4g63 break-in experience

[kjewer1]

I see this question come up a lot, so I figure I post what I have seen with my motors over the years as far as break in goes.

3rd factory motor went in the car (first three all eventually crankwalked). I got lazy and didnt change the oil until 3k miles. It looked as silver as the anti-sieze compound you put on your turbo bolts. When I tore it down at 50k miles, the main bearings all had grooves worn into them connecting the oiling holes from large particle contamination. I doubt the rod bearings looked much better. Rule number 1, change the oil frequently.

Next was a 100k mile used 6 bolt block. No breakin required. Jsut changed the oil at ~20 miles and again at 300-500. Went to 3k intervals after that. Motor went another 30k running low 12s and was fine when I pulled it. 155-160 comrpession.

Next was a SBR stage 2 block. I changed the oil soon after running it just long enough to check for leaks, at 100 miles, 500 miles, 1k miles, and 3k miles. Then went to normal change interval of 3k miles. Mike had told me to break the motor in hard. And I had heard this theory before then. I was reluctant, but figured I would give it a try. Unfortunately the turbo died very soon after starting to run that motor (In my epxerience breaking in a new motor kills the turbo every single time, even with frequent oil changes). So I couldnt break it in very hard. At 1000 miles, compression was still poor. And in fact, one cylinder lagged behind for some time. At 10k miles compression was finally getting up to where it should be, 170 or so. At 20k miles the number 2 spark plug lost the ceramic insulator, and that ruined the piston, ring, and wall. Sent it out to be rebuilt again.

SBR rebuilt that motor, a little higher compression and some other changes. I changed the oil as I decribed above. But this time I was able to break it in hard. I let it run for about 20 miles jsut to be sure there are no leaks, and then started to boost. I cant go below 20 psi, so thats the boost I used. I didnt rev it high, but boosted for short periods of time, letting off at say 5k rpm. Did that until 100 miles or so (the ride from my garage to my condo). Still no leaks or other problems so I gradually raised the RPM over the next hundred miles or so, still boost set to 20 psi. I checked the compression at less than 1000 miles, maybe 700 or so, and all 4 cylinders were at 195 psi. I can honestly say the hard breakin made a world of difference. I've never had a motor come to full compression so soon.

So the cliff notes version is this. Change the oil OFTEN after initial start up to remove the particles created in the "machining process" that we call break in. Dont be afraid to boost it, but watch the rpms until its got a couple hundred miles on it. The boost actually drives the rings into the cross hatch on the cylinder wall, seating them. Driving like a pussy for too long will allow the crosshatch to be worn off the cylinder wall before the ring is ground to the same shape! So dont be a pussy, drive it on!

NT cars, I cant comment on. There is no boost to help seat the rings, but cylinder pressure should serve the same purpose. I would suggest the same oil change intervals, and drive the car hard, but gradually increase the rpms as the mileage goes up. Watch compression to see when it is broken in. Bearings break in quickly. Its the rings that we're worried about.

Hope that helps.

[aaronh2005]

what is crank walk? ive heard before but its new to me

[joemathews]

Thrust bearing failure. Seeearch the forum, or check Kevin's thread at RacingKnowledge.org here:

http://www.racingknowledge.org/topic.asp?TOPIC_ID=185

Thanks for the write up, Kevin; I'll definitely forward that on to my buddy. I'll recommend he change the oil right away, because I don't believe he's done so since installing the new pistons during the 800 miles he's driven it.

[BoostedSpyder]

hey what about clutch master/slave cylinder break in? i was told by a buddy that i should wait to adjust the clutch pedal for a couple of weeks use to get the master/slave broke in. it is making me crazy disengaging all the way at the floor...

[1stGenRocks]

boosted just adjust it youll have to readjust it in a couple weeks when the seal seats is all

[BoostedSpyder]

ok cool thanks!