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!

<iframe width="560" height="315" src="https://www.youtube.com/embed/5Ruk6GLJgbA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

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.

Yes, but he never said drive it, when he was talking about flat tapit cams, which was my point. Sorry my choice of words.

What do you you think is required when you need to vary load and RPM? You can’t do that in the garage. You can do that on an engine dyno, a chassis dyno, or by driving it.

My takeaway here is this.

Pre-oil the motor.

Start and maintain at least 2000 rpm.

When the oil reaches 140 drive normally, (varying engine speed), without heavily loading the motor, and maintaining an RPM range of 2000 to 5000.

After 20 minutes, change the oil and adjust the valves.

Drive normally there after.

Some great information here. Really appreciate all the sharing.

Thanks for all the info guys!

My situation is a bit different. I've had my cams and rockers ground but haven't touched the cylinders or rings. In this case do I only care about getting up to ~2500rpm and holding for the cams as rings won't be an issue?

Is a valve adjustment really necessary at the end of that first twenty minutes? My thought had been to only change the oil after twenty minutes, and check rockers and valves at 1,000 miles.

BTW, I forgot to mention that I have modified cam oil restrictors. I drilled them out to 4.5 mm however, as mentioned here http://forums.pelicanparts.com/911-engine-rebuilding-forum/1122559-camshaft-oil-pressure-restrictors.html and in an older thread.

Perhaps during cam break-in no restrictor?

John Dougherty liked this idea...
 

Hi Gordon,
I posed this same question to John Dougherty, (since we both have his cams), and he liked the idea of running the big stock restrictor for cam break in, but did not suggest a mileage change over point or size to go to.
Looking forward to further input/clarification for the 2.8 hot rod build.
chris

This video seems to suggest breaking in cam first then going for a drive to break in rings....hmm.

https://youtu.be/MhA_nVRhYew?si=gFfFw8MaoMy638l6

Not really. They are talking about braking in the camshaft when you don't have access to a dyno. If you have access to a dyno, it is easy to keep the revs up AND to do the normal ring seating procedures.

Man this topic confuses me.

I guess I had always figured the 20 minutes at 2000 rpm with no load was to break in the cam without any load on the rings - preserving them in their "rough" state until the cams were broken in.

Then, get rid of the cam detritus via an oil change and then get on with breaking in the relatively "unmarred, untouched" rings via a drive with varying load and rpm.

I don't know what I will do with my 3.4 but by default I am following Wayne's book...

D.

Well they say break in the cam 20mins at 2500-3000 rpm in the driveway then go for a drive to break in the rings.

Yeah, I guess I was assuming this thread was mostly people who were going to be breaking in their engines in car not on a dyno.

You can always get rings to seat later (unless something is really amiss), you can't always get your cam lobes back.

Cam break-in, IMO is more important.

Does delaying the ring break-in procedure (to do the cam break in procedure first) compromise the end result?

I know that I am more concerned with seating the rings than I am with bedding in the cams and rockers...mostly because I keep the engine above 2000 RPMs for at least 20 minutes during the initial engine break in process...

I am concerned with that as well but find it difficult to believe i could keep the rpms above 2000 while navigating traffic. Good to hear seating rings can happen after initial cam break in.

C.