How to break-in a new engine for more power

[Interceptor]

Read the full story here:
http://www.mototuneusa.com/break_in_secrets.htm

It seems that this guy knows what he's talking about - what do the bimmer.info experts say on this topic? Bill R, Winfred, Lowell? Others?

[Dave M]

Hmmmm, I wonder if it would work to some degree with new rings on non-honed cylinder walls (hone marks on the new-used block still 'strong')?

Looking for an excuse to rat-bag my M50 minutes after the rebuild:)

Dave M

[Jay 535i]

I've seen this before. His logic is flawed.

He's asserting that in a normal easy break-in, the cylinder liners wear away the piston rings, making the rings match the not-perfectly-smooth surface of the new bores. But, he says, if you run the engine hard, the rings will wear the bores down so that they're perfectly smooth, and that's what creates more power.

What he misses is that the softer metal will always wear faster regardless of engine speed. He asserts that more throttle will push the rings against the bores harder, and so the bores will wear rather than the rings. This doesn't make sense. When you push a piece of cheese agaist the grater harder, does the grater wear down, or do you just get more mangled cheese? No amount of pressing is gonna make that cheese WEAR DOWN THE GRATER! Wear is a function of relative hardnesses in the metals. The engine is designed with this in mind. There are no tricks to get around it. In any case, the bores and rings are designed to seat properly under normal use. Smart guys with a lot of experience designed them that way, but this guy thinks he knows better because of some circumstantial evidence.

I find it shocking that this guy claims to know better how to break in an engine than the engineers that designed it. A lot of his matter-of-fact statements (e.g. after failure to let your engine warm up, easy break-in is the primary cause of engine failures) come with absolutely no support.

He says: "So why do all the owner's manuals say to take it easy for the first
thousand miles?" but doesn't answer the question. Still, he claims he knows better.

Anyway, that's my analysis of his logic. I'm not an engineer and I don't have a lot of experience with dynos, but this is how I see it. If dyno and longevity tests prove me wrong, I'll accept that, but this guy's argument is specious.

Lastly, his experience is only with motorbike engines, but he claims the method will work for all four-strokes. Car engines -- particularly big ones -- undergo levels of stress unseen in most motorbike engines just thanks to the weight of the rotating components. It's quite a leap to say that anything that works on a 750cc motorbike engine will also work in a 4-litre V8. I certainly wouldn't bet my engine on it.

[High Compression II]

There is nothing new to this process--Piston rings are nearly always hard-chrome plated on the rubbing surfaces, and are VERY much harder than the cylinder liner/bore..........

This method of break-in is nearly identical to that recommended by Mercedes for its new engines, which usually happens (or should) before the new vehicle is delivered.....

I have used this method and the 'conventional method', and find that engines run hard as described, perform much better through their lives than those that have been pampered.

The extra heat developed in critical areas during this process 'Work-Hardens' the metal surfaces, and they wear better.

The first oil change at a very low milage is pretty essential too and with the filter, although I tend to leave it to 50 miles on my rebuilt engines.......

[Dave M]

I've seen this before. His logic is flawed.

He's asserting that in a normal easy break-in, the cylinder liners wear away the piston rings, making the rings match the not-perfectly-smooth surface of the new bores. But, he says, if you run the engine hard, the rings will wear the bores down so that they're perfectly smooth, and that's what creates more power.

I gathered that his logic was as follows:

New rings, under less pressure, will not shape themselves into the hone marks as well as they would under greater compression (good seal=less blow-by=more power). Without enough pressure (whatever he thinks that is) he contends that the rings will simply 'file' down the hone marks without creating that necessary 'mesh' between ring and cylinder wall. I don't think he stated that if you run the engine hard, the rings will wear the bores down so that they're perfectly smooth, and that's what creates more power, I think he believes quite the opposite.

Either way, it is just a theory :)

Dave M

[Jay 535i]

I gathered that his logic was as follows:

New rings, under less pressure, will not shape themselves into the hone marks as well as they would under greater compression (good seal=less blow-by=more power). Without enough pressure (whatever he thinks that is) he contends that the rings will simply 'file' down the hone marks without creating that necessary 'mesh' between ring and cylinder wall. I don't think he stated that if you run the engine hard, the rings will wear the bores down so that they're perfectly smooth, and that's what creates more power, I think he believes quite the opposite.

Either way, it is just a theory :)

Dave M

That's not how I read it, but you may be right.

I'm not saying it doesn't work. But for me to be convinced, I'd want more than anecdotal evidence and unsupported assertions, which is all he provides.

[Interceptor]

There is nothing new to this process--Piston rings are nearly always hard-chrome plated on the rubbing surfaces, and are VERY much harder than the cylinder liner/bore..........

This method of break-in is nearly identical to that recommended by Mercedes for its new engines, which usually happens (or should) before the new vehicle is delivered.....

I have used this method and the 'conventional method', and find that engines run hard as described, perform much better through their lives than those that have been pampered.

The extra heat developed in critical areas during this process 'Work-Hardens' the metal surfaces, and they wear better.

The first oil change at a very low milage is pretty essential too and with the filter, although I tend to leave it to 50 miles on my rebuilt engines.......
Wow, this is the first REAL experience I've read about this method. So you definitely suggest the quick'n'hard brake-in?

[Torque]

Interesting read ... but, I trust engineers much more than someone I have never heard of.

[JohnC]

ive always wondered about hard driving on a new engine. this guy i know swears by it and drives his new cars like a maniac; full accelaration to near brake locking stops for the first few weeks of owning his cars.

if i take european delivery does that mean i shouldnt drive at 155 on the autobahn? because that would defeat the whole purpose of going there to get my car.

[Paul in NZ]

i beleive there is some merit to his arguments.I have run in a lot of new motorbikes and for the first few hundred would just ride it completely normally,but varying engine speed never labouring,and very soon in its life start giving large throttle openings,but only for short periods,and never let it get too hot...air cooled remember.My mates did this too and our bikes were always nicer than most others of the same model faster smoother AND more economical.I wouldnt baby a new car but i dont think i would go quite as far as this guy....oil change soon though