Perkins P3 engine mounting.

I thought this had been discussed before.I doubt that the P3 has enough power to run the alternator as I think it only puts out about

25kw max.

Mark.

He's only planning to draw 10kW from it, so it's well sized for the task.

Mark Rand RTFM

Yes, I did enquire when it was in the idea stage before, but now I have a practical problem that - maybe someone can comment on. I can post a picture of various attempts if it would help. Thanks George

George,

I am a lurking Stationary engine man who may have an idea, mount the engine and alternator into a rigid frame but mount the frame on resilient mounts to its base that way the engine and alternator move together and is isolated from the base so no vibrations transmitted.

Martin P

So you think it will only need 10kw to generate 10kw?

Mark.

Actually, the Perkins should produce about 30 Hp, which is equivalent to more than 10 Kw. The idea is that it will all be in a concrete building with lots of soundproofing, bolted to a concrete floor on it's own, but connected to the house by a trench in which will run insulated water pipes to a tank and cables to the electricity distribution so when it runs, waste heat is used in the house. It is not the vibration causing noise that I am worried about it is doing damage to the engine. Having said that, it must be quite quiet.

There is a description of the progress and pictures, on a page of my website

The point I`m trying to make is that you said earlier that you were reluctant to run it at full speed of 1500rpm. Is this 1500rpm what`s needed for the alternator to generate correctly? A P3 puts out it`s 25kw at 2000rpm,have you seen a power curve to see what it produces at 1500rpm,have you seen a power curve for what it produces at the low revs you were running it at? I would expect full power near enough at 1500rpm but what speed was it doing when it was jumping about?

Mark.

That's a good question, and it gives me another avenue, I could lower the running speed a bit. all I need is a bigger pulley size on the engine shaft. The weight and momentum of the alternator will both keep it all on the ground firmly and allow switch on loads to be absorbed. I could manage with quite a lot less power, I dare say.

I have been looking at rev counters to get an idea of what the engine rpm is, but everything I have seen has been a bit expensive. I can always find out the alternator output frequency by reference to my single phase supply with a couple of bulbs, but I need the engine speed first. The real question I have is, does the engine have to be mounted firmly and forced not to shake around or does it need a slightly flexible mounting on my frame? It is all a matter of making it run happily and not shake anything to bits.

Regards George.

George,these engines were mounted rigidly in tractors and plant,so,don`t see why you can`t do that too. How big a flywheel do you have on it? It might smooth out a bit at higher revs,it may not.I would try to find a torque curve for it,then,I would explore the possibilities of running slower (quieter) with gearing the pulley sizes but I would also try it at higher revs too. The fact it was used in plant suggests it was smooth enough running to operate across a range of rpm`s. The other thing to check is the pump/governor set up.It may be set for a fixed rpm duty at a different rpm from what you have tried. Presume you have checked injectors,valve clearances etc.?

Mark.

George formulated on Tuesday :

Take a look at cheap bicycle speedometers. You just need to glue a magnet on the coupling and fix the pickup within range of the magnet.

Mark, I quoted the engine serial number to Perkins and they could not find it in their records. I sent several pictures but they still could not identify it, so getting a power curve for it would be impossible. I rebuilt the pump and had the injectors set up to a typical 120 bar. It does run quite smoothly when on a slow tickover and I think it is in quite good condition, - lots of compression and I have not messed with the timing, either. Did you look at the pictures on my website, as there is one of the flywheel? Thanks for your comments.

Unless it is possible to change the parameters, a bike speedo set to indicate speed using a 24 inch wheel bike speed would need to read over 100 mph to register 1500 rpm. Thats quite high for most bikes. Worth a look at though. Thanks. Harry.

The wheel diameter can be set on the couple I've used, I think it's standard so you can set it for your bikes wheel choice which varies quite a bit depending on bike type. I have heard of people using them for cars with good results in excess of 100mph .

George, You can always get one of these,under a tenner delivered.

You can get injector info and other stuff but no torque curve here.Owners manual. Perkins are a total waste of time.Sabre Marine in Aberdeen used to have a guy who really knew Perkins but I`ve had no contact with him for years.Might be worth asking on some of the old tractor forums as there were a few about at one time.

You might try one of these:

non-contact RPM reading for model aero engines. £21. You could lower the range by using muktiple reflective strips on the flywheel and calibrating the reading accordingly.

Richard

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I've ordered one already. It is the setting up I need one for, I have plenty of those that vibrate a reed at 50 c/s. Thanks for the link. Regards. George.

There are lots of cheapo handheld tachos on ebay, such as item

120507106726, which cover the range you need quite simply.

It looks as though you probably have a pneumatic governor on that engine, they won't give the greatest level of speed control, really designed for vehicles - and make sure you keep a spare governor diaphragm, when they start to leak the speed goes up and control is eventually lost.

I used to have a 'shared' boat with a P3, ex-Trojan bread van, bolted down to timber bearers. I don't remember vibration being an issue.

Tim