procedure for breaking in an engine

[ckissick]

I'm ready to install my newly rebuilt 3.0. I have Wayne's book that describes in detail how to break in the engine. Should I follow his book, or is there a better way that anybody here might suggest? Thanks.

[Mr9146]

Take a long road trip ... seats the rings damn well.

Just holding it at around 3000 RPM for a couple hundred miles does wonders for the motor - I broke my 2.4S in on a trip from LA to Marin County.

An occasional zip to the redline - variations in RPM are necessary - is healthy during break in ... I'm sure people will disagree, but that's how I've always done it whenever I rebuild a motor.

[heirplane]

My 2 cents: Back in Nov. '81 I picked up a new 911SC at the factory, and their represenative's advice was quite the opposite. The factory admonished to not drive at steady speeds initially (first 1000 km), rather, to vary engine speed and load.

The factory rep also stated the RPM's should be kept below 5000 for the first 1000 km.

At the same time, a friend bought a new 924 Turbo. The break in recommendation was quite different, staging the max RPM starting at 3000 (again, not to be held steady at that RPM on the freeway or autobahn).

I tend to adher to the manufacturer's recommendations.

[Mr9146]

Told you they would disagree

But just to clarify - my motors don't leak and have 190+ compression in all 6 cylinders.

[Chuck Miller]

Marco's right,
As many theories as mechanics...


We did mine kind of conservative:

First 500 miles, varied RPM only up to 5000 max. - then oil/filter change and first valve adjust.

Then another 1500 miles, varied RPM only up to 6000 max. - then oil/filter change and second valve adjust...

Then the car was mine...

[heirplane]

Probably belongs on another thread, but now that we have you here, Chuck, how goes your high compression 2.7RS? Went the conservative route with my 2.4S to 2.7RS conversion--kept it at 8.5 CR.

Did you dyno your rebuild? Any comparison to low compression 2.7RS cars you've driven? Any problems with our low octane fuel here in SoCal?

[Chuck Miller]

Sorry I've been keeping my rebuild a little underground...
I promised John Dilger multi-part articles in the upcoming ESSES news letters.

However the short answer is... it seems all the decisions we made were in the right direction...

As you would expect the torque profile of the car is COMPLETELY different... I am almost up-a-gear everywhere!!! ... have to learn how to drive it all over again ... after havin to ring it's poor little 2.4-S neck for over 15 years... not knockin my old motor, but this is a whole different deal

From other 'good runnin' RS conversions my car seems to have a bit more in all ranges... from the jump, midrange, and on the top... not by much, but a bit more ... and VERY linier

It seems that all clearances are right on the money... so with 9.5 there is absolutely no trouble on 91 Calif. crap gas... even on a 2nd. gear take off, or 5th under 3000 under load.

The engine itself was not run on a dyno...
Numbers have never been a big deal with me... through the years I've gotten used to being the underdog... 'If that guy has a bunch of power, and I just got in front of him... then I have enough power... until the next guy up there with a lot of power, that I'm catching up to'... to me it's always been about driving...

I'm not sayin that tuning a car on a dyno isn't the best thing since socks... but to do it just for the numbers... ?

I don't know, maybe someday I'll put the car on a dyno and do the math deal...

So... All is well and cookin and happy... thanks for askin

Cheers,

[RSupdate]

Originally posted by Mr9146
But just to clarify - my motors don't leak and have 190+ compression in all 6 cylinders.

110% believeable and it doesn't surprise me one bit..... just another TLG motor......

[lbritish]

just about any manufacturer of engine tells you to run your first 100-200 miles under 50 mph speeds and vary the giving it gas more and less and never keep it on a constant rpm... after that then work it up 5 mph increments till you get to around 500 miles on the car again never really giving it a constant rpm and never gunning it hard till after the 500 miles.

That is generally the "part line" from the manufacturer. Then the "reps" selling you the car tell you something else... keeping in mind they're in the business of selling you parts and fixing it and selling you new cars when you wear the old one out etc... But.. at the same time they're also in the business of trying to tell you ways to keep you happy with the car too making you want another one...

*Shrug* go figure...

What I figure is kinda a little of both... start it up... let it run for a bit... warm up... get the fluids going.. drive it for around 100 miles.... drive it through residential... some 25 and 35 maybe even 40-45 back roads.... once you drive for awhile like that... work it up onto the highway... bring it up to around 50-55... the whole time up to the highway give it gas... get it to speed.... then let it go a little over... then coast for a bit slowly dropping down just below the speed... give it some gas and work it back up... lather, rinse, repeat... once you get on the highway after it running for a bit... hit it hard and go from 20 or so up to 55 pretty fast... then ease off.... do the speed... coast.. speed coast thing over and over. Do this several times until you get it to about 500 miles and then punch it...