What's the usual process for running in a rebuilt engine?
 

Rebuilding an impreza engine seems to be a fairly common affair!!
Just curious as to how you run them in??

Surely you can't/don't rag from the off??

How long does it take?? In miles obviously!!

500?

1000?

Does it matter if it's fully forged or just forged pistons? Is it the same length of miles?

Don't take the piss basically. You need to go reasonably carefully and avoid revving too high or running too much boost, but going too gently can cause issues - apparently it can cause things to not seat properly.

You may get many different answers to this, I personally did not rev over 3000rpm on my new engine for the first 250 miles, then not over 3500rpm for the next 250, then above 4000 rpm for the next 250 until I ran out of revs. By this time the oil had been changed twice.

I do something similar, no more than 1 bar of boost plus no more than 4k revs for the first 1k miles with an oil change at 200 miles then 700 miles and then at 1200 miles up grading the oil grade each time to finally reach fully synthetic and about 1500 miles then upgrade parts and remap to desires figures

Take it easy for 100 miles, change the oil and cane it.:D

+1

50 miles is ample .....:norty:

interesting...who can resist not booting until about 1k, that must be difficult.

Staying under 3K for 1000 miles, oil change at 500, 5th at 45-50mph, vary the revs - don't just sit on the motorway at one constant rpm.

500 miles or a 1000,taking the engine up the rev range gradually as the miles increase I don't like to baby the engine after about 500 miles,I Then start giving it a bit more right foot.There is a lot of variables to be taken into consideration warming up and cooling down the engine to make it bedding nice and easy.I laugh now when I rebuilt my Renault 5 GT turbo I gave it one lap of the m25 then dropped the oil the next day and switched up the boost:Dand let it rip,that was 13 years ago and the car is still running perfect now.SJ.

Everyone has different opinions/ideas. 1000 miles is overkill . On all engines I have had I use a cheap 20/50 on startup and 20-30 gentle miles with short runs basically heat cycles. Oil / filter change to your preferred oil, 50-100 miles more again varying heat cycles, oil/filter again job done. Too much of this gentle farting around, once the rings are bedded they are good to go. All imo. Do you buy a new car and fart around off boost for 1000 miles?

I have had more new cars than I can remember in 20 odd years of driving company cars, at one point for about 5yrs I worked for a company that had a lease rental agreement and the cars were not to go over 10k miles before changing, at an average of about 1000 miles a week I got through quite a few.

Not once did I take it easy, in fact I would often give them death from the moment I left with the car just because I could and bounce them off the limiter in every gear. :lol1: Never had one fail or sound any different when handed back and most didn't make it to 10k as soon as I got to bored and was near an airport or local depot i'd go see what they had in stock and swap.

Another little anecdote, there were 3 novas delivered to a firm I worked for many moons ago, 2 engineers faffed about running them in being all gentle etc the third was a reps car which he hated with a passion and caned the living daylights out of it from the word go, and yep you guessed it, his was the fastest by a country mile and never gave any trouble for about 3yrs.:lol1: