Heat exchanger

[jonesthenuke]

Spotted this and thought it may be of use to someone?

 

http://www.ebay.co.uk/itm/BMC-1-5-1-8-Exhaust-Heat-Exchanger-/191217501904?pt=UK_CarsParts_Vehicles_Boat_Engines_EngineParts_SM&hash=item2c857386d0

[Tony Brooks]

I very much doubt that's a heat exchanger - no sign of a core or filler cap. More likely a direct raw water cooled manifold (or keel cooled but used with a header tank IF the pipe bosses are large enough).

[MtB]

Which leads us back to the question posed in the other thread but never really answered, why water cool the exhaust manifold at all? After all they aren't cooled on the automotive version of this engine.

 

Or are they? I don't remember my old Sherpa having a water cooled exhaust manifold.

 

MtB

[Tony Brooks]

We know from certain Ford XLD and Barrus marinisations that it is not necessary to water cool the manifold. Both those use fiber glass blankets. Good practice, the BSS and the old Thames Launch Regulations all require the exhaust system to be protected from burning close by materials and people who manage to touch it when working. I suspect the lumpy stuff regs say something similar.

 

This is why we lag our dry exhausts. Personally I would hate to fall against a lagged manifold that was operating at near full power. I think one would still get a bad burn. I would also be less than happy with an unprotected manifold/dry exhaust in a GRP or wooden boats, especially if they operated at high powers for long periods. I have seen wood charred by air cooled Lister exhausts.

[MtB]

Hmmmm I see. Thanks.

 

This makes sense. I imagine a manifold on an engine working hard can reach 600 0r 700 degrees C so the fire risk is probably the biggest reason.

 

MtB