Been a while since I was on this forum last..but for a number of years I was dogged by running bearings in my Alpine powered 1960 Buckler race car. I have run both 1725 and 1600 cc Alpine engines consistently running Big End bearings in them.
To fix the problem I have used an Accusump, new oil pumps, drilled out the centre main oil gallery and oil galleries to number 2 and 3 big ends,beefed up the oil pressure by adjusting the oil relief valve made up complex baffles/windage systems for the sump, both lifted and lowered the height of the oil pick-up pipe in the sump. The engines always had great oil pressure (circa 60psi) until they were was raced hard... the end result was inevitably run big end bearings.
The FIX: A local race mechanic suggested it may be a cavitation problem with the oil-pump. Turns out he was right. Oil on the inlet side of the oil pump largely depends on gravity and a little bit of suction to get to the 2 gears that pump it through the engine. Once it gets on the other side of the gears the pressure ramps up to 60 psi + (depending what the oil relief valve is set at).
Any impediment on the inlet side of the pump significantly reduces the oil the pump has available to pump around the engine. The main impediment is the standard gauze filter on the end of the oil pick-up in the sump... The smaller the filter surface area and finer the gauze mesh the greater restriction.
The fix for me was to make a filter where the mesh size was around
4 mm... ie stops rocks but not the fine stuff... I figured the canister filter further down the line would deal with the fine stuff.
I also used a die-grinder to clean up the inlet track of the oil pump of all machining marks from when it was made.
End result 60 psi all day long regardless of how hard the car is raced.
I suspect much of the LOP (Low Oil Pressure) problems Alpine engines have historically had have at least in part been due to cavitation issues on the inlet side of the oil pump.
Hope this information helps someone else.
To fix the problem I have used an Accusump, new oil pumps, drilled out the centre main oil gallery and oil galleries to number 2 and 3 big ends,beefed up the oil pressure by adjusting the oil relief valve made up complex baffles/windage systems for the sump, both lifted and lowered the height of the oil pick-up pipe in the sump. The engines always had great oil pressure (circa 60psi) until they were was raced hard... the end result was inevitably run big end bearings.
The FIX: A local race mechanic suggested it may be a cavitation problem with the oil-pump. Turns out he was right. Oil on the inlet side of the oil pump largely depends on gravity and a little bit of suction to get to the 2 gears that pump it through the engine. Once it gets on the other side of the gears the pressure ramps up to 60 psi + (depending what the oil relief valve is set at).
Any impediment on the inlet side of the pump significantly reduces the oil the pump has available to pump around the engine. The main impediment is the standard gauze filter on the end of the oil pick-up in the sump... The smaller the filter surface area and finer the gauze mesh the greater restriction.
The fix for me was to make a filter where the mesh size was around
4 mm... ie stops rocks but not the fine stuff... I figured the canister filter further down the line would deal with the fine stuff.
I also used a die-grinder to clean up the inlet track of the oil pump of all machining marks from when it was made.
End result 60 psi all day long regardless of how hard the car is raced.
I suspect much of the LOP (Low Oil Pressure) problems Alpine engines have historically had have at least in part been due to cavitation issues on the inlet side of the oil pump.
Hope this information helps someone else.
