Running in new engine

[Riceburner]

Just wondering what you guys do when running in or breaking in a newly rebuilt engine?

 

I'll be building a new L31 bottom end with a very lightly refreshed PMC head. My last engine was all fully rebuilt, so I did a follows:

 

1) Prime oil system, start engine, run at 2,000rpm for 20mins then shut off and closely check over.

2) Start engine, get to temp, then drive, pick a quiet road and in 3rd gear do short full throttle pulls no higher than 5,000rpm then completely off the gas until revs drop below 2,000rpm and repeat many times.

3) Don't exceed 5,000rpm for the first 500 miles.

4) At 500 miles drop oil, change oil filter and enjoy.

 

Is this ok, how does your procedure differ?

If the cam/head is already 'run in' will that alter the process?

Does a dyno run in procedure differ from an on the road run in?

[44014]

No need to start and run it for 20 min at first start up as that's how you run the cam in.

All i have ever done is take it for a short drive using about half to 3/4 throttle every where and only going about half way through the rev range.

take it home and check it over for leaks and loose bolts.

Then flog the pussy out of it.

it will bed the rings in better with high revs and full acceleration due to the higher combustion pressures getting behind the compression rings and forcing them onto the cylinder walls harder.

There is science behind this.

Worse thing you can do is drive it gently when its fresh.

But you will also get a million different responses about this topic.

Most are outdated and have no credential other then "that's what i was taught"

Look at every performance engine and think what the first thing that is done to them... Run at max load at max rpm on a engine dyno.

Machining tolerances are much better these days and there is no need to "wear thing in"before being able to put load on them.

After first drive change the oil ( use cheap mineral oil for run in about 500km ) then change to a good quality synthetic.

 

Cheers Doug

 

[PZG302]

Yup, pretty much what Doug said.

 

My last few race engines have been run in tuning on the dyno and then out on the track competing.

[pauly_adams]

I used nulon 10w30 mineral oil when breaking in mine, all I did is just warmed up my engine to operating temp then just cained the backside out of it. it has been very happy with know signs of any trouble, it has even seen upwards of 20psi of boost

[PB260Z]

I was have always been told that you should avoid sitting on the same RPM for any length of time during the first 500 miles as well.

[Riceburner]

Interesting, thanks guys.

 

Ok, I'll bin the out dated steps in favour of the new short list. I'll keep the warm up cycle though as the oil filter bypass valve is gone, so I don't want to flog it before the oil is warmed up.

 

The Penrite 15w40 break in oil I have says to drive for 500miles and then change, is this wise or do I drop it and the filter after a few hours of running?

[Riceburner]

Good point PB, I have heard that too and adhered to it on the last engine. I'll probably do it on this one too.

[luvemfast]

I'd also recommend that all your core plugs are inserted correctly.

Wouldn't want to lose one at the track.

Or something........ 

[Clockwork]

What's the reasoning behind staying away from same rpm during first 500?

 

 

[Riceburner]

I'd also recommend that all your core plugs are inserted correctly.

Wouldn't want to lose one at the track.

Or something........ 

 

Ha! I'll be JB welding them again 

 

Clockwork, I'm not sure why. Perhaps it comes back to cylinder pressures and ring sealing?

[44014]

What's the reasoning behind staying away from same rpm during first 500?

Staying at the same rpm means you are cruising and have minimum throttle opening.

This in turns will mean you have a lower compression due to the butterfly's in the carbs/throttle body not letting much air into the engine.

This will allow the compression rings to relax and not push against the walls of the cylinder evenly or with much pressure. So before there is a chance for the rings to bed and find there " groove " there is a chance the rings could walk and possibly align the ring gaps and greatly reducing the performance of the engine.

 

Cheers Doug