Following on from Chips very good engine building discussion, here is the start of the “running in” technical discussion. Thankyou for volunteering me chip. I’ve done my best. I hope it makes sense.


With a modern engine the running in process is all about piston ring sealing. Not running in bearings or bottom ends. In theory big end and main bearings should always be running on high-pressure oil (apart from maybe start-up) not surfaces running together so shouldn’t need running in.

It is however critical for engine performance that the piston rings are bedded to the cylinder walls.

A common mis-conception is that the sprung rings push themselves out onto the bore to create a seal. This is wrong. Combustion pressures would easily overcome the springyness (word?) of the rings!

The only ring that uses its own pressure is the oil control ring that exerts light pressure on the cylinder
walls to scrape excess oil away.

It is the cylinder pressure that gets behind the ring and pushes it out onto the cylinder wall to create a seal.

When you run a fresh engine the bores have a slightly abrasive hone pattern that is used to help the rings bed in.

If you drive around for 1000 miles at 1500 rpm with no load you will use all the roughness of the hone with out the rings really being able to use it to bed in.

What you need is some decent cylinder pressures in the first few miles to push the piston rings out onto the freshly honed bore and enable them to run in together. This means putting the engine under load.

Basically if the rings are not forced against the walls soon enough, they will use up all the roughness before they seat. This can is sometimes referred to as glazing the bores.

This is why if you are replacing the rings on a used engine you should always get the cylinders re honed. Some people refer to it as breaking the glaze.

Years ago at a bike mag I used to read (Performance Bikes) the late great John Robinson did a test with two early SRAD GSXR750s. He thrashed one from the crate and ran one in for 1000 miles as with no load. They then put them on the dyno. The thrashed bike made 124bhp, several more than the run in one!
They then compression checked, stripped them down, examined and concluded that the extra power must have come from the better cylinder sealing.

Another mis-conception is that an engine has to go through a certain amount of heat cycles before it is run in. I think people believe that parts get heat treated as they are run??? Heat treating of engine parts is done at a temperature far in excess of that which will be reached by a running engine. Well at least one that has oil in it and is not welding itself together!

What are the advantages of better sealing rings I hear you ask.
1. No wasted cylinder pressure
2. Which equals more power
3. Less blow by of rings
4. Which equals less contamination of oil with combustion gases
5. Which equals better performing oil and an engine that lasts longer.

So we have established that what you need to do to run your rings in is put the engine under load and create greater cylinder pressures.

Ok, bearing that in mind, this is how I run my engines in, whether it be a CR125 or a 2ltr zetec.
Insert “at your own risk blah blah blah” clause of your choice!

1) Warm engine up (v.important)
2) Do a couple or three mile lap of my local lanes at 1/3 throttle with plenty of accel / decel
3) Another lap of lanes with ˝ throttle, plenty of accel / decel
4) As above ľ throttle
5) A couple of full throttle blasts.
6) Change oil and filter
7) Enjoy!

I always pull in and quickly check for leaks etc. in between laps.
Always keep an eye on the temp gauge and oil pressure if you can.
Change your oil and filter as frequently as you can afford. You can’t hurt an engine by changing the oil too much!

This how I run in my engines. If you are having an engine built by a tuner, follow their directions for run in or you may invalidate any warranty / guarantees they may give.

I’m sure there will be plenty of discussion on this topic, however it would be nice as a follow up to have some info / input from the oilman as to the technical reasons you should use different oils during break in

 

can also cause det too i believe

excellent read although does an engine need longer than the few miles you sdescribed to run in, or will the rings and bore bed in after those few miles??

 

As engine/car is not only pistons and cranskshaft bearings I would give it couple hundred km's at the begining for things ike camshafts to bed in. At least on new car or compeltly new engine. OR am I wrong?

 

This one should end up with a fair bit of discussion!

Im of the belief that you cant run rings in the way you described, due to the fact that if you do it like that its my belief you will see excessive piston ring blow by and this will stop them becoming air tight in the first place, so i always give them longer at small throttle openings and at lower rpm.

But the basic principle of increasing the load i do stick to, just over a logner period of time.

Its an interesting point you make though about "using up" the abrasive marks on the bores before the rings have really bedded in if you are too gentle.

I think of all the technical disucssions on here currently this one could be the one with the most actual discussion in it as its such a black art and everyone has their own preferred method of running in!

 

I run a cam in by giving it about 20 mins of moderate rpm useable (around 2500rpm but varies according to what cam)

I dont run bearings in AT ALL, im quite happy to fit new bearings, turn the key, warm the engine up, and thrash it round a track.


One thing worth mentioning on running is that its vital you DO NOT use a fully synthetic oil, they work too well and stop the rings bedding in!

 

The worst thing you can do with new camshafts is let them idle due to the high valve train loads.

 

Absolutly. This is MY preferred method and has worked for me. Everyone has thier own special ways of doing it. But as you say chip, I expect most tuners these days will not recomend 1000 miles of tootling around, as used to be the typical method.

 

i agree. when i used to race two stroke karts few years ago we used to run them in as follows

10 min @ 10k
10 min @ 12k
10 min @ 14k
10 min @ 16k
10 min of full throttle anyting up to 18k depending what gearing you ran


i once ran in a stage 2 cvh so gently for 1000miles at 2.5k in my old fiesta and it used so much oil all the time

carl

 

Boing... for the evening techies.

 

i have read various articles that compare the 2 methods of running in and to test only one engine using each of the methods is hardly conclusive

however, most of the articles come to the same conclusion, so that does tend to hint that one way is better than the other - the hard throttle version as described similarly by Garage 19 and Chip.

one thing i don't really understand though, is how combustion pressure can act on only the inside of the ring to push it against the cylinder wall. surely pressure acts over the top and both inside and outside of the ring?

 

Just to add to the toipic, I have found in the past that high engine speeds polish the bores and build up a glaze thus not bedding in the rings.

The way I ran my engine in is this..

Drove round up at varying rates of throttle and loads, keeping below 3000 rpm) for 100 miles and dropped the oil/filter. Replaced with fresh stuff.

Drove round for 400 miles at varying rates of throttle and engine loads still keeping below 3k until about 300 miles had been covered. Drop the oil/filter and fill with fresh.

Drove round for 500 miles allowing the turbo to come on boost occasionally and slowly reving it higher and higher as the miles clocked up. At 1k miles, drop the oil/filter anf put the good stuff in. Caned it for another 1000 miles before upping the power.

I live not far away from the pennines so have some ideal hills to load the car up with.

 

I always run my engines in fairly hard as like Garage 19 says they dont bed in otherwise....

Obviously you must have some mechanical sympathy and not treat them too brutally....

My friend and i both bought new Honda Fireblades in 1995,I ran mine in fairly hard and he listened to the salesman and ran his in at 3k for 1000 miles,with fairly shit results for him.....

My bike never missed a beat,started first spin,was quicker and more responsive,never used a drop of oil and generally did everything it said on the tin.....

His bike was a poor starter,used oil,and generally was a bag of shit....After numerous trips to the workshop he got pissed off and px`d it for a new one which he thrashed the tits off from day one...that one was mega....

 

"thrash the tits off" doesnt sound like good advice to me.



I would NEVER use high rpm when running in an engine.

 

May I add one question to the discussion - what about running in whole new car? Is there anything else apart from the engine we need to take into account? My mate is picking up a new Scoobie STI in couple of weeks.

 

semi synthetic oil for runing in then

what do you think? as they say ONLY use fully synthetic
for cosworth/turbo cars?

But i guess that is more to do with temperature range
and as you aint giving it large you wont need to worry about
hi temps etc too much?? ????????????

cheers!

 

I always had reservations about runing turbocharger on non-synthetic oil at any time.

 

Figment of speech mate.....

It`s a Scouser thing........You wouldnt understand...

 

Absolutly spot on Garage19

Few will believe you thou!




please can we call you something else thou garage19 is difficult lol


Alex

 

tried this on a r6 a couple of years ago.went like stink.run all our bikes in like that in a rolling road dyno

never had a problem with them

http://www.mototuneusa.com/break_in_secrets.htm

cheers

 

i have been told to use cheap shit deisel oil for running in
as its similar to petrol oil but cant take the high revs and temps the petrols make (doesnt matter for running in tho as revs are kept low)
plus it has a cleaning agent in it so wipes away the shit from the engine at the same time

ive done this a few times as have a few others i know and none of us have has problems.

i normally run an engine in as described above but for longer periods with increasing load and boost.


think of it this way tho,
any1 that has bought a brand new car, did u run that in or jump in and abuse it cos its got a warranty so doesnt matter if it breaks? and did you then have any troubles with that engine???

 

Everyone I now who bough one carefully run it in.

 

i have had 2 brand new cars and not run them in
i mean brand new complete cars from the dealer not a new modified engine


plus do you think the people who work in the garages drive them carefully for road tests?

 

i had a mondeo 2.2 tdci hire car, had just 13 miles on the clock when they gave me the keys.

its about 10 miles to the motorway so was varing throttle/load then got on the motorway and wound it up to 140 lol

car went like a c*nt

 

bttt

 

you should be on boost running in an engine.... that puts LOADS of pressure on the rings, which although they will get, for the purpose of beeding into the bores is bad bad news.

Alex

 

not really.

The engine is the main bit.... and new engines are built much much better than 20 year old cossys!!!!

Its moved on a bit since YB production

Alex

 

There is officiaal running-in procedure by Subaru Import Poland, which at it's end involves 150+mph (officially on German Autobahn )

 

Great thread

http://www.mototuneusa.com/break_in_secrets.htm is a great link on this subject.

I'd ONLY use mineral oil for running in (infact, I run mineral all the time anyway ).

 

we where over on daytona 200miles in 2000.then we had a chat with the guy that runs mototune.nice helpfull guy.knows a lot

btw we finished in 11 place (BEST PRIVATEER AND BEST YAMAHA)

oops cap lock

cheers

 

only a few replies.
i was expecting loads of useful information to read this morning. lol

 

Ok, try Doug

 

Whats your background Doug?

Your definatly knowledgeable and involved in some great projects (ms on the bmw for exmaple!)

Alex

 

what about when an engine is run in on an engine dyno?

What kind of rpm and load values do they use and for what periods of time?

 

I was advised to use plenty of full thermal cycles as possible in the first 100 miles by my tuner. This was nothing to do with running in the motor but was of benefit when running a tubular exhaust manifold.
I was also surprised to be allowed a max of 5krpm from 100 miles on.
Good Thread

 

Nothing interesting I'm afraid. I design traffic signals for a living!

I'm just a bit of a petrol head. Started with building crunch 90 track bikes as a kid (mine had high comp, re profiled cam, pocketed piston, homemade oil cooler) and gone from there. Picked up a lot of stuff along the way i guess. Try to have a winter project every year.

Heres one from a few years ago! My Blade flew after i put this back in





This years project, the kit car, isn't doing to well due to lack of time. Been working on other peoples cars (like the BMW) and busy with my small side business.

www.suffolkflockingservices.co.uk

Just lets me pay for my toys with out the missus moaning really.

Doug.

 

Back to the top for some avo discussion. I would have thought this this topic would have caused some right 'ol arguments. And I'm soooo bored.

 

anybody??

 

Depends on the engine obviously but when a pals 2.5 Scooby motor was dyno run in recently IIRC it was held at 2krpm till warmed up then cycled at varying loads with a max rpm of 3250 for first 2 hours then increased to 4000 then 6000 and finally mapped followed by a power run up to 8250.

 

Not really sure on this one as i am not lucky enough to have or have access to an engine dyno for development.

I should imagine enough load to re create aceeleration on the road in say fourth? And the load should not be constant, but raised and reduced?