flyingcow
Veteran Member
I know when I took IC engines in school, hmm, over 10 years ago, we did some calcs, at the time, a turbo, direct injection gasoline motor could get near 100% of the maximum thermodynamic efficiency possible, and was limited by some material properties to that. The potential gains were getting slim. You see that in the new Ford V-6, its getting close to the most we are going to get out of a gas motor for thermal efficiency.
Diesels at the time were were only getting to like half of the max possible thermal efficiency. Common rail, multiple pulsed injection etc was just getting going, variable geometry turbos being researched etc. Very little development since the first diesel had taken place. Professor was a firm believer in working to get the diesel efficiency up to at least 60-70%, which would improve mileage dramatically. Not sure where that number is at today in a commercial diesel.
What you described, I think, is what Cummins has been doing.Common rail, variable speed turbo's etc.