Quote:
Originally Posted by ERA Chas
Just a tech question David; were you running very tight bearing clearances for a race motor? I know you said the bearings looked good but then why high oil temps?
Well, maybe not too high for 7K+ RPM? |
I don't remember the exact bearing clearances, that's been 7 years and a few engines ago, but they were not on the tight side, I think more in the recommend range........
Looking back on it all, I think there were 2 or 3 things that contributed to the high
oil temps.....Even though I tried 3 different
oil coolers the high temps could be becasue of the location of the cooler and the protective screen I was using in front of it,blocking off some of the air flow......The 3 different oil coolers were of different types and sizes, yet the oil temp never varied more than about 10 degrees regardless of which one was on the car......
Anyhow,some of the top running cars in the Vintage class told me anytime their oil temp goes past 230, they pull off the track and park the car!!!!!
We normally run 15 to 20 lap races and usually by lap 10 my oil temp was in the 230 to 240 range and slowly kept climbing till the end of the race......the highest I've seen it at the end of a race was 275,I was running in 2cd place, running down the first place car and didn't want to let off........
Be that as it may, on the cool down lap, my oil temp would drop 30 to 40 degrees running the cool down lap in 4th gear at about 2500 rpms.....
I have 2 oil temp gauges,one in the pan and the other on the outlet side of the remote oil filter,after the oil has gone thru the cooler, at the begining of a race the temp difference was usually 20 degrees and would hold at that for a while, then slowly the difference would decrease till the end of the race, the 2 temp gauges were reading about the same......
The crank/rods never showed any signs of bluing or heat and the bearings looked what I would call normal for the useage they saw.....
My rpm range for a race was 3500 rpms to 7000 rpms, so that poor little engine ran for 20 to 35 minutes never under 3500 rpms and always under a load, I normally shift between 6000 and 6500 rpms.....it served me well..
David