View Single Post
Old 10-02-2008, 12:31 AM   #29 (permalink)
jamesqf
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 811 Times in 594 Posts
Quote:
Originally Posted by claytori View Post
Actuqlly, the bare engine has efficiency in the low to mid thirty percents but only in the "sweet spots' on the bsfc chart. After you allow for the mechanical losses and parasitic losses (alternator, ac, ps, etc.) the 25% number is realistic.
Yet in the searching I did, I found gas turbine efficiencies quoted in the 60% range. Granted, this is for large power-generation turbines, but they aren't fundamentally different than the turbines used in aircraft.

Haven't found anything that gives real-world numbers for automotive-sized units. I'd always gotten the impression that IC engines (gas & diesel) won out over other types for automotive use was not their efficiency, because they are pretty poor in that respect. Gas was cheap, after all, and the desire for fuel economy seldom showed up in other design decisions.
  Reply With Quote