DIYbanter - View Single Post

Anthony wrote:
wrote in news:nr6l42dk9piggu2iph2vtpks8ofqqjd92q@
4ax.com:

Why does an older enginr(class 8 diesel) vibrate more than
a new(newer) motor, same manufacturer?

i.e. what changes are happening as an engine ages/wears
that increases vibration/shake?

thanks
gary

Much tighter tolerances on the parts, including balance influencing
issues such as piston and connecting rod weights and clearances. There
has been a large jump in injector technology, meaning better atomized
fuel. The EPA regulations have required a change to a much higher
compression ratio, and this has resulted in basically a brand new design
of the engines from the ground up. In order to take the increased loads,
all the other parts of the engine have to be beefed up, which damps
vibration.
Gone are the aluminum pistons with a cast ring insert, replaced by, at
first a 2 piece steel/aluminum skirt piston combination, and as the
latest round of EPA tightening came into effect, an all steel piston.
There is another round of EPA tightening due this year, which will
require changes beyond that as the diesel manufacturers again bump
compression ratios in order to clean up exhaust emissions.

The side benefit to all of this, is a more powerful engine that uses up
to 20% less fuel than it's predecessors.

Seems rather obscene to say the EPA is driving such improvements(?)