BGTV8

I have been involved in motorsport for 43 years, and the WarmandSCSI description of breakin procedure is what I use for road and competition engines. You need sufficient combustion pressure behind the rings to get them to knock the highpoints (it is a relative term - measured in 10th of 1000th of an inch) off the bore so the rings seal properly and stop sucking oil into the combustion chamber and burning it.

The trick is not to let the engine "labour" under mid-range revs and high load and also not to let it idle or run at constant load for very long.

Whenever I pick up a new vehicle, it always gets a 200+ klick run and I like to pick a road that has a few hills and lets me use the gearbox - it is about keeping the revs up (3000 +), keeping the load up, but never WOT. My Z34 never used a drop of oil from day one - purchased in May 2009 and has covered 28,000klics so far, and run maybe a 800-1000 track klicks - still does not use oil. The Subaru Impreza STI I had before the Zed covered 180,000 klicks in 7 years (and maybe 35-40 track days) and it never used oil. The Impreza WRX I had before that was the same. The GM Small block engined car I had before that was the same .....

My competition engines are all broken in on an engine dyno, 15-20 minutes at 2000rpm to bed the cam and followers, stop the engine and let it cool overnight, re-torque the heads and then 20 minutes of 60-90% load at 60-75% rpm's (all varied, never constant load), to make sure the rings are thorougly bedded, then finish off with a couple of balls-out power pulls. If we don't like the results, we might then play with fuel and timings to get max torque, then it goes into the race car.