Ram HD 1000 lb-ft MPG loop

ShinerBock wrote:
Yes, at least from what I have seen in the dyno cells when I worked at Cummins. The crank and the internals can handle well over what the pick up truck puts out(I am talking hundreds, not tens) without any significant or even notable reduction in B10 and B50 life percentages. Have you seen otherwise in any of the engines you dyno tested when working for an engine manufacturer?

All anecdotal. In markets where there are no emissions, why don't Cummins or anyone offer a 500 kW stationary generator (say in Africa) powered by an ISB?

The first draw back is the turbo especially on the turbine side. It is a major bottleneck and causes temps to rise quickly along with high drive pressures which puts a strain on internals(and head gaskets). However, it was made to control emissions at all rpms like all stock VG turbos. It, like the rest of the hardware and tuning is made to meet emissions and therefore very conservative in regards to what it can actually handle.

Not sure what it has to do with durability.

Nope, it would not be reasonable at all. At least not with my 20+ years of experience in the medium/heavy duty industry working for various engine/truck manufacturers and dealership groups. How many years have you been the industry to come up with that theory?

I didn't ask for your credentials, and btw, are you a registered engineer or just the tech running the test bench? Why is it not reasonable to assume engines operating at lower power, which experiences lower mechanical and thermal stresses, to incur less warranty repairs?

^Settle down kids, this is a fun discussion...

"Thank you for the input. It was a Freightliner chassis 26k gvwr but I was only hauling around 10k. Which is the payload limit for non cdl and the limit for the rental. It was frustrating trying to merge onto expressways and limited at 70mph means no run at any smaller hills so cresting a 50 was not uncommon. It was a very easy truck to drive but you better be planning your moves way ahead of time."

And if we was back in the day, you coulda popped the hood up, moved the fuel plate forward, turned up the fuel screw, cranked the star wheel a couple turns and seen how high of egts you could blow with the little H1 turbo!

RoyJ wrote:
So you're saying given the exact same displacement, and the same metallurgy of the components - their operating life remains identical regardless of stress level?

Yes, at least from what I have seen in the dyno cells when I worked at Cummins. The crank and the internals can handle well over what the pick up truck puts out(I am talking hundreds, not tens) without any significant or even notable reduction in B10 and B50 life percentages. Have you seen otherwise in any of the engines you dyno tested when working for an engine manufacturer?

The first draw back is the turbo especially on the turbine side. It is a major bottleneck and causes temps to rise quickly along with high drive pressures which puts a strain on internals(and head gaskets). However, it was made to control emissions at all rpms like all stock VG turbos. It, like the rest of the hardware and tuning is made to meet emissions and therefore very conservative in regards to what it can actually handle.

RoyJ wrote:
Wouldn't it be more reasonable to state Cummins charge more for high hp rating engines, because they have a higher probability to incur in-warranty repairs?

We can also look at it the other way and say Cummins gives you a discount when you order a "de-rated" engine, because it's much less likely to fail.

Nope, it would not be reasonable at all. At least not with my 20+ years of experience in the medium/heavy duty industry working for various engine/truck manufacturers and dealership groups. How many years have you been the industry to come up with that theory?

So you're saying given the exact same displacement, and the same metallurgy of the components - their operating life remains identical regardless of stress level?

Wouldn't it be more reasonable to state Cummins charge more for high hp rating engines, because they have a higher probability to incur in-warranty repairs?

We can also look at it the other way and say Cummins gives you a discount when you order a "de-rated" engine, because it's much less likely to fail.

This is a list of all the horsepower ratings the ISB 6.7L has for a medium duty truck application. The more horsepower you want, the more you pay. Knowing Ryder as both a past fleet customer and vendor, they probably had the lowest amount possible at 200 hp in the "efficiency" ratings of these engines.

ShinerBock wrote:


That is not accurate and this old assumption needs to go away with the Dodo. Whether it is a 500 hp marine ISB or a 200 hp ISB in a school bus, the stock ECM has the ability to de-fuel to protect itself if need be no matter what peak power it is rated at. It is not like fixed mechanical fuel delivery systems of old. There are two main reasons Cummins de-tunes these engine and neither have to do with protecting the engine since it can already do that at various power levels.

The first reason is emissions. There different emissions certifications for each GVWR. Since US emissions is measured in grams per horsepower per hour, emissions play a major role in how much horsepower an engine is allowed to make along with the GVWR of the truck it is going in.

The second reason is because Cummins and most medium/heavy duty truck makes sell different power levels at a premium. An engine may have 5 different power levels for a certain GVWR and application with the only difference being engine calibration. Cummins and these truck manufacturers are able to up charge additional horsepower similar to how the up-charge HO outputs in the pickups.

Case in point, the trucks mich800 probably drove was either a Freightliner M2 or International MV. Both offer a Cummins ISB with several power ratings between 200 hp up to 325 hp. How much power you want depends on how much you want to pay. Being that Ryder is a rental company, they probably don't care to pay for the higher power and actually want you to take as long as possible with the truck so they can charge more. Another company that uses the exact same truck set up in their own fleet may want to pay for the additional power since time is money.

Thank you for the input. It was a Freightliner chassis 26k gvwr but I was only hauling around 10k. Which is the payload limit for non cdl and the limit for the rental. It was frustrating trying to merge onto expressways and limited at 70mph means no run at any smaller hills so cresting a 50 was not uncommon. It was a very easy truck to drive but you better be planning your moves way ahead of time.

Cummins12V98 wrote:

mich800 wrote:

Me Again wrote:

ShinerBock wrote:


I am also pretty sure that any class 7/8 truck driver out there would disagree with the not needing extra gears when towing too. Go drive an Eaton 8 speed, 10 speed, and 13 speed up and down a few hills behind the same exact engine and you will see what a few extra gears will do.

I drove a class 8 tractor with a 13 speed roadranger. It had a 8V71 350 that's power band was from 1900-2200 RPM. Today's trucks have much wider power bands and fewer gears are needed and/or installed.

If RAM gets more gears a lot the reason will be keep up with the Jones! Why would someone buy 6 speed when the other two have 8, irregardless that they are V8's and the Cummins is a I-6.

I had to drive a Ryder box truck a week ago with the Cummins and Allison transmission. It was a six speed I believe. That thing was a dog and could not get out of its own way. More gears definitely would have made the drive more enjoyable.

Nope! It was a dog to protect the engine. De tuned.

That is not accurate and this old assumption needs to go away with the Dodo. Whether it is a 500 hp marine ISB or a 200 hp ISB in a school bus, the stock ECM has the ability to de-fuel to protect itself if need be no matter what peak power it is rated at. It is not like fixed mechanical fuel delivery systems of old. There are two main reasons Cummins de-tunes these engine and neither have to do with protecting the engine since it can already do that at various power levels.

The first reason is emissions. There different emissions certifications for each GVWR. Since US emissions is measured in grams per horsepower per hour, emissions play a major role in how much horsepower an engine is allowed to make along with the GVWR of the truck it is going in. In almost all cases, the emissions requirements force the manufacturer to tune these engine well below what they can reliably handle.

The second reason is because Cummins and most medium/heavy duty truck makes sell different power levels at a premium. An engine may have 5 different power levels for a certain GVWR and application with the only difference being engine calibration. Cummins and these truck manufacturers are able to up charge additional horsepower similar to how the up-charge HO outputs in the pickups.

Case in point, the trucks mich800 probably drove was either a Freightliner M2 or International MV. Both offer a Cummins ISB with several power ratings between 200 hp up to 325 hp. How much power you want depends on how much you want to pay. Being that Ryder is a rental company, they probably don't care to pay for the higher power and actually want you to take as long as possible with the truck so they can charge more. Another company that uses the exact same truck set up in their own fleet may want to pay for the additional power since time is money.

gmcsmoke wrote:
Is it just me or did the payload seem low for a upgraded frame and increased towing?.... 5,300 seems low for a brand advertising over 7k in a regular cab

Keep in mind that 7K is with a stripped Tradesman and a 6.4 Hemi.

Will be interesting when all three are tested towing 30k up and down serious grades.

gmcsmoke wrote:
Is it just me or did the payload seem low for a upgraded frame and increased towing?.... 5,300 seems low for a brand advertising over 7k in a regular cab

My payload is over 6k following the axle ratings. That is all that really matters.