Running in

[Pinhead]

What changes occur to the car during the running in period? ie what is the point of running in a car, and how can the car become faster with age? Thanks

 

[philip]

youll certainly get a better technical explanation, but in plain English, a cars moving parts (pistons, gears etc.) are designed within certain tolerances. On most mass produced cars these tolerances are wide and can explain performance variations between one car and the next off the assembly line. By running in a new car/engine, you will cause the various components such as pistons to adapt to the cylinder bores and form a better seal. You will also avoid damaging the gear cogs in your gearbox, etc etc. That in turn leads to better performance, or I should correct that it leads to not losing performance. A good example is that ragging the car from day one and when its cold etc may cause improper seals between pistons/cylinder walls leading to eventual combustion gases (blowby) escaping past the piston rings into the cranckase and doing bad stuff down there etc.

Running in should be done properly at different rev ranges without unecessarily loading the engine etc. same with gears.

HTH

 

[BenR]

If you dont push the engine hard enoug during the first few miles then the rings will never seal properly and that will lead to a loss of power and blowby.

When running it in you should put full load on the engine. WHy, because the rings use gas pressure from combustion to press them againt the cylinder walls, when sitting normally they may only apply 5psi, and the harder you push the pedal, the harder they will seat against the wall. So a good full throttle run will help bed the rings properly, but be warned you only have a small window to do so.

SO dont fanny about babying the motor or it just wont be anywhere near what it can be.