Engine Operating Temps

[Greg Hermann]

>No from basic thermodynamics  the hotter the water jacket temperature the
>higher the mean effective presure (ie torque & power)  because less heat is
>rejected to the coolant,

Absolutely. This is also why polishing chambers and applying coatings will
EACH produce a real gain in power and efficiency.

in effect the cylinder pressure is higher at towards
>the end of the power stroke --

Actually higher most of the thru the P stroke--most heat loss occurs near
TDC. This is why some racers can get away with filling the bottom portion
of water jackets with epoxy for extra strength and rigidity.

effect of temperature is even more pronunced  on
>a turbo engine as this raises the gas temperature at the end of the stroke.

True, but more due to higher gas density all through  cycle than due to
different temps--unless no intercooler--then temps are higher all the way
thru cycle.

>The temperature is of course ristricted by other consideratons --- knock,
>engine materials particularly pistons, piston rings and valves   and also the
>boiling point of water.

If you are really going for optimum, boiling point of water is not a
theoretical limitation up to approx 713 degrees F/ approx 3500 psig (the
critical point of water)
Obviously, practical design considerations limit one to lower temp/pres
levels than this, but 15 psig/250 degrees F (see saturated steam tables) is
nowhere near the practical limit either for an engine or for a properly
built radiator.

Regards, Greg
>
>Andy MacFadyen