Ok, so what are the water pressure in the galleries, and the volume flow rates in both oil and water systems?

I'm having a thought here; it may or may not make sense, but oil pressure is more or less irrelevant. The oil pressure in the journal bearings is several thousand PSI, not 50 or so.

Or look at it another way; if you bung up the rising oil gallery just above the pressure sensor, the pressure (assuming the pump has sufficient power) will become nearly infinite, but the flow rate will be 0. See the distinction I'm drawing; a high flow rate is desirable, but pressure is only a crude indication of the flow rate.

The water pump isn't there to pressurise the system, that's done by the increased temperature, it's there to circulate it past the hot-spots of the exhaust valves and through the cold-spot of the inlet maniifold. Typically the coolant system works at between (I think) 3 & 5 psi - see the pressure cap on an older system.

High oil pressure is necessary to create that several thousand psi and that's through the restricted space of the bearings themselves. I know what you're saying about flow & pressure. If the bearings were loose, less pressure would be needed, yet the flow rate would have to be exceptionally high to maintain rotational integrity (to fill the gaps enough so that it turns without knocking). For this to work, one would fit ball mains & roller big ends. Worth it?

I'm sure that at least one of us is confused by the difference between a static "head" and a liquidynamic pressure here. I know that PhDs in Automotive Engineering have said that the difference in pressure in the mains between a standard and an HP oil pump is the difference in the 2 pumps' output pressures, which makes me think that the dynamic pressure is almost independant of the oil pump pressure (but not the flow rate).

It does pose another question though; would a roller bearing crank work better with a constant speed oil pump than with one that runs at engine speed?

I'm sure that at least one of us is confused by the difference between a static "head" and a liquidynamic pressure here. I know that PhDs in Automotive Engineering have said that the difference in pressure in the mains between a standard and an HP oil pump is the difference in the 2 pumps' output pressures, which makes me think that the dynamic pressure is almost independant of the oil pump pressure (but not the flow rate).

It does pose another question though; would a roller bearing crank work better with a constant speed oil pump than with one that runs at engine speed?

Gimme a break! I studied this 30 years ago as part of basic mechanic training in the REME and I've not used it since.

There's a thread here about electric lube pumps - Accupump of London do one - almost certainly with a dry sump system: Electric Oil Pump - 10 Tenths Motorsport Forum Also the Audi A10 uses one (from the same thread).

As I recall, volumetric flow is what determines pressure measured through a fixed cross section, the bigger the pipe, the more fluid has to be forced through to maintain the same pressure, therefore, the smaller the diameter, the less has to flow to maintain the same pressure. It's directly comparable to electrical resistance, voltage & current (ampage).

Actually, the mechanical pump is rated at about 90psi with a prv set at 50ish - same flow x smaller diameter = higher pressure.

I did this stuff in a similarish timeframe, as part of an unfinished Engineering degree. I think your recollection about volume flow and fluid dynamic pressure are correct. My point about the hot static head in a cooling system was just that comparing static head and fluid dynamic pressure is a classic "oranges and pieces of chalk" comparison. You use the same units, but the quantities are incompatible.

The bits I'm lacking in are the practicalities of volume flow rates in oil and water systems, and hydrodynamic pressure in water galleries, which is why the whole thing's a "would this work?" It looks like the answer's maybe "yes, in principle".

i'm sorry to throw a proverbial spanner in the works here but the oil pressure isn't actually that high at all, the oil pressure release valve will operate at about 30psi on most engines, after which, as you all know the excess pressure bypasses the pump

Tom, what I was wondering about was whether or not we could achieve an adequate volume flow rate for oil without an excessive one at high revs, using an electric oil pump, similar to what is now being done with electric water pumps.

The answer seems to be "yes, in principle, but we may need to redesign the oil system a bit more than is needed with a water system".

Fastest felly!

Fastest felly!

:thumbdwn:

I like the electric waterpump idea; I've seen claims that it's worth 2 or 3 bhp at high revs. If that's the case, there may be similar gains from an electric oil pump too?

I've just seen where the oil pump is on the 135/136 engine & it's not shaft driven off the camshaft & is quite a size, You'd still need to fit a hi-torq electric motor to the pump so that it could deliver 30+ psi to old cold 10/40 in the winter...

As for the water pump, all it does really is to encourage the water to circulate in one direction rather than forcing it round under pressure. An electric unit will probably not need any modification to the cooling system & can be larger than the original unit because it can utilise the space taken up by the pulley (which looks a pig to change...). Maybe not so easy on the 1.6 where the water pump is driven by the cam-belt.

:thumbdwn:

Im only joking, i saw a nice one today:thumbup:

Does help going down hill though, my acceleration is a lot better for it, though I think that works for all cars lol!

Im only joking, i saw a nice one today:thumbup:

I know I found it very funny really.

Does help going down hill though, my acceleration is a lot better for it, though I think that works for all cars lol!

I'll try it!