Originally Posted by Dominic Toretto
Very informative post, thank you. I don't think most people knew all of that information. In these cars it is impossible though, to figure out what oil pressure we have since the factory gauge doesn't give a reading in measurements of PSi... or any measurement for that matter. So we are forced to get an aftermarket gauge. But that's another topic all together.
I do have to ask though about the 10psi/1k rpm ratio. At operating temps at idle I would read 30psi at 800rpms with the LS1 using 5W30. With my 7MGTE at idle using 20W50 it would read just under 40lbs at 1,000rpm. So do you mean 10psi per 1,000rpm above idle?
-Alex
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Exactly. So at 7000k rpm you'd want about 70 psi plus or minus. Ferrari uses a pricnicple of 75 psi at 6k rpm. I feel that that is a pretty gd measuring stick.Some people have tried this and occasionally get a somewhat low oil pressure while at idle. This is fine. There is no stress on parts at idle, the smallest oil flow will do the trick. It is at higher RPM where more BHP is produced.
The temperature of oil on your gauge is not as hot as it really gets. This temperature is an average with oil from different parts of the motor. Some parts are hotter than others. It is said that some of the oil gets as hot as 400° or 500°F in these racing situations.
Since the oil with a viscosity of 10 cS at 212°F thins to a viscosity of 3 cS at 302°F we will get more flow. The pressure will go down some as well. This is OK as long as we have a minimum of pressure to move the oil.
This increased flow will result in increased cooling by the oil. This is a good thing. You would probably want more oil flow in these situations and you get it. The hotter oil thins and this increases flow. The higher flow works harder to separate the engine parts that are under very high stress. It all works out for the better. Higher revving engines need thinner oils. You do not necessarily need to go to a thicker oil while racing. Only experimentation will tell.