SOHC.co.uk Forums > The Black Bomber Board
450/500T Startup
taysidedragon:
SRM Engineering in Aberystwyth built a bench test rig for their uprated BSA oil pumps to check performance on each one. It's on one of their videos. Something like that would compare new performance to the old sloppy performance without needing to run, and risk, an engine.
K2-K6:
--- Quote from: royhall on January 29, 2021, 10:01:37 AM ---After building my engine I filled it with oil and ran it with the starter motor on the bench with the cam covers off and plugs out. It took a while on the very first run to fill the centrifugal filter and oil galleries. All runs after that produced a good supply of oil which arrived at the inlet cam within seconds with oil at the exhast cam a few seconds later. I wish I could compare those bench runs to an engine with an old sloppy pump fitted. I think the pump is at least the partial culprit here. A pressure gauge would be an ideal defense.
--- End quote ---
I feel that people head the wrong way in interpretation of oil pump wear. It's often given that the oil should be thicker to perhaps stay "stuck" to the camshaft instead of draining away when turned off hot. Just a cursory look at oil when it's 90 degrees C will show that's not of any significance.
Also oil viscosity is not protection !! It's just system resistance. When upping viscosity, the oil pump has to work under more duress but has no "extra" protection to prevent it wearing in this scenario.
My understanding is that this engine would run 30 viscosity when used in temperature above 59 degree F ambient, and 20 viscosity below that.
Has anyone got original specification for this ?
My understanding is that it would be ideal with a 0W 30 specification of modern oils to match in the best way Honda planning and intended flow rate when they made it.
It was designed with 20 and 30 viscosity tolerances hot when the R & D was carried out, that flow rate is important in the overall design for many reasons, most of which are never discussed within this topic.
K2-K6:
Also, threads like this http://www.sohc.co.uk/index.php/topic,24579.msg225043/topicseen.html#new and other experience of that engine, show very similar outcomes in terms of camshaft wear with nothing in common design wise to the 450 engine.
royhall:
Surely the viscosity will not change the fact the oil pump is worn out and not supplying oil in sufficient quantities to lubricate the entire engine. The exhaust cam is the last in line to be lubricated so will fail first.
K2-K6:
The oil pump will always have to work harder to pump a higher viscosity, potentially putting the pump itself above intended duty cycle.
It's an easy statement to make that the used oil pumps display of wear shows this is the case with whatever condition they've been used in, else wouldn't be worn.
Increasing the viscosity/ load on the pump just raises the sideways load on the piston as it's driven off axis by design. Rotory pumps don't do this and will more successfully take over rating loads.
It's one of these subjects that we quite happily a accept things like electrical design in using amps, volts, resistance etc and their interelationship, but ignore the same functionality within oil, hydraulic system.
Keeping viscosity at intended target will provide the most pace throughout the whole system, also leaking down as Honda intended. The oil flow should increase at the camshaft as a result, along with reduction of load at the pump's sliding surfaces.
The shame shear load capacity exists in an oil (within reasonable comparison) for different viscosity. The higher viscosity loads the whole system to a greater degree, with lower/on target putting less load into the pump components, if the higher promotes breakdown of the oil film with the lower within range, that will wear the pump and have no system lubrication advantage.
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