Does your engine warm up faster running in gear?

[GHA]

Hard to tell...

But moving on from this thread ...
http://www.ybw.com/forums/showthread.php?448327-What-to-do-with-boat-data

With new solar panels the Raspberry Pi onboard is running full time tireless recording everything once a minute 24H a day.

So below are 3 short motors adjusted sit on top of each other with SOG at the bottom.

Doesn't look like there's much difference but each time the engine was near full temp just ticking over for 10/15 minutes. Running was about 1600/1800 rpm, relatively new Beta 35 engine. Thermometer is cable tied to a lifting lug on the engine head.

What would "running under load" be anyway? Low revs in reverse?

Zoomed in a bit..

All good fun :cool
Techy wise the Pi gets everything from NMEA & various DS18N20 thermometers which it converts into signalk, then node red grabs the data from signalk once a minute and saves it into a SQLITE database, then Gnuplot makes the graphs.

 

[PaulRainbow]

I'd say a little over tickover, in gear qualifies as "under load". The engine will reach operating temperature quicker if it's under load. It requires energy to turn the drive train and shift a ton of water with the prop, that energy must create heat. Plus, more RPM = more explosions = more heat.

 

[GHA]

I'd say a little over tickover, in gear qualifies as "under load". The engine will reach operating temperature quicker if it's under load. It requires energy to turn the drive train and shift a ton of water with the prop, that energy must create heat. Plus, more RPM = more explosions = more heat.

More RPM = more water going through the impeller/engine = more heat leaving.

Here's one from a while ago using an arduino, the engine runs cooler at 1900 Rpm than at 1600 Rpm.

Thing about the universe is it's best to assume you might be wrong and measure to check

Feel a strong and pressing need to record RPM now as well..

 

[pvb]

More RPM = more water going through the impeller/engine = more heat leaving.

Here's one from a while ago using an arduino, the engine runs cooler at 1900 Rpm than at 1600 Rpm.

Thing about the universe is it's best to assume you might be wrong and measure to check

Feel a strong and pressing need to record RPM now as well..

Your life seems to be refreshingly free of distractions.

 

[GHA]

Your life seems to be refreshingly free of distractions.

What comes with not having a job
Or a house, shoes or a diary, just a good anchor

Though not all good, doesn't look like the batteries will get back to 100% today, maybe just 98%......
Data is lovely!

 

[PaulRainbow]

More RPM = more water going through the impeller/engine = more heat leaving.

Not if it's raw water cooled. More RPM = more explosions = more heat generated within the combustion chambers. This heat is dissipated into the fresh water cooling circuit and circulated by the fresh water pump. The raw water pump is indeed pump more cold water through the heat exchanger, but it isn't having any effect on the fresh water because the thermostat is closed.

Your graph shows that the temp dropped when you increased RPM to 1900, but that was after the engine had been running for 45mins and had reached operating temp. Once up to temp and the 'stat is open you'd be right to say more RPM = more cold water through the heat exchanger, by the look of it.

 

[RichardS]

Not if it's raw water cooled.

Richard

 

[GHA]

Ran in reverse about 1200Rpm for a little while, warms up a bit faster but not that much in it really.

So what temp does a thermostat open?

Interesting little plateau in the older green line when the engine went in gear & revs increased, it just shows up on the older data as well, though very subtle so might be unrelated to revs, plus the recording frequency is only once per minute unlike this morning where it was set to once a second.

But all in all fun and interesting, gnuplot is so powerful once you get into the command line interface and can read direct from a sqlite database file, sqlite is very handy for this as it's all contained in just one file so easy to copy across to a laptop from the Pi using filezilla.

Next up to chart the fridge duty cycle against the cycles of the moon...

 

[Heckler]

Not if it's raw water cooled. More RPM = more explosions = more heat generated within the combustion chambers. This heat is dissipated into the fresh water cooling circuit and circulated by the fresh water pump. The raw water pump is indeed pump more cold water through the heat exchanger, but it isn't having any effect on the fresh water because the thermostat is closed.

Your graph shows that the temp dropped when you increased RPM to 1900, but that was after the engine had been running for 45mins and had reached operating temp. Once up to temp and the 'stat is open you'd be right to say more RPM = more cold water through the heat exchanger, by the look of it.

Dont forget, as I said in one of the posts the other day, diesel engines are different. There is lo idle and hi idle. Tickover and hi tickover, not much fuel being burned at hi tickover BUT put a load on it at any point in the rev range and whilst the revs stay the same the amount of fuel used increases significantly. So a generator, you can increase the load at static revs and all you will hear and see as the load increases is a deepening of the exhaust note and black smoke as the load comes on. However, as you said earlier, if the prop is shifting a ton of water at certain revs then increasing the revs will increase the load by making the prop shift more water OR by pointing the boat uphill at static revs will increase the load as the boat slows down as it crests a wave, again you will hear the note deepen as you climb a wave, then it lightens as you descend the wave.
The propellor on a boat is similar to an automatic gearbox fluid flywheel, the faster it spins the more work it does and the more "grip" it develops.
An interesting phenomena is when you put the boat in gear tied to the pontoon, give it full chat and on mine I can get 2700 rpm with lots of black smoke. At sea, full chat gives, eventually, 3000 plus rpm. The prop is actually becoming more efficient as the boat speed builds up and peak revs are achievable. At rest it stays relatively inefficient. So, to warm an engine up quickly, put it in gear, it doesnt matter which way, and give it moderate throttle to put a decent load on.
Stu

 

[reeac]

My old sports car has an ether filled temperature gauge which has a big enough display to show that the thermostat continually opens and closes with a cycle period of about 5 to 10 seconds when at running temperature. ..it's binary. I assume that this is also the case with marine engines. You need to have the sensor immersed in the cooling water to pick up such an effect.

 

[Normalfornorfolk]

Does your engine warm up faster running in gear?

The question asked has nothing to do with running at various RPM, it is to do with warmup.

Simple thermodynamics (or common sense) makes it obvious that an engine will warm up faster if it is working harder, ie in gear and with a some throttle rather than idle/neutral. The harder it works the faster it will warm up. When it gets to working temp it won't - or shouldn't run at different temps at different revs if the thermostat is working correctly.

I'm not sure that the graph tells us anything about the question asked, the OP said the engine warmed up in 10-15 mins at idle as the three traces show. There appears to be no trace showing an accelerated warmup with the engine under load.

 

[GHA]

There appears to be no trace showing an accelerated warmup with the engine under load.

Looking at the same graph? The 3 shorter traces are under load slightly higher revs, obviously warming a bit quicker than the longer traces which were at tickover with no load. Not a huge amount in it though.

Also interesting though not visible here is when the engine goes back to tickover after a motor the temperatures actually go up a bit, so maybe "letting the engine idle to cool down after motoring" might not be based in reality.

 

[Normalfornorfolk]

Ah, OK, that's clearer in the graph above, it wasn't so obvious in the original.

The reason temps go up on throttleback is because there is an immediate correspondng reduction in cooling water flow but it takes a while for the full- power heat close to the bores to permeate through to the now less well cooled water jacket; less water and (initially) the same anount of heat and up goes the temp for a bit. Call it thermal inertia if you like. You'll sometimes see a rise in temperature on a car engine if you stop straight from high speed - eg motorway services for the same reason.

 

[<152587>]

I'd say a little over tickover, in gear qualifies as "under load". The engine will reach operating temperature quicker if it's under load. It requires energy to turn the drive train and shift a ton of water with the prop, that energy must create heat. Plus, more RPM = more explosions = more heat.

Oh do come along, do you have bits of the engine flying past your earholes when it fires? An explosion is the last thing needed. It is an internal combustion engine not internal explosion engine.

 

[vyv_cox]

Looking at the same graph? The 3 shorter traces are under load slightly higher revs, obviously warming a bit quicker than the longer traces which were at tickover with no load. Not a huge amount in it though.

It looks to me that it takes almost twice as long to reach the same temperature at tickover, ~ 15 minutes v nearly 30 for the upper pair of curves and not far off the same for the lower pair. But I don't really understand 'exhaust', as on a boat the bypass water and thermostat operation confuse the issue.

This mirrors my experience in my car. I live on a fairly steep hill that extends for a couple of miles both up and down. Going down my heater gives out nothing, and the temperature gauge barely stirs, for about four miles. Going up the gauge is almost to normal in two miles and the heater is working well.

 

[lw395]

Ah, OK, that's clearer in the graph above, it wasn't so obvious in the original.

The reason temps go up on throttleback is because there is an immediate correspondng reduction in cooling water flow but it takes a while for the full- power heat close to the bores to permeate through to the now less well cooled water jacket; less water and (initially) the same anount of heat and up goes the temp for a bit. Call it thermal inertia if you like. You'll sometimes see a rise in temperature on a car engine if you stop straight from high speed - eg motorway services for the same reason.

This^.
The engine is not all at one temperature.
The heat takes time to spread out.
Which is why the temperature gauge can keep rising with the engine stopped, and car radiator fans will often come on when cars are parked.

IME, diesels are often very slow to warm up at idle. There simply isn't that much waste heat. And a lot of what there is, is lost out the exhaust pipe not into the coolant. A lot of diesel cars have electric heating of the coolant for this reason, and others have eberbastos.

 

[GHA]

It looks to me that it takes almost twice as long to reach the same temperature at tickover, ~ 15 minutes v nearly 30 for the upper pair of curves and not far off the same for the lower pair.

Just to confuse things further the engine was in gear at probably 16/1800Rpm moving the boat on the green traces from about 09:45, around the end of the top traces so it wasn't at tickover all the way, didn't appear to have much of an impact on the curve. .

But I don't really understand 'exhaust', as on a boat the bypass water and thermostat operation confuse the issue.

The exhaust sensor is touching the exhaust elbow, eng is attached to a lifting lug on the head.

 

[PaulRainbow]

Richard

Oops, senior moment Richard

 

[PaulRainbow]

Oh do come along, do you have bits of the engine flying past your earholes when it fires? An explosion is the last thing needed. It is an internal combustion engine not internal explosion engine.

zzzzzzzzzzzzzzzzzzzzzzzzzzzzz

 

[jwilson]

This^.
The engine is not all at one temperature.
The heat takes time to spread out.
Which is why the temperature gauge can keep rising with the engine stopped, and car radiator fans will often come on when cars are parked.

IME, diesels are often very slow to warm up at idle. There simply isn't that much waste heat. And a lot of what there is, is lost out the exhaust pipe not into the coolant. A lot of diesel cars have electric heating of the coolant for this reason, and others have eberbastos.

+1
My old diesel Volvo V70 would just not heat up enough to get warm air to defrost windows at tickover in really cold -15C or less conditions even after 20 minutes parked running. You had to drive it, but you couldnt see much. Scrape the frost off the outside of the windscreen and by the time you got in it to drive your breath would freeze hard on the inside. So you drove away head stuck out of window.... I thought this was pretty silly for a Swedish car. Found out most sold in Sweden had Webasto cabin pre-heaters for this reason.