Proper engine break-in technique
 

This is probably useful information since some of these builds no doubt cost a small fortune.

i followed FM guideline and am going to break in by driving 200 miles under varying yet high load while keeping out of boost. proper ring seat needs high load, but the added boost fro the turbo can be excessive and leed to improper seating of the rings.

this method appears to be debatable. what is the ideal method for breaking in a turboed miata engine?

thread jacking f***ers , you know who you are.

I think that sounds great.

http://www.mototuneusa.com/break_in_secrets.htm

Thats a great article, similar to the method FM has. Vary the load, vary the throttle, no highway driving, dont be a pussy.

If you already have a good base tune. Run it once to full temp while still on stands, check for leaks, change oil, then put it on the road and beat the fuck out of it. Lots of high rpm and then let out the throttle to let it engine break and pull mega vacuum. This is how I've done it for years. I get perfect ring seal every time.

My breakin procedure was:

1) start it in the garage, check everything for 5 minutes.
2) drive around the block for 5 minutes, pull back into garage, check everything again.
3) drive around for 30 miles staying out of boost, doing the high-vacuum coast down thing.
4) change oil.
5) drive around another 270 miles at 7 psi.
6) 30 pulls on the dyno at up to 15 psi, added about 30 miles to the odometer doing this.
7) Laguna Seca. :)

--Ian

My break-in
1) idle for about 3-minutes on shitty Castrol GTX
2) cut cheapo filter to check for metal, smile at results, put a wix on
3) 5-7 runs of 4500rpm-1000rpm overrun
4) change oil and look for metal
5) road tune at 14psi
6) taking about 100-miles until 7000rpm
7) at 500 miles put in synthetic Rotalla, tune that bitch, track it, get bitches, make money

It appears that I may have made a mistake by using synthetic oil fromt he start. I wonder if this causes the ring seating process to take longer?

Break in for the past 2 motors I built:

1) Warm up, change oil and check filter
2) Disconnect wastegate, several WOT runs to 6k, then coast to 1k in second or third.
3) Change oil, check and change filter.
4) Reconnect wastegate, turn boost up and tune.

The break in happens in the first 20 or so minutes of you driving, after that, if shit is going to break, it *usually* would have done so. What I was referring to in the other thread was the 200 miles with no boost, there is no reason to do that. The rings need to seat, then after that, it is all over. Bearings don't need a wear in period.

Well then, I'm at 100 miles. When I get back from Indianapolis I will change the oil and start tuning boost. Should I run the boost in stages, i.e. run at 12psi for a while, then 18psi, then 22psi. Or just tune for 22psi and be happy? Honestly, if rings seat in the first 20 minutes, then I was not hard enough on the engine in the first 20 min. I was waiting to see/hear if anything was going to break while I was driving around during the first 20 min.

That is the mentality that most people have, but think of it like this. If something is going to break, it's going to break either way. You might prolong it by babying the motor, but the first time you go WOT, if it isn't put together right, you'll know :).

Most modern cars have synthetic put in from the factory. So even though that is a "myth", it's not true.

Good thread! I think this will be helpful to a lot of people.

Any break-in procedure should use graduated engine speed steps. You want to see high load and high vacuum, but set an rpm ramp up schedule. For the bikes my brother and I have always done something like 50% redline for 50 miles, then an additional 25% for another 25 miles.

It was helpful to me. I'm going to be breaking mine in soon

Explain to me why this matters. After the motor is warmed up, does the motor care what rpm its at? What empirical evidence do you have that shows that you need to graduate the rpms?

To explain my point using your numbers Go. Say you stay at 50% throttle for 50mi. Assume that you have a redline of 10k, not unusual for a bike, and you cruise at 50mph at a constant rate of 5k rpm. You would complete that graduated step in 1hr. In that time your engine would have made 300,000 revolutions. If you think that the rings have not seated well into that count then you are on crack.

I've heard the "step up the RPM" thing before too, but once again, after 20 miles (probably less actually) the rings are seated. The bearings don't need that kind of special treatment either, they are floating on a film of oil and don't need a 'break in' at all, aside from warming up the car the first time to ensure the clearances are correct.

Well, hopefully you ensured your bearing clearances well before first start, or assembly for that matter :P

Also, I disagree that things don't continue to break in after the first like 5min. Although, I would rather use the term "wear in". Sure your motor will continue to loosen up, but the initial ring seal is achieved mostly during initial warm up, then you get it on the road and beat it (with a good tune) with high rpm/very high vacuum to get maximum seal.

You can verify this simply with a compression tester. The last motor I rebuilt, in the miata I sold to nate the snake, I ran a compression test on it before I ever even started it for the first time while verifying that the tbelt was on properly. I achieved 150 or 160 (cant remembet) on all cylinders with no deviation before it was ever even started.

Indeed, but say you assembled your engine in your unheated garage, in the winter, warming the car up for the first time could actually bring things out of spec.

Just look at F1 motors, they run clearances to tight that they have to heat the motor up before they start it or they'll spin bearings.

Are you kidding? Engine speed kills everything. You're talking about flexing non-seated rings at twice the frequency. Simple dynamics, you're increasing the cycle of forces for a set amount of time on a parts that have not completely mated.

No, I don't have any empirical evidence, and it's only theory coupled with common sense, so feel free to disprove it.

I will admit that one good case for going across the whole rev range is to avoid ring ledges in the cylinder from forming. But that won't happen in 50 miles, and I still recommend varying the rpms, a lot, to aid that. Gradually stepping it up will see slightly more rod stretch and form a nice, smooth ramp at the top and bottom of the stroke as opposed to a ledge. I definitely don't recommend sitting at any given rpm, and it's better to really make it an analog increase, not a step-wise one as suggested by the manufacturer.

Regardless I think we can both agree that the more important aspect of a break in is load. BMEP is what really determines how well the rings seat. This can easily be achieved within a smaller portion of the rev range since peak cylinder pressures remain the same, only with lower frequency. Once the ridges have begun to wear down it would be prudent to increase that frequency, and prepare the motor for it's intended operation.


EDIT: A few other posts were made while writing...I definitely don't recommend just sitting on the highway at 5K rpm for an hour. That would be the stupidest possible way to break-in a motor. But if you seriously thing that engine speed doesn't have a negative impact on part wear you my friend are the one using the crack. There is absolutely no reason to "rev it up" from the get go. Yes, vary rpm, yes, increase rpm, yes, you need to be using the whole rev range in less than 100 miles, but have you done any real research on just how many revolutions it takes to seat the rings? I've seen UOAs from 250mile break ins that were still showing cylinder wall material removal.

I'm not kidding at all, the rings will not flex more at first start than they will during the duration of their lifetime. The purpose of getting high RPM soon and quickly is because the principle that ring seal works on is applying gas pressure to the top and back of the ring through load. The more load the more pressure.