How Does Friction Impact Car Engine Performance Across Different Speeds?

[Tier]

I really don't know how I would start to work this, but here is my problem...

I need to be able to determine the effects friction has on internal combustion engines, but as I said before, I don't know what to do to start.

I think that the weight of the piston and the torque generated by the turning of the piston would affect this, but I'm not sure. Also, there are no really particular speeds that I need to know this for, but more for a range of speeds, to determine how friction acts when a car is moving faster or slower.

 

[Tier]

Just looking up some more info, which unmasked a few more questions...

If I knew the rpm, could I find the torque?
How would I find the force of friction that the torque needed to overcome to keep the engine running?