Best way to quick break-in fresh engine

Hi

finishing my buid of RB30 engine and wanted to hear what do you think of engine break-in procedure?

How long, best practice and so on

I'm planing to do a quick break-in on the road something about 200-300km with low to moderate load and varying RPM from 2 to 4 thousands.

But i heard minds that it is sometimes better to jump staright on the dyno

If so how many hours to spend tuning low-mid loads and mid rpms before jump to ramp runs to tune fool power?

There are two thing affected by break in. The first is the sealing of the piston rings (and compression/leakdown). The "Wide open throttle break in" idea is that it helps the piston rings set into place. In a factory with a new engine, they might do a quick test up to WOT to check the power. So it's not bad for the engine to do that. However a lot of people argue that the piston rings are going to seal anyway and it doesn't matter whether you do it this way or not.

The second thing is reducing the friction of the engine by wearing in the components. The slower method of varying engine speed and load is there to reduce the friction. Friction at a fast rate in the beginning (say the first 100 to 200 km) and then slows down.

Since this is a "rebuilt" engine (not a brand new RB30 with all new everything) with reused components it may not even matter.

Well - buy rebuild i mean bulding an engine

New hone, new pistons, new rings, new rods, new bearings, refresh head, exhaust valve guide was replaced, new valve springs. Well mostly new engine )

Only crank is used RB30 and block is used )

You can run in the engine as easily on the dyno as you can on the road so it's not essential to do it in one particular way. I use a dyno because I have access to one but if I didn't then I wouldn't rent one just to run in the engine.

The key part that you are trying to bed in during this process is the rings. In order to do this effectively you need to use moderate amounts of load so that the combustion pressure gets behind the rings and helps force them against the fresh hone pattern. This however creates heat due to the friction. This is why it's important to vary the load - you want to use periods of moderate load (maybe 50-60% throttle) and follow that with periods of light load (vacuum/overrun). It's the same reason why you don't want to go straight to WOT and redline and hold the engine there.

In reality these days it's actually quite hard to mess up the run-in process due to modern rings and honing techniques but then why take chances? The biggest thing to watch out for or avoid is allowing the engine to idle for extended periods of time when it is up to operating temperature during the first 100-200 km of use.

Also, note this topic covered in detail in the Practical Engine Building course.

Thx for Advices

I put these topic to doublecheck my plans.

So now i'm sure that 200-300km on the road will be enough with mixing moderate load and overrun.