What us your opinion over horsepower? 500 v 455

This will be long. And I'm a afraid your the guy that has been selling this misconception on here. I could be wrong. The idea of gear fast run slower is a ploy for fuel milage buy mega fleets and pro epa dumb sheets. Keep in mind the idea is nothing new. Mack started in the 60's but had a proven set up for them pre emissions. Next if you wanna make a comparison a truck with 2.89 ratio gears cruising at the same speed as a 3.55 in direct, not over drive because we are making a apple for apple comparison will flat out spank it. One reason it's already on boost or starting too.


Now the myth, this is common on fleet operations for fuel economy, and emissions. This is not a tactic one would use trying to get a useful million miles plus from a engine. No mega keeps them that long anymore. They trade them before the warranty expires so who cares about long term life? Lugged and excessive wear and 75k oil changes? Why not? They just ran half a million miles on 7 oil changes over 5,000 trucks and wont own it when a O/O pays 52k for it and it chucks a rod at 678k. They saved money all the way around and dont care.

Next is since the idea of this, it has cause driveshafts to get bigger, joints get bigger and prices go up. Then with a faster ring and pinion come deeper teeth and less teeth. The gears are weaker. Again not lasting as long and more expensive to replace. While the tooth maybe larger and even the contact pattern larger over the amount of teeth the contact pattern is less. And the thickness of the ring gear is slimmer.

Lugging a diesel has never been the best idea for longevity. Or any engine. Even when it saves pennies of fuel. It works for the big fleets, not independents. I can only imagine how great some guys fuel economy could be with newer engines and no def, dpf. Some of the engines would be fine.

You dont have to run any manual truck in the top gear just because it has that gear. Your allowed to select the gear and rpm you want.

 

They should it's more impressive. I have a N14 at 2150tq. It's a bad SOB. But .5 to .75 mpg worse than my Detroit with 1650tq. At the end of the day doing the same job. Not a huge difference really, I drive the same and run the Detroit.

 

What I do, nothing is going to get good mileage, and we pull the guts out of what ever we have, no little detroits on the road, cuz they just don't have enough guts to start with. lol
I have known of a couple of detroits, 12.7's, that did get by for a few months, and some of the new ones are doing ok now.
Back when detroit had the 14 liter, one company had one and an auto to test. Detroit kept a factory rep up here riding with the various drivers and never could make it pull, they went so far as to even try a pp box on it. They finally just ran it, but I want to say it only had something like 68,000 miles on it when it came uncranked. lol it had an auto shift too though, and they never got it to perform satisfactorily on the steeper grades either.

 

Not sure what you do, but I have zero problems grossing 100k with a 12.7l. 1989 dad had zero problems with a 12.7l and doubles with 100-130 Payload. Side note In fleet operations anything that can be slip seated and driven 750k or 1 million is ok in my book.

 

I can do 100,000 with my 12.7 and have many times, but when you add in that 13% or steeper grade, it changes things dramatically. You can still get it done, but you are pulling it's guts out and very slow doing it. Plus when you have to take off on a grade like that with a load, the little detroits just do not have the torque to do it and be easy on the clutch and other components, and you will have to take off on them at times.

 

Were you out of, east, west, up north.

 

Thank you, thank you, thank you. My 1st job had 455 dd15 and the rpms cut to 1700. Ryder leases. Lug lug lug its entire life on top of 50k + oil change intervals.

Imo this whole down speeding fad is a trick to wear out your engine and wallet faster lol. Being down at max tq all day is real nice on internals. Both of our E-7s never see below 1500 for any extended length of time

 

Probably some DEF conspiracy too. No money in million mile motors, you know.

 

dang it man I was hoping the next time I’m over gross I could turn my yellow motor down a little to save weight !!