Motoman Break In

[Dr_Snooz]

Somewhere on here is a thread where I poo poo the Motoman engine break in method. The irony is that it is exactly how I broke my new engine in. I'm not a racer and I want the car to last forever, so what happened?

The method prescribes a series of 4th gear WOT pulls up to red line. This is in complete contrast to what you'll read in any factory owner's manual. Honda tells you to avoid WOT, stay below a certain rpm range, etc. Going so radically against this advice unnerving.

Motoman insists that you won't get a good ring seal if you don't hammer the engine and he has lots of pictures of pistons broken in his way vs. the standard way. It does appear that there is more blowby in the standard engines. I definitely don't want blowby, so I had to consider his advice carefully. He states that you have to force the rings against the cylinder walls within the first 20 miles or the cylinder honing will be worn off and the rings won't seat...ever. The only way to prevent this calamity is by running the engine flat out.

This is one man's opinion, of course. What swayed me was reading around the web. All kinds of motorcycle riders, racers, auto racers and even airplane mechanics ascribe to his method. Not one single person relayed a disaster story. There were also a lot of stories about how car factories take engines off the production line, fire them up and run them right up to red line routinely. What clinched it though was all the old time machinists and engine builders who chimed in on the discussion boards with their own versions of Motoman's break in that they've used since the dawn of time. Guys with lots of engines under their belts were saying that the only way to get an engine to run well and long was to hammer it after the first start up. I was sold.

The engine did not blow up. Oil pressure is somewhere over 60 psi. Vacuum is near 20 Hg. Hooray! It runs quiet and smooth.

If you want to try it, be careful, 6000 rpm in 4th gear is north of 115 mph. Have a long runway and no traffic. Vacuum loading is as important as WOT pulls, so don't run up to red line and then brake. You want to coast with the car in gear back down to the prescribed lower rpm. When you are done, CHANGE THE OIL. It will be full of metal and you don't want that circulating through your new engine. Change the oil again after 500 miles. Once you've done the break in, you're done. Go out and have fun!

[Bass Man]

What about spinning a bearing cuz you pushed it too hard? That's what I'm worried about with this engine I'm building for my dad.

[Oldblueaccord]

Its really dependant on type of rings used and the type of hone on the cylinder walls. The newer style aftermarket rings are very hard and do need to be run hard to be seated. I dont think I would be doing that on a brand new rebuilt engine myself but overhead cams would be safer then hydrualic lifters as far as cam wear.


wp

[ecogabriel]

What about spinning a bearing cuz you pushed it too hard? That's what I'm worried about with this engine I'm building for my dad.

If the engine has been machined and assembled right that should not be an issue. In fact, if there is any wear on the bearings so early in the life of the engine, then something is wrong either with machining work, assembly, or parts.

I got a mechanic rebuilt an engine for me several years ago; back then he had told me that the shop honed the cylinder walls with a very coarse pattern. That way they ensured that piston rings would seat properly and would not have complaints later; he did not like it at first but over time he saw that it worked fine.
He added that I should NOT drive the car like a sissy during break-in or I would have a crappy car afterwards - no power and high oil consumption. He suggested driving as to give it load -up to 70-75% of the rpm range was fine for him. Notice that machining was done differently.
After breaking-in the thing was a blast to drive; no blowby (endemic on those old engines), little oil consumption (1/2 liter every 5k) and it pulled very, very hard when pressed

Bottom line: that guy on the internet has a point, and especially so considering how machining is done today.

[ecogabriel]

Its really dependant on type of rings used and the type of hone on the cylinder walls. The newer style aftermarket rings are very hard and do need to be run hard to be seated. I dont think I would be doing that on a brand new rebuilt engine myself but overhead cams would be safer then hydrualic lifters as far as cam wear.


wp

If I remember right, the A20 head is designed in a way that the camshaft sits on top of an oil pool so the cam lobes are always covered with a layer of oil.

[87roach]

I also did the break-in on my new engine this way. However I did not have that huge of a runway to get up to that sort of speed... but I did what I could. I haven't been able to check the compression yet but she did put down 129hp and 131tq at the dyno.

[Dr_Snooz]

Just talked to an airplane mechanic friend of mine. They break in all their airplane engines by running them against the wall shortly after the first start. GM is said to fire up every engine off the line, and run it up to redline. The theory is that if the engine is going to blow, they want it to blow right there. Obviously, it doesn't hurt them too much. We'll see if she holds up over the long run, but I'm not terribly worried. It's hard to argue with the factory, but harder still to argue with all the old grizzled engine building veterans.

[AccordB20A]

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