On 12 Nov 2006 15:16:27 -0800, "Doug" <anothername@access4less.net>
wrote:

>Horsepower is torque times speed (and maybe a constant to get the right
>units). If your torque is in ft. lbs and you multiply by the rpm of the
>engine, you get your horsepower. You can look at the torque curves and
>horsepower curves for engines in car magazines that review the cars.
>
>When people talk about an engine that "has a lot of torque" what they
>mean, usually, is that it has a lot of torque at low rpm.
>
>The design of the engine, the bore and stroke and size of the pistons
>and weight and size of the crank and flywheel all play a part in how
>much torque and horsepower an engine has. I don't really think that a
>diesel engine has more torque by being a diesel. It's just that these
>are usually truck engines and they want it to have good pull at lower
>rpm, so they make it so it has good torque at low rpm. However, I'm no
>expert.
>


The burning properties of diesel fuel developes good low RPM power but
it has its limitations and with proper gearing a gas motor can do a
fine job. Most gas motors are just getting started when oil burners
are running out of breath and if you gear a gas motor a lot
differently than a deisel to use its power curve properly it will pull
well. Most do not because people have a mental block on what a good
axle ratio is for a gas motor and gear them wrong. BTW, 600 ft lbs of
torque at 2000 RPM is the same HP as 450 ft lbs at 3000 or 300 ft lbs
at 4000 RPM. Als remeber that a diesel needs a lot more size to exceed
the torque output of a gas motor either via more displacement or
boosting with increases its effective displacement. Take the turbo of
a CTD, PS or Dmax and it will be quite gutless.
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