RE: [A/S] Mercedes ML 500 and a 34 foot Airstream

["Oliver Filippi" <ofilippi@xxxxxxxxxxxx>]

Steve,

The Nissan Titan is more an American truck than a lightweight Japanese mini
pickup.

It was designed near me in La Jolla, CA (just north of San Diego)for the
American (not Japanese) market.  As the market has changed, so has the
design of the import econo cars. Many of the foreign automakers have been
playing "Catch Up" in the more powerful engine department.

Naturally there are a lot of design trade offs in how to get adequate
pulling power for a tow vehicle. Variable valve timing is only one. Engine
torque at various rpms can be adapted to the anticipated load by a judicious
conventional cam design.  (From Steve's comments, the latter approach seems
to be the one Nissan took.) An engine which develops its power at higher rpm
can work if the transmission gearing will allow the engine to quickly get to
it's high torque rpm range. (Also, a part of the Nissan design.)  The
biggest downside to this approach is reduced engine life.  High rpm is the
most significant factor in reducing engine life due to the higher loads
placed on the components that are trying to hold the reciprocating parts
together.

As long as you don't have to high rev the engine every time you pull out
from a traffic light, or pass a slow moving vehicle, such a design will work
fine.  Obviously, if the engine is too small, you will be in the high rev
zone most of the time - not a formula for long engine life.

Oliver Filippi