Cummins HP rating

[JohnEd]

Just from talking to truckers I have developed a fondness for Cummins.  Clifford once mentioned that a particular model was less than economical and another poster noted that some models didn't last all that long.  I would like to find out which models were dogs in power and longevity and efficiency.  L10 would work for the GMs but I think M11 and ISM are of more potential for interest in the 40 footers.  The ISM, for me, holds the greatest interest.

What are the disadvantages of the ISM?  What years are best?  What year saw the best fuel efficiency?  If you want to tell me to "go fish" well that's fine. Which pond?  I am starting from scratch.

I note on http://www.cummins-sp.com/document_library/Engine%20Ratings/ISM_engine_ratings.pdf  that the ISM ca e had in 450 and 500 HP configurations.  The problem that jumps out at me is that the 450 model is rated at 1200rpm and the 500HP model is rated at 2300RPM.  That is one heck of a leap.  I would think that an engine that was limited to 1200 would last a heck of a lot longer than one rated at 2300.  Am I missing something?  All the other Cummins engines on the list were rated at 1200.  The 500 sticks out like sore thumb.

I know the ISM came on some hi line coaches but is a good candidate for a re power in a bus?

Thanks,

John

[RoyJ]

If you click on the engine spec sheets for ISM 450 and 500, you'll notice the 2100 rpm rating (I don't see 2300 any where?) is a mistake.

The 500hp is rated at 1800rpm, with 1550 lb-ft of torque from 1200 - 1600 rpm. Any 1200 rpm rating for be for torque. Peak hp rpm, even for big block engines (ISX, C15, S60), is always 1600+ rpm

For a recreational bus, the 500hp is probably ideal; the 400hp versions would outlast the bus, without the benefits of increased power. Mileage shouldn't be a issue if you don't floor it all the time.

[HB of CJ]

It's quite possible the ratings were mis-quotes.  Most of the larger truck type Cummins were max hp rated at anywhere from 1600 to 1800 rpm, with some of the fire service types a little bit higher.  Max torque ratings were usually around 1200 to 1400 rpm.

The older Big Cam and NTC family of Cummins mills had ratings all over the map.  The Big Cam family were mostly mechanical engines....I don't know about the earlier NTC models. The N14 was available both ways.  My old Crown Supercoach had a Cummins.

Try Pittsburghfuelinjection.com or something close to that to learn more about the earlier mechanical Big Cam family of Cummins engines.  Seems now they are cheap and easy to modify and boost since most of the parts interchange.  Hope this helps. HB of CJ (old coot)

[TomC]

The L10, M11, ISM are all the same basic engine (just like you can't tell the difference between a 6V-71 and a 6V-92 from the outside).  The L10 is mechanically injected, has jacket water aftercooling, and made up to 330hp and 1000lb/ft torque (of which you now can get a ISC 8.3 at 350hp and 1000lb/ft torque).  The advantage is no electronics, and no extra plumbing for non existing air to air intercooler.  The M11 and ISM were both the same engine with up to 500hp and 1550lb/ft torque.  Although it has the same horsepower and torque as the Series 60, the Series 60 has a much fatter torque curve, hence better performance. But-the ISM is quite a bit smaller and a much easier engine to install.  Most all the ISM's were rated at 2100rpm (I think that 1200rpm rating was a misprint-I've never seen a truck or bus engine rated below 1600rpm).  You can set any of the electronic engines from 1600rpm up to 2300rpm. I would stay away from any engine with EGR (Exhaust Gas Recirculation-although my 1984 Mercedes-Benz 300 Turbodiesel has it).  Many trash trucks had the ISM and Allison world transmission combo.  Maybe you could find a complete trash truck and take the entire engine/transmission combo out of it.  If I were converting to a 4 stroke engine, the Cummins ISM would be one of my choices (along with the ISL, that's available up to 450hp and 1250lb/ft torque).  Good Luck, TomC

[JohnEd]

Guys,

Thank you for your comments.  Sorry about messing up the quotes.  My cataracts are getting pretty bad and surgery is still a ways off.

Avoiding EGR is something only those in the industry would know.  Also, on another post it was pointed out that adding almost any sort of  alt fuel gummed up the works of various smog devices such as catalytic converters and part traps and others.  What year did all that stuff start to be a requirement imposed on the Mfr?  Clifford, long ago, in a post forgotten by me, once said something about the series 60 having been a efficient engine up until year X and then dropped in power and efficiency from that point.  I assume it got better after it was introduced for some period of time. Was the DD record reflected in the performance across the industry?  Looking for that sweet spot(s).

Hoping for more,

John

[belfert]

The EPA's first real round of major diesel pollution regulation was for 2004 motors.  2007 got much stricter on pollution and introduced the particulate filter.  The Series 60 got EGR in October 2002 to meet 2004 regs early.

Electronics were introduced in the 90s to meet EPA regs, but I think most folks would agree that 2004 was the year the EPA really started cracking down on diesels.

[RoyJ]

Don't know about the larger Cummins, but on the ISB, EGR delete is not a hard thing to do.

In an old bus, chances are no body will bug you about emissions. Even with EGR and DPF unplugged, I'm sure the engine is many times cleaner than the old Detroit.

[TomC]

EGR started with the 2004 regs (2002 engines actually).  Pre 1998 engines were the most fuel efficient.  2007 engines have catalytic converters and Diesel particulate filters.  2010 engines added Diesel Exhaust Fluid (Urea).
Caterpillar engines between 2002 and 2007 had catalytic converters.  2007-2009 Caterpillar ACERT engines just had Diesel Particulate Filters with fuel injection after the turbocharger in a combustion chamber to create the heat necessary for the Particualte Filter regeneration (burning the soot down into ash).  Caterpillar does not make engines beyond 2009 for trucks or buses.  Good Luck, TomC

[belfert]

What changed in 1998 to make MPG go down?

The folks with 2010/11 diesel pickups so far are reporting better mileage than the 2007 engines.  Ford's 2007 MPG was really bad.  Owners reported getting as little as 10 MPG when they got 17 to 20 MPG with previous model years.

[TomC]

After 1998, the engine manufacturers retarded the timing to lower NOx levels, and that also raised fuel burn.

As to 2010, the Detroit Diesel DD13, DD15, DD16 are seeing the best fuel mileage since 1998.  In fact, a well driven 80,000lb truck is able to see over the 8mpg mark!.  Good Luck, TomC

[CrabbyMilton]

Fine with me. CUMMINS is now standard equipment in new MCI's and most VAN HOOL's plus almost all transit and school buses(expect NAVISTAR). Most fire trucks use CUMMINS as the standard engine or optional. I know this sounds like a commercial for them but they must be doing something right. Besides, I own stock in them so please think of me when the time comes to repower.

[belfert]

MCI and Prevost sold mainly the Series 60 for quite a few years.  The primary reason MCI went with Cummins and Prevost went with Volvo is because new Detroit engines are only sold to Diamler family companies (Freightliner/Setra/etc) and Cat dropped out of the on highway engine business.

Cummins is one of the few options left for a company who doesn't have their own line of engines.  I don't think MCI choose Cummins because they liked the Cummins engines, but rather because they have little choice left.  Do note that I don't think there is anything wrong with a Cummins engine.  I happen to have a Series 60, but I would take any modern 4 stroke.

Who besides Cummins is still selling heavy duty engines to any manufacturer?  Does Volvo sell to other maufacturers?

[CrabbyMilton]

Actually, PIERCE fire trucks have an almost exclusive agreement with DETROIT to offer their engines and MCI and VAN HOOL does offer DETROIT as an option. the folks at DAIMLER rethought their decision to offer thier engines in their own products since the market obviously speaks.

[luvrbus]

I see a few John Deere in the Petes and KW they are going on the market in 2012 so I was told.
They helped devlope the series 60 and 50 and looking at the engines they look like a series 60.John Deere and DD go way back till the Germans bought DD something happen there between the 2   

[TomC]

Now that Caterpillar has pulled out of the on highway engine business, Cummins is the ONLY independent engine company without being tied to a vehicle manufacturer.  Hence, Cummins being offered in the buses now.  Even though Detroit is still being offered in some buses, the Detroit engine would probably be more expensive then the Cummins.  I know at Freightliner, the DD13 is the least expensive engine, then the Cummins ISX 15 liter, then the DD15 , then DD16 (Freightliner hasn't decided yet whether to offer the Cummins ISX 11.9, since it is almost identical to the DD13 and since the DD13 has up to 470hp, but the Cummins ISX 11.9, just to 425hp).  Good Luck, TomC