HR2 Cooling duct

[nuttyprofessor]

Just a quick one… I’m going to rebuild the cooling duct tomorrow now that the weather is warming up…
In all the drawings and pictures I’ve seen of the HR units the hot air ducting is always facing upwards, is there a reason for this?
It would be much easier for me to remove the original ducting (facing upwards) and make new ducting coming straight out of the engine to the outside wall of my generator shed.
Is it ok to do this???

Thanks in advance

[LowGear]

My guess, my guess I write, is convection.

Casey

[dieselgman]

HR2 with ducting would typically be a marine application and they were designed to go straight up through the deck/s. There would be no penalty to forcing air sideways as long as there were not too many restrictions introduced in the process. The HR has a pretty hefty cooling fan incorporated with the flywheel so everything in the cooling system is forced-air.

dieselgman

[nuttyprofessor]

Thanks,
Another question...
Air filter, i'm planning on replacing the original filter system with a homemade unit containing Peugeot air filter/s reason being I can buy these filters from the supermarkets out here in France.
Does the air filter have much effect on combustion. Obviously small is going to be restrictive but is it possible to go to large?

[EdDee]

Hi NP,

Somewhat larger is not generally a problem, but if it has a "cyclonic" dust separator before the filter proper, if you are too large, the dust separator doesn't work properly. Take care to mount the filter housing in the correct orientation, as there are often drain holes for moisture on the bottom edge before the element, watch out for mountings that might fatigue due to vibration too, due to a larger than normal filter being shaken by a thumper. As long as the element itself is of good quality and the right particle separation size, you shouldn't have too much of a problem.... Now here is a complicating fact.... Paper elements are designed to clog somewhat to attain best filtration for a reasonable lifespan. The element passes a little dirt initially, until it "clogs" a bit, thereby blocking the passages in the element partially, allowing the element to catch finer and finer particles. If the element is way, way, oversize, it might pass a little too much of the bigger particles for too long and cause a minor amount of premature wear. It is a trade-off between expense/time between changes/wear etc... If you are in a relatively clean environment, minimal airborne grit and dust, smaller is not necessary a bad thing either...

Hope I haven't complicated your life too much!

Regds
Ed

[nuttyprofessor]

Thanks, no not complicated, just want to make sure I get everything right. Our only form of electricity is the HR charging a battery bank.

[nuttyprofessor]

 This might be a new one…

Is it possible to have a too efficient cooling system?

Since last post I’ve built new hot air ducting taking the blown hot air from the engine out of the generator shed. I’ve made sure the ducting is bigger than original and made nice radiuses where the air changes direction. I’m more than confident that there is no additional restriction to hot air flow. 

Yesterday I fitted 4 household extractor units. The type that have one big fan with 5 intakes, one for kitchen, one for WC, one for shower etc, etc.
I pulled them apart and using 125mm drainpipe created 4 very strong units pulling cool air into the shed, figures would suggest that I’m drawing in, in-excess of 1000 m3/hr. I’ve located them so they are blowing cool air to appropriate areas of the generator unit.

At the moment the only way for the air created by the fans to escape from the generator shed is via the engine hot air output.

The temperature in the shed has dropped from 40c to 20c (approx)
The genny has been running for 2 hours this morning (20mins at full load) and I can hold my hand on rocker covers without any discomfort infact they are only slightly warm , the fan/flywheel housing is cold as is the combustion air intake. The only parts which are HOT are exhaust and crank case.

I was going to fit outlets in the roof to allow hot air to escape but don’t have any…

My thoughts and questions…
Is it OK for the engine to be the only thing removing stale air from the shed?
I’m guessing I’ve created positive air pressure in the shed is this a problem?
When I build new air filter assembly I’m guessing I should incorporate some sort of heat transfer from exhaust manifold?

My only reason for concern and posting is that I now have a very small amount of blue smoke from exhaust. I do mean very small though!!!

Very interested to hear peoples thoughts on this.

[dieselgman]

It might be wise for you to instrument your engine temperature - Lister normally did this at the cooling air exhaust near cylinder head/s.
It is also likely that you will want to thermostatically control your cooling fans. I have operated the air-cooled Listers in enclosed spaces before with only wall mounted shutters to allow the heated cooling air to escape... but these were generally fairly leaky structures in cold climates. The shutters had thermostats to control opening and closing according to the room temp settings.

As far as positive pressure in the engine room goes I would think that this condition would be far better than any negative pressure. Is your shed really that tight? These conditions will affect combustion air drawn through the engine inlet to some degree and that might create some minor influence on engine operation. Blue smoke generally indicates lube oil consumption (past the rings or valve guides)... If you are running the Lister too cold, you might experience ring-seal issues. That condition usually will be related to longer hours of cold-operation and not just develop after a few hours of cold-running.

On your air-filter question, do you mean you are contemplating a heat exchange from the exhaust? Remember that cold air will contain more oxygen than heated air (provides better combustion efficiency) and you really do not want heated air introduced through your engine intake. This is the science behind intercoolers on turbo diesel inlets - drop that inlet air temp as much as possible after being heated by the turbo... I would suggest that you provide a cold-air inlet for your air-filter to draw from rather than trying to increase engine temps via heat exchange on the inlet.

dieselgman

[nuttyprofessor]

Hi dieselgman,
Thanks for all your advice.

I used to have a garage business back in uk mainly buying selling and tuning Cosworth’s , evo’s etc,ect. So totally understand cramming as much air into combustion chamber as possible with correct fuel ratio! (Burnt out pistons lol) Used to fit water spray onto charge coolers and even spray with co2 fire extinguishers before setting ¼ mile time.
These engines were all multi-valve running as high as 9000rpm.
The reason I suggested warming the air at the filter was because on smaller engine older cars they always had a shroud over exhaust manifold with a heat proof pipe attached to air filter box?
One of the fans is directed towards the air filter.
I’ll fit my temp sensor in the air stream leaving the engine, do you know what sort of temp the air should be?
Reading the user manual it states keeping the engine as cool as possible
After posting yesterday I had the same thought as you regarding controlling the fans. I’ll have 1 running all the time and then the other 3 coming on at different temps, 2 running at 30c, 3 at 35c and all 4 at 40c.
Yes the shed is really that air tight, my goal is to have it running almost silent. I’m getting there the only real noise is from the vibration now. At the moment the genny is just sat on 2 big bits of wood which in turn are placed on gravel. (French planning laws won’t allow me to make a concrete base)
I was going to fit the usual rubber feet but I’m now wondering about cutting down car suspension coil springs, then using shock absorbers to stabilize the unit, any thoughts on that?
I’m sure I’ll be asking more over the next couple of days as I complete the build.
When it’s finished I’ll work out how to post pictures and explain my to build to help others and give something back to this extremely helpful forum.

Oh! forgot I changed the oil a couple of days ago and overfilled it a bit, this could quite possibly be the cause of the smoke. It really is very faint though especially compared to the old ST3 I had. I got the wife to look yesterday and see couldn't even see it.

[dieselgman]

On your typical older carbureted gasoline automobile, quick warmup was desirable to reduce dependence on the choke and resulting poor fuel mixture. Thus the intake preheater you describe. The preheater tube was often controlled with a thermostat and shut off completely after engine warmup.

I do not recall the specs from Lister on exhaust air temps but can look up that detail for you... the usual problems with running cold should not be present if you are loading the unit at 75% capacity or better. I would keep an eye on that exhaust though. Cleaner is better for the engine as well as your breathing air.

Do not run the HR with excess crankcase oil because it sometimes will start leakage that can later be difficult to get stopped. The early ones used leather and felt seals on the crankshaft and all were designed to run a slight crankcase vacuum to keep the oil from seeping past the seals.

dieselgman