I realize that many things effect fuel economy, but with all mechanical things being equal (Trans - diff ratio - tires) do some makes of engines have a history of delivering better fuel economy ??? (New EPA regulations engines excluded) Thanks.

I have always noticed that Detriot S60 always seem to get just a weebit better most of the time

Detroits tend to be more forgiving to an unsympathetic driver, but driven right Cat engines can provide excelent economy. If you lean on it, they become thirstier than an alcoholic thats fresh of the AA wagon.

as for cummins, i hated mine so we wont go there

I have also noticed that my cats do better with one driver the seem to develop a pattern to match
running with my buddies cat doing the exact same thing in comprable truck the Detriot gets about 3-4 tenths better

Every little bit of information helps.

My cummins was always almost 1 mpg higher than the cats I was running with, and as for detroits I've never talked to anyone that had one that had more than half a load on

I pull tankers so they are 99% always a full load or nothing green enigines do just fine have 2 cats as well I like older cats but the twin turbos up are not so great I also have an old 8v-92 leaks like a sive runs hard as hell

It doesn't leak, it's marking its territory!

this looks like a good place to jump in...

I was at the dealership a few days ago and really found out nothing...

silly dealer wanted to sell a truck and not impart info...

to me... the mercedes get the very best mileage (period) nice broad torque curve for everything but colorado.

how long do they last? I wish I knew... can they be rebuilt??? I wish I knew... why do they need to be rebuilt??? I wish I knew....

all the dealer could tell me was they had a bad rap at the start for a plastic freeze plug that leaked and a bunch of guys overheated and junked the motors... prior to the recall...

??????b.s. ?????? I wish I knew... lol


anybody know the particulars???



and on the topic of fuel mileage....

whats the difference between a 10 and a 13 speed. no not three gears... i know that much... how much will it kill the MPG????

dealer said, not much... maybe a tenth is all.

I said I heard almost one MPG lost going to a 13 speed.

he said that's b.s. nobody has done any studies on the differences to back that up at all !!!!!!!!

so I asked... then how do you know its only a tenth at most???????

conversation over as he handed me an application for credit I didn't want...

parting words... " it's all in the gearing"

yeah??? what gear do I need????

"I dunno, we'll take you out on the lot and let you test drive a few or all of them til you find one that will work the best for you..."


oh K ! and alrighty then... I'll stop back by when I have more time...

like the second tuesday of the third week of the month.... hehehe...

__________________
Though your argument is very clever, I don't think it will lead to the results you desire. gandhi

I pulled food grade tanker.
I was either at 80k or empty at 30k.
Running mostly from Fl to Cali on I10 & back out on I40 or I80.

Loaded, I never had a cat that got decent fuel mileage. (4.75-5.25)
Under similar conditions, Detroits gave much better mileage (6+).
Both types of trucks had super tens.
I doubt the rears were the same & cannot recall what each were.

The caveats to my empirical measurements.
The cats were cut back from factory. (475 down to who knows?)
The Detroits were set for factory.
The cats were in T2k's while the Detroits were in T600/T800's.

My overall opinion is that ther bigger motors will generally give the better overall mpg.
A few OO's having 550 cats told me they got an average of 5.5 or slightly better running a lot heavier than me.

When I ran for a food grade joint that ran all Mack E427's, the factory settings gave me the best mpg.
After the garage turned them down, they couldn't pull themselves off a cliff & my mpg dropped from what was close to 7 mpg to barely over 5mpg. Some savings eh?

I tried driving the "cut back" truck differently to improve the mpg's.
Nothing I did including long stints at 55-60mph made any meaningful improvements.

I "got around" the computer & my mpg went right back up to where it was initially.