[VAC] Re: recommendation for tow vehicle

["Carol and Oliver Filippi" <ofilippi@xxxxxxxxxxxxx>]

Most all modern gasoline automobile engines are short stroke, relatively
high compression, high RPM engines.  This design typically produces low
torque at low RPM so the engines get their power and torque in the higher
RPM ranges.  In short, they are street versions of racing engine technology.

The goal being to get the most power from the least weight and good fuel
economy (which is done with computerized engine management systems).  The
only way to improve the torque at low RPM on this engine design is to add
variable valve timing.  Variable valve timing works remarkably well but is
somewhat complex and requires significant engine redesign - something the
bean counting automakers are reluctant to do.  I will bet that most new
engine designs will incorporate computer controlled variable valve timing,
but I am not going to hold my breath waiting, as the current sluggish
economy is not condusive to heavy investment.

Ford, for example has developed a "Modular engine" such that the V4, V6, V8,
and yes, V10 is simply a longer version of the same basic components.

It really doesn't matter whether the engine is a straight or a vee or an "X"
or "W".  The bore and stroke ratios are essentially the same.  The only
reason for the V 6 (vs. the straight 6) these days is to make the engine
shorter to fit in the engine compartment - often sideways in the front wheel
drive configuration which provides more room in the passenger compartment.

Obviously, heavy duty truck engines are less concerned about weight and fuel
economy and more about low end torque and durability.  Here and there, one
will find an older engine design which hasn't yet been retired which does
not fit the modern design formula.  Hence the, "My old straight 6 had more
torque than ----"

Realistically, one has to chose from what is available.  So, with a higher
RPM engine and its characteristics, the fix (or partial fix) is to go with
lower gearing in the rear end (higher numerical ratio).  This will cause the
engine to run a little faster for any given road speed.  This
results in the engine having more torque and power at a given road speed
delivered to the rear (or front) driving wheels.

Oliver Filippi