2014 dodge diesels

rhagfo wrote:

Hannibal wrote:

rhagfo wrote:
My 01 has 3.55 gears and less than 300 hp, but about 550# of torque. I move a 32' 5er weighing 11,000# at speed up hill and down hill.
Darn, forgot the the gasser folks will say it is all about HP, moving a load!

At what speed? 45mph? Lol!

Sorry, I have not seen south of 50 on 6% and 7% grades unless held up by traffic, I can hold 55 most of the time, I can also hit the base of a 6% grade at 25 and be doing 60 in about 1/2 to 3/4 mile. I only need to drop to 4th (direct) in my 5 speed to do this. This is is on curvy twisty secondary roads with 45 mph curves one needs to speed up from, on the interstate, just never seen the south side of 60 mph.
I know the formulas, but torque accounts for something.
11,000# 5er GCVW 19,000# to 19,500#, that is why I like my diesel.

I agree with you Russ. Back when I had my 02 Dodge/Cummins 6 speed manual with Arctic Fox 990 Camper (4500 to 4800lbs) and towing my car trailer with my Jeep on it (6000 to 6500lbs), it would pull any Interstate grade at or above the speed limit in direct (5th gear). The only mod was an Edge EZ which gave it 290/590 on the Dyno.

Rich

It is for two related reasons with regard to gas engines. The higher gears produce better results with the EPA fuel economy testing which is done indoors on a dynometer and this fools many customers who still believe the numbers and the higher fictitious highway MPG helps the manufacturers meet the federally mandated fleet economy standards or CAFE.

When the most profitable products sold by the manufacturers are pickup trucks and at the same time these vehicles lower the fleet average for all vehicles sold in a given year, the manufacturers need to find a way out. They have use two tactics, one being the very tall gears which do not truly improve fuel economy with the truck empty and can actually reduce fuel economy when hauling or towing a heavy load as the engine spends more time outside its peak power band (which is why everyone is going to 8-speed transmissions).

The second tactic which is quite ingenuous is to get customers to buy diesel powered cars and trucks. The higher cost for the engine, for maintenance, and for fuel is shouldered 100% by the customers and the manufacturer gets a higher fleet average MPG.

Notice though that the higher gears also reduce towing capacity by 20-25 percent. A 2015 Chevy Silverado 1500 with the 6.2L gas V-8 and 3.73 gears is rated for towing over 17,000 lbs., or 5,000 lbs. more than the same truck with the same engine but with 3.23 gears.

With diesel trucks the engine produces peak torque at half the RPM's as gas engines so the gearing can be higher without much of a penalty in towing capacity. There is still a penalty and it is most apparent when you compare the towing capacity of the F-350 with that of the F-450 pickup truck with the latter truck's much lower rear end gearing.

10 years ago 3.73 and 4.10 was used on typical 3/4 and 1 ton diesels. Transmissions used 4-5 speeds with the highest ratio about 0.70:1. Torque was about 500lb-ft.

Today, 3.31-3.55 are common and GM still uses 3.73. Transmissions have 6 gears with the highest ratio as low as 0.63:1. Engine torque is now 750-850 ft-lb.

A 2015 Ram diesel with 3.42 and Aisin trans has 16% more torque in top gear than a 10 year old Ram diesel with 4.10.

Why lower gearing today? More power available and compromise on using some of the power/gearing to save fuel when not loaded. All this to compensate for the extra diesel emissions required in the last 10 years.

Hannibal wrote:

rhagfo wrote:
My 01 has 3.55 gears and less than 300 hp, but about 550# of torque. I move a 32' 5er weighing 11,000# at speed up hill and down hill.
Darn, forgot the the gasser folks will say it is all about HP, moving a load!

At what speed? 45mph? Lol!

Sorry, I have not seen south of 50 on 6% and 7% grades unless held up by traffic, I can hold 55 most of the time, I can also hit the base of a 6% grade at 25 and be doing 60 in about 1/2 to 3/4 mile. I only need to drop to 4th (direct) in my 5 speed to do this. This is is on curvy twisty secondary roads with 45 mph curves one needs to speed up from, on the interstate, just never seen the south side of 60 mph.
I know the formulas, but torque accounts for something.
11,000# 5er GCVW 19,000# to 19,500#, that is why I like my diesel.

rhagfo wrote:
My 01 has 3.55 gears and less than 300 hp, but about 550# of torque. I move a 32' 5er weighing 11,000# at speed up hill and down hill.
Darn, forgot the the gasser folks will say it is all about HP, moving a load!

At what speed? 45mph? Lol!

PINION STRENGTH. The lower the gear the smaller the pinion. ie. 3:42 has larger pinion than 4:56. 4:56 larger pinion than 4:88 etc.
Pure speculation. These trucks have double overdrive tranny's, so why not a lower R&P?

Darn, forgot the the gasser folks will say it is all about HP, moving a load!

X2

And those same "rocket Scientists" argue jet engines and rocket engines, power is measured in HP... :S

My 01 has 3.55 gears and less than 300 hp, but about 550# of torque. I move a 32' 5er weighing 11,000# at speed up hill and down hill.
Darn, forgot the the gasser folks will say it is all about HP, moving a load!

My 2013 Ram 3500 Megacab dually has 3.73 gears and the G56 manual transmission. It works very well, but I would not be afraid of the 3.42 gears after owning this truck for a while now. The Cummins has so much low end torque that lower RPM will not be a problem at all.

The Ram 2500s got the new frame in 2014 models. The 3500s got that frame in 2013 models.