it seems reasonable that if the oil pump is in good shape and the pickup screen is clear that it should function as before providing the oil cooler lines are big enough and as short as possible . one of the side benefits would be the easy connection of temperature and pressure monitoring.G-Man wrote:I haven't been an engineer since 1738 but have heard of Mr Bernoulli.
The important thing here for the oil pump is the friction in the pipe which is related to the diameter of the pipe, the length of the pipe and the viscosity of the fluid. The surface roughness has an effect too.
http://en.wikipedia.org/wiki/Friction_loss
The longer the pipe the higher the friction losses. The Honda oil pump is quite leaky, so if you give it more work to do it will leak more. i.e. more of the oil will leak back in to the sump if you restrict the output.
The important thing for the hot parts of the engine is how much oil you can get to them and the temperature rise you can tolerate in the oil at the interface. You can keep the peak temperature low by flowing more oil or by flowing the same amount of substantially cooler oil.
10-40 oil just has a lower viscosity vs temperature gradient. It behaves like a 10 at low temperature (easy start up and quick oil circulation) at higher temperatures it behaves like a 40 oil as it doesn't thin so rapidly with temperature rise.
In order to generate a high pressure (the Honda pump will only generate 2-3 psi at high revs and almost nothing at tickover) you have to pump it onto something like a plain journal with a small leakage path. You simply cannot generate any oil pressure into a ball or roller bearing as they are so leaky. The Honda pump is designed accordingly.
The Suzuki produces about 3 times as much power (and heat) as the Honda in an engine of about the same physical size so it needs a lot more help to get that heat away. Most I/C engines will put roughly the same amount of heat in the cooling system and exhaust as they make in power.
There's nothing to stop you putting cooler on the CB72 and it would be interesting to measure the bulk oil temperature before and after modification. Then again, the problem you are seeing with blackened oil on pistons etc. may be more about improving flow to the very hot parts than lowering the bulk temperature of the oil. As with all engineering solutions, it depends on what problem you are trying to solve....
seespotweld1 wrote:physics 101 :Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy, potential energy and internal energy remains constant.[2] Thus an increase in the speed of the fluid – implying an increase in both its dynamic pressure and kinetic energy – occurs with a simultaneous decrease in (the sum of) its static pressure, potential energy and internal energy. If the fluid is flowing out of a reservoir, the sum of all forms of energy is the same on all streamlines because in a reservoir the energy per unit volume (the sum of pressure and gravitational potential ρ g h) is the same everywhere.Bernoulli published this in 1738R100 wrote:With this my first CB77, I have yet to ride one or look deep inside its engine.mike in idaho wrote:Looks like(a very expensive) solution looking for a problem to solve. The old Honda twins didn't have much oil pump volume or pressure there to start with. They really didn't need much, ball and roller bearings everywhere, just enough oil flow to keep the valve gear happy. You start pumping that through a cooler, lines and a paper filter element you will have reduced the flow and the pressure. The stock centrifugal oil filter does a great job, it's end-fed, basically no restriction. By design, that paper filter will let particles through that the stock filter will trap. I would save my money and go with a modern quality motor oil, that will more that adequate to protect a 28 horsepower motorcycle engine.
The physics of what you are saying makes perfect sense to me.
PS: oil pumps do not leak.. hopefully ..they do lose efficiency as explained in the rebuild thread
