New motor Breakin

MMARSH · MMARSH's Garage

Reading Supermans thread got me thinking. What is the proper way to break in your newly rebuilt motor. How many miles should I put on it before I can drive it flat out at the track. TIA

Leland Pate · 02-19-2002, 08:28 AM

I had read somewhere that you should first let the car run for about 20 minutes at high idle to initally bed down the cams etc. then change the oil. Then to drive easily, not reving over 3K for 4 or 500 miles...there after increasing the revs to as high as 4500 with the occational burst to redline for the remaining 500 miles.
But,
Mr. Early S man later told me that the factory has a breakin procedure that only lasts about 20 minutes... 5 mintes at 3K...5 minutes at 4K...etc. maybe he'll chime in here and clear this up.
I tried doing a search for it, but came up bust.

02-19-2002, 08:40 AM

DO NOT RUN THE ENGINE AT IDLE DURING BREAK-IN!!!

Run it 2000 to 2500 RPM for about 1/2 hour.

The CAMS will not get enough oil unless the RPMs are about 2000.

After that, it would be nice to get a 100 miles or so before track time.

If it is track only engine, an hour or so running time is probably OK.

I think this is Andersons book.

Ken

Leland Pate · 02-19-2002, 08:51 AM

Oops...well thats what I consider a "high idle" ... 2000-2200 rpms.

Guess that's only because that's what my car Idles at when it's cold!

boyo · 02-19-2002, 08:54 AM

Varying the RPMs (i.e. NOT the same RPM for a long time) is ideal. Don't take it to the freeway and put on the cruise control, do take it out on the street and do some light duty starts and stops.

-Boyo

Superman · 02-19-2002, 09:58 AM

BA told me in a recent e-mail that since I am not using new cylinders, my rings may have trouble seating. He advises breakin on a dyno or, if that's not feasible, DRIVE IT. Don't let it sit and idle, he says.

So, I won't.

MMARSH · MMARSH's Garage

Even though the motor is going in my track car, it is still street legal. My plans were after the initial breakin (running for 20-30 min at about 2500 rpm) I was going to drive it to work for three or four days. I have a 140 mile commute so I thought that would be a good way to throw some miles on it. I could vary the speeds from 50 to whatever. If I only get about 600 miles on it before I go to the track, how big of a deal is that? I'm spending to much money to mess this thing up again

Matt Holcomb · Matt Holcomb's Garage

Michael,

This was the break-in procedure for my 2.7 race motor:

Oil change at 300km; couldn't -- didn't -- rev past 5,500rpm.

Oil and filter change at 1,000km; artificial rev limit set (on cap) at 7,300rpm, although I avoided hitting redline regularly until about 2,000kms. The artificial rev limit won't be increased to 7,600rpm until I do at least another 2,000kms -- I've now done just over 4,500kms since the rebuild.

Hope this helps!

Matt Holcomb
1974 911 Carrera 2.7 Euro
1975 Mercedes-Benz 280SE
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Doug Zielke · 02-19-2002, 04:45 PM

Mike,
Whatever you do, don't get the fresh motor overheated!
Therefore, avoid traffic jams and the like.
Take a short trip, then allow a cooling period, repeat. Vary the rpm's, use the gearbox (don't lug).

Change oil and filter at 250 miles, 500 miles, 1000 miles.
(Cut open the filters after each change and examine the pleats for excessive metallic debris.)

Don't "baby" the motor too much or the rings may not seat properly.

curtisaa · 02-19-2002, 05:12 PM

Mikey....let me know if you're coming over the Crest. We might want to do a little scrubbing of those tyres.................

911pcars · 02-19-2002, 05:18 PM

Hey Mike,
I'll do it for you. No charge.

To reduce wear and tear on your track car, install it in my car for a couple of weeks.

All of the above advice is good. In addition, don't forget to lift throttle periodically to draw oil up to the cylinders (good for the rings). However, don't do this in the middle of those high speed Angeles Crest sweepers.

Sherwood Lee
http://members.rennlist.org/911pcars

pwd72s · 02-19-2002, 05:20 PM

Michael? I may be wrong here...but think I remember reading something about using regular ol' oil is best for break in...before adding synthetics. Something about the cams breaking (wearing?) in properly. Anybody else hear this???????? I mean, what do I know? I've never had to break in a P car engine...

Randy W · Randy W's Garage

Hi Mike, I broke mine in as follows: Initial start up with Kendall GT1 - 2500 RPM 5min, then add 500 RPM every couple of minutes, up to 5000 RPM, then varying RPM for another ten. Then up on the lift to check for leaks. Then to the dyno for under load tuning - it's OK to get it pretty hot here - mine got up to 230 before we shut it down! Then oil change with Kendall. Then on the road tuning with varying RPM for 100 miles. Change oil with Kendall. Then a one hour drive on the freeway with increasing blasts up to 5000 RPM after fully warmed up. I got the rings to seal well here by accelerating in third gear pulls and then lifting completely off and letting the engine compression slow the car - I did this repeatedly for ten minutes three separate times. Then a National Tour autocross with a 6800 RPM limit setting. Then adjust valves and change oil with Kendall. After a total of 500 miles, we changed to Mobil 1 and reset the RPM limit to 7100 (my 3.2 has ARP rod bolts). The engine is a stock longblock US 3.2 with Motec and dyno'd at 222HP to the rear wheels on race gas.

curtisaa · 02-19-2002, 08:21 PM

Mikey...Randy, et., al, are very articulate and very knowlegeable P-Cars guys but sheeeetttt... your car is NOT an ol' girlfriend. Get in the damn thing and "do it". Do ya really think Hurley, ever "broke in" a new motor, da think Vasak EVER told his drivers "go easy the first few laps".....dude...put oil it in, and if your mechanic messed up, he'll hear about it down the road....

Tyson Schmidt · 02-19-2002, 08:26 PM

Michael, how much of the engine is new? If you are re-using the cams, then they are already broken in.
The high RPM thing is so the oil supply is adequate, as well as the fact that idle is the hardest on a cam from a valve spring pressure standpoint. Kind of like jogging being harder on the body than sprinting, which is smoother.

The above info is great, but I'd like to add one more thing. This only applies, however, if you re-ringed/honed or replaced pistons/cylinders. Use NON-detergent oil for initial break-in. This will help the rings seat.

speeder · speeder's Garage

I always understood that Porsche's claim to fame, (at least in the good-old air-cooled days), was that they rolled every car right off of the assembly line and on to the test-track and drove it flat-out to test performance; tolerances were so good that basically no break-in was required. Maybe doesn't apply to rebuilds.

Tyson Schmidt · 02-19-2002, 08:39 PM

You've got a point, speeder. The cams and crank are surface treated. I've personally never seen a 911 cam go flat. Or seize and break for that matter. I see it ALL the time on Hondas that don't get their oil changed.

However if you regrind cams, and hone/re-ring cylinders, then it's just not like it left the factory and needs to be broken-in.

Randy W · Randy W's Garage

Curtis, is right of course. When I asked my mechanic, Chris Powell (who worked on Bruce Leven's 935 and 962 in the '80's) and Greg Fordahl (racecar guru) if exceeding 5000 rpm and getting the oil temp up to 230 was too much with less than 100 miles, they both said "NO! You have to wring it 's neck out to get the rings to seat properly". That's what my co-driver and I did at the National Tour with less than 200 miles on it (we won our class), and it is now a 10,000 mile very strong engine with normal oil consumption and no leaks. Tyson, yes, it was re-ringed and honed.

Early_S_Man · 02-19-2002, 08:52 PM

The non-detergent oil THING ... is a REALLY, REALLY OLD WIVE's TALE!

Thr factory service manual says to use Heavy-Duty SAE 30 motor old ... which your non-detergent oil ISN'T!

I have always used Valvoline Racing SAE 30 oil for break-in, and have yet to have any problems with cam lobe or rocker wear problems, and the rings always seat within five minutes during warm-up!

Check the following procedure ...

Tyson Schmidt · 02-19-2002, 09:18 PM

HeeHee! I love this! Well, I guess I'll stop listening to old wives then! My bad.

I think I got that tip from an old Bruce Anderson Tech article in Excellence. (The non-detergent oil thing)

On the ring break-in, I've heard that "..if they are going to break-in, they'll do it in the first 5 minutes" as well.

Boy, ask 100 mechanics how to do it, and you'll get 100 different answers. Of course, make sure you ask the right mechanic, and you'll only need to ask one!

I certainly agree with what Randy W. and Warren have to say on this. I think a lot of the methods that are quoted are heroic measures to try to get stubborn rings to seat. Sometimes they work, sometimes they don't. If it was built right, you'll be good to go.

I think what happens is that, when giving advice, people try to give all-inclusive worst-case-scenario type advice. I think that is where the high RPM, don't let it idle advice, and change revs, etc. etc., come into play.

Unhardened cams need to be broken in. Porsche cams are pretty damn tough, and are surface-hardened. They really don't need to be broken in. (Unless they have had the surface hardening removed from aggressive re-grinding.)

Porsches also use chro-moly rings, which pretty much will not tolerate bore taper, or out-of-roundness in the cylinder. They are too slippery to cut their own shape in the cylinder. They either seal, or they don't. Not very forgiving.

Warren, I stand corrected on the "non-detergent" oil issue. Whew! I feel better already.