Dual Circuit Cooling Systems on Diesels

Moto Guzzi's technical helpline might be able to refer. It's worth a phone call, surely?

Actually I'm surprised there's really only 1 or 2 articles that seem to even mention this bike, but I guess that's because it never got beyond a concept. I have looked to see if they hold a patent on this tech, but again nothing really comes up.

There are several dealership numbers but I doubt very much they'll have access to info on such concepts.

I believe that there is no fixed ratio being that as any load changes the thermal and mechanical stresses and related friction will change where heat is being built up at any one point in time.

Relating to which point will be hotter the whole purpose of the cooling and lubrication systems is to keep the entire engine at a near equal working temp so there are no extreme variations in temperature from one point to another.

I'm sure that's the case for an engine under varying loads, but for 'a diesel running under optimum BSFC conditions' it ought to be quite straightforward to measure (or model) the heat flows from different regions I think.

Surely, a cooling system is designed to ensure that extreme variations in temperature don't occur at different points - My understanding is that if water/coolant is used then the water channels in the head are likely to be more concentrated close to the exhaust valves, as the valve components are most at risk of damage from overheating - No?

My understanding is that if water/coolant is used then the water channels in the head are likely to be more concentrated close to the exhaust valves, as the valve components are most at risk of damage from overheating - No?

Yes. And manufacturers have both the 3D flow models and empirical data used to determine cooling passage size, orientation, etc. However, getting access to that info for a particular engine can be nearly impossible.

My old Alfa Romeo had sodium-cooled valves, for similar reasons, but loads of engines do remarkably well with ordinary valves. Moto Guzzis are not known for high specific output -- so this strikes me as lipstick on a pig.

Yes, "lipstick on a pig" - very good! And probably true.

Though I'm pretty sure I read somewhere that they'd used the heatpipes because it allowed them a more aggressive timing map without failing emission standards. As you say though, without detailed data on heat flow (finite element modelling, etc) it is just a guessing game.

Even though coolant load is often at least a third of the the waste heat energy, there never been any way of making use of it because it's not hot enough - a heatpipe or two might be a way to partially change that by 'rescuing' the portion of that waste that is of better quality.

The sodium cooled valves are also basically a crude heatpipe ain't they? They move lots of heat very rapidly, giving the valve an increased surface area to get the heat away. Valve and seat degradation with normal valves is lower than it was in the past, but I wonder how much this is down to better refined fuels and how much from better material tech.

http://www.d.umn.edu/math/Technical%20Reports/Technical%20Reports%202007-/TR%202009/TR_2009_4.pdf

Some of this heat and its fluxes looks pretty valuable if it could be transported away near to these temps (by heatpipes).