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I'm in the process of building an V6 engine from scratch that isn't well supported or used in the racing world. I'm considering dry sumping the engine to ensure it gets good oil flow and pressure throughout the system as I'm turbocharging this engine as well. My concern is with a dry sump (3 stage..2 scav, 1 press) is the possibility of starving the piston wrist pins of oil as there would no longer be any oil knocking around in a stock sump for splash lubrication and the main oil gallery is not accessible to drill and tap to install oil squirters to spray oil up into the pistons.
Is this a massive problem I should worry about or would the wrist pins still get enough lubrication with a dry sump system?
I'm not sure if the 1UZ you guys used have factory oil squirters but was wrist pin starvation an issue on the GT86 engine?
I have had a vast array of engines I have built over the years (excess of 80 different dry sumped engines) using this type of dry sump and have never had oil starvation to the little ends
I think the film of oil still floating around seems to be adequate to lube them
let's see what others have to say on this.
Thank you for that information Ross. I will go forward with it as my engine will have two small garrett journal bearing turbochargers, along with slightly larger bearing clearances and I'm not sure if the stock oiling system would be enough to keep the engine happy. My sump is designed like that of the 1UZ as well so I will be using their idea of fabricating a lower pan to scavenge the oil pan to send back to the tank.
This can be a concern, however you're unlikely to have any issues with only 2 scavenge stages. This can be more of a problem when you're running 3-4 scavenge stages and you're aiming to pull a high level of vacuum in the sump. In this situation you may reduce the amount of oil mist available for splash lubrication. Solutions to this include forced oiling from the big end, or under piston oil squirters.
Thanks for this information Andre.... Will go ahead with my plan with this info.
I may be missing something here, but it isn't oil splashed up by the crankshaft that does the lubricating - we do everything to avoid that - but oil thrown of from the crankshaft that came from the main and big ends. A such, the higher the rpm, the greater the amount of oil one would expect to be getting to the 'pin. That means a dry sump should have sod-all (negligible) affect on that.
The primary reason for oil squirters to be used is to cool the underside of the piston crown, to help preserve their strength as aluminium weakens with temperature.