Power gain from breaking in an engine? Still possible with under-used 996 engine?

I�m wondering if anyone has ever measured or knows how much power an engine gains as it gets broken in? I�ve recently driven back-to-back two very similar 996s and one felt stronger, or at least livelier, with more aggressive throttle response (which is more important to me than power). I�m pretty sure neither has any (detectable) mechanical problems. And I don�t think either has been chip tuned (though I can�t really know). What I do know is that the one that seems livelier is approaching 80k miles. The other one has only done about half of that, and the data from the computer shows the engine has had a very gentle life. So much so that after a PPI a year (and a bit over 10k miles) ago, the recommendation was to drive the next 500-1000 miles as though breaking in a new engine. What are the chances that engine will still get noticeably stronger (and livelier) as it gets broken in more? Thanks in advance for any thoughts about this!

Who is advising to follow break-in procedures on an engine already with 40,000 miles on it? Never heard of such advice. At 40,000 miles the engine is well broken-in.

I don't think that mileage is making the difference. What year were the engines manufactured? A reman 996 engine with all the upgrades of a later model year will feel different than an earlier engine. My crate engine built in 2006 feels a lot stronger than the original engine in my 996.

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Interesting - could you elaborate for the benefit of a new guy? Mine was replaced with a remanufactured unit in 2008 under CPO warranty, but having not driven the original I don't really have a frame of reference.

I don't have any info or solid evidence, other than my own experience. I assume some of the engine internals were upgraded over the years. Hoping some others with more knowledge can chime in with a better explanation.

You my friend, have some very interesting OCD analysis traits that even goes beyond the traditional RL crowd. You should really see someone for that condition. The only things I can think of is the use of fresh gas and burning off carbon deposits that would make a dormant car more lively once again. You maybe able to gain 0.0005mpg too if you brush off the cobb webs.

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Nil. Zilch. Zero. Nada. While lab and field tests have found an engine break-in continues for some thousands of miles after the break-in period it doesn't continue for in this case 38K miles. That's 2K miles factory break-in period and the remaining 38K miles to get to the 40K miles. The differences between the engines above and beyond what could possibly be due to normal differences between two otherwise "identical" engines can be due to gasoline and engine/fuel system hygiene. Whenever you buy a used car my recommendation is to consider using a bottle or two of Techron (as per directions) to clean the fuel system, injectors, and combustion chambers, sensors, and converters of any deposits. In the case of the car that was "babied" it probably has a good amount of engine deposits. Or instead of using a bottle of Techron just run a tank or two or 3 of Chevron gasoline. Briefly, my experience in switching from Shell to Chevron gasoline had a noticable positive effect on my Boxster's engine after just a few tankfuls of gasoline. There was no improvement with my Turbo's engine. But more recently circumstances prompted me to try a couple of bottles of Techron in the Turbo and after the tank with the 2nd bottle added to it was nearly gone the engine started to feel a bit peppier. Not to the degree the Boxster engine felt after a few tankfuls of Chevron gas but I'll take what I can get.

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safe to say you have read the OP's past threads

My engines pick up an average of 11lb/ft of torque after the first 52 mile break in loop. I typically see a very marginal difference for the first 3,000 miles after that, but between 3-6K, they'll pick up another 5-7, lb/ ft. The average HP will typically improve by 7% all totaled in the first 10,000 miles. This is due in part to the dramatic friction reduction we see from Nikisil cylinders. The low tension rings take a while to scrub in, even with proper break in oils, and regimens. I've been perfecting my break in, since day #1, and today, after a customer receives a car back, I tell them to do nothing special- just drive it. We've already put the miles on it, my way. The UOA proves what works, and what does;t; the dyno confirms it, and a decade in the field of practical application backs that up.

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Wow, that's a substantial difference. If it works that way for stock engines, it would mean over 20 hp. Though I guess it's hard to generalize about either the power gain or the number of miles from your engines with nikisil to stock. Indeed, I've heard that with the stock engines the ideal break in method might be a bit different from doing nothing special as with yours, in that it's best to run them hard at high revs (after an initial gentle period of course). That's not really how the low milage car i referred to has been driven. Rather city/town driving 1-2 times a week and a lot of highway cruising - though that's at 4000 rpm plus (I'm not in the US). Still zero track time :-(. And limited country road blasts without squeaking sounds from the passenger seat :-((

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Can�t really comment, neither knowing nor caring what OCD is. If it�s of interest, in this case, as well as in many others, learning about this could have significant practical benefits for a decision I need to make quickly. To be fair, I can�t say this is always the case. In at least one, after making the decision I needed to make, there were lots of interestng posts from others, and lots of things mentioned that I might want to buy in the future, so I asked follow on questions that had no short term relevance for me. Is that a bad thing though? Lot�s of others who posted seemed to find the discussion interesting. At least one made this quite clear. And that discussion was about (lots of) mods. I�ve learned the hard way that expensive mods, even those that get a lot of praise online, can have undesirable consequences, or even fail to provide the expected benefits. And that you need to know a lot more than whether a few people say they are one-dimensionally good or bad to avoid bad decisions. Anyway, back to breaking in engines. Lots of very helpful and interesting posts here (including yours, Alp, which is half about engines). Helpful for me, and hopefully helpful and interesting for lots of others. Thanks everyone!

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Thanks! I didn�t know of the lab tests. I had the impression from scattered references in many years of car magazine reading that 30k miles might be the sweet spot. But those were just references like �now with X miles, the engine has really come alive�. On the other hand, based on Jake�s experience, I guess it depends on the engine as well. Also interesting about the techron. Are there no disadvantages or dangers? I seem to recall that after buying some car, I thought of using techron and concluded better safe than sorry. But I really don�t remember why that might have been �

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That isn't by chance because your 2006 engine is a 997 engine (as implied by your signature)? Otherwise, very interesting question. The livelier enine is model year 2005. The other is 2002. But I thought there were zero differences, other than the 2005 model year cars having 997.1 IMSs and RMSs. Can the IMS and RMS have any performance benefits? Or are there other differences???

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I was just reading your post again - as is often the case, there are a lot of interesting things there. Even if Shell doesn't have as many additives as Chevron or Techron, does it matter if one uses Shell or similar fuel often enough? For the past 10k+ miles, my car has used brand-name, high octane fuel with additives 99.5% of the time. Is is possible I'm still missing the benefits of the full Techron treatment?

One final comment for this evening. I have one other clue about what could make such a difference - the air filter and mass air sensor. More on this later, but first I want to do a bit of testing this weekend. Be back soon!

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Yes, but isn't the 3.6L 997 engine supposed to be the same as the 3.6L 996 engine, except for a bigger IMSB? Or so Porsche would have us believe. I beg to differ. There is something different about these engines that gives the later builds a stronger feel. Not sure if that means more horsepower, but it certainly has more torque.

Picked up my '04 996 exactly 15 months ago. It had only 56k km and ran well. I've driven over 50k km since then and the car definitely feels stronger and revs more freely. Only regular maintainable since purchase. This only anecdotal as the car hasn't been on a dyno but seat-of-the pants tells.

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Different cars/engines different break in mileages... When I bought my 2002 VW Golf TDi owners were offering up that break in took 60K miles... One concern I have with using Techron is the possibility of an increase in oil contamination. I've never bothered to try to detect this with an oil analysis, if it is even detectable. I just am aware of it, or at least of the possibility of it given how Techron is supposed to work, and whenever I use Techron do so a few tankfuls of gas before an oil/filter service is due.

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Possibly. To know you can if convenient and price is not an issue switch to Chevron gasoline and see if after a few tankfuls the engine runs any better. My experience is it did. Better enough that it was quite noticable. Or you can use a bottle of Techron per instructions. I just did this and the label on the bottles I bought -- I bought two bottles -- is one bottle treats 20 gallons of gasoline. I used a bottle per tank of gas which is about 16 gallons which is not quite according to the instructions but I didn't want to fool around with trying to measure out the Techron and then dealing with a small left over portion of the stuff. If you notice an improvement the recommendation is to use a 2nd bottle after the first one is used up. If you notice an improvement then your choice of gasoline coupled with how you drive your car is not obtaining the benefits of the engine deposit additives in the gasoline you use or the additives are not up to the task of keeping the engine clean even when the car is driven optimally for these additives to have a chance to work.

While assisting with the EPA certification process of 2 different new cars, (1994 Saleen S351 & 1999 Shelby Series 1) both certification engineers insisted upon nothing but Chevron supreme fuel going into the fuel tanks.

power gain at that mileage.....highly unlikely

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My info is Porsche uses Chevron gasoline for its USA emissions certification testing. I do not recall where I got this info so I have no source to provide. Given the positive effect switching from Shell to Chevron had to my 2002 Boxster I could believe it. Understand I'm not advocating everyone switch to Chevron. In spite of the benefit I had switched from Chevron to Exxon simply because the price of Exxon gasoline was 5 cents a gallon less than Chevron and we are talking about two stations almost directly across the street from each other. But if I stay with Exxon and I will as long as the price difference remains you can be sure that once in a while I will fill up the gas tank with Chevron gasoline. And in fact I did just such a thing before I took the Boxster in for its smog test last Tuesday. Before the test I ran the tank down to nearly 1/4 tank then filled it up with Chevron gasoline and drove enough to use up about a 1/4 tank of gasoline. The car passed with no problems. No sniffer test though just the plug and pay test. The tech plugs in a computer to the car's OBD2 port and a few minutes later I pay $78.

A bit of an update. Forgot if I mentioned this, but after driving both cars back-to-back, both the local Porsche dealer and a local specialist told me that the car with more miles had a distinctly livelier engine. This was without prompting except to ask them what they thought of the cars. I had already told them the higher milage car was louder. So after their reports I asked if it wasn’t just that it sounded livelier. “No – it’s definitely livelier” they both said. The specialist thought it could be the air mass sensor or the air filter, so we swapped both. Then I drove home in my car and I thought it made a difference in both liveliness and noise. This weekend however we took both cars out and did a series of acceleration runs on the highway. From various speed between about 2750 and 4000 in 3rd and 4th, It seemed immediate throttle response was too close to call. From 2000-2500 in 6th gear, immediate throttle response was again too close to call. But then the car with fewer miles began to pull away. (I think the 6th gear test, while probably no better for testing immediate throttle response, was better for testing total power, because is was possible to separate the effects of who hit the throttle first (which car jumped forward first) and which car pulled hardest.) What’s more, the car with fewer miles is probably a bit heavier. But … it’s not a definitive test. The car with fewer miles has substantially lighter wheels. It has 17s (the 10 spoke 17s which I seem to recall are around 8kg), where as the other car has 18s, and not Porsche’s best (the ones that look like multi-piece wheels - I seem to recall they’re over 12 kg). The 17s are Eagle F1 Asymmetric 2s, a modern tire with lower rolling resistance. The 18s are Zero Rossos. And it’s 255 vs. 285 in the rear (though unusually, both are 225 in front). So is the lower-milage car really faster? Who knows? How much difference can these wheels make? Still, it seems the cars are close. But what’s not close is the sound. Despite changing the air filter and air mass sensor, the higher-milage car is still perceptively much louder. Particularly when blipping the throttle, when it has a nice deep, aggressive bark. It still feels faster, and is more fun. By the way, I do mean “perceptively” louder. I’ve recorded both cars using my smart phone’s camera, played the videos back on my PC, and measured with a decible meter. The louder one is at most 1 decible louder, if even that. I had thought – and after switching the intake bits and this weekend’s adventures (sorry, tests) – I still think that this is due to the exhaust tips. The lower milage car has standard ovals. The higher mileage the optional sport double tips. The ovals might have been ever so slightly compressed by contact with the ground – though not to the extent my eyes can see it. We did switch the tips a while back (mentioned in another thread), but I only got to drive one of the cars after the switch, so I can’t be 100% sure how much difference it made. So what shall I do? Buy some “sport tips”? Nope. Why buy tips when I can buy a new, lighter, 200 cell exhaust? That should be loud enough ;-) I may also try to always fill up with the best gas I can find (not Chevron, alas) and find more occasions to use high revs …

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Well, if the 3.6L 997.1 is the same as the 3.6 996 except for the IMSB, then it is the same as the 2005 model year 3.6 996. The 997.1 engine is supposed to have 325 hp versus the 320 in the technical documents and everything else I've ever seen for the 2005 996 - but that proves absolutely nothing. The only other thing I know about these engines is that, according to EVO when the fist tested the 997, the engine doesn't sound as aggressive (and good) at the tip of the rev range. Interesting questions. Are the 997.1 and 2005 996 engines the same? Or are the 2005 996 and earlier 996 engines the same? And are the differences torque, or power? Or perhaps just sound??

I think the 997.1 has a different exhaust than the 996. Exhaust and engine tune could easily make up the extra (published) 5 hp, if in fact it is true and not just promotional. I agree, these are very interesting questions. My mechanic, who has been working on Porsche 996 cars and engines for may years came to the same conclusion as me - that my 996 with the replacement engine he put in my car feels significantly stronger (or as you put it "livelier") than the typical 996. I do have a dyno test readout from before the engine was replaced. Would be very interesting to get another dyno test with this engine.

Go test drive 10 cars, and one is faster than the rest. I see this all the time as I test my engines back to back, one always ends up stronger, and sometimes a less- prepared engine makes more power than it should, and one thats more prepared makes less. Why? Engines are mechanical, and nothing mechanical will ever be accurately predictable. Other things that play into this is injector age/ cleanliness, wear on timing chains and wear pads, and etc. As these engines wear the valve timing events retard, and retarded valve timing makes more top end power. The same goes with carbon deposits on the piston crowns, which bump up the compression ratio of the engine just a tad, as it reduces deck volume. One reason we see higher mileage cars make more power, than lower mileage cars (even with the exact same engine) is due to drivetrain wear. Keep in mind that what you feel in the car is rear wheel power, meaning the power must make it through the drivetrain for you to feel the difference. The dyno is the same way, it just gives a value to the power that your butt cannot do. So, a more worn transaxle, and CV joints, and even the condition/ compound of brake pads will play with this, a lot. The less miles, the tighter everything is. Loose= fast. When my wife was Land Speed Racing a 996 (she holds 4 records still today) I replaced all the drivetrain in the car with high mileage, used parts. That alone picked up 12 lb/ ft of torque average, across the board. That said, choosing an M96 car only from the net power you sense while test driving it, could be a very, very poor method of choosing the car that you really need.