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Discussion Starter · #1 ·
The RS has an oil cooler that we all recognise, but the Tornado has this strange setup that passes coolant from the pump to a heat exchanger at the oil filter then back through the radiator at high pressure (and presumably high flow) while the thermostat is closed. As the thermostat opens, the coolant flow through that circuit must decrease when you would think that it would be needed more.

Can anyone explain why it is there?
 

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The RS has an oil cooler that we all recognise, but the Tornado has this strange setup that passes coolant from the pump to a heat exchanger at the oil filter then back through the radiator at high pressure (and presumably high flow) while the thermostat is closed. As the thermostat opens, the coolant flow through that circuit must decrease when you would think that it would be needed more.

Can anyone explain why it is there?
Are you sure that is how it works Errol,
Coolant to oil heat exchangers are not that effective. To regulate , what is normally ,at running temperatures, a 10 C difference, oil being the higher.
With the thermostat shut , it is only a bypass of coolant from the radiator, it allows a flow around that base of the oil filter, until the thermostat opens , it dissipates heat to the oil ?
High pressure / high flow would seem unlikely given the output of the impellor is directed through a small calliber pipe , about 10 mm. Whilst all the impellor "pressure " is directed through it , the flow rates are hardly astounding.
When the thermostat opens , it now has two routes, around the oil filter heat exchange and through the cooling system and radiator.
I think it only offers marginal stabilization of oil temperture control, not an effective cooler.

Only an observation,
I remember old BMC OHV engines had a similar system, only the go faster versions had the extra air cooled oil cooler, like RS , 1130 Tre and TNT Titanium
 

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Discussion Starter · #3 ·
Are you sure that is how it works Errol,
Honestly, I'm scratching my head over this one.

I was talking to the Davies Craig engineer and he mentioned in passing that there must be a bypass circuit for a one way thermostat, otherwise the seals in the water pump wouldn't last long. At the time I couldn't think of any, other than the 2 mm hole in the thermostat itself. I had forgotten about the heat exchanger circuit. I suspect that Benelli devised this system purely to protect the seals in the pump, as it can't possibly be effective as an oil cooler. The flow would be lower when the thermostat was fully open, and hence heat transfer out if the oil would also be reduced. Ideally the system should work the other way around, increasing flow as the temperature rises!

I have built a bypass system of my own design that circulates coolant through the engine as it warms up, to eliminate local hot spots, as is done on most modern cars with a bypass thermostat - the Fiat 124 Sport Coupe had this in 1972. I'm thinking of disconnecting the heat exchanger circuit to improve flow through the engine. The new bypass system should help to regulate inlet coolant temperature at small thermostat openings, as suggested by the Davies Craig engineer. It makes sense.
I have a solenoid valve in that bypass circuit that closes when the thermostat is half open to maximise radiator flow when it most needs it.
 

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Discussion Starter · #4 ·
Been thinking about this a bit further, and I'm still baffled. The RS doesn't have a similar circuit to take the pressure off the water pump seals, other than the bleed hole in the thermostat, so the Tornado wouldn't be any different.
This is the cooling circuit:-
Font Rectangle Parallel Slope Diagram

I don't think that the "Shutter Jet" exists. Certainly not as an individual component. Maybe as part of the heat exchanger.

Another observation:
The "Continuous Purge Line" currently drops down after it leaves the downstream side of the thermostat, creating an air pocket at the thermostat. I think that it is possible to re-route that hose so that it rises continually to the top of the radiator, when on the paddock stand, eliminating the air pocket and making bleeding a doddle.
Vehicle Automotive tire Motor vehicle Automotive lighting Hood

I think there is room under the tank and inside the top fairing, but I haven't confirmed it yet. It may need a smaller tube to clear it easily.
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A doddle? Well almost a doddle. The thermostat has a bleed hole that will slowly, very slowly, allow air trapped on the upstream side to bleed to the downstream side, and to the top of the radiator if the purge line is re-routed.
(I've added a bleed line upstream of the thermostat which speeds the whole process up immensely.)

Anyway. If anyone can explain how the heat exchanger can possibly work, I'm all ears, but I think freeatlast and I concur - it's next to useless as an oil cooler.
 

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Errol, you mentioned the need to protect the water pump seal, but as you would be aware, the water pump creates flow but very little pressure. The seal would be subject to more pressure from system pressure due to radiator cap than from the pump. Shutter jet? is this just a restriction? Being a non-positive displacement pump, I would have thought it would flow enough coolant to circulate in the engine with thermostat open, as well as directing enough through the heat exchanger. Nigel.
 

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Discussion Starter · #6 ·
..the water pump creates flow but very little pressure. The seal would be subject to more pressure from system pressure due to radiator cap than from the pump.
I agree. I think the Davies Craig engineer was having a lend of me.
Shutter jet? is this just a restriction?
No shortage of restriction! The hose and pipe are roughly 50mm^2 and close to 1m long, while the engine galleries are 1/3 the length and several orders of magnitude in area, so the relative resistance to flow to the heat exchanger would be enormous.
Being a non-positive displacement pump, I would have thought it would flow enough coolant to circulate in the engine with thermostat open, as well as directing enough through the heat exchanger.
I'm going to measure it when I get a chance.
 
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