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Peter7307 · 10-08-2008, 01:41 AM

Kane66,
There are many factors determining the optimum FE for a vehicle as you already know.
One is the BSFC. Have a look at the Autospeed website and type in Brake Specific Fuel Consumption into the search box. This will give you a detailed explanation of how to read and understand those curves.

As a rule of thumb, most engines achieve their best fuel economy at an RPM corresponding to a piston speed of 5 to 6 m/s (16.4 to 19.8 ft/s). Piston speed (ft/s)= 2*stroke(inches)*rpm/720.

Piston speed = 2 x Stroke in inches x rpm / 720

As stated this is a rule of thumb only and specific cases may well alter the final numbers.

Pete.

10-08-2008, 01:41 AM	#7 (permalink)
Peter7307 Master EcoModder Join Date: Jan 2008 Location: Victoria , Australia. Posts: 499 Thanks: 20 Thanked 46 Times in 33 Posts	Kane66, There are many factors determining the optimum FE for a vehicle as you already know. One is the BSFC. Have a look at the Autospeed website and type in Brake Specific Fuel Consumption into the search box. This will give you a detailed explanation of how to read and understand those curves. As a rule of thumb, most engines achieve their best fuel economy at an RPM corresponding to a piston speed of 5 to 6 m/s (16.4 to 19.8 ft/s). Piston speed (ft/s)= 2stroke(inches)rpm/720. Piston speed = 2 x Stroke in inches x rpm / 720 As stated this is a rule of thumb only and specific cases may well alter the final numbers. Pete.