12 replies to this topic

[Brown Mini]

Hi

What are the general rules for 'running in' a rebuilt engine that has new pistons ?

Max speed?
Max RPM?
For how many miles before oil change?

Thanks

[ANON]

CLICKY CLICK

100-150 miles or so should do. try to do it in one run if you can.

[monkey]

Normally people say take it steady.. but im sure i read somewhere you should cane it straight from the off?

EDIT: Just checked out the above link... thats where i read about driving it hard

Edited by monkey, 03 May 2009 - 10:06 AM.

[Brown Mini]

Yeah i read that this morning - it made me cringe

Think I'll just drive it easy with an occasional blast

I've got straight cut drop gears so even taking it easy sounds like I'm canning it !!

[MRA]

Have only had new pistons ?

Take it easy (no more then 3000 revs) gradually building up the revs for upto 1000 miles (yes one thousand)

Have you had a new camshaft, you must start it and run it at about 3000 revs for about 30 minutes NOT under any load..... any issues switch it off straight away rectify and carry on..

150 miles will just waste your time and money..... this is what main agents tell you as most engines are run up on a test line for a certain period before even getting in to a new car, also they want to be able to sell you another car in so many years because your engine has failed....

I had a main agent telling me not so long ago to bed in the brakes by stamping on them hard from 50mph to a dead stop ASAP do this a couple of times he said and my brakes would be bedded in !!! needless to say they won't be getting any work off me in future.

[Brown Mini]

Hi. sorry what I meant wasn it was a full rebuild and not just shells. Yes new camshaft, reground crank, new pistons etc

Yes i did the 3000 rpm from start up for 30 mins

I've tried to keep under 3500rpm so i'm close.... it's so hard !! - have done a whole 165 miles !!!

Was hoping to get it run in before london to brighton

[Jordie]

Mixed reviews.

I was took the take it steady advice. But I was passed a link from an engine builder to a guide, which basically said after inital starting, oil pressure checks and bedding in the cam, you need to drive it hard in the first couple hundred miles and get the engine under load to bed things in properly.

Everyone as a different opinion on it. Ive just drove my last few like normal, i don't red-line engines or anything anyway.

[AndrewJ530]

Talked to my dad about this before. He basically said run it to about 800 miles not revving the nuts off it and not [putting the engine under load (i.e. 30 mph in 4th gear). Then afterwards, you can use it 'properly' .

[MRA]

Talked to my dad about this before. He basically said run it to about 800 miles not revving the nuts off it and not [putting the engine under load (i.e. 30 mph in 4th gear). Then afterwards, you can use it 'properly' .

Yes but don't take it "easy" for 800 miles and then cane it relentlessly....

Build up gradually.... start at 3000 revs if you have an 800 mile limit and a redline of 7000 thats 500 rpm increase for every 100 miles..... which means that you should be able to take it to 3825 max

I suspect that Jordies engine builder friend does more diesels than petrol, in which case the pistons and rings are of a completely different material which does need to be under load to work and bed in fully..........

Edited by mra-minis.co.uk, 03 May 2009 - 05:04 PM.

[AndrewJ530]

Talked to my dad about this before. He basically said run it to about 800 miles not revving the nuts off it and not [putting the engine under load (i.e. 30 mph in 4th gear). Then afterwards, you can use it 'properly' .

Yes but don't take it "easy" for 800 miles and then cane it relentlessly....

Build up gradually.... start at 3000 revs if you have an 800 mile limit and a redline of 7000 thats 500 rpm increase for every 100 miles..... which means that you should be able to take it to 3825 max

I didn't mean redline it straight away from 800 miles onwards. Just that you can start revving it after 800 miles.

[MRA]

3825 miles refers to your 165 miles what do you mean then by revving it after 800 miles ?

[Paul Wiginton]

Us lot that rarely do more than 2000 miles in a year just give 20 mins at 3,000 revs then nail it. This is tried and tested by a lot of the Mini 7 racers I know of round this area. Selby claims its the best way and if not done can result in lower power output from dyno testing. I know its always worked for me and my customers

Paul

Edited by Paul Wiginton, 03 May 2009 - 05:15 PM.

[MRA]

I do it my way..... that's why my engines last.

A lot of engines for race cars last how long ? 1 or 2 seasons, I would agree with the dyno report, simply because by "nailing" it you are bedding it in quicker or more to the point wearing it out with a massive dose of bore wear.

This has the effect of polishing the bores, which over a long period of time would also polish the rings, however at this accelerated rate the rings do NOT bed in, but the friction value is decreased and therefore more power..... which for a race engine not doing a great deal of miles is fine.

After a 1000 or so miles a well bedded in engine will "loosen up" and generate more power, as the bores and rings are seating in and working together correctly.... this then gices you a better longer lasting road going engine