savvy

iTrader: (1)

hahahaha

daveZ insanity

iTrader: (4)

True enough, but incomplete. It's primarily the rings that need "seating". Rings expand like springs to keep pressure against the cylinder walls. So the smoother the mating surfaces are, the less "leakage" blows past them from the combustion chamber into the crankcase because there's a better seal.

Valve stems are solid surfaces - there's no inherent pressure sealing them to the valve guides like expansion of rings seals them to cylinder walls. So smoothing the stem and guide won't make a better seal. Since valves ride on a film of oil anyway, it's not a big deal and is irrelevant to modern engine break-in. The surfaces are finished with a fine roughness that helps hold a film of oil, and the metal rides on oil - not metal.

There shouldn't be any oil on valve seats, as it will simply burn and leave a deposit that can prevent complete closure. There may be a minor improvement in valve seat sealing over the first few miles of operation, but after that the valve seal simply degrades over time. I've measured this many times in dozens of race engines. I lapped valves and re-ringed my formula vees after every race for a while and looked at leak-down to decide how much maintenance was enough. There was a consistent 99%+ seal from first start of a rebuilt engine that was maintained for several races. I actually ran 31 races on one engine with nothing more than hand lapping the valves after every 5 to 8 races and new rings at about 15 (Total Seal rings - I don't use anything else in race motors).

To help smooth off any significant irregularities and mazimize ring seal, you want adequate oiling along the cylinder walls. That's why traditional advice is to vary throttle opening frequently during the break-in period. Closing the throttle at higher revs increases manifold vacuum, so it supposedly helps suck oil down around the valve stems and past the rings ("supposedly" because with modern manufacturing tolerances, I strongly doubt that it makes any real difference - it mattered in 1950). Operating under load does nothing to help "seat" valves or rings - it's closing the throttle on a revving motor that is supposed to help. In fact, loading the crank drives the journals into the bearings harder, so it could embed some of those little irregularities in bearing surfaces and increase long-term crank wear. Changing oil and filter at 500 to 1000 miles makes sense to minimize this risk - but a modern oil filter will trap particles on the first pass, so even this effort is probably not helping anything today.

I don't think any of this matters in a modern engine. But unavoidable minor irregularities in metal surfaces do smooth off a bit over the first few hundred miles of use, so I take it easy. The "structured" break-in is a thing of the past - it just doesn't matter in a modern engine.

ZBigDog

I'd take it easy and break her in.

I pay $76.15 for auto insurance a month from Nationwide, full coverage with rental car option. Most don't believe me but I'm 25 with absolutely nothing on my record expect a Safe Driver status. My whole family uses them so I get a family discount which makes it such a good deal.

Spoiled Z

iTrader: (30)

130 a month

CaliTouring

iTrader: (5)

100 bux a month but then again im 19 and its my dads policy but the car and everything else is under my name and i pay for all of it

MulhollandDrive

Well that does not jive with almost everything i have read about "seating" rings.

http://www.ntnoa.org/enginebreakin.htm

B.M.E.P is an important part of the break in process. When the engine is running, B.M.E.P. is present in the cylinder behind the piston rings and it's force pushes the piston ring outward against the coarse honed cylinder wall. Piston rings are designed to take advantage of the pressure and us it to push the rings out against the cylinder wall. Therefore, as pressure builds during the compression stroke, the rings are pushed harder against the cylinder wall which aids in seating the rings.

http://www.stealth316.com/2-breakin.htm

During those first 500 miles, the loading on the rings should be moderate and varying. This is accomplished by varying speeds (no long-distance constant speeds, especially full-throttle) and occasionally increasing the cylinder pressures by quick acceleration or full-throttle uphill climbs. Stay away from redline though. If very-hard rings are used with hard cylinder liners (which are not used in the Mitsubishi 6G72 cast-iron block), the full break-in period may take longer than 500 miles.

Miko

iTrader: (2)

In other words, go do some daily joyriding in your Z (in the city)

bailey bill

1) Read the instructins in the Owner's Manual.

2) Decide whether you want to follw them

On any message board, about half will tell you no break in is needed (including me),and the other half will tell you its very important to follow the instructions.

what do YOU want to do?

SIRCRASHALOT

dood i got my car and 5 days later i took it to the track so i dont belive in a break in period.... flog it.... have fun and worst case its covered

Zmazing03

iTrader: (9)

This is really an opinion question. There are experts that say "don't worry about break in, they beat the hell out of it before they drive it out of the factory" and there are experts that say "drive her like a grandma for at least the first 500".

Roughly $175. $1000 comprehensive deduct, $500 collision, ERSA, rental coverage. 23 years old with a perfect record.

MulhollandDrive

Actually a third opinion, that I lean to, is that you should not beat the hell out of it, _nor_ should you drive like grandma.

"During those first 500 miles, the loading on the rings should be moderate and varying. This is accomplished by varying speeds (no long-distance constant speeds, especially full-throttle) and occasionally increasing the cylinder pressures by quick acceleration or full-throttle uphill climbs. Stay away from redline though"

Armitage

iTrader: (15)

OMFG I can't believe people are actually answering the insurance question. LOL.

daveZ insanity

iTrader: (4)

Unfortunately, much of what's on the web lacks any evidence to back it up - it's opinion. As virtually none of us has had an oil-related engine failure in a vehicle we bought new, there's really little experience out there on which to base advice. Unless the advisor has built, broken down and measured many engine parts knowing how they were made and maintained, the advice is kinda hard to accept without proof. The simple truth is that a modern engine is so well made that break-in is not a major factor in reliability or performance for at least 150k plus - and few of use have our cars that long so we just don't know.

This is a verbatim quote from dozens of websites that use the same source - and it's wrong. If there are any engineers out there, please weigh in. The definition of BMEP is "the average pressure which, if imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured power output". The units are lbs-ft/cubic inch - it's a mathematical calculation of the average ("mean") pressure in the cylinder throughout the power stroke, not a physical force per unit area (the definition of pressure). It can't be "present" in a cylinder because it's only a number. The first hit on Google for "BMEP" (http://www.epi-eng.com/ET-BMEP.htm) contains the same definition that I learned decades ago, and the next 250 confirm it.

No disrespect intended, but BMEP has nothing to do with break-in or anything else in the actual operation of a car. The only practical use for us is to see if claimed power is reasonable for a given engine. Calculate the torque at the claimed HP peak using the formula torque = HP x 5252 divided by RPM. Then calculate BMEP. To break 200 requires some top-level design and manufacture. A Z with 300 hp at 6800 RPM shows a BMEP of 231 - this is pretty good!

Kolia

iTrader: (2)

You mean, someone like the engineer that built our engine and told the guy in charge or writing the owner manual what to put in it?

Would that guy be knowledgeable enough?

daveZ insanity

iTrader: (4)

Absolutely - I follow the car maker's instructions myself because it saves aggravation in the unlikely event of a problem (eg OBD can tell them the highest revs you hit etc). But they're trying to minimize warranty claims and lawsuits over design flaws etc, not educate their customers about automotive engineering.

Nothing I said contradicts Nissan's instructions - it's the explanations offered on the board that are a bit off. Nissan isn't the source of the erroneous definition of BMEP etc. I don't care what others believe - it's their right to think as they wish. But when there's a major error I try to set it right if I have the knowledge and experience to back it up. I've built, rebuilt, and raced dozens of engines in the last 40 years (SCCA, SVRA, VSCCA, VARAC). I measure every bit every time I take one apart and compare what I find to my logs for build, maintenance etc. I think that gives me a bit of an edge in deciding what practices are effective and what aren't.

I mean no offense to anyone on this board - and I could be wrong about any of the above. But as Mr Monk says, "I don't think so". If Nissan were seeing oil-related failures within the warranty period, they'd do something about it. Since no one throws rods, breaks rings, spins bearings, or loses compression in almost any modern car in the first 50k ("almost" because it does happen - Porsche is having a lot of engine failures right now in Boxsters and water-cooled 911s) they have no reason to change their recommendations. We're fortunate - our cars are really very well made and trouble-free. So anyone who wants to change his oil ten times and use WOT 43% of the time during the first 1000 miles is welcome to do so - but I don't believe it matters at all. And my experience, based on facts, visual inspection and measurement of engine parts, leakdown tests and oil analysis, supports this.

bailey bill

Unfortunately, the "guy in charge or writing the owner manual " is more likely to be in the legal department than he is the engineering department.

While I concur that is generally a wise practice to follow the advice set out in the Owner's Manual, DaveZ's comments about modern engine tolerances and assembly is certainly correct. All of the cars that I have owned in recent years (except the Z) included language in the Owner's Manual to the effect that "no special break-in procedures are required". I would certainly hate to think that my Z was built to lesser standards than the several Toyotas, Mazdas, and other Nissans and that have inhabited my garage.

But as I say, you really can't go wrong following the instructions in the Manual. (And as I have acknowledged, I didn't).

bill

Manu

If the break-in period was of any importance, my Euro-spec German owner's manual would mention it. It doesn't.

Give an enthusiast a brand new car that he likes, tell him not to exceed 4000 rpm, you'll see him change up at 2500 rpm all the time, thinking that he is doing good to the engine. You end up with an engine that has been lugged for the first 1200 miles.

Moral of the story :

350Zteve

iTrader: (6)

http://www.mototuneusa.com/break_in_secrets.htm

SekZee

iTrader: (1)

my 1st car in the US was a brand new '00 Mustang GT. I drove it off the lot and redlined it a few times... I never cared about a break-in period, I was beating the hell out of that car everytime I drove it. I sold it after 3 years with 65k miles on it and it didnt have a SINGLE problem in 3 years and we kicked alot of a$$es together too hehe... It was the best car (maintance-wise) ive ever owned

Kolia

iTrader: (2)

Lol ! That's a good reference. Sold the car at 65k.... haha