New car doubts

[dimlight]

So we bought a Peugeot 407 ST Sport pack V6. Of course i had to kidnap it and go for some twisties ..

My question is .. Why should you wait a certain amount of time, or better yet, a couple of thousand kms till you can rev new cars really hard?

[whiteballz]

to give the engine time to wear itself in.. like how shoes feel very hard till you use them for a few hours. when they start to fit your feet better.

[dimlight]

to give the engine time to wear itself in.. like how shoes feel very hard till you use them for a few hours. when they start to fit your feet better.

yeah i know.. but i want a more technical explanation.... Matra????????

[johnnynumfiv]

The piston rings need time to seat right(wearing away a little at the cylinderwall to get a good seal). Along with other components of the motor.

[PerfAdv]

The piston rings need time to seat right(wearing away a little at the cylinderwall to get a good seal). Along with other components of the motor.

Spot on!



This isn't the most technical explanation but these guys are some sort of experts:
http://www.cartalk.com/content/colum...3/July/03.html

[Matra et Alpine]

You need to "harden" the moving surfaces.
Bearings need to "bed in".
You can extend an engine life 10-fold by proper running-in to allow all the surfaces to smooth out and harden.
How much detail do you want ? We coudl go through the metallic change that happens by gentle increase in heat and pressures and how htat leads to a surface which is "stronger" with less friction.

[RazaBlade]

Obviously you have to do that will all cars, but why dont specialist companies that make less cars do that for you? I wouldnt want to buy a Porsche, and have to drive it for half a year carefully... or am I missing a point?

[Matra et Alpine]

Obviously you have to do that will all cars, but why dont specialist companies that make less cars do that for you? I wouldnt want to buy a Porsche, and have to drive it for half a year carefully... or am I missing a point?

It's usually only about 500 miles.
If you were only doing 500 miles in 6 months then you likely earn enough money to PAY someone to run it in over a weekend

It's a difficult line. EVERYONE wants a car with zero delivery miles. Their ego can't stand that the NEW car could have a couple of hundred miles on it Manufacturers can avoid the run in by treating the components and/or bench running in - but then the buyer has to PAY for that in teh cost of the car !!

[dimlight]

Thats exactly my point .. thanks for your answer Matra. I wouldnt want to drive my car knowing i have good power just a stomp away. Anyways, its true what they say about this car.. it handles like a dream, i thought it was all just hype.. ill post pics soon !

[MrKipling]

I heard engines also bed in differently according to how you drive them during the run-in period. As in, it'll end up a bit looser and freer revving if you drive it a touch harder to start with. Could be bollocks - but I can kinda see ow it would work.

[hightower99]

Actually through my own experience and that of some others I have come to the conclusion that the soft running in that is suggested in the manual can actually damage your car!!!

just so everyone understands the rings in an engine will seat (grind off what little they can) in about 50-120 miles depending on what they are made out of and what oil you put in. After this time if they have not ground properly then you are screwed because they won't grind down any more. also the myth that motor surfaces need to harden with gental temperture change is not true as the temperatures are not high enough and because heating metal slowly and letting it cool off slowly will actually soften it in some cases (however don't go out and rev the motor like crazy and then shut it off!!) however the idea that there are some surfaces that can be work hardened is true and to get the most out of that they should be worked hard. So I suggest you read the website I will post in a minute and try it (I have used this system on over 20 motors and they are all doing better than is expected!)

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

[Matra et Alpine]

Your points are valid HT and WHY the figures in each models manual should be respected.

The materials the manufacturer uses determine what if any reun-in is needed. Also I find that often drivers take it the wrong way and that has introduced major problems in other areas. So the indication to keep revs below 5000 and then they drive around pulling at 1000 revs in 5th adn the huge TORQUE that puts back through the engines screws the main bearings due to crank twist.

He's using race-engine break-in knowledge to suggest street use - they're totally different Different rings, different materials. Though the results are well within the ballpark for rings and some liners. Some liners aren't nikasil coated and so do need a littel more care about bedding in and where "torque" on the cylinder can be an issue.

HIs experience is BIKE ENGINES which dont' get very much torque stresses as most folks dont' ride 2 up with full luggage and a trailer in their first few miles. Cars have different stresses.

Varying the speed is the BIG win and was always "common knowledge" long time ago when everyoen knew about their engines and run-in periods in much more detail than modern cars require owners to think about. My dad NEVER sat at a fixed speed on a motorway. Engineers back then "knew" all this stuff. It's the simple instructions to most owners that the books make the mistake over. BUT the run-in for SOME engines is a necesssity for long life of max power.

I'm not sayign he's wrong, he is right.
It's just not the WHOLE story for all cars.

eg Ford camshafts requred a 20 minute bed-in run to get maximum life. OEMs are the same with the exception of Burton power adn some Kent which smooth and harden the surface as part of production, you have to use matching followers equally smoothed and hardened all at a cost 5-10 times the OEM/original part replacement. If you cut your own cam lobes for different tracsk/setups then you get WELL used to that 30 minute boredom

[hightower99]

actually I got my hands on an unused factory stock FORD 3.8 V6 used in the '93 taurus(all new parts with no running in) and used this break in and I can tell you it works really well compared to the one in my dads taurus!!! I have also followed some of his tuning tips as well as some of my own and now this engine produces a healthy 280bhp at 4500rpm and 300lbs. ft. of torque from 1800-2500rpm so it seems that if you use your head anyone should be able to apply this to any 4 stroke engine.

[Matra et Alpine]

actually I got my hands on an unused factory stock FORD 3.8 V6 used in the '93 taurus(all new parts with no running in) and used this break in and I can tell you it works really well compared to the one in my dads taurus!!! I have also followed some of his tuning tips as well as some of my own and now this engine produces a healthy 280bhp at 4500rpm and 300lbs. ft. of torque from 1800-2500rpm so it seems that if you use your head anyone should be able to apply this to any 4 stroke engine.

Definately, BUT it should also reflect any knowledge given by the manufacturer and what their reason may be. See the Ford cam example

Bike engines are quite different from cars, especially older cars.Bieks have used much of the engineering "technology" now being presented as new an dinnovastive in car engines They also are MUCH lower mass. MASS is the problem that affects all the other parts

[hightower99]

the Mass doesn't have that great of an effect cause I used this system on a 3.8L V6 plenty of mass but for all that extra mass and power the support systems and the systems that are effected by the mass are also larger and stronger.... and this system being used on bike motors I can tell you that the internal stresses and accelerations are much higher in a bike engine then in a car motor. So use your head and use this system and see between 5-10% increase in power and economy!!! (if you haven't buggered the motor yet!)