At the moment I have a 3 piece system from my 320 - with single pipe on back box. I'm fitting a 2.5 engine and from what I can make out the exhaust manifold is different (although I've also read people saying its the same!). Are there any parts that are the same? Backbox obviously isn't but what about center, down pipe?
Cheers
Is a second hand 320 auto rad worth anything?!
Some Exhaust questions...
Moderator: martauto
Is the car a pre facelift? What about the engine - what year?
To be honest if you need a back box anyway you would be as well picking up a semi decent 325 system to suit the engine.
To be honest if you need a back box anyway you would be as well picking up a semi decent 325 system to suit the engine.
Phase I - Bodywork Complete
http://www.e30zone.net/modules.php?name ... by+restore
Phase II - 2.8 stroker- Complete
Project II - 325 Motorsport Cabriolet Restoration.
http://www.e30zone.net/modules.php?name ... by+restore
Phase II - 2.8 stroker- Complete
Project II - 325 Motorsport Cabriolet Restoration.
-
daimlerman
- **BANNED**
- Posts: 15968
- Joined: Mon Feb 27, 2006 11:00 pm
- Location: Grumpy Old Man
Manifold's main difference is the downpipe connection,some have 3 studs,others 4.
Early 320's had a single pipe rear section,all later 6 cylinder cars had a twinpipe system.
Late 320/325 systems differed only in the tail pipe,325's got a slightly bigger one!
Other considerstion is that some cars have a two piece system,others have a three piece system,interchangeable as a whole(if the downpipe fits the manifold!)but not in part.
If you are thinking about a tubular exhaust manifold,you really need to fit the three piece system,as the tubular manifold is usually a direct swap for the cast item and the front pipe.
Think that covers most of it...
Early 320's had a single pipe rear section,all later 6 cylinder cars had a twinpipe system.
Late 320/325 systems differed only in the tail pipe,325's got a slightly bigger one!
Other considerstion is that some cars have a two piece system,others have a three piece system,interchangeable as a whole(if the downpipe fits the manifold!)but not in part.
If you are thinking about a tubular exhaust manifold,you really need to fit the three piece system,as the tubular manifold is usually a direct swap for the cast item and the front pipe.
Think that covers most of it...
Youth is wasted on the young.
-
allstar_07
- E30 Zone Newbie
- Posts: 153
- Joined: Wed Aug 19, 2009 11:00 pm
Thanks for the replies. So I could in essence keep the 320 manifold (pre-facelift - 3stud), downpipe, center section and just change the backbox and have the same or very similar system to the 325. OR are the pipe diamters for the center section different. Are the diameters of the 320 manifold the same as the 325?
I suppose I'm being cheap but if it's all the smae apart from the backbox it makes sense. Otherwise I'll just get a whole 2nd hand 325 exhaust with ot without manifold (if they're different size/stud pattern).
I suppose I'm being cheap but if it's all the smae apart from the backbox it makes sense. Otherwise I'll just get a whole 2nd hand 325 exhaust with ot without manifold (if they're different size/stud pattern).
If you've got an early system it will be a single pipe all the way through so not really suitable for the 325. Best bet is get a good secondhand twin pipe system (twin pipes from the manifold back).
There are indeed two different versions of the facelifts exhaust manifolds (4 studs in a diamond shape) on the 325i just to confuse matters even further. I found out only after buying a complete brand new bosal 325 exhaust system
Pacerpete has a good complete 320 twin pipe system that has had 325 tail pipes welded on @£50 and I think he's including the manifold
This would work as daimlerman has already stated
HTH
Charlie
There are indeed two different versions of the facelifts exhaust manifolds (4 studs in a diamond shape) on the 325i just to confuse matters even further. I found out only after buying a complete brand new bosal 325 exhaust system
Pacerpete has a good complete 320 twin pipe system that has had 325 tail pipes welded on @£50 and I think he's including the manifold
This would work as daimlerman has already stated
HTH
Charlie
BMW E30 344i track car 
BMW F31 335d xdrive
BMW F31 335d xdrive
-
allstar_07
- E30 Zone Newbie
- Posts: 153
- Joined: Wed Aug 19, 2009 11:00 pm
The one on at the moment has twin pipes from maifold to the middle box, then single after that!
Ideally you want a twin pipe from front to back for the 325i engine. I don't think any of your original system can used in combination with other parts to create a full twin pipe system.allstar_07 wrote:The one on at the moment has twin pipes from maifold to the middle box, then single after that!
I'm not sure if your downpipes would match up flange wise to a 320/325 twin centre box. What do the flanges look like that join the downpipe to centre box..
http://www.realoem.com/bmw/showparts.do ... g=18&fg=05
My concern using the single pipe parts are that it would strangle the engine and create extra back pressure although I don't know what effect/damage this would do.... it may be fine but I'm no expert.
Personally I'd just source a complete twin pipe 320/5 system
HTH
BMW E30 344i track car
BMW F31 335d xdrive
BMW F31 335d xdrive
-
allstar_07
- E30 Zone Newbie
- Posts: 153
- Joined: Wed Aug 19, 2009 11:00 pm
The flanges look like they do in the link - more confusingly they list the same mid section/backbox for the 325 engine thats in the link, although they have the twin system if you look under rear exhaust sections!
I think you're right - full 325 system the easy option. Just didn't to have to pay out for manifold etc if not needed. I'm still not sure how much the manifold varies apart from the flange.
I think you're right - full 325 system the easy option. Just didn't to have to pay out for manifold etc if not needed. I'm still not sure how much the manifold varies apart from the flange.