Engine Break-In - Found the answer

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One of the more controversial topics within the automotive world is how to properly break-in an engine. There are two camps - 1. follow the owners manual 2. run it hard the first few miles. The common denominator among manufacturers is keeping the RPM's varied and never exceed 4k rpms. Engineering Explained did a nice video of why you should follow the owners manual. I did some searching and found a good explanation from a Porsche engineer that makes sense and confirms why they want you to stay below 4k rpms. *Unfortunately for me, my car had 63 miles on it already so I have no idea how it was broken in. The Subaru had 3 miles. In bold is the anwer: New Engine Break-in Conundrum By: Ken Koop Since I was a young boy, I have always wondered why it takes so long to break-in a new engine-especially those built by Porsche. Most people driving new cars also do not fully understand the real reason for the break-in period. Are you one of them? A good friend of mine just picked up his brand new 911 Turbo and complained about the break-in period taking so long (2,000 miles, not exceeding 4,000 RPM). We have talked about this issue many times over the past few years, always coming up with many scenarios of why such a long break-in period is required. However, we have never agreed on a reasonable answer. Well, you are about to find out the reason Porsche requires the break-in period it has today. The answer comes directly from the engineers at Porsche. I was on a recent Porsche factory tour and was watching an engine being built and dyno tested. Each engine is built by a single person on a moving production line. Porsche feels that they can obtain better quality control with one person building an individual engine from start to finish. In addition, each engine builder can assemble every type of production engine that Porsche produces and every gasoline engine is still built at the Stuttgart factory. It takes 2-3 ½ hours to assemble each engine, depending on the type. Afterwards, the completed engines are either used in the cars produced at the Zuffenhausen factory or are boxed up and shipped to Leipzig (for the Cayenne and Panamera) or off to Finland (for the Boxster and Cayman). Before all of the parts are assembled for a particular engine; the pistons, connecting rods and valves are individually weighed and grouped together using similar weights to optimize performance. They are put onto a cart that moves along the assembly line with each engine block. This cart contains every part required to assemble that particular engine which includes each washer, nut, bolt, bearing etc… As a result, if any part is left in the cart at the end of the assembly line, then-Houston, we have a problem!At the end of the assembly line, the engine is filled with Mobil 1 Synthetic Oil. Each engine is then dry run (without fuel), pressure tested and checked for leaks. Every car coming off the production line is also run on a rolling road dyno. This enables all cars and engines to be tested at highway speed before they leave the factory. Some of the engines are also randomly selected to be tested on a dyno stand before they are installed into the car. The assembly plant has 5 dyno rooms located directly off the production line. The day I was on the tour, there were around 40 engines lined up on dollies. Some of these engines were in the process of being tested for quality control purposes. Once the engine is bolted onto the dyno, warm water is circulated throughout the engine to bring it up to temperature. The operator then starts the engine and checks for the correct pressures and temperature before the actual test begins. Engine speed is then increased in RPM steps to about 80% of its red line (the engine's maximum RPM). The entire engine run takes around 30 minutes. Since each engine type (Turbo, GT3, Boxster or Carrera…) has a different red line, all of the data is recorded and analyzed after the test is completed.After the engine is turned off, the engine is again checked for seal leaks and its actual HP is compared to its advertised HP. To pass final inspection, the engine has to develop, at a minimum, 100% of what its advertised HP rating is. Also, the engine cannot produce more than 5% over that same advertised rating. If the engine falls out of those parameters, the engine is rejected and then torn down to determine why it did not deliver the anticipated HP. When the test was completed, a Porsche engineer came over to review the results. I couldn't resist asking the question that I had been searching to find an answer to for all these years. I asked "why does Porsche feel it is safe for a new engine to run at nearly full throttle in the factory, while the customer must keep the engine speed to no more than 4,000 RPM for a 2,000 mile break-in period?" I thought that was a logical question and if I do say so myself-well stated! The engineer replied, "Herr Koop, you do not understand (that I already knew). When we do our engine test, the metals inside the engine never reach the temperatures they would when driven on the street since the test session is fairly short. In other words, the bearings, pistons and cylinders never get a chance to thermally expand to their maximum. Therefore, there is little wear on the moving components. But when you drive a car on the street, the engine parts expand considerably more because of the heat being generated from the engine running for an extended period of time. No matter how tight the tolerances are, there is always a slight amount of expansion in the material. The moving parts can wear quickly if exposed to excessive heat and not always in a uniform way. We also constantly vary the speed and allow the engine to run at both high and low RPM's". "Porsche wants the engine to break-in slowly, which means it needs to maintain a lower operating temperature (below 4,000 RPM) and to allow all parts to adjust (wear-in) within their own thermal expansion parameters. This is also the reason why Porsche wants the owner to vary the RPM throughout the break-in period; therefore the engine doesn't get use to one operating temperature range". "Porsche has been using Mobil 1 Oil since the early 90's. With its superior lubricating properties, it takes many miles of driving (without getting the engine too hot) before the components actually seat (or break-in). Porsche's own tests reveal that after 2,000 miles have been driven, all of the moving parts have had a chance to wear into their adjacent surfaces and then an increase in engine RPM is permissible." I replied, "JA DAS SOUNDS GUT, when you explain it that way, it makes a lot of sense." I thought to myself "You Dummkopf, why didn't you think of that". The engineer commented that there were many other moving parts other than the engine that needed break-in as well. Wheel bearings, constant velocity joints, tires, brakes and transmission were just some of the other components that were mentioned. So breaking it down into layman's terminology, it all comes down to; higher RPM equates to more heat, which leads to greater expansion. For a new engine, that can mean uneven wear on certain parts if excessive heat is allowed to build up. In Porsche's opinion, the thermal expansion of different parts and various materials need time to adjust to one another. Porsche's time frame for that to occur is calculated to be 2,000 miles, with the heat restriction being 4,000 RPM. So simple; who woulda thunk. Many experienced Porsche engine builders and experts on the Flat-6 engine state that the peak power of a Porsche engine is developed around the 20,000 mile mark. This coincides with the principle of what the Porsche engineer was telling me; "Break it in correctly and the engine will last longer and perform better". It only took me 45 years to find out the real answer to this puzzling question. After I returned home, I explained this to my friend. As for our ongoing debate, we now feel a solution to this riddle has finally been reached. Neither one of us had the answer to this complex question totally figured out, but we were on the right path! I am finally able to resolve another one of my life's unanswered mysteries and now it's been crossed off the list. I hope this helps explain one of your unanswered questions in the car world as well.
 
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The breaking in of other components, is the main reason. When you rebuild only the engine, it can be rather advantageous to run it harder faster. Also, most re-builders do not have the engine shop Porsche has, so have built the engine a little bit looser.
 
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Now if you get a few beers in the engineer he could very well say, "American drivers are horrible so we keep them under 4k rpms for a couple of months so they won't crash our beautiful Porsche." BMW tells its customers something similar (irrc it's 1,000 miles, 4k rpms). Years ago I read somewhere that not only should you vary the rpms but it should be on and off power (ie, engine braking). Apparently most of the ring seating occurs within the first 25 miles or so. My own anecdotal experience seems to support that (see below) Oil Burners: E46 ZHP (manual): Followed BMW recommendation but did not vary rpms nor did I utilize engine braking. Basically drove it as a commuter which included a lot of short low speed trips. The M54 was a notorious oil burner, but it seemed to impact AT cars more. Scuttlebutt was that it occurred because a torque plate wasn't used during the honing of the cylinders. shrug E90 330 (AT): Already had 75 miles on it when I took possession. Not Oil Burners: Drove up and down hills and on hwy at various speeds using manual mode for the first 20 miles with 4 periods to cool down (idle). E90 335d (AT): F32 435i (AT) (same) Benz CLK 320 (AT) Benz SLK 230 (AT) Benz C300 (AT)
 
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Ws6

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My ls7 burned about half a quart and sooted the tail pipes up for the first 500mi. After that, nada. Rings apparently take longer than a few miles to seat in some engines...
 

CT8

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What was the question? Would an engineer use tolerances to describe the clearances in an engine?
 
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I cant see how it could be advantageous to run it harder or faster under any circumstances. The only thing you are doing is generating more wear faster and not in a nice way.
 
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Thanks d00df00d. Trav, I agree. You're creating hot spots and uneven wear-in when going hard on the engine early on. This article essentially confirms the common sense approach. You don't want to lug the engine, but don't want to go nuts on it either. Medium load, vary rpms, avoid continuous speed and stay below 4k rpms when possible.
 
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Ah. It is just One answer, not THE answer. But I cannot argue the point other than, high rpm alone does not generate the heat that high RPM and High load would. Turbocharging presents its own problems as it can present high loading at low rpm. More points: - Varying rpm keeps reciprocating systems out of certain resonant antinodes. - Lubrication splash and coverage patterns will change at different rpms. - To improve efficiency, ring gaps are kept tight, under high load and rpm, they can be overheated to the point the gap is reduced to zero, then you will have loss of finish and material properties of the rings and the liners. Possibly irreversible. German engineers are so good that is why the 996 was designed with a Intermediate jack shaft for cam drive AND with it's non-pressure lubricated IMS bearing to boot - all causing high failure rates in these engines. Add to that, they lost the Big One. Ask Ten engineers and get at least three different "opinions" -Ken New car daddy, enjoy the truck Buster!
 
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German Engineers are not the only smart ones, however they think they are. I worked for a German company for 24 years, they think differently than North Americans, lots of planning and theory done before execution, versus the NA approach of getting into the problem, shirt sleeves rolled up, right away and finding a solution after multiple attempts.
 
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Well I guess it depends on the engine. Maybe motorcycle engines are unique, or at least Ducati's. Case in point, I broke-in my new 2013 Ducati myself, following recommendations in the manual which were not unlike most auto makers recommendations. After I totaled that one in a deer collision at 21,000 miles, I replaced it with a new 2016 of the same model and displacement but that model update became notorious for having a bit less real world punch to the "DVT" engine than the previous gen bikes like one Bambi destroyed for me. Before delivery, I called Commonwealth Motorcycles of Louisville and ordered a "Dyno Break-in" from Chad, the chief mechanic, master tech, and experienced race engine builder. That's where after unpacking and prepping the bike they put it on the dyno and do a specific regimen of runs once it's up to operating temp, for the final run they execute a full horsepower pull to yield a rwhp number for the buyer. Mine tested @144.1 if memory serves, Ducati having rated the 2016 1198cc DVT engine @ 160 crank hp, they ended up down rating it to 150 by model yr 2018 I think. These bikes are chain drive so figure about 10% loss. They did not provide a torque number but the factory rated that engine at 101 lb-ft I think. Well, if you ever followed the introduction of this all new update of the 1198cc which Ducati launched in 2016 models you would hear about a Notorious "flat spot" for power between 4000 - 5000 rpm (11,000 redline). Amid many complaints of lower real world power than the previous gen by other beta testers who bought the first year of that engine like me, I will say mine was a complete rocket that was clearly quicker than the previous gen model I'd owned. I attribute that to the dyno break-in. Now it's true that the engine might have fell part down the line due to this concept of heat flare during high rpm high load operation jouncing bearings and other moving parts, however I never got to find out due to totaling that one just under 5000 miles (gravel kickout on a curve). But that bike was a beast and oil level never budged in the sight glass, appeared not to consume a drop. Believe cylinders were Nikasil, but can't confirm.
 
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With this never-ending controversial topic, it looks like there are actually some things upon which we all, including German engineers, agree: -Vary the RPM during break-in. -Rings need at least some time to seat. -Other components need to break-in, as well. -German engineers are methodical. -Germany lost WWII. -Before they ultimately lost, they put a pretty quick and sound beating on France.
 
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Oddly enough, the two cars I babied did consume oils vs the two I did a few WOT that did not. 2001 Corolla - consumed oil - broken in gently (too much highway driving though and also known engine for oil consumption) 2004 Dodge Ram - Hemi - WOT - never consumed oil 2005 Accord - 2.4L - gently broken-in - consumed oil from new 2007 Mazda 3 - no oil consumption 2014 Mazda 3 - no oil consumption 2015 Mazda 3 - no oil consumption - all Mazdas broken in with several WOT However, I attribute the oil loss due to the engine/piston oil control ring design, not how the engines were broken in as most of the aforementioned engines that consumed oil are known oil burners.
 
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Originally Posted by IndyFan
With this never-ending controversial topic, it looks like there are actually some things upon which we all, including German engineers, agree: -Vary the RPM during break-in. -Rings need at least some time to seat. -Other components need to break-in, as well. -German engineers are methodical. -Germany lost WWII. -Before they ultimately lost, they put a pretty quick and sound beating on France.
LOL cheers
 
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So it seems they're circulating warm water in the engine to help speed up the warmup process and the dyno test run lasts about 30 minutes and they also go to 80% RPM in several increments. I would imagine the engine is at full operating temp after about 20 minutes of this. I guess since Porsche engines are packed in the back, the engine can get hotter in some rush hour traffic, but I don't believe in this engineer's statement "When we do our engine test, the metals inside the engine never reach the temperatures they would when driven on the street since the test session is fairly short.". Never is quite a bold statement. Driving on the streets can mean many, many different things. And I guess that's the crux of the problem. There are so many variables that manufacturers simply want to play it safe. If they printed that hard break in was allowed, I bet some moron would go out on the highway and go 100mph because he needs to brake in his engine properly. People simply have different understanding and interpretation of things. Manufacturers don't want to deal with this. So they say take it easy and set the acceptable oil consumption levels really high to minimize warranty expenses.
 
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I follow Mototune method on the brand newones. Prefer to seat the rings better, and yes Jeep indirectly says breif full throttle acceleration within limits of the law and varying RPM constitutes good break in right in the owners manual for break in.
 
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