Engine and Transmission Tech

I'm about to take the plunge. (4) stage dry sump. 4L. race only. 2.8" stroke, up tp 8,500 rpm. ? I like the idea of feeding into oversize, main cross bolts, on left/driver side. One question is , best compromise angle of oil feed hole, into bottom bearing shell ? Seems like 90 deg. would offer least wedging action, and steeper/better. How steep ? Invert the bearings ? Another method would feed through the main girdle, into bottom of main cap, sealed with an o-ring. Oil restrictors to the cam bearings ? Using mech. roller or mushroom cams, with through push rod oiling. Anybody ? Thanks, roverman.

On the cam bearings it was found that oiling from the 3:00 position gave a favorable wedge of oil for good continuity in the oil film and best load bearing. Perhaps the crank would benefit from a similar geometry?

Jim

Jim, 3.00 position on the mains, would put the oil feed at the part line ? I want to feed-in at 6:00 o-clock/bottom position, but I'm unsure as to best "tragectory" angle. Onward, roverman.

I don't think the trajectory matters much, being essentially a hydraulic circuit. Give it a straight shot and minimize flow restrictions. However, you should run some calculations to see if your system pressure stands any chance of competing with the power stroke loading of the lower bearing shell. If it does not (my suspicion) then all you are doing with an oil groove on the lower shell is giving the oil film another space to squish out into. That would explain the top oiling position and the ungrooved bottom shell, and also helps to explain why a 3:00 position works well as that is the point at which the oil begins to wedge out. A little above or below to avoid the parting line and I think that is as good as it is going to get. But I could be wrong. Run those numbers and you'll know.

Jim

Jim and clan,I've heard one argument that highest loading is on upper shells, with exhaust on TDC. I have not seen any math to support this. This 4L should produce "approx" 800 psi, when mixture burns. Inline 4 cyls and single plane V8's are said to have more side to side loading on mains, than 90deg. cranks. I'm thinking about putting the oil feed log, machined into side overhang of girdle. This should reduce plumbing and leaks. Onward, roverman.