We have recently broken an engine in our SCCA FP Spitfire due to spinning
the # 3 rod bearing. Leading to a severed Carillo rod, a cracked and dented
crank, a customized skirt to the piston and cracks in the bottom of that
cylinder. Rod bolts broke at about 7000 RPM. # 2 rod bearing and center
main were also found to be down to the copper, but showed no signs of
heating. Others were still teflon coated.
In searching for cause it has been proposed that since the engine stayed
above 5000, the majority of the oil may have been stored in the upper
portion of the engine and trapped in windage rather than being in the pan
and available to the pump. We have not had this sort of problem in the
previous 5 years of running the car but have not had such sustained high
RPMs before either.
The competition prep manual suggest the pan should be extended downward an
inch, which we have not done. This would presumably decrease windage. We
have baffles in the pan, top side and front as well as an extended pick up.
We had tried a windage tray but the force was such that the tray was sucked
up and partially re-machined by the rods and crank throws. We are working
on a stronger tray but did not have one in.
The manual also indicates that the dropped pan is to be considered full
when the dipstick shows at the low mark. This seems to suggest that the oil
volume is standard and not increased by the dropped pan.
Comment and suggestions are solicited and appreciated.
Matt Matthews
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