Beta 43 with 5000 hrs

[Cheshire cat]

Our shareboat had a replacement Nanni for the original BMC. The Nanni had 10,000 hours on the clock and ran very well. Unfortunately, it's party trick was to break alternator tensioning brackets on a regular basis. Being made specifically for the engine they weren't the cheapest of components.

[dmr]

15 minutes ago, cuthound said:

 

On the rare occasions that a BT standby generator racked up high hours, it would be overhauled at 18,000 hours

 

 

I suspect that generating electricity is a good thing for a diesel, but endless hours on idle/standby waiting to generate electricity is not so good.

[cuthound]

58 minutes ago, dmr said:

I suspect that generating electricity is a good thing for a diesel, but endless hours on idle/standby waiting to generate electricity is not so good.

 

Indeed, diesels do like to be worked hard.

 

The main issue diesels used with generating sets is the tendency for the bores to become oval, due to always running at the same constant speed.

[dmr]

57 minutes ago, cuthound said:

 

Indeed, diesels do like to be worked hard.

 

The main issue diesels used with generating sets is the tendency for the bores to become oval, due to always running at the same constant speed.

Why? How? what is the mechanism of this? I have read often that a diesel does not like running at a constant speed (especially during breaking in) but what actually happens?

[cuthound]

2 hours ago, dmr said:

Why? How? what is the mechanism of this? I have read often that a diesel does not like running at a constant speed (especially during breaking in) but what actually happens?

 

When an engine operates across a wide rev range, such ss in a car or to a lesser degree a boat, the maximum side forces between the piston and bore occur at many different points, so wear is more evenly spread, unlike an engine operating at a constant speed, where the maximum side forces occur on the same section of the bore.

[dmr]

2 minutes ago, cuthound said:

 

When an engine operates across a wide rev range, such ss in a car or to a lesser degree a boat, the maximum side forces between the piston and bore occur at many different points, so wear is more evenly spread, unlike an engine operating at a constant speed, where the maximum side forces occur on the same section of the bore.

OK that makes sense, so its not oval over most of the bore, just a small part of the bore?  I have been thinking about this for other reasons, and once a small section of bore wears does this cause the rings to "work" more so that the bore wear spreads????

 

We purchased our boat with a very sick engine and when I stipped it most of the bores were good, with just a smallish area of very significant wear. However I do suspect that the engine had ingested something metal at some stage which might have contributed.

 

I suspect that most canal boat engines spend most of their lives working over quite a small speed range.

[Tony Brooks]

17 minutes ago, cuthound said:

 

When an engine operates across a wide rev range, such ss in a car or to a lesser degree a boat, the maximum side forces between the piston and bore occur at many different points, so wear is more evenly spread, unlike an engine operating at a constant speed, where the maximum side forces occur on the same section of the bore.

 

I find that hard to square with basic trigonometry. The position of maximum side force I would think is determined by the angle of the con rod relative to the bore, and that does not alter with speed. I accept the force will increase with cylinder pressure, but at the same piston position.

 

 

[cuthound]

21 minutes ago, dmr said:

I suspect that most canal boat engines spend most of their lives working over quite a small speed range.

 

Indeed, say 800-1800 rpm for a typical high speed automotive based diesel engine.

 

Regarding your earlier comment about breaking or running in an engine.

 

Many years ago I bought my one and only new car, an Alfa Romeo. I devised a plan to run it in carefully, limiting the revs to 2,000 rpm for the first 500 miles cand then increasing the revs by 250 rpm every 100 miles until I reached the red line a couple of thousand miles later. 

 

I shared this with the garage foreman who was showing me around the car. His response cut me to the bone. "You've bought an Alfa mate, not an f'ing steam engine!"

 

Years later I bought my current car, a Skoda Yeti 2.0 Tdi, which had only covered a couple of thousand miles as it was an ex-demonstrator. I was advised to regularly run it to the red line, albeit not on full throttle, and use 4th, 5th and 6th gears on a motorway for a mile or so at a time (whilst maintaining a constant 70mph) until it had done 5,000 miles. Apparently this was to run it in because the modern fully synthetic oils lubricate so well that the engine doesn't bed in of driven gently and this causes increased oil consumption. I followed this advice, and at about 73,000 miles now it still doesn't use a drop of oil between annual services.

 

 

 

7 minutes ago, Tony Brooks said:

 

I find that hard to square with basic trigonometry. The position of maximum side force I would think is determined by the angle of the con rod relative to the bore, and that does not alter with speed. I accept the force will increase with cylinder pressure, but at the same piston position.

 

 

 

Don't forget that a standby generator often runs at close to full load for long periods of time, so the amount of fuel being ignited will always generate a high cylinder pressure, whereas an engine operating over a wider rev range will have much lower cylinder pressures on average.

Edited October 25, 2023 by cuthound
To add spaces between merged posts

[dmr]

2 minutes ago, Tony Brooks said:

 

I find that hard to square with basic trigonometry. The position of maximum side force I would think is determined by the angle of the con rod relative to the bore, and that does not alter with speed. I accept the force will increase with cylinder pressure, but at the same piston position.

 

 

 

Its a function of engine trigonometry and the cylinder pressure profile, so load rather than speed could be the bigger factor, but I suspect engine trig is more important than pressure profile. I used to have a huge database of cylinder pressure data and the software to work this stuff out but that is one of the many interesting things that I left behind when I re-organised my work life to live on a boat. Probably a good decision as in ten years time knowledge of how engines work will be pretty much worthless 😀

 

I believe that in most diesels the cylinder pressure does not increase much at all as the engine works harder, the pressure (and hence torque) "pulse"  just gets wider and extends a bit later into the cycle.

25 minutes ago, cuthound said:

 

Indeed, say 800-1800 rpm for a typical high speed automotive based diesel engine.

 

Regarding your earlier comment about breaking or running in an engine.

 

Many years ago I bought my one and only new car, an Alfa Romeo. I devised a plan to run it in carefully, limiting the revs to 2,000 rpm for the first 500 miles cand then increasing the revs by 250 rpm every 100 miles until I reached the red line a couple of thousand miles later. 

 

I shared this with the garage foreman who was showing me around the car. His response cut me to the bone. "You've bought an Alfa mate, not an f'ing steam engine!"

 

Years later I bought my current car, a Skoda Yeti 2.0 Tdi, which had only covered a couple of thousand miles as it was an ex-demonstrator. I was advised to regularly run it to the red line, albeit not on full throttle, and use 4th, 5th and 6th gears on a motorway for a mile or so at a time (whilst maintaining a constant 70mph) until it had done 5,000 miles. Apparently this was to run it in because the modern fully synthetic oils lubricate so well that the engine doesn't bed in of driven gently and this causes increased oil consumption. I followed this advice, and at about 73,000 miles now it still doesn't use a drop of oil between annual services.

 

 

Did they not recommend using a "running in" oil for the first 5000 miles? Ive never had a new car so wouldn't know, but did buy a brand new engine for the boat and this had "special" oil in it for the first 100 hours.  100 hours is probably 5000miles😀

I suspect that special running in oil is essentially API CC

[cuthound]

24 minutes ago, dmr said:

 

Its a function of engine trigonometry and the cylinder pressure profile, so load rather than speed could be the bigger factor, but I suspect engine trig is more important than pressure profile. I used to have a huge database of cylinder pressure data and the software to work this stuff out but that is one of the many interesting things that I left behind when I re-organised my work life to live on a boat. Probably a good decision as in ten years time knowledge of how engines work will be pretty much worthless 😀

 

I believe that in most diesels the cylinder pressure does not increase much at all as the engine works harder, the pressure (and hence torque) "pulse"  just gets wider and extends a bit later into the cycle.

 

Did they not recommend using a "running in" oil for the first 5000 miles? Ive never had a new car so wouldn't know, but did buy a brand new engine for the boat and this had "special" oil in it for the first 100 hours.  100 hours is probably 5000miles😀

I suspect that special running in oil is essentially API CC

 

The Alfa, back in 1981, had to have its first oil and filter change at 1,000 miles, so it probably was a running in oil.

 

The Skoda was initially filled with its normal 5w-30 fully synthetic oil which was changed at its first service at about 8,000 miles.

 

The long term average speed indicator on the Skoda shows about 30mph, (it has a mix of Mrs Hound doing 3 mile runs when shopping locally in it and me doing 150 mile each way motorway trips monthly or more) so 1000 hours for that would be about 3,000 miles.

[Tony Brooks]

1 hour ago, dmr said:

I believe that in most diesels the cylinder pressure does not increase much at all as the engine works harder, the pressure (and hence torque) "pulse"  just gets wider and extends a bit later into the cycle.

 

Diesel indicator diagrams confirm this, they are much more constant pressure engines than petrol units. I suspect because of the time taken to ignite and burn the fuel droplets. The higher the power, the more fuel is injected, so it takes longer to get all the fuel into the cylinder.

 

1 hour ago, cuthound said:

Don't forget that a standby generator often runs at close to full load for long periods of time, so the amount of fuel being ignited will always generate a high cylinder pressure, whereas an engine operating over a wider rev range will have much lower cylinder pressures on average.

 

I agree the amount of side thrust will depend upon the cylinder pressure and thus load, but I don't see how the position in the cylinder can alter, whatever the load. If you draw a force diagram, this is clearly shown.

[dmr]

6 minutes ago, Tony Brooks said:

 

Diesel indicator diagrams confirm this, they are much more constant pressure engines than petrol units. I suspect because of the time taken to ignite and burn the fuel droplets. The higher the power, the more fuel is injected, so it takes longer to get all the fuel into the cylinder.

 

 

It was a long time ago that I did cylinder pressure measurements, things might have changed, but I remember that the compression pressure of a diesel is about 60 bar. Interestingly  a petrol going at full load also gets to about 60 bar. I suspect that if a diesel could somehow inject and burn really quickly that the resulting high cylinder pressures might cause all sorts of problems, including loads of NOx.  I suspect that more modern diesels inject later and faster to put combustion well after TDC to keep the pressures, and hence NOx, lower.

 

My new years resolution is going to be to stop thinking about diesels and think about electric motors instead😀   (but they are just not as interesting)

[dmr]

16 hours ago, Tony Brooks said:

 

I agree the amount of side thrust will depend upon the cylinder pressure and thus load, but I don't see how the position in the cylinder can alter, whatever the load. If you draw a force diagram, this is clearly shown.

I've thought about this and tried to remember stuff I used to know 😀and so think the position of the side force is very speed dependant. The sideforce is a component of the vertical force acting via the angle of the con rod. The vertical force depends on both the gas (combustion) force above the piston and also the inertial force that is accelerating the piston (F=m.a). This inertial force is very speed dependant so the position at which the force is "significant" will vary with speed. I think these two forces cancel out at some (speed dependant) point giving a reversal which is when the piston moves side to side and hence giving the slap if there is any play.

[IanD]

16 hours ago, dmr said:

It was a long time ago that I did cylinder pressure measurements, things might have changed, but I remember that the compression pressure of a diesel is about 60 bar. Interestingly  a petrol going at full load also gets to about 60 bar. I suspect that if a diesel could somehow inject and burn really quickly that the resulting high cylinder pressures might cause all sorts of problems, including loads of NOx.  I suspect that more modern diesels inject later and faster to put combustion well after TDC to keep the pressures, and hence NOx, lower.

 

My new years resolution is going to be to stop thinking about diesels and think about electric motors instead😀   (but they are just not as interesting)

 

Yeah, they're just too simple -- which doesn't stop them being misunderstood all the time though, especially for boats... 😉

[jonathanA]

18 hours ago, dmr said:

 

 

Did they not recommend using a "running in" oil for the first 5000 miles? Ive never had a new car so wouldn't know, but did buy a brand new engine for the boat and this had "special" oil in it for the first 100 hours.  100 hours is probably 5000miles😀

I suspect that special running in oil is essentially API CC

 SWMBOS car is a lease car changed regularly at 3 years thinking back the Mini  One, 2 x Mini countrymans, 1 x BMW X1 and current Audi Q2 had  no specific running in instructions (all petrol) other than avoiding full throttle for the first XXX miles (usually less 1000),  I think all reached the 1st year anniversary before requiring a service /oil change and thats despite doing reasonable mileages - say 10K (less during lock down ) 

 

my current Mercedes doesn't even have a dip stick....  (other than the one driving it) 

[dmr]

56 minutes ago, jonathanA said:

 SWMBOS car is a lease car changed regularly at 3 years thinking back the Mini  One, 2 x Mini countrymans, 1 x BMW X1 and current Audi Q2 had  no specific running in instructions (all petrol) other than avoiding full throttle for the first XXX miles (usually less 1000),  I think all reached the 1st year anniversary before requiring a service /oil change and thats despite doing reasonable mileages - say 10K (less during lock down ) 

 

my current Mercedes doesn't even have a dip stick....  (other than the one driving it) 

Yeah, in modern cars user convenience and zero user maintenance is king, but I also read that fully synthetic oils prevent breaking in, so I wonder what they have done to get round the running in issue?

I have heard that some delivery drivers use full revs on brand new cars to get them up onto the transporter, maybe thats the running in 😀

[IanD]

4 minutes ago, dmr said:

Yeah, in modern cars user convenience and zero user maintenance is king, but I also read that fully synthetic oils prevent breaking in, so I wonder what they have done to get round the running in issue?

I have heard that some delivery drivers use full revs on brand new cars to get them up onto the transporter, maybe thats the running in 😀

 

Since the majority of new cars nowadays are automatics, surely that would be likely to lead to a lot of new cars being crashed into the end wall of the transporter or the back of the car previously loaded... 😉

[nicknorman]

37 minutes ago, dmr said:

Yeah, in modern cars user convenience and zero user maintenance is king, but I also read that fully synthetic oils prevent breaking in, so I wonder what they have done to get round the running in issue?

I have heard that some delivery drivers use full revs on brand new cars to get them up onto the transporter, maybe thats the running in 😀

Running in was an alternative to properly machining all the parts to exact tolerances! These days, parts tend to be machined to pretty exact tolerances so running in is much less of an issue.

We recently installed a new engine in the gliding club tug, a Lycoming 6 litre 4 cyl jobbie. Designed in the 1950s and probably still manufacturered to 1950s tolerances, you have to put "straight" mineral oil in for the first 50 hrs or until oil consumption stabilises. Only then can you put a modern multigrade oil in with built in anti-scuffing agents etc. They don't call it running in, they call it breaking in. Which mostly consists of using full throttle as much as possible once it's warmed up.

 

Even so, the engine in good condition tends to use about a litre of oil every 7 or 8 hours. Such was the way of things in the 1950s!

I am getting a brand new car at the end of the year, as far I can make out there are no "running in" instructions in the user manual, you just drive it. It has an a DSG box so will do its own thing re gearchanges, and since its top speed is 155mph limited, the major problem will probably be working it hard enough.

Edited October 26, 2023 by nicknorman

[ditchcrawler]

49 minutes ago, nicknorman said:

 

  1950s tolerances, you have to put "straight" mineral oil in for the first 50 hrs or until oil consumption stabilises. Only then can you put a modern multigrade oil in with built in anti-scuffing agents etc. They don't call it running in, they call it breaking in. Which mostly consists of using full throttle as much as possible once it's warmed up.

 

 

And when you ran new car engines in you use to drive gently with a notice on the back as to why you were holding people up, not full throttle 

53 minutes ago, nicknorman said:

 

I am getting a brand new car at the end of the year, as far I can make out there are no "running in" instructions in the user manual, you just drive it.  

I didn't know you had to run electric motors in 😈

[dmr]

1 hour ago, nicknorman said:

Running in was an alternative to properly machining all the parts to exact tolerances! These days, parts tend to be machined to pretty exact tolerances so running in is much less of an issue.

We recently installed a new engine in the gliding club tug, a Lycoming 6 litre 4 cyl jobbie. Designed in the 1950s and probably still manufacturered to 1950s tolerances, you have to put "straight" mineral oil in for the first 50 hrs or until oil consumption stabilises. Only then can you put a modern multigrade oil in with built in anti-scuffing agents etc. They don't call it running in, they call it breaking in. Which mostly consists of using full throttle as much as possible once it's warmed up.

 

Even so, the engine in good condition tends to use about a litre of oil every 7 or 8 hours. Such was the way of things in the 1950s!

I am getting a brand new car at the end of the year, as far I can make out there are no "running in" instructions in the user manual, you just drive it. It has an a DSG box so will do its own thing re gearchanges, and since its top speed is 155mph limited, the major problem will probably be working it hard enough.

 

or is breaking in just American for running in????

A litre of oil every 8 hours is quite impressive, how many litres/hour of fuel does it use?, are you getting close to a potential runaway?   When we got our boat with the sick engine we were using a similar amount of oil, but the fuel economy was very good 😀

[nicknorman]

13 minutes ago, dmr said:

 

or is breaking in just American for running in????

A litre of oil every 8 hours is quite impressive, how many litres/hour of fuel does it use?, are you getting close to a potential runaway?   When we got our boat with the sick engine we were using a similar amount of oil, but the fuel economy was very good 😀

30 to 40 litres per hour of petrol depending on power setting. The manufacturer states that the maximum oil consumption for a serviceable engine is 0.6 litres per hour! But each cylinder is 1500cc so it is a bit of a beast!

[dmr]

48 minutes ago, nicknorman said:

30 to 40 litres per hour of petrol depending on power setting. The manufacturer states that the maximum oil consumption for a serviceable engine is 0.6 litres per hour! But each cylinder is 1500cc so it is a bit of a beast!

Not so dramatic at all in those terms, so 8 hours at 30l is 240l of fuel, and 1litre of oil, so thats 0.4% consumption.

 

For our "little" John Deere a normal consumption of up to 0.5% is specified, but think about a rebuild when it gets to 0.6%

[manxmike]

I don't like modern cars - open the bonnet to find a plastic cover over everything, probably with a sign reading "no user serviceable parts". Imagine if narrow boat engines had a similar cover - it would probably "fall accidentally" into the cut the first time the engine hatch was opened.

[IanD]

4 minutes ago, manxmike said:

I don't like modern cars - open the bonnet to find a plastic cover over everything, probably with a sign reading "no user serviceable parts". Imagine if narrow boat engines had a similar cover - it would probably "fall accidentally" into the cut the first time the engine hatch was opened.

You mean like this? 😉

 

[dmr]

I believe these are fitted so the owner can look at his engine, or show it off to his mates, without seeing anything scary that he does not understand.