Sensational headline I know but some of that was my fault. I have a 1970 BBB that I had finished and put it on an engine dyno for testing. Had 10W-30 conventional VR1 with a can of GM EOS added for break-in and remained in the crankcase for the duration of testing. Made a large number of pulls and ended up with a best of 595 hp/ 625 ft-lbs on 93 pump gas. Specs are 10.7 CR, ported aluminum heads, roller cam and rockers, dual plane intake, carburetor, headers, offset ground crank for increased stroke, 482 ci, stock oil pump with higher pressure spring. Upon initial startup and cold oil, oil pressure was really good at idle (like 56 psi).
The part that was my fault: The bearing clearances were big at .003 to .0033 on the rods and .0035 to .004 on the mains. I did not adjust to a thicker oil. Decided to wing it and hope for the best. We also let the oil get too hot during some pulls and oil pressure was low at just under 60 psi at 6000 rpm on a few occasions because of it. Ended up spinning rod bearings 7 and 8 (The last to get oiled on this engine).
The reason I blame VR1 in part was due to a later conversation with a Buick engine builder. He stated that he always saw a large drop in oil pressure with VR1 as the oil heated up compared to room temp oil. He switched to Driven break in oil and saw much less pressure drops with temperature during his dyno testing.
What we have corrected: after a rebuild rod clearances are now .0021 to .0022" and mains are .0023 to .0025", crank was replaced, extra qt oil pan, additional windage screen, new aftermarket timing cover with oil pump and improved oiling, added an external oil line which oils from the rear, larger Baldwin B9 filter, Driven BR30 break in oil, limits on oil temp during pulls.
Why a temperature stable oil is more critical in this engine vs others: the oil pump is external and is steel gears inside an aluminum housing, main bearings are not priority oiled - lifters and cam bearings are oiled first, then the mains, oil pump oils from the front first.
The mPAO oils intrigue me due to their VI and other marketing terms but wanted to get some expert opinions on which oil to use after break in.
The part that was my fault: The bearing clearances were big at .003 to .0033 on the rods and .0035 to .004 on the mains. I did not adjust to a thicker oil. Decided to wing it and hope for the best. We also let the oil get too hot during some pulls and oil pressure was low at just under 60 psi at 6000 rpm on a few occasions because of it. Ended up spinning rod bearings 7 and 8 (The last to get oiled on this engine).
The reason I blame VR1 in part was due to a later conversation with a Buick engine builder. He stated that he always saw a large drop in oil pressure with VR1 as the oil heated up compared to room temp oil. He switched to Driven break in oil and saw much less pressure drops with temperature during his dyno testing.
What we have corrected: after a rebuild rod clearances are now .0021 to .0022" and mains are .0023 to .0025", crank was replaced, extra qt oil pan, additional windage screen, new aftermarket timing cover with oil pump and improved oiling, added an external oil line which oils from the rear, larger Baldwin B9 filter, Driven BR30 break in oil, limits on oil temp during pulls.
Why a temperature stable oil is more critical in this engine vs others: the oil pump is external and is steel gears inside an aluminum housing, main bearings are not priority oiled - lifters and cam bearings are oiled first, then the mains, oil pump oils from the front first.
The mPAO oils intrigue me due to their VI and other marketing terms but wanted to get some expert opinions on which oil to use after break in.