Dilatant lubricants

[kiwi2]

Hi,
I have just about got to the stage of running my modified beam engine and I'm wondering about the sort of oil to use in the piston and valve assembly.
One of the problems with model engines is that they run very fast compared to the full scale versions. I suppose this could be corrected using a governer of some sort but the idea occurred to me of using a dilatant lubricant where the viscocity of the oil increases with speed rather than decreases. This would result in slower engine speeds while retaining relatively high air pressures. While uncommon, these oils do exist and are used for chainsaw blades ( see http://www.motipdupli.de/?L=2&id=944).
Has anyone tried an oil like this?
If not, what would the recommendation be for a suitable oil i. e. should it be thick, thin or just an average auto engine oil?

Thanks,
Alan C.

 

[kvom]

A few drops of air tool oil in the air intake should be plenty for most engines of the scale we build. The easiest way to slow an engine is to increase the mass of the flywheel.

 

[Tin Falcon]

I use instrument oil on my engines.
Tin

 

[kiwi2]

Thanks for the info. I've got some air tool oil so I'll give that a go.

 

[Tin Falcon]

Kiwi : I run my engines on air Ihave several general purpose regulators to regulate air pressure . most of my engines will run nicely on about 3 psi.

If you ar running steam use an in line oiler with steam oil.
Tin

 

[OrangeAlpine]

While the models rotate faster than their big cousins, I'm not so sure the piston and bearing speeds in fpm would be higher. Revs are not important, speeds are. That's why short stroke engines are so popular.

Bill

 

[BronxFigs]

Could this "dilitant" lubrication find an application for valve train and cams, lifters, rocker-arm pivot points, push-rod tips etc? Or would high-pressure grease work better?

Very interesting to read about this dilitant lube and its properties.

 

[kiwi2]

Thanks for all the replies. The general consensus seems to be to use a thin pneumatic oil when running a machine on air which makes sense.
The engine I'm making is a slightly modified version of the Elmer beam engine. I got it running for the first time yesterday and I was really chuffed. It runs well at about 5psi and if I increase the pressure to 15psi the engine develops a respectable amount of torque. I'm going to pull it apart to get it tidied up and I'll post some pictures when it's back together again.