Thoughts on running in engines

[ChaosAD]

What are your guys thoughts on running in rebuilt engines?
Some people say to run it in like youd normally drive it, ie if its going to be revd up a lot then rev it right up.
But other people say not to take it over 4,500rpm etc cos the bearings etc have to bed in.

What if the engines got big cams in it and barely wants to move under 4,500?

[Muzzie]

I treat rebuilt engines like a new one. No thrashing for 5000km and then build up to it. Better to be safe than sorry I always say.

You dont want the bearings to lock up or get damaged, so if it doubt go easy on it.

[kingcorolla]

yes and no. U want to take a rebuilt engine for a long drive after start up, because this runs in the new rings on the freshly honed bore, if not done, the rings mite not seal.

[RedMist]

Short answer: Belt the poo out of it. Long driving, but vary the RPM, DO NOT KEEP THE ENGINE UNDER LOW LOAD AT ONE SET RPM. Make sure it's warm, has very good oil / filter, and is maintained perfectly (no missing).

Long answer: Someone else has already written a million times over, do a search on the web in regards to bedding rings.

Graham A Bell has a good section in "4 stroke performance tuning" (only I'm too lazy to type it out, or even find the bloody book!) I think there is something very important in regards to decelleration.. but I can't remember.

[evil_si]

ok i believe in not taking it easy, get up to operating tempurature, make sure there is good oil pressure, with a mechanical guage if necessary, dont nana it, give it a good work out, dont let it idle for extended periods of time, like over 5 minutes.
i dont believe in the 5000k run in. believe me if sumthings goin to go wrong it will happen pretty much straight away,

bearings will only run on a poorly assembled engine, or an engine that has little or no oil pressurel.

the heavy diesels i build on the first test run i give it full fuel, full rpm, make it develop full hp and torque,

[Tofu]

firstly make sure u crank the motor round and round but dont fire it up....let the oil pressure build up and lubricate all the engine internals

0 - 500km = up and down the revs, no full throttle or boost (if turbo), no more than 3500rpm

OIL CHANGE

500 - 1000km = up and down the revs, no full throttle or boost (if turbo), no more than 5500rpm

OIL CHANGE

can drive normally, u can full throttle or boost (if turbo) but not too hard just be careful (no redline bouncies )

i've done this techniques with all my rebuilt motors and i havent had any problems....all my motors are still running to this day so i guess my technique should be ok

[solberg Fan]

Ive been told to keep the revs at about 2000 revs as soon as it sarts up, drive it for about 20 min using about half to 3/4 throttle and if its a race engine (sounds like it is) dont go above 5000 revs, 4500 is ok but only a few times and not for long. But dont do this....
Ive just had my engine going to day after rebuild. (Race engine)
You wouldnt belive what i did tho..... ... it was really stupid of me. I disconected the coil and got the oil pressure up before i atempted to start it. Couldnt get it going after messing with the timing, got tired of it and left it for the morning.
Went out there to day, cranked it and it started It was probly running for 10 sec and then i realised it had no oil pressure. Truned if off and relised that id left the bolt holding the dissy in out (helical gears for the dissy have axel thrust and pushed the drive out of the oil pump)
I dont know what damage ive done, but i cant do anything about it. Any way, got it going again (with oil pressure!) and is seems to be fine. But then again i have no idea what damage ive done to the bearings. Ahh, but whats done is done, but ill definetly be getting a HUGE RED F&$K OFF light for oil pressure.
Dumb ass..... - so yeah, make sure you have oil pressure!!

[boyracer69]

I did exactly what Tofu explained when i rebuilt my engine a few months back and its running mint as now
And when i put the ground cams in at the same time of the rebuild, all the cam dudes told me was no idle the car for 500k's, so isnt really a problem unless u do a lot of city driving within the break in period.

[Dell'Orto]

Ive been told to keep the revs at about 2000 revs as soon as it sarts up

Thats pretty much for breaking in new cams, keep it around 2k rpm for about 10 minutes to let it bed in, then it should be fine.
There are heaps of varying methods of how to run in an engine...best guess would be to just go with what your engine builder tells you

[Mr Revhead]

Graham A Bell

i think thats A Graham Bell, and thats a damn good book, care to give me your copie redmist?
there is soooo much in there......

[thaphatty]

a interesting read on the subject (but somewhat lengthy)
http://mototuneusa.com/circular_logic.htm

[FLAWLES]

i think there are two many different opinons to these but redmists "in my opinon " is the most correct one vering the revs would help
i would talk to some one who as been buliding race engines for years like speedfactor tauranga of flowtech racing engines tauranga <- this would be the best beat if it were me
they should be more than happy to help and give you a straight answer

[ChaosAD]

In my haynes manual it say to start it up and let it get up to operating temp, then take it for a drive and do about 10 repititions of full throttle, no throttle, full throttle etc.
I read somewhere not to keep it at one particular rpm (like sitting at 100k on the motorway) as the rings have to bed in at different rpms otherwise they will only seal at a particular rpm. Is this true? cos how will I get it to seal at 4.500rpm - 8,500rpm when I shouldnt rev it over 4,500?

[10k 20v]

the best way to run an engine in is to simply drive it. OF course checking for any noises before you rip of down the road. and change oil twice before 1000kms.

A certain team i know that used to race toyotas for toyota nz (dx corrola-ae86-st165-st185-st205) never used to run in engines.
Everything went basically in this order.
Build engine.
Start engine checking for various things like oil pressure, leaks, rattles and bleed cooling system.
Warm engine (still bleeding cooling system).
Go round the block to check how it runs.
Put on trailer.
Enter stage 1

[RedMist]

Warwick.... yep A Graham Bell. I'm a dyslexic bastard. And NO, you can't have either of my copies! The big / tiny port was generated using this book as the bible. The smallport you supplied me will be built using this as a guide with 4917 web articles to fill in the gaps!

Ewan, fantastic fact! Good to know how the gods do it!

[ChaosAD]

But a race engine and a road engine are clearanced differently.

Redmist - do you have a list of those web pages?

[YeMs]

well i have been told it goesd a lil like this. if u nana the motor all the way through the run in then basically the motor is gunna b a nana motor. i have been running in my engine and i drive it between 2000-3500 on the road, but every now and then i take it up to about 5500-6500 rpm under full boost. varying the rev range etc etc.

[CAMB01]

The best way to help bed the rings in is to put the engine under load, ie driving up hills at about 3000 - 5000 RPM, dont be afraid to really rev the engine just don't over rev it. As for bearings they don't need a run in period. There made up of about 3 - 7 different types of materials designed to withstand high temperatures and pressures, and the correct clearances for the oil film. If you have sufficient oil pressure and don't let the engine idle the bearings won't even get touched unless at low RPM's