The place to look for extra power is in that
6% lost as
oil drag. In a well-designed modern motor, the oil doesn't have
to cover up
for wide clearances, poor oil pump capacity or flexy crankshafts,
so it can
be quite thin. How thin? Well, take a look at these dyno results.
A few months ago we ran three Silkolene performance oils in a Honda
Blackbird
motorcycle. This fearsome device is fitted with a light, compact,
naturally
aspirated 1100c.c. engine which turns out 120+ BHP at the back wheel.
The
normal fill for this one-year-old engine was Silkolene Turbolene
GTI 15W/50,
so the first reading was taken using a fresh sump-full of this grade.
(The
dyno was set up for EEC horsepower, i.e. pessimistic.)
Turbolene GTI 15W/50
Max power 127.9 BHP @9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm
After a flush-out and fill-up with Pro S 5W/40 the reading were; Pro S 5W/40
Max power 131.6 BHP @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm
Then we tried a new experimental grade, Pro R 0W/20, yes, 0W/20.
This wasn't
as risky as you may think, because this grade had already done a
season's
racing with the Kawasaki World Superbike team, giving them some
useful extra
power with no reliability problems. (But it must be said, they were
only interested
in 200 frantic miles before the engines went back to Japan.)
Pro R 0W/20
Max power 134.4 BHP @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm
In other words, 3.7 BHP/2.9% increase from GTI to Pro S, a 2.8 BHP
/ 2.1%
increase from Pro S to Pro R, or 6.5 BHP / 5% overall. Not bad,
just for changing
the oil, eh? More to the point, a keen bike owner would have paid
at least £1000 to see less improvement than this using the conventional
approach of
exhaust / intake mods, ignition re-mapping etc.
Am I recommending 0W/20 for high performance engines? Well, perhaps
not! The
Pro S 5W/40, which is a 'proper' PAO/ESTER shear-stable synthetic,
will look
after a powerful engine better than a heavier viscosity 'cave at
the back'
conventional oil, and provide a useful few extra BHP. (On the other
hand,
the 0W/20 was very thoroughly developed to give good anti-wear protection.
I think I was on 'Blend 6' before Kawasaki was happy with it!).
