Jump to content

J2 Exhaust system


Mike Adams

Featured Posts

My J2 has what appears to be a small water cooled expansion box on and above the end of the exhaust manifold. It has been blanked off at some time in the past so that no water flows through it maybe because it leaked between the water jacket and the exhaust. There is no other silencer fitted so the engine is loud. What would be the best type of silencer to fit bearing in mind it does send out a lot of smoke when cold and starting so I wouldn't want one that clogs easily. Engine dates from 1935 and this part does not seem to be shown in the spares listing I have and from images of others I have seen in NBs not fitted on all engines.

Link to comment
Share on other sites

I don't think the J series had a Kelvin globe silencer. They were earlier. I could be wrong though. No doubt my brother will be along shortly to prove me wrong. They were water jacketed too. Interestingly, we are prototyping a new globe silencer based on the Kelvin design

Regards

Dan

Edited by stagedamager
Link to comment
Share on other sites

My K1 came complete with missing water cooled expansion box. I fitted it as it was but the exhaust was just a shade too harsh on the ear so I welded my own expansion box into the exhaust which looked EXACTLY like a 3.9kg propane bottle. Softened the exhaust note perfectly.

My K2 however needs no expansion box and sounds lovely. 

I guess because each cylinder is only working half as hard.

Link to comment
Share on other sites

Here are photos of a few Kelvin silencers, 

early J typeIMG_1933.JPG.f27e84d0aa05edeef6437eb908b60b64.JPGIMG_1932.JPG.6960b959d59fe0f3ea96872b821ea9c7.JPG

 

Ricardo type from an F4

 

IMG_1929.JPG.4bc7dc90c440313b7f3c84536b1f8248.JPG

 

Globe silencer for 3 1/2" poppet valve from 1915 onwards

 

IMG_1931.JPG.d36cda3965fe0fcbc29d5c6d983d7780.JPG

 

and the early poppet valve type pre 1915

 

IMG_1930.JPG.401139b5081a3abc510c75d2e247e38b.JPG

 

 

this one one is also for a 3 1/2" bore engine

Tom

  • Greenie 1
Link to comment
Share on other sites

My J2 has a 9x9 in x 2ft 6 long rectangular box across the deckhead.  Inlet at one end exhaust at the other.  One end is removeable so I can 

clean the soot out about every three years.

N

Link to comment
Share on other sites

This is a picture of the expansion box, I am assuming it is supposed to be water cooled becuse of the number of inlets. Both the water inlets are blocked off. Not sure yet if this is due to an internal failure or to reduce the load on the skin cooling tank.

DSC04488.JPG

Link to comment
Share on other sites

1 hour ago, Mike Adams said:

This is a picture of the expansion box, I am assuming it is supposed to be water cooled becuse of the number of inlets. Both the water inlets are blocked off. Not sure yet if this is due to an internal failure or to reduce the load on the skin cooling tank.

I think my ‘48 J2 has the same box as yours Mike.

I’d assumed the two blanking plates (different sizes) were for cleaning ?

This has now been added to my extensive “do list” together with sorting one of the top fixing bolts which I’ve just noticed is missing, but not blowing.

 

22872BD5-D4A1-492A-81C0-4837CA4DA9BC.jpeg

0A2D2F4A-6C7E-4E0B-A4B0-26DA5FB26487.jpeg

Link to comment
Share on other sites

34 minutes ago, Mike Adams said:

Perhaps who ever gets around to taking it off first will find out. As you can see mine has  a blanked off water pipe going into it......

If one flange is for water in and the other for water out, why the big difference in size between them?

I know I’m missing something here ?

Link to comment
Share on other sites

2 hours ago, gbclive said:

If one flange is for water in and the other for water out, why the big difference in size between them?

I know I’m missing something here ?

 

Kelvins may originally have been intended to be installed with wet exhausts, being fishing boat engines. One flange may be for water injection and the other for cleaning. 

Link to comment
Share on other sites

3 hours ago, Mike the Boilerman said:

Kelvins may originally have been intended to be installed with wet exhausts, being fishing boat engines. One flange may be for water injection and the other for cleaning. 

That’s the point I was missing - It makes sense, thank you Mike.

Link to comment
Share on other sites

13 hours ago, Mike the Boilerman said:

 

Kelvins may originally have been intended to be installed with wet exhausts, being fishing boat engines. One flange may be for water injection and the other for cleaning. 

Yes they were. The wet exhaust causes clouds of "steam"( water vapour) to  be emitted from the side exit pipe, particularly on cold days . Accusations of  causing  serious air pollution are sometimes made or advice to the effect that we need new piston rings,cylinders or engine. Even get  "Is it a steam engine?". Running without water to the expansion box causes it to get very hot, to the extent that it needs to be insulated . There aren't many intact original boxes around, they fall apart after years of hot sea water, so a dry modern silencer thing is usually fitted. Or just a straight  pipe if you like the noise!

Link to comment
Share on other sites

5 minutes ago, billh said:

Or just a straight  pipe if you like the noise!

 

Curiously my K1 with a straight pipe had too sharp a bark to be comfortable on the ear, so after a fair bit of experimentation I welded in an expansion box that looks exactly like a 3.9kg propane gas bottle. (But definitely isn't, for the avoidance of doubt, before anyone starts ok?!) This softens the bark perfectly. 

 

A K2 with a straight pipe however sounds lovely with no expansion box. I put this down to each combustion stroke having to do only half (approximately) the work.

Link to comment
Share on other sites

8 hours ago, billh said:

Running without water to the expansion box causes it to get very hot, to the extent that it needs to be insulated

Inspected mine this morning as we were working it quite hard on the Old River Nene.

At a steady 625 RPM = about 115 Celsius.

OK for a quick dab.

So far no burns, so will live with the risk as I like the shape of it ?

Link to comment
Share on other sites

  • 3 months later...

I have removed the 'silencer' which turns out only to be a water injection elbow. Not used since I have skin tank cooling. It does not seem to contribute to silencing so I have removed it. So no silencer fitted at all. The required pipe is only about 2 inches in diameter which seems a bit small. Because of the amout of crud that comes out of the engine I think a normal silencer would soon get blocked up so looking at fabticating one from a bit of 4 or 5 inch tube which will hopefuly quieten the engine a bit.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.