New 2.4 - Break In
 

I'll be reassembling my 2.4 engine soon after getting it back from Ollies and I'd like to know what is the best recommended break in procedure and oil recommendation.

Hi GotaT! Here's a pretty good thread discussing break in oil. There seems to be a lot of different recommended brands based on expierences:

https://forums.pelicanparts.com/911-engine-rebuilding-forum/756001-break-oil-first-20-minutes-brad-penn-standard-non-detergent.html

As far as the break in procedure itself goes, I would recommend checking out our DIY articles.
We have two on engine rebuilding and towards the bottom of the articles you can find details on break-in recommendations:

Rebuilding Your Engine

Engine Rebuild Overview

Both of those links have you letting the engine run at high idle for 20 minutes.

Don't let the engine run at high idle for 20 minutes.....that is bad for the rings. Vary of the RPM and load for 20 minutes keeping the RPMs above 2000.

Scott is spot on. I normally get it running, check for leaks, check timing and get in and drive it. Load it up to bed the rings in.

20 min initial run time is to break in the camshafts. If the camshafts and rockers are used then that’s not required and you can then drive with varying load to break in the rings.

I would recommend watching some videos from Lake Speed JR. he’s an engine break in expert. This is a very controversial subject. I always do the conventional cam break in on first start up which is 20 minutes of 1500 - 3000 rpm. I think part of the thought process for this practice is to well lubricate the top end (more rpm more oil). I don’t like the idea of running the engine this long with no load which is not going to bed in the rings but I also don’t want to destroy new cams n rockers.

Daniel

You are not going to destroy cams or rockers by running the engine with vary loads at varying RPMs over 2000 RPM for 20 minutes. The idea is to not idle at 1000 RPM with news cams and rockers....and you certainly don't want to run at a constant RPM with no load for 20 minutes with new rings.....

I have been wondering if it is necessary to run the motor for 20 minutes with no load to break in the cam. Don't most cam grinders say to do this? The idea is to make sure the cam has plenty of oil during it's initial break-in, I have read.

The question is, will the cam suffer IF it is subjected to much higher RPMs? And how long does it really take to break-in the cam?

From the Porsche work shop manual. (original)
http://forums.pelicanparts.com/uploa...1656101843.jpg
Then from the owner's manual;
http://forums.pelicanparts.com/uploa...1656101952.jpg

Controversial for sure, but the bottom line is this. You want to do everything so that it lights off right away and starts splashing oil everywhere. Ignition timing correct, ample fuel in the carbs or to the injectors (and in sufficient quantity to run for half an hour), double and triple check oil connections to minimize the chance of oil leaks, etc. Extended cranking for any reason is very hard on new cams. And quite frankly, I've seen a lot of cams with pitting. Could be metallurgy, could be lack of cam lube, I really don't know, but at least do what you can to give the cams a fighting chance.

I have always turned the motor over with the plugs out using the starter to get oil pressure before firing the motor. Is there a better way?

Melling makes a pre oiler that can be teed into an oil galley that will supply oil pressure before initial engine start up. Small electric oil pumps are frequently used on dynos and engine test stands to achieve oil pressure before initial start up, too. Accusumps are often used as well. I would use any of those methods before cranking with the ignition disabled, but if that's all you have, it's all you have.

Yes, most cam grinders will tell you ~2000 rpm for 20 minutes. What the cam grinders tell you supersedes everything else. Want to see that in writing? Here you go.

https://www.us.mahle.com/media/usa/motorsports/mms-break-in-recommended-procedure-web.pdf

"for proper camshaft and tappet break-in"
Camshaft break-in on a Porsche aircooled engine probably isn't that critical given its non-tappet design and abundance of lubrication.

If you have watched any of Scott's in car camera race videos you probably would not be questioning his recommendation for break-in . His car and engine are definitely impressive , along with the driving .

The question is, at what rpm will it begin to harm the camshaft before it is broken in?

If you break-in the engine right, it won't see anything under 2000 or above 5000 RPM in the first 20 minutes. The cams and rockers will be married by then.

I love these Kiwis!

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HP Academy is great. We have all of their content and classes as resource material for our technicians. I am actually wearing my HP Academy T-shirt today lol.

We have built a pre luber to fill engine with oil prior to start. It works amazing on wet sump motors, we can't quantify the affects on dry sump motors as we still need to fill the tank. But Pressure is built almost immediately. Get pressure on the rings (accel and deccel) as soon as you can. Load the rings without going crazy on RPM. It has worked for us for years. Others may have different approaches with success as well.

Cheers

Most cam grinders don't provide instructions that take into account a new air-cooled Porsche engine build and the need to break in rings. If I had an already broken in air-cooled Porsche engine that I changed cams or rockers or both, I would have no issues running it at 2000 RPM for 20 minutes.

There is no way I am going to let a air-cooled Porsche engine with new rings run at 2000 RPM for 20 minutes. I don't care what Mahle's document says.....

In the video he says to run it for 20 minutes at 2,500 rpm. At the 30min point in the video.

Go to the 23 minute mark and listen.....he quite clearly says bring the engine up to 2500 RPM and then vary the RPM for up and down for 20 minutes. He says the same thing at the 30 minute mark. Get the RPM quickly up to 2500 RPM and vary the RPM up and down for 20 minutes.

No where does he say hold it at 2500 RPM for 20 minutes.