponsored Links
Advertisement
 
Status: 159 2.4 20007 plate 19,500 DPF/EGR by Adie (AHM)
AO Silver Member
 
Join Date: May 2009
Location: United Kingdom
County: Wiltshire
Posts: 2,322
10.9 will be plenty in this application. Studs are in aluminium so won't take lots of torque without stripping threads. Even though yours have snapped it's the aluminium to worry about not the stud strength.
kandlbarrett is offline  
(Post Link) post #3 of 12 Old 10-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
Studs in aluminum???? They are made from steel and are coated to prevent oxidation. Aluminum and 100% stainless steel donīt react to magnet.
Manifold torque specs are 23-38 Nm, so even 8.8 are strong enough but is thermal expansion force that we have to worry about.
Is this torque spec ok? Itīs from e-learn. Autodata also says 25 Nm.

IMO, the main culprit is the lack of washers that led the manifold to seize on the nut, while expanding.
Xinoka is offline  
Status: New quiet lifters, aircon works!
AO Silver Member
 
halftone's Avatar
 
Join Date: Feb 2012
Location: United Kingdom
County: Greater London
Posts: 1,752
Garage

Member car:

147 Sport Q2

He meant the cylinder head, that the steel studs screw into, is aluminium. So the strength of the studs is a lot greater than the thread in the head can take.
halftone is offline  
Status: -
AO Member
 
Join Date: May 2012
Location: United Kingdom
County: Hampshire
Posts: 517

Member car:

1.9CDTI 16v

If the manifold is warpped then you should have it skimmed as you'll not get a good seal. It is very common on the Vauxhalls for the manifolds to warp and when having hybrids made up I usually have the manifold skimmed.
nutron is offline  
(Post Link) post #6 of 12 Old 11-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
The stud is stronger than the head thread but they snap because of perpendicular force of manifold and the stud thread act as rupture point. The lack of washers just made it worse. Think i'll go for M10 on cylinder 1 and 5.

It's being skimmed at the moment and flanged for GTB
Xinoka is offline  
Status: 329 hp
Club Member
Membro Medio
 
JS JTD's Avatar
 
Club Member Number: 1004
Join Date: May 2009
Location: Netherlands
County: Noord Brabant
Posts: 1,712
The solution here is obviously not to modify the bolts, but to modify the exhaust manifold and/or to decrease the EGT.
JS JTD is offline  
(Post Link) post #8 of 12 Old 13-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
Can you guide me on the right direction?
Xinoka is offline  
Status: 329 hp
Club Member
Membro Medio
 
JS JTD's Avatar
 
Club Member Number: 1004
Join Date: May 2009
Location: Netherlands
County: Noord Brabant
Posts: 1,712
Quote:
Originally Posted by Xinoka View Post
Can you guide me on the right direction?
Increase the holes of cyl 1 and 5. The further from the middle, the bigger the hole position difference from thermal expansion. Also you can cut the manifold flange inbetween the cylinders to create extra room for expansion. Yan.ko did that with his 156 JTD project.
JS JTD is offline  
(Post Link) post #10 of 12 Old 20-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
This manifold already came with oval stud holes and individual flanges from standard.
The nut clearly show that there was no thermal movement were it should be.
Attached Images
File Type: jpg rsz_img_20160219_164205.jpg (92.1 KB, 26 views)
File Type: jpg rsz_img_20160220_070829.jpg (180.4 KB, 20 views)

Last edited by Xinoka; 26-02-16 at 20:41.
Xinoka is offline  
Status: -
Newbie
 
Join Date: Feb 2016
County: -
Posts: 2
Quote:
Originally Posted by nutron View Post
If the manifold is warpped then you should have it skimmed as you'll not get a good seal. It is very common on the Vauxhalls for the manifolds to warp and when having hybrids made up I usually have the manifold skimmed.

This is very true of Vauxhalls my modded Astra VXR has killed two manis in my 5 years of ownership always the damn studs snapping causing movement so the mani cracks in the same weak spot on the oem one, changing over to tubular is a great way to prevent the mani crack, Luckily no damage to the Ali head but all is sorted.

I digress

This is no different for any vehicle if the bolts sheer then the mani will more than likely crack not a huge problem as a new one can be sourced BUT if the bolts are stuck in the head get em drilled professionally and check for cracks in it as a cracked head can be game over in many cases.
Skimming is a must for a snug fit, As for the studs you are best with oem ones in my own experience.
themanflu is offline  
(Post Link) post #12 of 12 Old 26-02-16 Thread Starter
Status: -
AO Member
 
Join Date: Jul 2014
Location: Portugal
County: Portugal
Posts: 94
There is no cracks.
Two of them have to be completely drilled but the other two came out easily with t20 torx bit through 0,2 mm smaller diameter hole.
Going to use original studs with BMW copper plated nuts.
Attached Images
File Type: jpg rsz_img_20160225_104948.jpg (49.5 KB, 25 views)
Xinoka is offline  
Reply

Go Back   Alfa Romeo Forum > Supported Alfa Romeo Models > Technical & Vehicle Assistance > Tuning & Upgrades

Tags
exhaust , manifold , waped

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome