View Single Post
Old 12-01-2010, 11:15 PM   #64 (permalink)
dcb
needs more cowbell
 
dcb's Avatar
 
Join Date: Feb 2008
Location:
Posts: 5,038

pimp mobile - '81 suzuki gs 250 t
90 day: 96.29 mpg (US)

schnitzel - '01 Volkswagen Golf TDI
90 day: 53.56 mpg (US)
Thanks: 158
Thanked 269 Times in 212 Posts
Quote:
Originally Posted by Old Mechanic View Post
Do a coast down test of a vehicle.

In high gear with standard engine. Highest loss
In neutral. No loss related to engine
Pull the plugs to eliminate the compression.
Pull the head to eliminate valve train losses.

You would have to push the car to speed in tha last two tests.
unfortunately that doesn't really answer the question... when the pistons (and some fraction of the connecting rods) are accelerated and decelerated energy is lost, question is how much. I did figure it out on the valves once and it was a trivial amount of power, assuming you aren't approaching redline.
__________________
WINDMILLS DO NOT WORK THAT WAY!!!
  Reply With Quote