On Thu, 11 Jan 2001, Kev wrote:
> guess that on a 100 horse engine, the mechanical pump will use some
> 5-8 hp. This of course varies with temperature, rpm and pump
> condition. Let your battery do the work.
5-8 hp!! I better get my Briggs and Stratton engine off the garden
tractor and mount it to my water pump.
According to Heywood's "Internal Combustion Engine Fundamentals" an engine
under full throttle loses 10% of its indicated power to frictional work.
The oil pump, water pump, and alternator create 20% of the frictional work
*combined*, with each one being about equal. Therefore the water pump
will use 33% of 20% of 10% of the engine's power, so maybe 0.5 hp on a 100
hp engine. This study was done in 1982, SAE paper 820085: "Engine
Friction Reduction for Improved Fuel Economy."
This archive was generated by hypermail 2b29 : Thu 11 Jan 2001 - 05:11:27 UTC