Performance curves for Universal M30

[dcmeigs]

Has anyone ever seen performance curves for universal diesels? I know they must exist but I have never seen them published. I'd like to see a fuel burn vs. RPM curve for my M30 (24hp).

[JimsCAL]

You'll never find one like that because fuel consumption vs RPM is dependent on the boat and prop in addition to the engine. Diesel fuel consumption per horsepower (lbm/hp-hr) is pretty constant in the middle to upper middle part of the operating range. The power it takes to push the hull through the water increases with about the cube of speed. So a 25% increase in speed takes twice as much power, more as you approach hull speed.

[dcmeigs]

Originally Posted by JimsCAL

You'll never find one like that because fuel consumption vs RPM is dependent on the boat and prop in addition to the engine.

Here is link a to a typical yanmar performance curve. It's on the second page. http://www.yanmarmarine.com/uploads/.../BY/6BY260.pdf

The curves are predicated on a prop choice that yields a proper RPM vs HP curve. What this really means is a predictable manifold pressure curve.

These curves are common in aircraft engines (required as a condition for certification) and they are expressed on a pair of graphs that begin with manifold pressure and RPM and then transisition to fuel burn on the second chart. It's really the same thing except that since our boats normally have a fixed pitch prop the relationship between manifold pressure and RPM is fixed and therefore known for a given prop. The assumption is made that the boat is proped correctly.

I'd like to see these curves for the Universal M30.

[wwilson]

And Volvo curves...

http://vppneuapps.volvo.com/ww/PIE/V...605&lang=en-US

[JimsCAL]

The standard way engine performance curves are presented are HP, torque, and Specific Fuel Consumption versus engine RPM. Tests are run on a dyno at full throttle. See www.betamarinenc.com/722.htm for an example.