I've resisted joining the recent discussion on this subject, but today I
tore down my Triumph TR4 race engine and thought others might be
interested in my findings. I tore it down because although it still had
excellent oil presure, it was exhibiting too much blowby. Tests showed
10 - 15% leakdown, confirming my suspicions of leaky rings.
The engine has thirteen events on it, amounting to about 40 hours at
racing speeds. We intend to limit rpms to 6000 but occasionally exceed
that. When starting the engine, we always crank it over until we see oil
pressure before turning on the ignition.
Rod bearings: Excellent -- virtually no wear
Main bearings: Excellent -- small shiny areas at edges of rear main only
Valves: exhausts ready for grinding
Chain tensioner: Surprise! very little wear
Rings: Little tension. The pistons almost fell out.
Pistons: virtually no scuffing
Conclusions: The oil we're using is performing superbly. We use Mystik
semi-synthetic 15W - 50 and change only twice a season. This oil is not
mass-marketed, but rather targetted for the trucking, agricultural, and
construction industries. It's about a third of the price of oils like
Mobil 1.
--
uncle jack
TR4 - 10 mpg
TR6 - 30 mpg
(plus a few other differences)
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