Particulate Filters - petrol and diesel

[Quacker]

Originally Posted by Goodshot

I was joking about the 2500 rpm!

Hard to tell without an emoticon.

If you were a Volvo FH truck driver with their D13K engine, you would try to drive economically at between 1000 and 1400 rpm, but could rev to the governor for short acceleration periods, maxing out at 2500 or so for the 500hp model. You'd also be blesses with 2500Nm torque at between 1000 and 1400rpm, spot on where maximum efficiency is achieved.

I mentioned four cylinder engines having an operating range starting at a low of 1500rpm and you may be wondering how the big truck engines have an operating range from 900rpm upwards. It's to do with the inherent balance forces in four stroke engines verses six, plus the piston speed, which is higher than you may think at lower revs in those big engines due to their much longer stroke.
Four cylinder engines require balancer shafts and weights to run smoothly at higher revs. Six cylinders don't, but do require dynamic balancers, usually incorporated in the front crank pulley, external to the crankcase, in order to counter the elastic twisting/ocillating tendencies of six cylinder engines.

[gaby]

Originally Posted by GuidoBrunetti

Why is this necessary since I didn't think they produced carbon particles to anywhere near the same extent.

Its the direct injection technology that causes incomplete burned particles. By introducing it to petrol engines they
also inherited this "feature". Since the fuel is injected a very short time before the ignition takes place, (some of?)
the droplets don't vaporise enough to be completely burned during the combustion cycle.