340 break in question

krazykuda said
I let the engine warm up to full temperature before going to 2000 RPM or revving it.... I keep it at 1000 - 1200 RPM until it reaches temperature and the thermostat opens...

85% - 90% of engine wear happens when the engine is cold and the friction is higher... The faster you rev it, the more forces are on the moving parts, especially the ones with shear (rubbing) force acting on them... When you let the engine warm up before letting the rpm's get too high, it will last longer.... When the engine warms up, the friction goes down and less wear....

My #1 rule: NEVER REV A COLD ENGINE!!!!

If you rev a cold engine you increase the wear on the bearings, cylinders, crank, cam, etc.... Warm it up first, then rev it all you want....

Do you jump right out of bed and run a mile immediately??? No, you wake up, drink some orange juice, stretch a little, then run...

Same with an engine, it needs to warm up....

I'm not an expert by any means, but you have to remember that during break-in, the engine is not under load as if it were on a dyno or pushing the car down the road. So the actual load the bearings see is significantly less than if it were under load and the risk of damage occurring is low. The caveat is that there is sufficient oil pressure and supply present when you take it up. Running the motor at 2-3k rpm under no load is not significantly different load-wise than at idle. And if anything the bearings should be seeing higher oil pressure at 2-3k and thus reducing the chance of metal to metal contact.