Foretravel Owners' Forum

Here is the Cummins Torque Chart
Cummins Torque Chart (http://beamalarm.com/Documents/cummins_torque_chart.html)

Nice chart, sure not up to date and looks like a truck engine selection, not RV.
If you need the actual numbers for your engine, get the engine serieal number from the data tag, get  a Cummins shop to print out the actual facts about your engine.
Or give the serial info to me, I might be able to find it in my QSOL system.
Cheers

A slightly different take on diesel fuel additives:

If storing diesel, yes, use a BIOCIDE and make sure the tank is full to reduce condensation.

The other time an additive is  needed is if you fill up in the summer or fall and will not burn that fuel over the (cold) winter.  Diesel stations  do switch to winter grade fuel with lower cloud point as temperatures drop.  You need to do the same for the summer grade fuel in your tank-- add an anti-gel.

PS and others have these in virtually all Walmarts, etc.

Brett

For Cummins information on Motorhome version of ISL400 torque and horsepower, try http://cumminsengines.com/assets/pdf/4971107.pdf (http://cumminsengines.com/assets/pdf/4971107.pdf) 

Peak torque is stated to be 1200 RPM.  I've been told that adding 200-300 RPM to that puts you in your sweet spot for performance.  For my rig, that translates to 58-62 MPH.  I've noticed that driving much beyond that can erode MPG.

Not sure what dates the brochure on this website covers, but the info is consistent with what I found a couple of years ago about the ISL400 in my 02 U270.

Bob

thanks to all.....I did talk to a helpful fellow at Cummins, I had the serial number, and he told me it is an ISL03, 1200 ft-lb at 1300 rpm.  From a torque curve, I see the decrease in torque out to 2000 rpm is quite small.  I was trying to figure out how to respond to the FT books that came with this, which said, do not go to full accelerator below the peak torque for more than 30 seconds.  I thought one would never go to full accelerator anyway, but with respect to that, Mr. Cummins said it would not harm the engine at all if I am above the 1300 rpm.  Fascinating, sure not like a gasoline engine.  Thanks again to each of you, Mike

Let me show my ignorance. I'm pretty good at that.

Why would one not want to go full throttle for more than 30 seconds before entering the peak torque range? Why would that hurt the engine?

Kent, I will take a stab at this one, below the peak torque point, you would be lugging the engine at full throttle, not a recommended operating area at full throttle,  get it above the 1300 rpm or what ever the rating is, and hang your foot in it, not below.
Use the transmission gearing to get it up into the torque area, this is true for any engine, gas or diesel, do not lug the engine.
Hope this helps.
Dave

I would expect that extended use of full throttle below the peak torque point is not an issue for those of us who have those nifty Allison automatic transmissions. It could possibly happen with a manual transmission and a poor operator. That is not a likely combination among the readers of Foreforums.

Many times I have the throttle floored when I take off from a stop. Is that a bad thing? It sure sounds like it. Of course that never lasts over 30 seconds. Maybe that's the answer.

Pretty hard to "lug" a diesel with an automatic transmission. Starting uphill from a traffic light or stop sign, it might be 5 or 10 minutes "pedal to the metal" in our U300. Was thinking of the AG check at the California border at Truckee and then up Donner Grade to the summit on I-80.

From a cold start in the Fire Service, we were instantly at full throttle with all of our Detroits as were the County guys with their 4 cycle CATs. With a manual transmission, any time the engine was not pulling well (starting to lug), we shifted down.

I don't know of any Detroit Diesel forum or web site that the term, "drive it like you stole it" does not come up many times.

I have a Mercedes 1984 300SD with 442,000 original miles with NOTHING done to the engine OR transmission. I have done coast to coast trips with aircraft on a trailer behind me and have had the throttle on the floor not for seconds but DAYS. When I get to my destination, my MB always whispers to me, "I'm ready, lets head home" On one trip, I met a guy with a Ford 6.9 pickup with one of those LONG horse trailers behind. 614,000, most at full throttle with no trouble.

When the temp starts above 210 or so, I do back off or shift down a gear. Not that I don't kick back and watch the country side go by at a 55 mph a lot but I sure don't worry about pushing it to the floor and leaving it there if I need to.

I can't imagine anyone on this forum with an Allison having to worry about starting with a lot of throttle. The time you have to use your head is when the temperature gauge on the dash starts to head up.

You may do a search on the net but here is a partial quote from one of many on the subject:

" The Idiots Guide To Driving A Detroit Diesel
0Most people say you gotta "drive it like you stole it," but for those of you who haven't been dumb enough to steal a Detroit, here's a step by step process on how to drive a Detroit Diesel powered rig:

1) Fall out of bed onto that alarm clock you swatted off the night stand 2 hours ago,
2) Get dressed, get bit/trip over the dog,
3) Make a cup of coffee, just to spill it all over your self as you trip over the dog... again,
4) Slip off the icy front steps, fall into that patch of colorful snow the dog made last night.
5) Dust your self off and check the oil,
6) Pull the dipstick out rather angrily, sending that drop of oil into your eye,
7) Add that extra quart you know you'll burn eventually,
8) Now your fingers are numb, you drop the keys, they slide to the LEAST accessible spot in the yard,
9) You finally dig around in the snow and find them,
10) Get in the truck, Slam in the clutch, turn the key, and take off.

Now Every step is recommended, but the mandatory ones are#'s 1, 2, 6, 7, and 10."

Accelerating the engine is not the same as seeing the RPM drop below peak torque RPM.  The result of keeping the accelerator pedal depressed while the engine is slowing down under load will result in connecting rod bearing damage.  When the engine is losing speed during driving, the action of the fuel system governor is to increase fuel delivery to counter that.  If the RPM holds the engine is not being over loaded and may accelerate.  If the RPM continues  to fall, the governor cannot deliver more duel to counteract, hence the engine is entering a state of lugging which will result in major engine damage plus the cooling system is now having to deal with much slower water pump speed, slower fan speed and major heat rejection into the coolant......net result, a much hotter engine with oil temperatures elevating which will also contribute to connecting rod upper bearing half damage.

Gary, that's a great explanation. It makes a lot of sense and is a relief based on my acceleration patterns.

We are driving with automatic transmissions. My understanding is that the transmission will downshift to maintain an engine speed in the safe range, even if road speed is decreasing because of a hill. We do need to be mindful of temperatures of the exhaust, transmission fluid, and engine coolant. If any of those climb to unsafe territory, we must back off the accelerator. However, the issue of lugging the engine with an Allison automatic transmission seems not to exist. Am I missing an important point?

You are correct, with an automatic trans, downshifting will occur to prevent lugging.  I forget sometimes that MHs do not use manual transmissions.  :)  I have worked in the truck world for 21 years.