Engine management (split from Re: ISX engines)

Topic: Engine management (split from Re: ISX engines) (Read 659 times) previous topic - next topic - Topic derived from ISX engines

Engine management (split from Re: ISX engines)

June 29, 2019, 12:43:57 pm

Anytime you increase the HP from stock, you run the risk of problems. Sometimes, the manufacturer figures it out ahead of time but occasionally, the consumer is the guinea pig. Added horsepower over stock will almost always shorten engine life.

An example is the Detroit 2-cycle generators the railroad used for many years. A two cylinder 2-71 running at 1200 RPM producing 20 Kw at 60 Hz. Some from the 1950's still have not been overhauled and are still considered very efficient. Same with the gasoline fueled Ford 6 cylinder generator with some over 70,000 hours before overhaul.

Our 350 HP 6V-92TA is also used in fire trucks, boats and many other applications. Many in marine use are bumped up to at least 535 HP and since they may run at full throttle for extended periods, engine time between overhaul is reduced to 2200 hours or so. The versions that are 620 HP not only have a shorter TBO but may blow up too.

So, when I say, "drive like a car", you can't just head up a long grade in hot weather and high altitude and expect to transport 30,000 lbs or more to the top without some engine management. The higher the HP, the more heat that is produced. For most, engine management only comes with education that trucking companies, bus companies, fire departments provide for their employees. The Allison transmission can only do so much to mitigate the poor driving habits of the RV driver.

So, when you think about your engine when heading upgrade, your engine is thinking about your pocketbook at the same time. Engine abuse is cumulative and may not show up until much later at the most unexpected time.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #1 – June 29, 2019, 02:51:47 pm

Pierce... "engine management only comes with an education that trucking companies, bus companies, fire departments provide for their employees." Can you give us some general tips on engine management no matter what diesel engine one has? Thanks in advance.

George

Re: Engine management (split from Re: ISX engines)

Reply #2 – June 29, 2019, 04:37:46 pm

George , I'm not Pierce but will name a couple things that come to mind of things a driver/owner can do to make a good Diesel engine last longer. Most are obvious and you probably already practice.. Clean oil, clean fuel, Try to never run one hot and never shut down a hot engine IF you can avoid it. Obviously there are times during eq failure you would have to shut down a hot engine but try to avoid it. Try not to over rev rpm and try not to lug an engine under load. Keep nitrates in check in the cooling system, a Diesel engine can be eat up inside due to electroisis. Just a few that comes to mind and others will add to the list.

Re: Engine management (split from Re: ISX engines)

Reply #3 – June 29, 2019, 07:01:05 pm

Quote from: George Hatfield – June 29, 2019, 02:51:47 pm

Pierce... "engine management only comes with an education that trucking companies, bus companies, fire departments provide for their employees." Can you give us some general tips on engine management no matter what diesel engine one has? Thanks in advance.
George

George,

Compression ignition engines have unique differences from gasoline engines. Books can be written on all the aspects (and are) from fuel to cooling to idling to... Dub above has some good places to start.

Fuel: diesel fuel and the fuel system probably cause the most problems as it has to be clean and the right viscosity for the season. And the fuel system depends on the starting system to crank the engine fast enough to create the heat need to explode the fuel. And the starting system depends on the charging system to replenish the batteries so they can supply the starter with enough voltage so it can do it's job. With bio-diesel in the mix now (NPI), new concerns and the knowledge to avoid problems in storage, treatment, etc are important.

Again, as Dub mentions, avoiding overheating,not shutting down your engine after a climb are important. Prolonged idling is also discouraged by all the diesel engine manufacturers as well as against the law in more and more states. Studying the reasons for the turn away from the old school, let it idle all night will help understand why this is no longer a good practice but like many other engine related topics, are the reason many engines don't make their B-10 and B-50 lives. Good explanation of those terms at: B10 & B50 Life of Diesel Engines

With a car, we don't think much of altitude other than our vehicles don't have as much power up high and we get tired on trails in high National Parks. This topic has many hidden facets to it. Unlike our gasoline cars, our diesels run on an approximate mixture of one part diesel to 140 parts of air by weight at idle to 1 part diesel to 14 parts air at full output. The amount of fuel injected is the gas pedal and determines how fast you go down the road. So, since a cubic foot of air at 8000 feet only has about 75% of the density that it does at sea level, the temperature of the air when compressed is lower causing slower starting. Not only this but the temperature lapse rate is 3.5 degrees Fahrenheit per thousand feet so 8000 foot nights are 8 x 3.5 or 28 degrees colder at night than sea level. With our Detroit, Foretravel made a colossal error in the placement of the block heater so many hours of generator time are required to warm the engine so it will start. Compounding this, turbocharged engines usually have a lower compression ratio, in our case 17/1 rather than 19/1 so less heat is generated as the piston compresses the air. This leads to owner frustration and the use of ether. Not a big deal on a cold engine but since it worked so well, many owners use it when they change fuel filters and can't get a warm engine to start. They use ether again and wonder what the huge knocking noise it. It's not opportunity knocking. All this contributes to engines that don't make the B-50 mark. A well treated engine with regular oil changes, good driving habits, can go 2x, 3x the B-50 mileage without a problem. But engines like ours with poor block heater location, poor hydraulic belt alignment, and the air intake at ground level so as to ingest everything the rear tires throws up sure don't help longevity.

While I'm at altitude and summer has just started, many owners that have not experienced overheating at lower elevations, wonder why the engine has so much less power but yet gets hot quickly on grades. Since the air is less dense, the fan is less effective, there are less molecules to transfer heat to the air going through the radiator and less molecules of air available to the intercooler/CAC so the engine has a higher thermal load because of the higher incoming air temperature. To compound this, the mechanical injection engines inject more fuel at altitude relative to the amount of air so drivers much watch the exhaust pipe and back off the throttle to keep black smoke to a minimum. The excess fuel also causes higher EGTs that may damage the engine. A good source of altitude/EGTs is at the Banks site: Why EGT is Important | Banks Power

So, I can go on forever but Google will do a good job finding sites with real answers like Banks has but you do have to watch sites that rely on wive's tale information that is second or third hand. Yes, clean fuel, keeping the engine within specs will sure help your engine last a long time. Knowing the little details on exactly why you have to consider altitude, temperatures, etc connect the dots for complete understanding (if that's possible) and make driving your motorhome a pleasure, not a worry.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #4 – June 29, 2019, 07:26:41 pm

Quote from: John44 – June 29, 2019, 07:06:00 pm

Think the bottom line here is it's not Pugmonm's fault that they did or did not drive the coach the "optimum" way,you would think
the newer ones would have less problems then the old ones.

A couple three things come to my mind here. 380 HP is pretty normal out of a Cummins 8.3 now. Has some reliability been compromised for power?

Emission controls may be part of the problem with EGR valves sticking and allowing too much carbon into the intake.

Injection pumps (CAPS) are not as reliable as the older Bosch mechanical pumps. Marginal lift pumps may also contribute. Wiring to the injectors may not be mil spec and an injector failure can lead to a ECM failure. Common rail injection has incredible pressures and the related parts have very close clearances requiring very clean fuel.

The fellow in the video does point out a few problem areas in the newer engines.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #5 – June 29, 2019, 11:15:48 pm

Sitting for any length of time will not hurt an engine. Our Detroit sat for over two years. Many others sit for far longer. RV use is more problematic but not because of sitting. You can't compare the typical RV driver with a professional driver who feeds his or her family from the road. While some of these failures may be manufacturing defects, most are from lack of proper training.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #6 – June 29, 2019, 11:56:15 pm

At this point I will bow out of this conversation and give my cheap KISS cat another hug..

Driving a diesel

Reply #7 – June 30, 2019, 12:01:53 am

Interesting discussion. I make sure the oil is clean, the coolant is good, the fuel is thoroughly filtered and the batteries are at full charge when starting (with the boost switch). I also use biocide regularly.

Some additional (dumb) questions...

1. Regarding sitting... I was under the impression that "exercising" your engine was the thing to do. That is, get out and drive it for 25 miles or so until it is at full temp and do this every month. Not needed?

2. What about using biodiesel blends (5% or 20%)? OK to use, or better to stay with non-biodiesel. We always try to fill up at truck stops, but here in Anacortes, the Casino station, which has a good price, only has the blend.

3. Idleing... I've been letting it run while refueling. Bad idea? Or are we talking about avoiding idling for much longer periods?

4. Driving it hard... On hills, I try to keep the engine temp less than 190. If it gets above that temp, I slow down. Too conservative? Typically I run in 6th gear on the flat highway at a speed no greater than about 65. What is meant by "driving it hard?"

5. Shutting down... If the temp is at 180, even after pulling a long hill, is it OK to shut down? If not, how long to let it cool and should it be done at idle if one is at the end of a trip. Best procedure?

That should do it.

George

Re: Engine management (split from Re: ISX engines)

Reply #8 – June 30, 2019, 01:12:04 am

1. Always best to do as you do and exercise the coach but only after the coolant temp has reached 180 degree or so does it start to evaporate the condensation in the crankcase. Ford pushes each new car a couple of yards every few days. Oil today has additives to keep rust at bay for the short startups to move the coach, etc. A micron of so of oil film stays on parts so even after an engine sits, there is never metal to metal.

2. We have mostly biodiesel where we live. I like it. Better lubricity than petro diesel now that <15 ppm ultra low sulfur is the rule. Biocide has an advantage as biodiesel absorbs more water than petro diesel. A cetane improver is a good idea heading into winter if the tank has summer diesel in it. Petro diesel is about 139K BTU/gal where 100 percent biodiesel has 132K BTU/gal so with B5 or B20, there is not going to be a measureable difference in power or mileage.

3. Bad for a lot of reasons. Why not turn it off? It's against the law in more and more states. A health hazard from the particulates and does not do your engine any good.

4. Driving it hard is not shifting down on grades to keep EGTs in check. If it won't accelerate up a grade, best to select a gear where it will and then back off the throttle so you circulate coolant better and keep the EGTs down. I try to keep ours around 2000 RPM while climbing grades. 2130 is fuel cutoff. I let it go to 2130 on every upshift and usually use full throttle when accelerating. This is not driving it hard. The Allison tries to protect the engine but can't do it all.

5. No, it's the oil temperature that cokes the turbo not the water temperature. Oil takes much longer to cool than the coolant. Any kind of grade where the engine works fairly hard is best to use about 1000 RPM for 5 minutes to cool the oil. If you use synthetic oil, this is not required. If you drive it down your street and park it, just shut it down. Heat sink from high oil and turbo temperatures is what causes petro oil to coke.

Why do you use the boost switch to start your engine? If you use the boost switch and listen to the starter and then with the engine batteries alone and hear any difference, you have a starting battery/terminal/cable problem. Using the boost switch each time only masks the problem. Good for an emergency if start batteries won't do to the job but then it's the first thing on the list to fix.

I never use the boost switch even in winter. I do listen to see if the solenoid clicks occasionally.

No dumb questions, these are good ones! The only reason we used both batteries on the fire trucks was that one 8D was not enough to start the Detroit reliably and there was not room in each battery box for two batteries. The Detroits were non-turbo 8V-71 with 19 to 1 compression ratios so lit off instantly even in cold weather but required a little more juice for the starter. The truck came with a gasoline engine and one 8D was plenty for it but after the La France trucks were repowered with the 2-cycles, the single battery didn't cut it.

Again, no dumb questions. It's dumb not to ask if you have a question as that's what the forum is for.

This forum makes the jump for members from a plunk your cash down and buy and RV owner to a knowledgeable operator of a large and complex vehicle. Lots of different opinions but what family doesn't have them?

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #9 – July 02, 2019, 01:28:11 am

I would venture to say that any engine that is intolerant to various load conditions is a major loser. Reality is there ARE uphills and downhill runs.

Re: Engine management (split from Re: ISX engines)

Reply #10 – July 02, 2019, 02:38:33 am

If as Bob says it was designed for 80k weight and hard use then why in Heavens name are they using it in these coaches?Seems
like Foretravel and others should have researched more and maybe geared the trans differently or set the engine up differently.
We all want to buy and use something made here but I bet the Japanese have an engine alot better than Cummins.
PS Can hear Cummins already if Heaven forbid something happens,"He towed too much and drove it too hard".

Re: Engine management (split from Re: ISX engines)

Reply #11 – July 02, 2019, 11:01:46 am

Why not put the pressure on Foretravel to spend a little more $ and put Detroit (Mercedes) DD15s and DT12 automated manual transmissions in the new coaches? No clutch pedal, just the brake and accelerator. No heat exchanger either. Up to a 6 year, 600,000 mile warranty also (2 year, 200,000 at no charge).

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #12 – July 02, 2019, 11:22:53 am

Pierce,

Is that the transmission that requires one to let off the throttle to upshift?

Re: Engine management (split from Re: ISX engines)

Reply #13 – July 02, 2019, 11:46:45 am

Quote from: Old phart phred – July 02, 2019, 01:28:11 am

I would venture to say that any engine that is intolerant to various load conditions is a major loser. Reality is there ARE uphills and downhill runs.

Yes, but with the uphills comes the RV operator hot shutdown error that not only can ruin the turbo but with the turbo damage, the seals can leak causing high EGTs and fatal piston damage. It's not the ups and downs, it's how you consider them in your driving habits. View the first part of the video below.

Pierce

https://www.youtube.com/watch?v=yve303tuaHo

Re: Engine management (split from Re: ISX engines)

Reply #14 – July 02, 2019, 12:04:56 pm

Quote from: John44 – July 02, 2019, 02:38:33 am

If as Bob says it was designed for 80k weight and hard use then why in Heavens name are they using it in these coaches?Seems
like Foretravel and others should have researched more and maybe geared the trans differently or set the engine up differently.
We all want to buy and use something made here but I bet the Japanese have an engine alot better than Cummins.
PS Can hear Cummins already if Heaven forbid something happens,"He towed too much and drove it too hard".

The ISX could pull way more than the Foretravel hitch could handle. Many coach drivers do abuse their engines with improper warm up and/or cool down, and also general babying that never puts a load on the engine. It seems like prior to owning an RV, some people's experience with "big and powerful" vehicles is limited to an Accord with a V6 and they just don't really know what they are doing (not a criticism, just an observation).

IF the Japanese made a HD diesel engine and it was superior to what is made here or in Europe, we would probably know about it.

Re: Engine management (split from Re: ISX engines)

Reply #15 – July 02, 2019, 12:09:45 pm

Quote from: wolfe10 – July 02, 2019, 11:22:53 am

Pierce,
Is that the transmission that requires one to let off the throttle to upshift?

Petal to metal. Check the video of an actual drive with the DT12 at the bottom. No retarder with this transmission. It has a selectable 3 stage Jake brake. It's got 12 speeds, from economy to manual. GPS engine loading and shifting depending on exactly where you are. It even goes into coasting on slight downgrades to save fuel.

A couple of sites before the video: Getting to know the New Cascadia and Detroit DT12 Transmission – Crete...

Start with the left video first. Detroit videos here: Detroit DT12 Transmission | Demand Detroit

Now, they only need to put a 6V-92TA in front of the tranny.

YouTube DT12 in on the road action: https://www.youtube.com/watch?v=PKZlfQ3HvZA

Re: Engine management (split from Re: ISX engines)

Reply #16 – July 02, 2019, 12:19:14 pm

Agree it would be nice if you could specify what engine you wanted in your coach. But believe today, every class a rv manufacturer except Newell, buys the engine/chassis off Spartan, Freightliner or Prevost. Cost prohibitive to customize them. Did meet a guy that had a early 2000's Monaco that paid $10000 extra to have the factory install a Series 60 instead of a ISM.
Sure would be nice though, to have a DD15 in a IC37.

Re: Engine management (split from Re: ISX engines)

Reply #17 – July 02, 2019, 12:49:21 pm

The truckers that buy their own fuel often shift them a lo t sooner then we do with the autos.

Re: Engine management (split from Re: ISX engines)

Reply #18 – July 02, 2019, 12:54:50 pm

Quote from: Protech Racing – July 02, 2019, 12:49:21 pm

The truckers that buy their own fuel often shift them a lo t sooner then we do with the autos.

Yup. Most fuel efficient way to drive a modern diesel is just above peak torque RPM. Period. Gone are the days when you heard a trucker with engine on the governor (unless someone else is buying the fuel).

That was a left over technique from the old Detroit Diesel two strokes. VERY different beasts.

Re: Engine management (split from Re: ISX engines)

Reply #19 – July 02, 2019, 06:10:32 pm

Quote from: wolfe10 – July 02, 2019, 12:54:50 pm

That was a left over technique from the old Detroit Diesel two strokes. VERY different beasts.

Since it's a two cycle, it only sounds like it's turning a lot of revs. Actually, quite a bit lower than a Cummins 8.3.

The Detroit 2-cycles are torque kings from the old days. Our Buffalo Bus didn't even have a tachometer. Lots of torque right at idle and above. That's why I have to go down my driveway in neutral because the brakes won't do the job if in gear. Don't want to hear about my brakes needing adjustment as they will lock up all six on the road. Also the reason "The Duce" put out 20Kw/60Hz at 1200 RPM. The old two cycles were held back by the low efficiency of the roots blower at higher blower RPM. With The Duce at low RPM, the roots blower was operating at about 90 percent efficiency. Spin it up to our fuel cut off speed, the blower efficiency goes way down and the fuel mileage suffers. Since it's a 2-cycle, it puts out great power but suffers from the positive displacement blower. Our engine will put out over 600 HP in marine use but the blower kills the efficiency at this high output.

For marine or generator use, the 2-cycle is king for fuel efficiency and is the only diesel to even approach 50 percent efficiency (about 51 percent) Don't think the 4 cycles can even get out of the low 40%. The giant 2 cycles use electric fans to start the engine and then the turbo takes over. Most powerful diesel engine in the world

New technology diesels: https://www.technologyreview.com/s/420818/the-two-stroke-engine-reconsidered/

With the introduction of electric motor powered turbos at startup, the old Roots blower is history for the two cycles for most of the heavy duty two cycles.

The submarine twin crankshaft Fairbanks-Morse 2 cycle is still in production from way back in the late 1930's for generators and even powers Coast Guard ships today. No valves and almost trouble free. They burn 40 parts natural gas to one part diesel in power plants.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #20 – July 02, 2019, 06:27:36 pm

Pierce,

Perhaps I did not state it correctly.

One should NOT LUG a DD two stroke. Opposite of modern 4 strokers that are happy at or slightly above peak torque RPM at high loads.

Re: Engine management (split from Re: ISX engines)

Reply #21 – July 02, 2019, 06:39:12 pm

That OPOC engine is interesting. Had to do a double take to see that it does have two connecting rods per piston on the outermost pistons. At first I thought. Man, That's a heck of a lot of twisting force with one connecting rod so far off the bores centerline.

Re: Engine management (split from Re: ISX engines)

Reply #22 – July 02, 2019, 07:19:17 pm

Quote from: bigdog – July 02, 2019, 06:39:12 pm

That OPOC engine is interesting. Had to do a double take to see that it does have two connecting rods per piston on the outermost pistons. At first I thought. Man, That's a heck of a lot of twisting force with one connecting rod so far off the bores centerline.

Ultra short piston stroke with the pistons meeting and NO VALVES, NO HEAD GASKET, NO VALVE TRAIN. This design will save a lot of weight over the twin crankshaft engines plus no gears between the cranks so the engine can be physically smaller. Normally, the higher the RPMs are, the lower the EGTs are and this should be a very high RPM engine with no valve train and such a short stroke. No wonder Bill Gates invested money in the company.

Don't know about the new engines but our 6V-92TA blows so much air through the engine with the blower and turbo ( 5 inch exhaust stock) that EGT is never a problem. I've heard they don't go over 750 degrees but don't have a probe in ours.

Brett, with the 6V92TA's 1020 lbf⋅ft @ 1200 RPM is the reason Foretravel had to change from the 6xx series transmission. Since the Detroit never develops high EGTs, as long as you can accelerate in any gear upgrade (the same as 4 cycles), you are well on the safe side. If any coach won't accelerate upgrade in the gear it's in, downshift. Remember, higher RPM means lower EGTs.

Pierce

Re: Engine management (split from Re: ISX engines)

Reply #23 – July 02, 2019, 08:20:17 pm

John44 the rv industries total volume is probably a rounding point versus commercial users.

Like the tires that release flex agent to help the sidewall cracking during 20k miles a month use on a rig.

Versus rv'ers using the same tires a small fraction of those miles might get cracking.

The engines were designed to be ridden hard and be put away almost wet.

Versus conservative rv'ers who are afraid to hurt their motor and have auto trans.

Most rv'ers panic if the temp gauge moves off the peg.

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