I'm one of those people who fully believe engine break in periods are old wives tales. I have never had any engine related problems when punching my cars right off the lot. In fact, my stock cars always run faster quarters then other completely stock car (could be the driver). It's an old wives tale... propagated probably cause car companies want you to put "600" miles on the car simply to get used to driving it before you punch it (Law suit related probably). If an engine is gonna have something major wrong with it, you'll know it within 50 miles of owning it. Hell, most of us wont own it long enough to even notice a problem with the engine at this point.

In many years, I have never heard any real evidence saying why you should "break" it in.

 

I tend to agree. If the break-in period were THAT sensitive, then it wouldn't be left up to the owner. It would be broken in at the factory or some other means. Motors, especially the F20c, I can't imagine, just aren't that sensitive...

 

It all depends on your goals with the engine... if longevity is your goal, then be gentle for 1000 miles. If the engine is just for racing, then go at it right away. There's a reason your cars were faster in the 1/4, it's because they were looser. A looser engine is faster. But by loosening the engine up early, you will cut some life off of it. How much life is debatable... If you use good lubricants, I'm sure 100k is still attainable. An 'anal' break-in and a granny driver may yeild a 200k mile engine, but as far as I'm concerned the S2K is for driving hard. If I have to rebuild the engine at 75k, so be it. I'm going to have more fun during those 75k than the 200k mile guy!

 

The valvetrain can take a beating, Especially in the first 30 min of operation, Im not sure how long its run or what they do at the factory? When I finish putting an engine together, thats my first worry is the valvetrain. The first few hundred miles harden the cam surfaces AND gear surfaces AND differential parts AND wheel bearings . . . In a new car anyway. . .
Very important if you dont want scoring on the gear faces or cam lobes. Of course there is the problem of seating the rings, its recommended that you accelerate at WOT and decelerate at closed throttle w/ engine brakingso the cylinder pressures push harder on the rings. But after that its back to being easy on it.

Of course you can get lucky when skipping a "Break in" but I wouldnt want to chance it.

 

I disagree, break-in is important on any engine whether it is hundreds of miles on a street engine or an hour on a competition engine.

If you have built or re-built any engines you quickly come to appreciate all the many friction surfaces that have microscopic irregularities on their surfaces that must be

 

And now for something completely different.

I have seen studies showing that engines broken in with synthetic oil and upper cylinder lubricant additives break in the best. Awesome bore / ring seal. BUT it takes longer. Some claim that if you can live with the longer process you'll get the best results of all. (I haven't tried this out.)

Stan

 

[QUOTE]Originally posted by E30M3:
[B] I have seen studies showing that engines broken in with synthetic oil and upper cylinder lubricant additives break in the best. Awesome bore / ring seal.

 

<<A study by Redline Oil suggests exactly the opposite, and the machine shop I worked with building engines always recommended against synthetic for break-in. >>

What is the URL for this study? I don't know about this one but I have noticed that many break-in suggestions are oriented toward getting the break in over with as quickly as possible. Almost as if it's an emergency or something. As in someone is complaining that they had to spend big bucks on two quarts of oil due to oil consumption and they want this to stop IMMEDIATELY. It might be the case that the best break-ins are not always the fastest and vice versa. Some street car motors ssem to turn in their best accel times after around 30,000 miles. They are broken in well before that point of course.

<<What study are you referring to and can you post it or a URL.?>>

I don't have any URLs. Correspondance in one of the English race car tech journals, Circle Track magazine, etc. I might have one handy from David Vizard. I'll see if I can locate the article from one of his many books. I think thst in the DV case break-in took about twice as long as usual. Visual inspection of the bore surfaces showed a more refined finish. If I can locate some of the above I'll try to type in the main points.

Another thing about break in is that a wide range of loads and RPMs are needed. Preferably no constant load, constant RPM efforts.

Another factor is that the piston / rod asembly stretches a bit at high RPM. So the piston can rise slightly higher up the bore at high revs due to the higher loads. Some improved touring racer friends suggest that when they drop in a new used street motor that they need to be careful about RPMs at first. Cuz a used street motor which was rarely revved has a portion of the upper bore that has seen little wear. If you just start racing the motor right away you can crack a ring since it can hit the start of the ridge that deveops at the top in some cases.

For the S2k you sorta need to break it in at 6000 and below at first and then 6000-9000 RPMs since the high rev cams don't get much use during the nonvtec period. And the rod/piston stretch is insignificant below 6000 RPM too.

Stan

 

I agree that break in is a necessary action if you want your engine to last.

A personal story - I bought the first Toyota Supra to be sold in South Carolina in 1982. Unfortunately, the dealer had allowed many people to test drive the car and they, of course, were not light footed. It had almost 400 tough miles on it when I took it home. At less than 7,000 miles the head had to be pulled and resurfaced. It had warped badly due to the initial stress put on it in that first 400 miles according to the machine shop. It just managed to keep the head gasket in it until a little bit later.

After an appropriate break in when I got it back, the car went over 125,000 miles before I finally sold it with no other engine related problems.

 

[QUOTE]Originally posted by E30M3:
[B]<<A study by Redline Oil suggests exactly the opposite, and the machine shop I worked with building engines always recommended against synthetic for break-in. >>

What is the URL for this study?