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  • #16
    hi-idle

    Our rescues with the Cummins engines all have an automatic hi-idle feature when they are placed into neutral with the park brake on. It just makes sense for both the engine and with all the electrical items and a/c turned on.In fact all of our rescues, even back to the gas days, had hi-idle features. Anybody remember the Vortec systems and then the Ford programmable hi-idle systems? I still want diesel.

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    • #17
      People will buy trucks and do with them whatever they want to. Either they hold up or they don't. I read Fleet Manager magazine and the industry trend of large truck fleets is to reduce and/or eliminate extended idling as its proven to waste fuel and may harm the engine in the long run. It is discussed all the time in these publications. Fleet managers see big dollars being wasted in those millions of trucks idling and potentially causing higher maintenance costs later on. Whether or not folks do that is up to the individual or company policy. If you have a need to idle...then thats fine. I am simply just repeating what manufacturers have put in writing. Our trucks sometimes end up idling for longer than they should. But I don't let it worry me.

      Ford puts it in writing not to idle the PowerStroke for more than "X" many minutes. Cummins does the same...as does other companies. Most modern diesels run so much more efficient and pump so much cool air into the heads...they can be harmed by extended idling. Its their words...not mine. I just try and follow their suggestions to avoid warranty problems later.

      In speaking of idling...I wasn't talking of increased idle speeds. I was refering to low idle. Our trucks with the exception of the V10 have high idle switches for when sitting in cold weather or when its known they must be kept running. Thats a different story. They will run at 1200 rpm to keep temps up and systems charged.

      Some trucks are going with compact diesel generators on-board to keep the main engine coolant warm for heat, and to keep the electrical system of the truck functional for laptops, fridges, A/C etc. They claim they will pay for themselves.

      But this is really off topic for the question of why diesels in fire/ambulance applications. Totally different needs and job description. A lot of big trucks can get by with low idle for durations because they will heat way up on the highway for many hours to burn off carbon etc. Some fire apparatus won't see hours of use on a daily basis and suffer more.

      Again...don't take me wrong. I'm not advocating a V8 Gas engine in a 100' tower ladder. Pumpers deserve diesels. I'm just thinking its possible to go gas in an ambulance or light rescue...or chief truck etc without severe consequences these days. If you look at the Freightliner Sprinter vans...you don't need all that much horsepower to make a decent sized ambulance go down the road well.

      We gotta keep in mind the original question of the bystander asking about ambulances specifically and why the need for a diesel in this specific application. Ford got away from gas busses in the 80's. There have been major improvements in gas engines since.

      As far as less chance for carbon monxide entering a patient compartment...I'd say keep the exhaust inspected. Many a gas van haul around little league teams and the like...and nobody mentions carbon monoxide entering the compartments here. Or family cars or ???
      Last edited by fpvfd502; 08-29-2006, 07:47 PM.
      Assistant Chief

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      • #18
        Diesels are still more efficient than gas....any way you cut it. Per gallon of fuel, diesel engines produce more hp and torque than gassers. Also its not the manufacturers that are trying to crush the idling....Its the EPA and tree huggers. It is harder on an engine to start and stop than to idle.
        Buck
        Assistant Chief/EMT-B

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        • #19
          Originally posted by Frmboybuck
          Diesels are still more efficient than gas....any way you cut it. Per gallon of fuel, diesel engines produce more hp and torque than gassers. Also its not the manufacturers that are trying to crush the idling....Its the EPA and tree huggers. It is harder on an engine to start and stop than to idle.
          No it's not. The Slick 50 people were the ones who propagated that fallacy. When an engine is idling it is wearing itself out and burning fuel without any benefit to the owner. Cylinder packs are a lot more expensive than starters and ring gears. Shut it off when you can.

          Old diesels were even worse because of lower operating temperatures and inferior injection systems. Ever seen what a 3208 does after it has idled for half an hour? Could fog the whole freeway. Even the last PLN Cummins engines could get fuel dillution in the lube oil from long idling. I imagine the common rail ones are better. The Powerstrokes don't seem to have any problem with it. But just the same shutting an engine off and restarting doesn't hurt it one bit. The oil remains in the bearings, etc. The oil pressure is not what holds them apart, the residual oil does that just fine, and don't use the dash mounted gauge to tell you that anyway. The engine has oil pressure to the galleries within 1/2 of a revolution, probably before it even fires.

          There, did I miss anything?

          Birken
          ASE Master Medium/Heavy Truck

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          • #20
            Well in 735K on my C-12 I have replaced the starter 5 times and never touched the engine besides 1 injector and normal maintance. My 3406 was the same way. I did all the injectors at 750K and never had one problem with the engine. I sold it at 1,200,000 miles and it still ran great. The 3208 was a really bad excuse for an engine anyway. Every one of them smoked like a chiminey.
            Buck
            Also ASE Master....worked for freightliner and Peterbilt for 15yrs.
            Buck
            Assistant Chief/EMT-B

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            • #21
              OK, but how did you arrive at the conclusion that it is harder on an engine to shut it off and restart than to idle. Contrary of course to what you find in the basic operator's manual. And have you not seen the fuel dillution in lube oil, upper cylinder wear from fuel washing the lube oil, and valve stem/guide problems that are the most common problem with long idling?

              Birken

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              • #22
                torque

                what is the comparison of torque between a triton v10 and a powerstroke v8? also, will chevy allow the gasser on an ambulance?

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                • #23
                  Powerstroke = 570 @ 2000
                  V10 = 457 @3250

                  Both numbers are substantial when compared to engines of even a few years ago.

                  The Cummins "B-Series" in Dodges used to have 400 ft-lbs for a long time...and that was considered enough to move a house.

                  My department once considered purchasing a used 1996 Chevrolet 3500 4x4 Type I ambulance as a support vehicle. It was built by one of the bigger builders...I don't remember which. It had a 454 EFI engine.

                  More recently...an area combo department bought a light rescue unit in 2001. It was one of the last Chevy 3500HD's (19.5" wheels) available in the old body style...but was available with the newer 8.1L V8 Gas. They like it.
                  Last edited by fpvfd502; 08-31-2006, 11:14 AM.
                  Assistant Chief

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                  • #24
                    Maybe to help bring the question to a close (diesel vs. gas discussions in pickup forums have been known to go on forever)...Ford Motor Company only sells their vehicles with the Powerstroke if you want the Amb Prep Pkg. Their legal definition of an ambulance is "a vehicle which transports patients and/or carries life saving equipment similiar to that of an ambulance...and uses a idle kicker device..."

                    Ford QVM manuals and Incomplete Unit Body Builders manuals are very very informative and give many details of what Ford expects from upfitters. They do not leave any stone unturned and describe wiring modifications, heat shielding, body mounting, frame alterations etc. Its more than an average person wants to read. I've read them and read the new ones as they come out. There is ALOT of information available from Ford on the web on ambulance topics...and all other vocational topics.

                    Since we don't transport and we don't have an idle kicker...Ford had no problems with our use of the V10. They said it would serve our needs well...and it does just that. Our truck in not considered an ambulance. As a side note...they do have a manual on how to install a high idle kicker on gas engine equipped trucks. It will show all the PCM taps required etc. But...not if its a gas engine on an ambulance.

                    But with ambulances...Ford has literature why they do not wish to offer a gas ambulance. And if you know Ford ambulance history...you'll know their elevated underhood temperatures in E-Series trucks with gas engines was not a total success. I won't go into their reasoning. Their literature library is very extensive and the information is actually neat.

                    Point being...they don't discuss the efficiency of diesel versus gas...nor the horsepower/torque required to move an ambulance. They discuss heat sheilding requirements and fuel systems in general. They wish to only offer diesel platforms in the Prep package for ambulances.

                    Thus...the answer to the original question is simple. Ford ambulances do not use gas engines because Ford Motor Company has chosen to only focus on a common platform which they feel comfortable with has a proven track record of not causing them (FoMoCo) problems. They are not going to devote the engineering and time required to develop a gas platform...although possible. Most want diesel anyway...and sales of gas platforms would probably not meet the goals Ford would have. If there was a large demand...they would most likely follow suit. Departments like having one type of fuel for rigs...and the ideology of "diesels are heavy duty engines".

                    For us...the $6000 price tag couldn't be justified.

                    I think thats the real reason to the original question. Its not because they save so much fuel, have so much more power that both the taxpayers notice a substancial savings and patients get to the hospital faster. Ambulances are junk at 100,000 miles anyway. Your taking a risk pushing them any further do to chassis wear etc.

                    Man...I think I'll bow out at this point. Not to offend anyone...its been a great discussion...but I'm tired of typing. And all of this is just my opinion. Maybe Nascar should go diesel. Refuel less and more power??
                    Assistant Chief

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                    • #25
                      Actually Cummins had a diesel race car in the 1950s. It did very well but DNF for some dumb reason or another. Too bad it did not continue.

                      Birken

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                      • #26
                        diesel engines

                        Audi won this year's 12 Hours of Sebring and 24 Hours of Le Mans endurance races with diesel powered cars.

                        They are actually diesels converted from their base gas race engine. Shades of GM. But these actually hold up. Expect two more brands with diesel race cars next year.

                        Diesels are more fuel efficent. Thats why 60% of the cars now sold in Europe are diesels. Watch how many car manufactuers start offering diesel engines again next year with gas prices pushing $3.00/gal.

                        As for diesel's in rigs, they are the way to go. Idling at the scene with lights on is what they do! Diesel's generate less heat under the hood, helping the life of alternators and batteries. But yes, you should change the oil and filter more often when idling for long periods regardless of gas or diesel engines. IMHO

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                        • #27
                          Originally posted by BirkenVogt
                          OK, but how did you arrive at the conclusion that it is harder on an engine to shut it off and restart than to idle. Contrary of course to what you find in the basic operator's manual. And have you not seen the fuel dillution in lube oil, upper cylinder wear from fuel washing the lube oil, and valve stem/guide problems that are the most common problem with long idling?

                          Birken
                          Yes, ive seen all of the above. I have also replaced more parts due to starting and stopping an engine than I have from extended idling. If you use a high idle(800-1000rpm) you wont have the fuel washing problem. Those trucks you see with that prob, never used a high idle. I still prefer to let them idle at 1000 rpm. They will run longer than any department will have them unless they plan to run them in the ground
                          Buck
                          Assistant Chief/EMT-B

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                          • #28
                            This is getting off topic but what parts other than starters and ring gears can you attribute to repeated starting?

                            Birken

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                            • #29
                              Just about every major part is affected upon startup....Mains, rod bearings, valve stems, cam bearings....ETC. Cold starts are extremely hard on an engine. Ecspecially in our line of work as alot of fire apparatus might sit for days to weeks at a time before they are started. I do understand your point on extended idling though. One main reason to leave public service vehicles idling is that on scene you have warning lights on.
                              Buck
                              Assistant Chief/EMT-B

                              Comment


                              • #30
                                Right, we have to leave them idling to provide power for all sorts of things.

                                But I am asking, what specific problems can you attribute to the list of parts you gave? All the engines I have taken apart, even after sitting for years, still had plenty of oil in the bearings, cam lobes, etc. and turned freely so long as the parts were not the ones that tatered. I have never seen any evidence to support that repeated starting does any damage. I send in oil samples at every oil change and all my engines that are not broken show no evidence of excessive wear in iron, lead, aluminum, copper, or anything that would tend to be elevated if this hypothesis was correct. If I am going to be idle for more than 5 minutes, I shut it off.

                                Birken

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