5 hours ago, flybynite said:

I avoid 2 things, 'labouring' and 'thrashing'. I avoid them by more of a margin when the engine is cold.

100% agree.

Some good advice here. Thanks for that. I'm sure there's a science behind it, but how does 'labouring' harm the engine if the car is always driven gently? Or is it that a 'laboured' engine will wear much worse than a properly run in one if it is then stressed at high revs?

6 hours ago, SkodaAsh said:

Some good advice here. Thanks for that. I'm sure there's a science behind it, but how does 'labouring' harm the engine if the car is always driven gently? Or is it that a 'laboured' engine will wear much worse than a properly run in one if it is then stressed at high revs?

 

The argument is that torque hurts engine more than revs/power. 

 

When two surfaces are running together, like a cylinder bore an a piston ring, in the first hours of operation there will be micro hot spots where raised portions of the piston ring profile will be running against the bore so it is wise to give the two running parts time to "mate" under low load/torque conditions so those localised hot spots do not turn in to micro seizures and score the bore and therefore lead to leakages of exhaust gas  later on in the engine's operation.

 

I prefer to let the engine rev a bit under light load then let it bog down in the lower revs and apply more torque to get the car/bike moving in the traffic.  Seems a more empathetic way to go about it.

 

Not revving the engine, under light load, can create a lower and upper ridge within the bore which suddenly gets hit against if one suddenly revs an engine higher than the imposed rev limit when one passes a certain mileage and fells that one can then suddenly rev to another 1,000 or 2,000 or so revs.  Therefore not how i do it and it has worked for the fifty or so vehicles I have had.   Blown up lots of two stroke engines but, touch wood, no 4 strokes.   

  

6 hours ago, SkodaAsh said:

Some good advice here. Thanks for that. I'm sure there's a science behind it, but how does 'labouring' harm the engine if the car is always driven gently? Or is it that a 'laboured' engine will wear much worse than a properly run in one if it is then stressed at high revs?

 

Not difficult to imagine really, In simplistic terms, low revs, high gear you are using a lot of 'leverage' against the engine. if you start putting lots of throttle in it has nowhere to go because it doesn't have the 'leverage' to do anything. Again, in simplistic terms you are forcing the piston down against a highly levered drivetrain and at the lower end of the rev range it does not have as much momentum to counteract more sideways forces.

 

In older engines you could hear it. It was when they 'pinked' i.e. detonation. These days the cars are clever, they have knock sensors that will retard the ignition to stop the detonation, however the cause is still there.

 

In older engines it caused the pistons to kick, often to the extent you would get piston-slap and when you take the engines apart you can see the evidence of witness marks on the bores and piston skirts. Modern engines have tight bore clearances but the same force exists trying to twist the piston. If this is occurring it does not surprise me that the engines have issues later in life with rounded or loose upper piston rings and damaged oil-control rings.

 

It is demanding a huge amount of throttle from low revs that does it, the trouble is people just keeping it in high gear tend to do just that because in a very high gear it takes more throttle to get anywhere. Better keep in a lower gear and rev the engine a bit

On 04/07/2018 at 20:02, themanwithnoaim said:

I rent my cars so.....

I drive them like I just stole them

1st day, last day, everyday

Once that oil is warm....crack on. 

 

Just don't sit with cruise on for first 200 miles. Mixed driving. 

 

Surely better for the pistons etc to used at different rev ranges than getting upto 2.5k and changing. 

 

I certainly didn't red line it from the off but didn't potter about. 

 

Look at aks tuning write up on their estate. They thrashed it for first 200 or so miles then swapped oil out. And let's face it that octy has some serious power and is still going strong.