Originally Posted by Cab_Burge
I disagree on the use of the high volume oil pumps, they where designed for racing motors, not worn out stock motors tsk
I like and use loose bearing clearances on all the motors I build, race or HP street motors. I've never seen or heard of a rod bearing spinning do to much (.002 to .0035) oil clearances, same thing on main bearings (.0030 to .0045)work
I like and use the 10 lbs. per thousand RPM rule with hot oil (150F+)and trim or shim the bypass spring to get that if needed up
I also run 5W20WT oil on my street motors now, Valvoline VR1 10W30 WT in my race motors up
I use to use 50W racing oil, years ago realcrazy
I've done a lot of engine dyno testing and found out that the oil temps can have a direct affect on HP, 30 W oil at 130F would not have as much power as it would at 170+ F oil temps, 8 HP gain with hotter oil up I then tried 10W30 wt and saw 5 HP differences between 130 F and 160F, the next test was with straight 20W and I saw no HP gain from 70F up to 210F shruggy work
That is why I use that weight oil now in all my street motors and low (below 750HP) HP bracket motors up


I have watched so many Dyno runs on TV. They always do major changes between pulls so you never know what was the major gain in power.

But we did a Dyno run on a 513 BBM years ago using 20W50 racing oil. All tests were at 180 degrees F. We then replaced the HV oil pump with a standard one and gained 10 HP. Then we dumped the 20W50 and ran 5W30 and gained 15 Horsepower. So a gain of 25 Horses. After 30+ runs the main bearings were pulled and had very minor wear as was normal.

I have not run anything above 10W30 in any car except my Subaru Outback XT turbo, it gets Rotella T6 5W40.

Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015


Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.

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