re: watter (sic) wetters

["Jeff Loh" <jeff.loh@fluordaniel.com>]

     Reading the thread on if water wetters reduce engine
temperatures, 
     there seems to be a misconception on how a cooling system 
     functions.

The t
     em
     perature of the engine is determined by the overall temperature
of the 
     coolant circulating in it. The thermostat governs what tempera
     ture threshold the coolant flows from the radiator into the
engine.
      Whether the thermostat is mechanically, electronically, or
compute
     r controlled, it opens at a predetermined temperature.  But once
that 
     happens it's strictly a function of the thermal transfer
capacity of 
     the radiator. The control loop only serves to monitor the engine
temp.
     
     Water wetters, by reducing the surface tension of the fluid,
increase 
     the efficiency by which thermal transfer occurs. Therefore, it
makes 
     the fan better able to extract heat from warmed coolant. There 
     _should_ be a measureable difference. On our race cars emprical 
     evidence shows that cylinder head temps are lowered after adding
water 
     wetter. 
     
     Now a real way to lower engine temperature would be to run the
cooling 
     system BACKWARDS; cold coolant comes from the radiator, goes to
the 
     HEAD first, then the block. ZR-1's have that feature now, and
some 
     oil/water heat-exchangers on VWs do too I think.
     
     YMMV etc.
     
     /J.