Dirt racer's engine goes up in smoke........

[Jeff70]

Yes it is a wet sump system, we use a melling oil pump and at race RPM we usally had 60-70 lbs of oil pressure. My UOA came back, but i don't have it in front of me, but the TBN was around 10, the wear meatals were both in the critical range and the Silica content was high, there probale cause was dirt ingestion, also there was no fuel dilution, and the Visc @ 100 C was like 16.9 which is in the range for a 50W oil. Its a chevy block(line bored, honed and decked, and the rotating assy was balanced) which all of you know lubes the top end quite well so some of the top end lube ports are capped to help keep the bottom end lubed. The thing that still bothers me the most is that the rod bolts were extremly tight, when we tore the engine down we felt like the rod bolts had been over tightened. Although your explination of a vapor lock in # 8 cylinder which was the cylinder that were had been having problems with due to the mag makes alot more since to me than the rod bolts being too tight........I will post the UOA when I get it back from the driver.......Is it possible that we had too much oil pressure and were blowing the oil past the bearings?????

 

[1sttruck]

Methonal, 8000 rpm, 13 races.... how many races / miles do people usually get from their engines ? They aren't going to last forever under those conditions, so is this 'normal engine life' ? Pitting on bearings suggests that you're pushing the limits of the bearing area / load / lubrication, so if you're not getting 'normal' engine life are doing / using something different than others who are ?

If you use the same engine builder and are concerned about rod bolt tightness, maybe watch him plastigage a rod with the torque that he uses, if people still do such things to check bearing clearances.