An HGV driver I spoke to the other day was telling me that his oil filter was due a clean. I remarked that a new filter for a Scania V8 must cost a bit and he told me that they have a centrifugal filter. I never knew and I had to discover more. It seems to me that centrifugal filtering is a much more efficient and cost effective method of keeping your vital lubricant system working at its best. There’s a fascinating video here. Of course this opens up a discussion as to whether it is Centrifugal or Centripetal forces at work.

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In the US they are known a spinner filter systems and I think they are used in a variety of combustion engines. I feel it is one of those ideas that ought to be more widely adopted as the oil is one of the most important parts of any engine.

Speaking of Oil:

How lubrication works in an engine.

In most car engines the sump is located at the bottom and looks like a pan full of oil. There is a scavenging pump that sucks the oil from the pan and forces it through a filter and then pushes the oil around the engine. The crankshaft is partially in the sump and the rotation splashes the oil around the bearings and conrods etc. There are two issues here; first hard cornering (centripetal force again) can flow the oil away from the main bearings and they could be temporarily starved. Secondly there can be a problem with windage or frothing. The high swirling motion in the crankcase can cause the oil to froth and all the air bubbles in the oil are detrimental to its lubrication efficiency.

With a dry sump these problems are solved, there is a separate tank to hold the oil where any air and froth can distill. This tank would likely be larger to hold a bigger volume of oil which could slow the breakdown of the chemical chains of the lubricant. Most race cars and continuously running engines (like a generator) have dry sumps. Another advantage in a vehicle is that the engine, missing the oil pan, can be mounted lower in the engine bay improving the centre of gravity.

Quite a few high performance cars have a dry sump system, most notably Porsche 911.

Singer Porsche
Obligatory image of a Porsche… Excuse me for a moment!