leaving the forced air cooling

[arnaud]

Hi, i just read a thread about someone porting a 406 china diesel in an enfield, and removing the cooling systme from the flywheel and housing.
Maybe the riding wind is enough and removing the scoops of the flywheel will save some power.
But, will the cooling be enough?
How reliable is oil temperature measurement for temperature indication what's happening above the piston??

[oilburner]

A cylinder head temperature gauge will give you a good idea what is going on in the combustion chamber. You can likely find a used gauge on EBay for $50. Allow another $20 for a thermocouple if there's none with the gauge. Accompanied by an oil temperature gauge, you should be able to determine if the engine can be safely run without the shroud.

OTOH the Chinese engines are cheap enough that you could pick up a spare engine, and take a chance on running one without a shroud to see what happens, provided you don't mind walking home if it um, doesn't work out.

[andrewaust]

It will certainly be interesting to see how the engine goes, maybe by placing some larger fins on the head would help.

I think it is to hot where I live to go without force air cooling without larger fins on the engine, but then again? The only other problem is getting held up in traffic, again larger fins would be a good idea, depends on where and how you ride

[Jonny]

Hi folks,been gone a while but nice to be back again. I took off the engine-driven fan when I built my bike - dnepr with a Lombardini 191. As I understood it from old land rover days, it was thought (maybe wishful thinking) that the old setup could take up to 25 per cent of the power,so an electric fan used only for stationery situations gives you that back. So I just flick a switch at the lights.....as long as I remember! Since my memory is disappearing as rapidly as my youth, I'm hoping one of you geniuses has an idea for automating this - including which temperature to kick in at? (Yes I could run a temp gauge off the head or oil to figure the latter, but reckon somebody has the knowledge to save me the time and Dosh!). Fire up those brains lads! Cheers, Jonny.

[the grinch]

i have to switch my fan at the moment i am gonig to put a switch in my radiator its an old polo they have a switch and can trigger a relay but i wonder if it would still work if it was attached the the head or somthing like that. it may be woth a try if they are about 7-8 quid.

alex

[Diesel Dave]

There are quite a few options for triggering an electric fan, rads designed for use with electric fans have provision for a bolt in temperature switch, otherwise there are versions that can be strapped to the rad tank (Kenlow used to sell them). Or there are inline versions that can be installed mid-hose.

[Jonny]

Good try guys, thanks... but it's an air-cooled engine. No rads or hoses.

[gilburton]

You can get temp sensors that use a ring that goes under the spark plug. Whether this would work under a bolt on the head of a diesel I don't know but here is an example. I think you can get cheaper versions ??
Personally I would leave the cooling alone. As yours is a twin inline or fore and aft( ex navy me lol) the rear cylinder won't get much cooling from the moving air.
https://www.mainline-sensors.co.uk/prod ... 1123137089

[Diesel Dave]

If it’s an air cooled lump then it’s easier, just but a temperature switch (perhaps 150C) and use this to ground activate a relay and fan setup.

Heat in heavy traffic or stationary wouldn’t worry me as diesels gulp full air and little fuel at these times but full throttle climbing is where you will see it heat up.

[Diesel Dave]

BTW unless you have a 188 motor with the removeable plastic fan don’t go to all the bother of grinding off the impellor blades just fill up the voids with builders foam until you are convinced it’s the right thing to do.

Ask me how I know.............

[Jonny]

Hmmm, interesting thoughts Dave, I figured over say 30mph the draught probly equates to the same amount of ventilation that the fixed fan would give? Soo, wtf is a temperature switch? Sounds like the business

[Diesel Dave]

Plenty available on eBay, make sure you use a relay...

[Jonny]

Ok, great,erm... what do you fix this onto as your heat source? A head bolt (like a cht sensor)?

[Diesel Dave]

They need a flat surface so just drill 2 small mounting holes on a top fin and use some thermal paste on the contact face as you would when heatsinking electronic components.

[Jonny]

Clever! And you reckon 150C (on a fin) is the right setting to protect the engine?

[Diesel Dave]

The only way you are going to find the engine max temp would be to install a temp sensor and do some heavy load testing.

Do you have any 33% hills locally?

Air cooled motors can run very hot, for example my Velosolex moped can get over 200C and I’ve tested Chinese pistons in C90 engines and they seize at exactly 204C......

I usually treat above 180c as entering the danger zone.

[boutje]

I once did an oil temperature measurement with a 186 diesel where forced cooling was removed.

Even on a very hot day and low speed the oil temperature was never over the 100 degrees C.

[Jonny]

Thanks very much Dave (and all). Interestingly, researching stuff around the subject I came across 1 website where it was stated that ally based alloys start to break down at 180C. So I'll be making sure I don't melt my engine