Exactly right.

There is no disagreement that a reduction in engine speed will improve the fuel economy of a vehicle with a diesel engine. You definitely will not lose.

The issue is whether or not your percentage gain exactly matches your axle ratio change. This was his original premise.

i will concede everything if someone has hard evidence to refute my experiences.

i will also concede that my statement near the end of my post in which i stated the savings would equal the ratio change is not very likely to be true except in some exceptional situation. but my statement in the first part of my original post said nearly equal, and i will stand by that.

now we can argue about what nearly means, i suppose, but i would like to see evidence.

even engineers eventually have to put the car on the road and see if their calculations are correct.

even mercedes conducts extensive road testing and we all agree they have the best engineers in the world, right?

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

You've got some evidence that suggests that you get better fuel economy with taller rear axle ratios. Nobody will refute this.

Nobody will refute this either.

Nobody knows what "nearly equal" means so nobody is going to refute this either.


Thanks for your post.

and you dont have any hard evidence, do you?



tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Let me pose a question to you.

This is especially appropriate since you're an architect.

A fellow comes in to you and tells you that he used a 2" x 4" header above his garage door.........a garage with a second story above. He tells you that the header was fine and it supports the load perfectly.

Now, as an architect, you clearly know that this fellow is full of $hit and there is no way that such a header can do the job.

But, he claims to have the evidence that supports his position.

Do you accept his evidence.......or do you realize that he is clearly in error and that 2" x 4" is already bending significantly and may fail in the not too distant future?

Of course, you don't have any hard evidence to refute this fellow......because you'd never do anything so stupid as to put a 2" x 4" above an 8' door.

The analogy is identical.

and you dont have any hard evidence do you?

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'm sorry to tell you that you.......as the thread starter........have the onerous of providing the hard evidence. You've provided anecdotal stories without a shred of hard evidence concerning a back to back test on a M/B diesel.


And, you've clearly ignored the very good analogy of an architect who would laugh in the face of someone who demanded hard evidence of the fact that a 2" x 4" won't work as a proper header above an 8' garage door.

You do know that this header would be inappropriate.......don't you?? Maybe I'm making some cavalier assumptions regarding your knowledge of building construction??