Best pre emissions engine for mpg

Never had a ved12, but hands down hard to argue, the 12.7 built and tuned correctly will deliver the best fuel Mileage.

 

I just picked up my 2013 cascadia with 12.7 Detroit freshly rebuilt and 13 speed . Drove it all the way from SLC . So far i like it , hopefully to load tomorrow and drive several weeks/months playing around and testing how i like it . Its so oversize compared to my t660

 

I'm pro detroit, but I managed a shop with volvos and VD12. Yes I know VED, I called the the VD. 96/97/00 models. Lower on power than detroit, but better on fuel. However the WIA trucks were very well built, they were heavy.

The engines were very reliable and cheap maintenance till about 850k-1mll. Seem them go well over a million. But nobody except volvo knew how to work on them. Normally had them towed back to are shop. Between 850-1mil everything was worn. Water pump lasts a million. But all the pipes that fit water pump are specific volvo parts. They are shot at the same time. Turbo? Volvo only with exhaust brake. Something like 2200 bucks back then. Plus oil lines, and exhaustblrake line from volvo. Every thing was volvo only! Cheap and efficient engine. Till they had miles on them. Only ever rebuilt one. That was a expensive mistake. Mind you this was 20 years ago. No one stocked anything for them. The shop I worked at had to stock alot of specific volvo parts. So bad that the local volvo, who we did not do business with used to call us for parts.

Very cheap and efficient 75% of its life.

 

Itll depend on what you think of as fuel efficient and where you run and if you will be driving it correctly and if its van vs flat vs heavy haul, how heavy you normally run etcetcetc

"Best"? No idea what that means.

For the year, bearing in mind this includes someone stealing 60 gallons off me no apu and quite a bit of idle time over the winter, rest of the year will steadily improve a bit.
My numbers tell me my truck is pulling 5.8 mpg

Of interest to note
1. Stretched truck
2. Flatbed
3. High idle time, no apu
4. If i stay in the plains, mpg goes up drastically
5. Most of this actually includes tires that put my running rpm too high

Since switching back down to better tires and keeping in the plains, i got close to 7 mpg

3406e (1lw ecm, base engine, 5ek)
T600 1994 (definitely more aerodynamic than a w900
3.36 rears
13 speed trans
22.5 talls/24.5lp
Run 1250-1350 rpm on the average (1350 is 70 mph in 13th)

Hills and taller loads are the mpg killer for me not weight...

Fueling in a minute, will show what pa did to my 7 mpg plains running

Adding for clarity, when i say hills are a killer for me, i mean mpg, grossing 80k i still pull up a hill fine barely dropping gears

 

Your right foot will make the biggest difference. 60 series just for the ease of finding parts

 

Just don’t get a 14 liter Detroit if your looking for fuel mileage. I had one that consistently made 4.3 mpg. It was practically bulletproof on the bright side.

 

My uncle's 02 500 60 series has a 13 and 3.42s gets right around 7mpg doing short haul loaded 1 way. Not bad for large car 280wb classic 84in bunk

 

Any idea what you will be pulling ?

 

05 14l series 60 3.58 rear 7plus with a egg under your foot 1400-1700 rpm with a good tune and a fresh overhead makes a big difference. series 60s dont like to lug. another thing that helps is get a boost gauge if u dont have one already and learn to drive by that and u will save even more mpg.