How Should A New Car Be Run In?

[dss123]

Bit of a random one,

 

My bro is a biker and is about to buy a GSXR

 

Apparently, current thinking in biking circles is to rag the crap out of a new bike, in the first few hundred miles, to to achieve a superior piston ring seal?

 

This sounded like a bit of a no-no until I read the attached article, which apparently applies to any 4 stroke engine. It seems to make sense?

 

Anybody have any thoughts on this or do we all follow the softly softly approach?

 

Cheers

 

Dunc

breaking_in.doc

[catboy]

the runnning in process used to be for knocking burrs and things off newly machined components, however with new de-burring techniques, even micro-burrs are removed, and theres little evidence for running in for that reason any more...

 

However, the running in process also has other benefits. Generally when an engine is built, a thinner than std oil is used. This allows oil to penetrate small remote areas, into all the seals, etc, and remove any air from small spaces that would normally be far enough away from the oil pump (with higher viscosity oil) to be immune. This is why a first service is often included gratis with a new car, and is early on in the cars life (6,000 miles or so)

 

There is also the case for allowing seals and gaskets to bed-in and give a more consistent seal. On a k-series engine this is also important in terms of the engine integrity; the head bolts (which hold the whole engine together) stretch during assembly to give a pre-tension on gaskets from top to bottom of the assembly, hence need replacing with head gaskets, rebuilds, etc. By allowing the engine a run-in period, these stretch slowly, over a longer period of time, and can apply a more even pressure across the gaskets, etc.

 

Although most people say "modern engines dont need running in" I would always take the time to do this... 1500-3000 miles under 3000rpm and no heavy loads is not too bad; were talking 60mph+ in most modern cars, which is pretty much bearable. I think its a bit like allowing your engine to warm up before thrashing... some people will say theres no need with modern synthetic oils, etc., however I think its well worth the time, for the extra peace of mind

 

b

 

ps.. once more, sorry for the mega-respose; Im gonna get a reputation as a rambling fool

[Rich111s]

For what it's worth, I think that a run-in period should be adhered to. My girlfriend and I have just completed the run in of our other car, a new M3 Coupe. I spoke to a mechanic at Sytners BMW in Notts and asked the relevance of having to keep below 5k revs for the first 1,200 miles. His response was rather technical (for me!) but the bits I got focussed on the fact that it's thinner oil in the running in period as it can reach the parts other oils can't - which makes it the Heineken of the oil world I guess. It's flushed out and replaced with std stuff in the (free) 1,200 service. He was adament it was necessary, but he would be 'cos it keeps him in a job...!

 

When I got my first S2 111s, Lotus nearly refused to give me my warranty as the bloody print out taken from the car showed I'd spent too much time over the 'allowed' rev limit! Cheeky sods told me I was lucky not to lose it, so they must allocate some importance to it at Hethel?

[PPPMAT]

There are 2 schools of thought I suppose - all I know is, when I got my civic type r a couple of years ago, I ragged the nuts off it from day one and come 7,000 miles or so it was really really fast. It felt even quicker than the s2000 which has another 40 bhp.

 

Modern engines get hammered on the test bench anyway

[dss123]

My understanding from the article is that you need higher revs to get good gas pressure in the cylinder bore which is what forces the piston rings out and onto the cylinder bore surface.

 

When new, this surface is "honed" which gives it a surface like a very very fine file. This surface wears the mating surfaces to create a good piston seal.

 

If you take it easy during the run in process, this bedding in wear still occurs but without the higher gas pressures so the piston rings are not forced out in the same way. A gas tight seal is therefore not achieved by the time the "honing" has been worn smooth.

 

Combustion gases can therefore get past the piston rings loosing power and possibly allowing contaminents to get into your oil and around your engine.

 

Makes sense to me but seems to go against conventional wisdom.

 

Not that I'm fussed - I'm not likely to get a brand new motor any time soon!

 

I just thought it was quite interesting.

 

Duncs

[Tango190]

... Apparently, current thinking in biking circles is to rag the crap out of a new bike, in the first few hundred miles ...

<{POST_SNAPBACK}>

Aah, the Nigel Mansell School of Engineering quote