Wednesday, April 21, 2010

Engine exhaust.......

Jim, the guru is trapped in Urop by the evil Icelandic dust so I have time to try and plan the engine exhaust system. From the measurements, I will need a 20"dry insulated riser, with the cooling water injected on the down side.

These are the measurements on TIH.

These are the recommendations from the Vernalift website;

(diagram courtesy of Centek Ind.)

Obviously I have to watch out for excessive back pressure. Any advice welcome.


robert said...

On back pressure. Drill and tap a port (maybe 3/8 inch) in the first exhaust fitting downstream of the exhaust manifold. In normal conditions you will have it plugged with a brass plug (with anti-sieze) but you can use this port to attach a slack tube manometer to accurately gauge back pressure when the engine is running.

Probably the only "proper and accurate" way to measure back pressure inexpensively.

Of course, consequences of excessive back pressure are slow and gradual loss of cylinder pressure in the form of worn rings and/or valves (dont ask me how I know).

Worth the investment if you plan on keeping the boat for a long time.

Many yards and even production builders will test with a wand probe at the hull discharge port, which is not at all very accurate (if at all). Measuring as close to the engine is the best.

navarch said...


When I repowered my Whitby with a Westerbeke, I installed a Vetus muffler. To get it lower, I cut a hole in the shelf, just slightly larger than the muffler. I glassed in a shelf for it to sit on, and it sits in there nicely. I also put a temperature sensor in the muffler.

Thanks for the fuel tank panel dimensions. It's a big help.


The Incredible Hull said...

Thanks all for the advice. Does anyone have a source for dry risers.

Ocean Dove said...

Hi Bruce
I this winter I re-power Ocean Dove with a Vetus VH4.80 and Vetus muffler.
I would like to some photos of your install.
I haven't started my engine yet, but would like your input.