Russell Newbery exhaust

[starman]

Our DM2 exhaust is a bit of a one off. It comes off the manifold via the usual flexy pipe into the ‘silencer’ (just an open expansion box) then exits through the roof via a 2 inch internal diameter pipe. This has a sleeve so it can carry a 3in stack. 
It’s all a bit fussy but the chief question is - is that 2in bore outlet pipe large enough?

Second question: does anyone make 3in   stacks (not in stainless)? The MC ones are horribly cheap and flimsy. 

[BEngo]

 

 

Photos of general layout would help.  I assume the pipe from the engine is also 2in dia.

 

Two inches ID will be fine, provided the bit  between the engine and the expansion box is no longer than it has to be and any bends are as large a radius as practicable.  Swept bends are good, screwed  or welded elbows are not.  Flexy pipe should be, in practical terms, straight, not used for forming bends as it tends to reduce its internal  area when bent.

 

Try Ady Brindle for a stack. He made our stove chimney, so should be able to make an exhaust chimney.

 

N

[David Mack]

14 minutes ago, starman said:

Second question: does anyone make 3in   stacks (not in stainless)? The MC ones are horribly cheap and flimsy. 

Why not stainless? I made an exhaust stack by using something like this. As I needed an odd size I used a larger diameter, slit it down its length, pulled it in with jubilee clips, drilled and pop riveted through the overlap, then painted it with black heat resistant paint.

[starman]

1 hour ago, BEngo said:

 

 

Photos of general layout would help.  I assume the pipe from the engine is also 2in dia.

 

Two inches ID will be fine, provided the bit  between the engine and the expansion box is no longer than it has to be and any bends are as large a radius as practicable.  Swept bends are good, screwed  or welded elbows are not.  Flexy pipe should be, in practical terms, straight, not used for forming bends as it tends to reduce its internal  area when bent.

 

Try Ady Brindle for a stack. He made our stove chimney, so should be able to make an exhaust chimney.

 

N

The rest of the system is all bandaged up so I’m a bit loathe to unwrap. The system comes off the manifold in a swept elbow similar bore to manifold IIRC then about 10in straight flexy about 21/2. 
In short the rest of it is bigger bore than the 8in of tailpipe. 

57 minutes ago, David Mack said:

Why not stainless? I made an exhaust stack by using something like this. As I needed an odd size I used a larger diameter, slit it down its length, pulled it in with jubilee clips, drilled and pop riveted through the overlap, then painted it with black heat resistant paint.

I’ve always been a bit wary of painting stainless … and of my metalworking skills

[BEngo]

13 minutes ago, starman said:

In short the rest of it is bigger bore than the 8in of tailpipe.

From that, and your general description,  I cannot see any major problem arising.

Giving the pipe a sweep every 7-10 years, or if it starts spitting chewable lumps of soot onto the roof , would not be a bad idea.  I know my exhaust will soon need a sweep when I get sparks coming from the cutter in tunnels.

 

N