View Single Post
Old 02-28-2013, 06:30 PM   #228 (permalink)
ERTW
EcoModding Apprentice
 
ERTW's Avatar
 
Join Date: Jan 2012
Location: Toronto
Posts: 120

Bu - '08 Chevrolet Malibu LS
90 day: 32.29 mpg (US)
Thanks: 51
Thanked 65 Times in 31 Posts
From an sae paper l'm currently reading:

Tuning: characterised by increased volumetric efficiency...but decreased bsfc.

Anti-tuning: characterised by decreased VE...but reduced bsfc.

Also, fuel consumption is proportionately correlated with pumping work.

I was considering disconnecting half of my engine valves, and in consideration of this info, i would double my pumping loss and potentially increase VE - hurting fuel consumption.

Late intake valve closing does wonders for efficiency - the toyota 2.5L is 37% thermally efficient - and gives the turbo lag feel. It seems that a large engine with the performance of a small one may be better than a small engine with the performance of a larger engine. Fwiw downsizing more than 30% hurts transient response, and turbo engines aren't as fuel efficient as they're marketed.
  Reply With Quote