This might slow my oil burning

10-30 non detergent and add zinc is what I do. I went to the store at 8am today and it was 6 below. Cranked a little slower but started, and I sat and kept it running till the chill was gone.
 
Another major reason for very heavy weight oil in full-on alky and nitro motors is related to having huge bearing clearances. Where we might run .002 on a high-performance street engine (.001 per inch of journal diameter), the full-on top-fuel and alky motors will run twice that. With those large bearing clearances, you need a heavier film of oil to take up the larger gaps. Also, with dry-sump oil pumps, they're running over twice the oil pressure that we run on the street.

At Bonneville in our FlatCAD motor, we run about 120 PSI from the dry-sump pump and run 50 wt racing oil. Our bearing clearances are about .0025 on the rods and .003 to .004 on the mains. The rear main is always looser than the rest as that part of the crank tends to get the hottest (expanding more).
 
Bored&Stroked said:
Another major reason for very heavy weight oil in full-on alky and nitro motors is related to having huge bearing clearances. Where we might run .002 on a high-performance street engine (.001 per inch of journal diameter), the full-on top-fuel and alky motors will run twice that. With those large bearing clearances, you need a heavier film of oil to take up the larger gaps. Also, with dry-sump oil pumps, they're running over twice the oil pressure that we run on the street.

At Bonneville in our FlatCAD motor, we run about 120 PSI from the dry-sump pump and run 50 wt racing oil. Our bearing clearances are about .0025 on the rods and .003 to .004 on the mains. The rear main is always looser than the rest as that part of the crank tends to get the hottest (expanding more).
Click to expand...

Thanks you! All very interesting.

Glenn
 
Bored&Stroked said:
Another major reason for very heavy weight oil in full-on alky and nitro motors is related to having huge bearing clearances. Where we might run .002 on a high-performance street engine (.001 per inch of journal diameter),
Click to expand...

You jogged my memory of a fully machined 283 305HP Corvette Engine I bought from a hot rod friend. Unbeknownst to me it had been blueprinted and clearanced for racing. When I put it together with a new stock oil-pump and fired it up, I couldn't figure why there was so little oil pressure. Even after changing to a high output pump it still read quite low at idle with regular weight oil. It made my '57 Chevrolet go like a bat out of hell. On the Dyno it put out more than 1 HP per CI! I think it was 335 HP.
 
J Franklin said:
You jogged my memory of a fully machined 283 305HP Corvette Engine I bought from a hot rod friend. Unbeknownst to me it had been blueprinted and clearanced for racing. When I put it together with a new stock oil-pump and fired it up, I couldn't figure why there was so little oil pressure. Even after changing to a high output pump it still read quite low at idle with regular weight oil. It made my '57 Chevrolet go like a bat out of hell. On the Dyno it put out more than 1 HP per CI! I think it was 335 HP.
Click to expand...

Yeah, one thing you learn in purpose-built race engines as far as bearing clearances go -> "loose is fast" . . . "tight is death"! LOL
 
You must log in or register to reply here.
Back
Top