Operating temps

[Shannen Durphey]

Aaron Willis wrote:
> 

> >Also, my temp was measured in the intake's water
> >passage by the thermostat housing.
> >
> >sQuAsH
> >
> >
> >>      Bruce,
> >>      Only testing I've done is run the same car, same
> >> timing, same gas, same
> >> jetting (I know this is an EFI list) at same ambient

> >>
>         My temp is measured right under the thermostat, and the car typically runs
> right at the thermostat opening temperature, regardless of ambient temp.
>         Gauge accuracy has been confirmed with a seperate thermometer.
>         Engine is an aluminum-head Hemi style four.
>         And I'm outta here...not wanting any argument, just offering my
> observations for what it's worth.
> 
> 
>         Aaron Willis
Observations are good, and welcome.  There are too few honest ones
around.  

Anyone who spends time learning about cars realizes that observations
are just that, and they can lead to more questions than answers.  So
with that said I want to ask about your notion of engine temperature. 
If you measure the water temp at the thermostat, it stands to reason
that the thermostat temp and the water temp will agree, as long as
engine load stays within a moderate range.  But what if you could
measure temp in different areas in the heads, at the intake and
exhaust valves?  Under the valve springs?  Near the exhaust ports?  At
the manifold where the lh and rh heads exhaust coolant into the
manifold (in a V engine : ))?  How about front to rear of block and
head?  Top to bottom?

You can probably make some educated guesses about the general results
for your engine.  That's what the temp gauge is doing.  But when
you're looking at the localized average temp around the gauge sender,
how often do you consider these other factors?  Just because you keep
the coolant in the engine for a little less time doesn't mean you've
reduced the hot spots or cured the steam traps that occur in cast
parts.  

For average guys, hunting these problems down is a matter of
time/money/need.  We have 3 or 4 different temp thermostats (I think
some marine stuff runs at 140d F) available, and we run the one that
seems to work best.  If dropping to a cooler thermostat cures pinging,
and we're happy with the time/power level it produces, we stick with
it.  Very few people continue to question themselves after they've
cured the problem.

Does dropping the temp in your engine reduce detonation?  I'm sure it
does.  Can running the engine colder help prevent detonation? 
Certainly.  Is that the only way?  

Shannen