I6, V8 diesels in OTR and off road applications

[Bill Stockard]

If I remember correctly, the Cummins ISB6. 7L engine used in medium duty trucks has the valve gear train at the rear of the engine instead at the front as in a Dodge product. Cummins Engines - On-Highway - Medium-Duty Truck - EPA 2010 ISB6. 7



Bill

 

[HBarlow]

Thanks, Bill. I completely forgot about the 6. 7s used in real medium duty trucks. I thought he was asking about the Ram 4500/5500s. Is the commercial version of the ISB6. 7 assembled in a different plant? I would be surprised if it is but don't know.

 

[bheiting]

Thanks, Bill. I completely forgot about the 6. 7s used in real medium duty trucks. I thought he was asking about the Ram 4500/5500s. Is the commercial version of the ISB6. 7 assembled in a different plant? I would be surprised if it is but don't know.

When I toured the CMEP plant in Columbus IN a year ago, they told me that location was the only plant that produced the Dodge engine. There is another ISB plant in, I believe, Memphis. They did not tell me what or why the different location. Someone on the forum a while back mentioned the connecting rods on the later pickup engines are not as beefy as earlier versions. I'm suspicious that the older ISBs were so overbuilt for our trucks that Dodge cut a few corners for weight and cost savings. I just called the Cummins Customer Assistance line. The guy told me that the commercial versions are completely different engines. He would not elaborate except to tell me the obvious, ecm and exhaust systems were different. He would only say that there are many differences depending on the application. He would not give me any specifics without my serial no.

 

[mwilson]

I am leaving for 10 days and when I get back I will compare ESN's between a Dodge 6. 7 and a medium duty. I will be very surprised if there are many internal differences.



The blown up short bus we have at work right now has the front gear train and is a 200 hp medium duty powerplant.



Will be interesting to see the results.



Anyone with a 6. 7L in a Dodge please pm me your ESN when you get a chance so I can use it for comparison.



Mike.

 

[The patriot]

I cant see Cummins making a special engine just for Chrysler.



Now, maybe some earlier engine parts are different, but for Cummins to re design an Chrysler specific power plant? No way.

 

[mwilson]

If I remember correctly, the Cummins ISB6. 7L engine used in medium duty trucks has the valve gear train at the rear of the engine instead at the front as in a Dodge product. Cummins Engines - On-Highway - Medium-Duty Truck - EPA 2010 ISB6. 7



Bill

Haven't seen any consistency to the rear gear train, see quite a few in Fed-Ex delivery trucks.

But the same horsepower in a bus will have a front gear train.



Will try to get more info on what dictates forward or rear gears.



Mike.

 

[bheiting]

In Cummins 10-K annual report with the Security and Exchange Commission, our engines are listed under the engine section as: Light Duty Automotive - customers: Chrysler and Class A RVs. Medium and Heavy Duty are a separate section. That's not very reassuring.

 

[Nyoest]

Furd 7. 3s, 6. ohhs, 6. 4s, and now 6. 7s are not now and never were medium duty engines. Look at the engine tag and you will clearly see light duty. Not even Furd or obama motors ever claimed their engines were medium duty.



Neither is a Furd F-450 a medium duty truck.

There were plenty of the 7. 3's powering international 4200 trucks. They were labeled 444 for the displacement and painted smurf blue but they were the same ol engine as in the ford pickups. I've seen the 444 in wreckers, rollbacks, box trucks and service trucks. I would call that medium duty.

 

[Bill Stockard]

Haven't seen any consistency to the rear gear train, see quite a few in Fed-Ex delivery trucks.

But the same horsepower in a bus will have a front gear train.



Will try to get more info on what dictates forward or rear gears.



Mike.

Mike,

I remember reading information when Cummins first introduced the rear gear train that it would make the engine quieter and would make the installation of engine driven power take offs easier to install. However, I don't see how moving the gear train closer to the cab would help reduce the engine noise. Also, I think there are few applications where this engine would be used in medium duty service where an engine driven PTO would be utilized.



I don't know where the ISB6. 7 series engine is assembled other than the MREP in Walesboro, IN. When Cummins was building the B5. 9Ls, almost all the on highway B-series engines were built at MREP. The only way one could tell which engine was going where was to look at the oil filter. The Dodge product had MOPAR oil filters and the medium duty truck engines had Fleetguard filters on them.



Is Cummins still assembling the C-series on highway engine at the joint venture Rocky Mount Plant? I had read that the joint venture with Tenneco/Case/New Holland/Fiat/et al was dissolved, but didn't know if it affected the plant.



Bill

 

[AH64ID]

Regardless of service life parent bore blocks are often refereed to as "throw-away". . has to do with design, not service life.

A good motor is one you can divide the cylinders by 3 and not have a fraction, V or I. In very large applications, you have to go V or your motor is too long. But a V18, V12 are all very smooth running motors.

 

[HBarlow]

In Cummins 10-K annual report with the Security and Exchange Commission, our engines are listed under the engine section as: Light Duty Automotive - customers: Chrysler and Class A RVs. Medium and Heavy Duty are a separate section. That's not very reassuring.

Read the engine data plate attached to the engine.

 

[HBarlow]

There were plenty of the 7. 3's powering international 4200 trucks. They were labeled 444 for the displacement and painted smurf blue but they were the same ol engine as in the ford pickups. I've seen the 444 in wreckers, rollbacks, box trucks and service trucks. I would call that medium duty.

A TDR member who was a salesman, sales manager, and later owner of an International dealership for about 30 years in total told me they were school bus motors which rarely ever saw more than 80k miles.

I have seen one in an underpowered wrecker. U-Haul had hundreds of them in F-350 box trucks used as rentals for people moving. When U-Haul retired those trucks they bought GM gas engines. I suspect U-Haul had a reason for that decision.

Anyone who compares one with a Cummins doesn't understand his Cummins engine.

 

[AH64ID]

Ford 7. 3's were a great motor and most certainly were a medium duty enigne, they were the last good motor ford every used. Not an I6 but held their own as a V8.

 

[RustyJC]

A good motor is one you can divide the cylinders by 3 and not have a fraction, V or I.

Ummm..... I've worked for an engine manufacturer for 38 years as of this December in engineering and technical management and would greatly appreciate hearing your source and rationale behind this new engine design law. A 3 cylinder inline engine and a 9 cylinder inline engine both have balance and/or couple problems but satisfy your law (although you may not be familiar with it, the inline 9 design can be found in large marine applications, as by the way can an inline 7. ) An inline 8 and a V-16, on the other hand, violate your law of 3s, but both are exceptionally smooth engine designs.



Rusty

 

[mwilson]

In Cummins 10-K annual report with the Security and Exchange Commission, our engines are listed under the engine section as: Light Duty Automotive - customers: Chrysler and Class A RVs. Medium and Heavy Duty are a separate section. That's not very reassuring.

Different Emission Requirements, I believe.



Mike.

 

[AH64ID]

Ummm..... I've worked for an engine manufacturer for 38 years as of this December in engineering and technical management and would greatly appreciate hearing your source and rationale behind this new engine design law. A 3 cylinder inline engine and a 9 cylinder inline engine both have balance and/or couple problems but satisfy your law (although you may not be familiar with it, the inline 9 design can be found in large marine applications, as by the way can an inline 7. ) An inline 8 and a V-16, on the other hand, violate your law of 3s, but both are exceptionally smooth engine designs.



Rusty

Did I say it was a law?



It was info from Cat. Just a general statement, anything that can have cylinders 120° apart has the ability to be smoother.

 

[RustyJC]

It was info from Cat. Just a general statement, anything that can have cylinders 120° apart has the ability to be smoother.

There's really nothing magic about a 120 degree bank angle for a V-6 over a 90 degree for a V-8, a 72 degree for a V-10, a 60 degree for a V-12, or a 45 degree for a V-16. A desirable bank angle is generally calculated as 720 degrees divided by the number of cylinders. Even at that, most V-6 engines that aren't made on V-8 assembly lines use a 60 degree compromise bank angle as the 120 degree would be too wide for many applications.



Having said that, as far as non-inline engines are concerned, an engine using a 180 degree bank angle (a flat or boxer engine) would conceptually be optimum as secondary balance forces from the 2 banks would tend to cancel each other out.



Rusty

 

[rscurtis]

Ford 7. 3's were a great motor and most certainly were a medium duty enigne, they were the last good motor ford every used. Not an I6 but held their own as a V8.

When I was a member of LICROC, the group visited Pro Torque, a converter rebuilder on LI. At the time, they were running E350's with 7. 3's as delivery vehicles. The engines would go 400K before they got tired. I would imagine the rest of the van was also pretty tired at that mileage, espescially after being beaten to death on the area's lousy roads.

 

[HBarlow]

I heard of a few of them that ran 400k miles as RV transport trucks but even the engine data plate did NOT claim they were medium duty motors. They had connecting rods, bearings, and crank journals very similar in size and structure to small block Chevy gas motors.

I say again, Navistar 7. 3 engines compared with Cummins inline six diesels only in that both burned diesel fuel.

 

[AH64ID]

There's really nothing magic about a 120 degree bank angle for a V-6 over a 90 degree for a V-8, a 72 degree for a V-10, a 60 degree for a V-12, or a 45 degree for a V-16. A desirable bank angle is generally calculated as 720 degrees divided by the number of cylinders. Even at that, most V-6 engines that aren't made on V-8 assembly lines use a 60 degree compromise bank angle as the 120 degree would be too wide for many applications.



Having said that, as far as non-inline engines are concerned, an engine using a 180 degree bank angle (a flat or boxer engine) would conceptually be optimum as secondary balance forces from the 2 banks would tend to cancel each other out.



Rusty

It was a simple statement that engines with cylinders than can be divided by 3 can generally be smoother running. That does not mean that V-8's and V-16's cant be smooth, just that 120° on engines divided by 3 allows for forces to cancel each other out easier. Just another benefit to our I-6 over the V-8. 120° also helps with torque production, which as we all know is better on an I6 vs V8 of similar size.