Fine Tuning Tickover speed

[cereal tiller]

Thinking of enhancing engine Tickover.

 

The Boat's main engine is set to idle at 550 RPM,this speed is perfect to enable smooth shifting for ahead and astern

 

However,if the 880 watt kettle is switched on while the engine is at tickover and in gear the engine can become "lumpy"

 

A solution would be an inductive switch which would energise a solenoid when the inverter has a load greater than ,say. 300 watts.

 

The Solenoid could then raise the engine idle speed by aroumd 150 RPM

 

Any Ideas?

 

CT

[RLWP]

Put the kettle on a gas hob? Take up drinking beer instead of tea?

 

Richard

[cereal tiller]

Put the kettle on a gas hob? Take up drinking beer instead of tea?

 

Richard

Thanks SPQR

 

will consider that option.

 

OR,i may just choose to resolve the minor problem with TechTrickery,it is a weakness of mine!

 

CT

[RLWP]

It sounds like your governor isn't doing it's job properly

 

Alternatively, is the alternator belt slipping? Or are some of your injectors dodgy?

 

Richard

[cereal tiller]

It sounds like your governor isn't doing it's job properly

 

Alternatively, is the alternator belt slipping? Or are some of your injectors dodgy?

 

Richard

The Governor is fine,when propellor load is applied the tickover adjusts back to the 550 RPM ideal.PDQ

 

The kettle is too light a load to cause sufficient Governor reaction,bigger kettle would be wasteful.

 

CT

[RLWP]

If the load is that small, how can it make a difference to the engine - and apparently it does!

 

What you are suggesting is sort if what your governor should be doing anyway - except without the increase in engine speed

 

It sounds to me like not all of your injectors are delivering extra fuel when the load comes on. Some are and some aren't - hence the lumpyness

 

Richard

[nicknorman]

No, I think its a good idea. On our boat, when the 2kw electric kettle, or worse (because its on for longer) the 2kw tumble drier is on, whilst the TravelPower can deliver that power at tickover, the engine/alternator combination doesn't sound very happy. In part because there is a lot of load on the belt (there would be less load if the belt were going faster) and in part because the engine does sound a bit lumpy.

 

If you think about it, the lumpiness is not caused by any defect, but merely that, whilst the alternator belt load is pretty constant and high, the extra oomph from the increased fuel flow comes only sporadically (once every 1/2 rev to be precise) and so the fluctuation in crank speed per 1/2 rev will be much more than if the engine were lightly loaded (eg by a prop turning slowly). I think it is this rpm fluctuation that causes the lumpiness and of course the engine is working not too far off its max torque for the low rpm. Not the best way to treat an engine.

 

As to how to do it, depends on the type of inverter, but if you have a databussed one such as a Mastervolt and probably a Victron has the capability, in conjunction with one of their databussed switches, to operate a solenoid when a specific condition is met such as AC load greater than a specified amount. The solenoid could be use to move the idle stop on the engine's throttle lever.

[onionbargee]

not sure about this but decompressing or cutting off fuel pump on one cylinder at a time will reveal if one is below power, that might be the injector is not calibrated.

 

Certainly more high spec engines are checked by the temperature of the exhaust manifold adjacent to each cylinder.

[cereal tiller]

No, I think its a good idea. On our boat, when the 2kw electric kettle, or worse (because its on for longer) the 2kw tumble drier is on, whilst the TravelPower can deliver that power at tickover, the engine/alternator combination doesn't sound very happy. In part because there is a lot of load on the belt (there would be less load if the belt were going faster) and in part because the engine does sound a bit lumpy.

 

If you think about it, the lumpiness is not caused by any defect, but merely that, whilst the alternator belt load is pretty constant and high, the extra oomph from the increased fuel flow comes only sporadically (once every 1/2 rev to be precise) and so the fluctuation in crank speed per 1/2 rev will be much more than if the engine were lightly loaded (eg by a prop turning slowly). I think it is this rpm fluctuation that causes the lumpiness and of course the engine is working not too far off its max torque for the low rpm. Not the best way to treat an engine.

 

As to how to do it, depends on the type of inverter, but if you have a databussed one such as a Mastervolt and probably a Victron has the capability, in conjunction with one of their databussed switches, to operate a solenoid when a specific condition is met such as AC load greater than a specified amount. The solenoid could be use to move the idle stop on the engine's throttle lever.

Thanks Nick

You have a good grasp of the situation

The Engine and all it's components are fine ,no-one else on the boat would notice the effect,but I do!

 

So,I was hoping to source an Inductive switch that could sense loads on the Inverter output wiring,am sure a suitable solenoid would be readily available

 

CT

[ditchcrawler]

Thinking of enhancing engine Tickover.

 

The Boat's main engine is set to idle at 550 RPM,this speed is perfect to enable smooth shifting for ahead and astern

 

However,if the 880 watt kettle is switched on while the engine is at tickover and in gear the engine can become "lumpy"

 

A solution would be an inductive switch which would energise a solenoid when the inverter has a load greater than ,say. 300 watts.

 

The Solenoid could then raise the engine idle speed by aroumd 150 RPM

 

Any Ideas?

 

CT

Should make you popular passing moored boats when someone puts the kettle on.

[nicknorman]

Should make you popular passing moored boats when someone puts the kettle on.

Not really. In my case we are talking about going from 850 (normal tickover), down to 800 and struggling with the kettle in, or going up to say 950-1000 with the adjusted idle speed. Still fairly slow and what I do manually anyway when I am driving. But in locks etc I have to pull the throttle lever out so as to raise the neutral rpm - a pain!

[JohnB]

I wonder if this might a problem with the engine speed being set rather too low; Normally narrowboats need only little power and engines tend to be run at tickover very close to the edge of the design range and rather near the limit of the governor control.

 

We had a similar issue on our boat when the washing machine went to spin as we were manoeuvring at low speed (e.g crossing between locks on a flight) and we needed to speed up the engine--- mildly inconvenient as it could screw up one finely balanced approach ;-)

The tick over speed had been adjusted whilst trying to compensate for drive plate problems and had been left set far too low.

Once I had changed the drive plate to the correct type for our application and got the engine set up all was fine, the engine note sounds just a "bit more solid" as the load goes on but the speed barely changes.

 

 

John

[cereal tiller]

I wonder if this might a problem with the engine speed being set rather too low; Normally narrowboats need only little power and engines tend to be run at tickover very close to the edge of the design range and rather near the limit of the governor control.

 

We had a similar issue on our boat when the washing machine went to spin as we were manoeuvring at low speed (e.g crossing between locks on a flight) and we needed to speed up the engine--- mildly inconvenient as it could screw up one finely balanced approach ;-)

The tick over speed had been adjusted whilst trying to compensate for drive plate problems and had been left set far too low.

Once I had changed the drive plate to the correct type for our application and got the engine set up all was fine, the engine note sounds just a "bit more solid" as the load goes on but the speed barely changes.

 

 

John

Problem now resolved!

 

There is now a voltage sensitive relay Actuating a wee solenoid which compensates for alternator load.

 

when the battery voltage drops to 13.6V The Solenoid moves the injector pump quadrant by 2M.M. which lifts the tickover back to 550RPM.

 

Simples

 

CT

[nicknorman]

I wonder if this might a problem with the engine speed being set rather too low; Normally narrowboats need only little power and engines tend to be run at tickover very close to the edge of the design range and rather near the limit of the governor control.

 

We had a similar issue on our boat when the washing machine went to spin as we were manoeuvring at low speed (e.g crossing between locks on a flight) and we needed to speed up the engine--- mildly inconvenient as it could screw up one finely balanced approach ;-)

The tick over speed had been adjusted whilst trying to compensate for drive plate problems and had been left set far too low.

Once I had changed the drive plate to the correct type for our application and got the engine set up all was fine, the engine note sounds just a "bit more solid" as the load goes on but the speed barely changes.

 

 

John

Certainly raising the tickover cures the problem, but then one ends up with a rather fast tickover when the electrical loads are off. Our boat will do around 2mph in deep water at the manufacturer's recommended idle setting of 850rpm which is already on the fast side. Hence the idea of raising the tickover only when heavy loads are on. I think some folk don't appreciate the problem because they only have a 70A alternator which doesn't draw a significant amount of mechanical power. A 3.5kw TravelPower is equivalent to about a 300A alternator and puts far more load on the engine at low speed than the propellor does. Add to that a 175A alternator recharging the domestic bank and you have a lorra lorra load (as Cilla would say).

[Athy]

 

 

The Boat's main engine is set to idle at 550 RPM,

How many has it got?

[cereal tiller]

How many has it got?

2 The other one is a Generator

 

CT

[JohnB]

Certainly raising the tickover cures the problem, but then one ends up with a rather fast tickover when the electrical loads are off. Our boat will do around 2mph in deep water at the manufacturer's recommended idle setting of 850rpm which is already on the fast side. Hence the idea of raising the tickover only when heavy loads are on. I think some folk don't appreciate the problem because they only have a 70A alternator which doesn't draw a significant amount of mechanical power. A 3.5kw TravelPower is equivalent to about a 300A alternator and puts far more load on the engine at low speed than the propellor does. Add to that a 175A alternator recharging the domestic bank and you have a lorra lorra load (as Cilla would say).

 

 

Yes that is some load on the engine compared to what is needed to move the boat. I came across a load dumping switch fitted on a 2L2 installation to alleviate the issues you describe ,in this instance the engine would stall with a heavy alternator load. I rather like this solution if the speed changing when steering isn't a problem.

 

For our boat (by design) the ancillary loading is modest compared to the needs for propulsion but unexpected variations in engine speed can cause problems, It does quite noticeably change the speed of turning. Unless we find some deep water we rarely need more than 800rpm or so ( that seems to be 4mph).

 

right this is getting a bit purely academic

regards

John