FoxGT

There's a reason people run their engines full throttle when they're breaking it in. The more pressure in the combustion chamber the more pressure there will be pushing the piston rings against the cylinders. If you've honed the cylinder right the design acts like a file and files down the piston rings to make a good seal. The piston rings are going to wear down the filing surface rather quickly. New rings are sharp and at an angle the cylinder doesn't agree with. You don't put much pressure behind the rings then they wont wear as much and soon the file like surface will be gone with rings that aren't broken in. On top of full throttleing you have to let the engine slow the car down a few times. Like when you're coming up to a stop light doing 55mph put it in 4th gearand let the engine slow down the car a bit. It's best to do it on the first engine warm up and Don't start the car and let it idle until warm-up.The idea is to start the car up, drive and vary the rpm until it reaches operating temperature, then open it up, but don't go to redline at any time until after the 500 mile break in. Just take it full throttle to 4000rpm is fine, then let the engine slow the car back down to the rpm you started at, dont use the brakes. Around three bursts the first time you run the car, then for the next 500 miles just try not to keep the rpm constant and open it up occasionally, but never to redline.

The other alternative to that is the same process, take it easy with short full throttle bursts and let the engine slow the car down a few times. The only problem with that is by the time you do put lots of pressure on the rings the file like surface is already rubbed away. Which way you choose to do it is up to you.

It's very important that you dont get on it during the break-in and after the break in while the engine's still cold this will cause lots of wear on parts. And important that you change the oil after 500 miles.

luckythirteen13

ive also heard its good to let the motor do some breaking when slowing down. ive also heard that you should get the car rolling from second and then shift into 3rd to put a load on the motor

2 kwik

pretty much all the above is bullsh!t.. first thing to be known is what type rings you will be using will dictate break in procedures!!!!!!!!!!!

luckythirteen13

so how about for moly rings?

2 kwik

moly don't "cut in" like iron.. hence why they are honed lighter with a different stone...they seat quickly... a great choice....

luckythirteen13

so what would you recommend for my new motor? i know to stay out of boost, thats a given. but ive heard more "propper" break in procedures then i can remember

2 kwik

where the rings file fitted? I have pushed engines to 9200rpm after a 30 mins break in

luckythirteen13

what is file fitted?

2 kwik

this is when you "file" the gaps on your rings as each cyl warrants

Chitown racer

Lmao...Now thats about the truest statement Ive seen in this threadso far. First of all, the rings used in todays engines whether they be moly or plasma moly are seated from the moment the engine fires. Do to the advancesmade over the last 2 decades in ring design and cylinder prep, most of that advice is outdated and some of it was never really valid to begin with. Any engine builder that gives you the ring break in speech either learned to build engines from his grandpappy or from a how to book copyrighted before 1985. Bearings do not need to "settle into anything" careful machine work and proper clearances are set up when the engines are built (hopefully).As far asthe statement about thecylinder walls are honedbecause theyfile the rings down, which is how they seat,let me say this. Like the bearings, careful attention is paid to piston ring clearance during the building of any engine. The rings are carefully checked and accurately gapped within a thousand or so forthier particular application ( blown and nitrous applications prefer alittle wider end gap than an N/A engine). This filing you speak of would cause an excessive gap and serious blow by by cutting into the cylinder wall and effectively "unseating" ordestroyingyour rings.As wellit would introduce shaved metal into the cylinder which wouldcontaminate the oil and circulate into the rest of the engine and at the very least destroy the bearings. Without getting too technical, the reason a cylinder is machined to a particular finish and not polished smooth is simply to retain the oil that lubes the pistons and rings. As for the rest of it, roller cams dont need to be broken in period, any cam manufacture worth a damn will tell you that.

I'm not saying run right out and peg the tach first time out. Care should always be taken with a new engine the first time out. Dont hammer on it until you test drove it a few times and have done a few part throttle blasts, just to insure nothing drastic is going to happen. It will give you a chance to check for leaks and insure you havent missed anything that might come back and bite you in the ***.