engine break-in methods and reasons?

[BerniniCaCO3]

Hi!

Hopefully, hopefully, driving off next thursday with my new engine. Every little thing is adding more time, if this had been a straight swap, would've been done a week ago...

Anyway, here's the advice I've heard from a few sources.
To keep the revs high, over 2000 rpm anyway and specifically avoiding idling
Also to keep the revs varying, avoid letting the engine stay at just one speed?

I've also heard, from more than once source, to use standard oil for the first two oil changes (at say 50 miles, and at 1500) and THEN to switch to synthetic, and importantly-- that the reason wasn't just to avoid wasting good expensive synthetic, that there was an engineering reason...


I was wondering if this matches what you've heard,
But really, I have no problem with the above, but I would like to know WHY. What's important about keeping the engine speed up? And why would, say, my sister's nissan user manual tell her to avoid staying at any one speed for too long? Everything is spinning in the engine at any speed, so jogging it from 500-3500 and back again, what is the idea behind it?

Finally, I don't mind advice that tells me to use cheap oil for my first two throw-away oil changes, but what would synthetic do? Is it just too thin...?

thanks for the enlightenment!

[1990LTD]

You break it in at 2k if you have a flat tappet cam. They wear differently than a roller cam and need to be broken in properly or else the camshaft itself will have worn unevenly causing lots of fun problems. Yours is a roller motor IIRC... not an issue.


I could be completely wrong in my understanding of engine assembly

[sly]

roller: take a moderate trip and don't use the cruise control. City driving for first 100-500 miles. Change the oil. Then go on that trip or put some good highway miles on it. or so the rumor goes.

flat tappet: umm... yeah... never played with these and haven't heard anything either.

That's what I've heard. YMMV

[gadget73]

The reason you don't use synthetic initially is because you need the friction to seat the rings. Synthetics are slick enough that it will cut enough friction between the ring and cylinder wall that they will not wear to each other for a proper seal.

[86VickyLX]

I broke my engine in on an engine dyno. when I put the engine in the car, the first drive was 5 miles home, the next was 110 miles to skippyville for scottfest. then hilly driving during the cruise. a couple burnouts, highway trip to junkyard and back. then back home. that was my break in period.

[1987cp]

My biggest concern about engine breakin used to be minimal friction; now after a grand total of two rebuilds of my own and helping with two others, and lots of reading, my priority if there's a next time will be proper ring seal. My original education was to always slather the pistons and rings and cylinder walls in lots of heavy oil to ensure minimal friction at first startup. I've since learned that some guys actually install their pistons bone-dry to ensure that the rings break in and establish a wear pattern as soon as possible, and then beat the %&#! out of it as soon as they know nothing's grinding and the tune is safe.

IMO, no one these days ought to use a flat-tappet cam for the most part, so all that garbage related to making sure the cam breaks in properly goes right out the window for my purposes. The best thing about a roller cam is its performance potential, the second best is the potential longevity, and the third best thing, except it's a huge one at assembly and first startup, is that there's ZERO need for that stupid 2500-rpm-for-lots-of-minutes routine you may have read about in the past.

[cld783]

I like to beat the piss out of em.. that way they know what to expect from future use.

[86VickyLX]

Once you've determined that there's good oil pressure, no leaks. etc. beat the fuck out of it. if it breaks right then and there you fail at building engines. pay someone who knows what they're doing build one.

[1987cp]

I guess that might be one argument for getting a custom-calibrated carburetor for a newly-assembled engine. Probably far less likely to be firing it up with an unsafe tune than by slapping an OOTB carb on something that is to you an unknown quantity.

[1980c10]

If flat tappet, follow the manufactures recomended break it for the cam. Then rip on it hard lol. If a roller just go rip on it. I do use magnetic drain plugs I also change the oil after 100 miles then 500 then up to the normal 3000.

[91waggin]

Here's what I've heard:
1) Roller cam? Beat the piss out of it. That way you get a good ring seal. Read this: http://www.mototuneusa.com/break_in_secrets.htm scroll all the way down and look at the pictures. Unbelievable.
2) Don't use synthetic until you're a couple oil changes in. You need some friction to get the rings to seal.

[sly]

fascinating reading in that link.

the only new vehicle I've ever had was that 06 super crew... and I beat the hell outta that truck. I did not, however, know to change the oil that soon at that time. (most of the stuff I've learned about newer engines, I've learned in the past 3-4 years) I've only ever dealt with old stuff that was new to me.

[PushnFords]

I guess that might be one argument for getting a custom-calibrated carburetor for a newly-assembled engine. Probably far less likely to be firing it up with an unsafe tune than by slapping an OOTB carb on something that is to you an unknown quantity.

I always tried to get the carb rebuilt and tuned, ignition set up, and all of that related stuff on the old engine. Then I'd swap that over to the new engine so I could get it fired up and run the cam break in period without worrying about something else screwing up.

As far as engine assembly, I use assembly lube on everything and the pistons/rings get dipped before assembly. I'll wipe most of the excess out of the cylinder above the piston though...just leave a light film there. For the first couple of oil changes use a diesel or specialty oil that is high in zinc and get some of the cam break in supplement from the cam companies. The new oil doesn't have as much zinc and there have been tons of cam failures shortly after break in. Either way I change oil right after break in, at 500 miles, 1,000 miles, 3,000 miles and then usually go to around 4500 depending on what use the engine gets. After the initial break in I drive "normally" with no racing or extreme use and varying speeds. After 500 miles or so just drive as you usually do.

[sick88tbird]

There's a lot of good information in here...most break-ins with flat-tappet cams require varying rpm between 1500-3000 and an oil with high zinc content. After 15-20 minutes of that, change the oil. Than easy driving with varying engine speeds and change again at 500miles then go every 3000miles. Roller cams are much easier...no break-in required for just a new cam. The traditional engine break-in with a roller cam was 2000rpm for 20 minutes to seat the rings...but a lot of people in the past few years have said full-throttle accel and decel helped seat the rings better....regardless, use a quality oil and make sure everything is right before beating it to death and you'll be fine.

Good luck,
Don

[1987cp]

I always tried to get the carb rebuilt and tuned, ignition set up, and all of that related stuff on the old engine. Then I'd swap that over to the new engine so I could get it fired up and run the cam break in period without worrying about something else screwing up.

Ah, see, I was assuming a given new engine was liable to be totally different than the old one. I figure a tune that's perfect for one engine could conceivably run its replacement way lean and punch neat little holes in the pistons, thus the concern.