http://papers.sae.org/2003-01-1993/
Toyota paper...save your $26, as it's not that impressive.
Paper is around Toyota's drive to optimise (and reduce) the volume of oil circulating around their CART engine to reduce friction and subsequently increase available power.
Quote:
Oil flow volume to the main journals, connecting rod journals and piston cooling jets are represented in figure 8. Oil flow to the piston jets and heads did not increase with engine speed as much as the oil flow to the journals did. The authors considered the following reason for this
1. Centrifugal forces in oil passages for conrod journals...
2. Journal Bearing clearances expand with rotation speed...
3. Oil Viscosity in the clearance is reduced with increasing frictional force.
Re. 3., like I've mentioned before, the jets are pressure/density, and respond to kinematic viscosity, while the bearings respond to the (lower) HTHS.
Goes on to explain how they use stoichiometry to modify the heating of the piston, and reduce oil requirements there.
Compared the motoring friction of the bearings with varying flows from 7 to 12 l/s, then set a target oil flow for temperture rise and reliability.
Quote:
Fig 9 shows the influence of oil supply reduction to the main journals on engine motoring friction. The oil flow was not easily reduced by means of reduction in passage diameter. Rather it was found that 86% of area reduction led to a friction reduction of 2Nm and a bearing temperature increase of 20C. After sufficient testing, the temperature increase was judged to be acceptable.
that 2Nm is about 4.5hp at 16,000RPM...
Toyota paper...save your $26, as it's not that impressive.
Paper is around Toyota's drive to optimise (and reduce) the volume of oil circulating around their CART engine to reduce friction and subsequently increase available power.
Quote:
Oil flow volume to the main journals, connecting rod journals and piston cooling jets are represented in figure 8. Oil flow to the piston jets and heads did not increase with engine speed as much as the oil flow to the journals did. The authors considered the following reason for this
1. Centrifugal forces in oil passages for conrod journals...
2. Journal Bearing clearances expand with rotation speed...
3. Oil Viscosity in the clearance is reduced with increasing frictional force.
Re. 3., like I've mentioned before, the jets are pressure/density, and respond to kinematic viscosity, while the bearings respond to the (lower) HTHS.
Goes on to explain how they use stoichiometry to modify the heating of the piston, and reduce oil requirements there.
Compared the motoring friction of the bearings with varying flows from 7 to 12 l/s, then set a target oil flow for temperture rise and reliability.
Quote:
Fig 9 shows the influence of oil supply reduction to the main journals on engine motoring friction. The oil flow was not easily reduced by means of reduction in passage diameter. Rather it was found that 86% of area reduction led to a friction reduction of 2Nm and a bearing temperature increase of 20C. After sufficient testing, the temperature increase was judged to be acceptable.
that 2Nm is about 4.5hp at 16,000RPM...
