Running in a new engine - Run it Hard or easy-in ?

[Sharpie]

Just looking around at what has been done over the pond and see some people running-in a new engine "Hard" rather than the more traditional way.

Supraforums thread:
http://www.supraforums.com/forum/showthread.php?t=56491

Running in the engine the hard way:
http://www.mototuneusa.com/break_in_secrets.htm

Obviously, I'll be taking the advice of my engine builder but, wondered what other's opinions were ?

[Mike M]

Interesting stuff there from moto man's site but surely companies haven't been giving false info to cause earlier engine failure? Who's to say new cars don't get the rough treatment from the factory.

[JohnA]

There are strong proponents for both schools of thought.

I think that it has more to do with age of design (metalurgy, coatings etc)
Back in the sixities and seventies one had to carefully bed in the mating surfaces, progressively getting a better seal. That's when the 'take it easy' approach was developed, for good reason I'm sure.

In the last decade or two most manufacturers have been use
ing cylinder/ring coatings that don't really need any bedding-in (in the traditional way).
So they give them hell from the factory as a stress test and won't really matter if you do the same.

I'd find it hard to rev a brand-new engine to the redline, but that has to do more with mechanical sympathy on my part and not a real risk of failure.

[stupra]

I remember a test on motorcycle engine's a while ago where they run one engine in carefully, and another hard, i.e they thrashed it from the off. The thrashed bike made more bhp, but the carefully run in engine lasted longer.

I think it's best to give varying loads on a new engine as in town driving, and differant motorway speeds. I don't think the rev's will matter to much, but the way in which you rev it might. I'd just drive normally myself, but I wouldn't thrash it. Just my 2p worth. :)

[Sharpie]

removed

[Kranz]

Ideally the break in procedure should be idle for 1 min to check for leaks, then starting at low rpm (about 1500 rpm) & low load for about 10 mins at each speed/load, then increasing the speed & load until after about 1 hour, max power revs is reached at about 50% load.
Then run the same speed sites again at higher loads..... until finally you end up at 100% load at max power revs.
Then run a power curve and do an oil change.

Gentle to start with, but adding load progressively is the order of the day. And don't use a high quality synthetic oil! Just stick in a moderately good mineral oil :)

[steb9780]

I have talked to two of my workmates about it in the past.

Jon has a Dodge Charger with I think something like an 8.1 Hemi in IIRC, he said he was told to run his re-built engine in hard.

My other mate Mark (Cord on the GTR forums) works at RB motorsport, and he said they run re-built engines in over gently for 1000 miles. He said they'd rather have engine longevity than a few extra horses.

[JODY T]

My other mate Mark (Cord on the GTR forums) works at RB motorsport, and he said they run re-built engines in over gently for 1000 miles. He said they'd rather have engine longevity than a few extra horses.

Thats how we do it at Interpro... :thumbs:

[mattanna]

ran mine in max 3000rpm no second turbo boost, about 85mph top for 1000, she runs like a dream, oil and filter change again after the 1000 and away you go:)