> There must have been a reason for designing the cooling system
> so the engine ran at a temperature higher than what mine seemed to.
Vizard also points out that for the A Series, maximum power occurs
when the engine runs at 160 degrees F. He further points out that
this is too cool for properly volatilizing the blow-by compounds that
slide past the rings etc. into the oil, and that these will build up
in the sump. Not an issue for a race motor that gets changed every
event, but for a street-driven car, Vizard says the oil change interval
drops to about every thousand miles unless you can get the oil up to
something over 210 degrees F. You'd also want to match the oil's
viscosity and operating temperature range to the engine's temperature
under these circumstances.
Beyond that, engine temperature has an effect on performance, pollution,
fuel economy, and of course component life. Insert ubiquitous it's-a-
system tirade at this point...
> Maybe the gauge was off.
(That was my first thought too...)
> Since there was only one thing to try that was relatively easy and
> cheap, I bought a new thermostat and pull the water pump. Hmm, the old
> thermostat was badly corroded and frozen in the fully open position.
You're lucky it froze open (maybe that's part of the secret to the
Slant Six's reputation as being bulletproof :-). The last Ford V8
I had got the thermostat wedged shut once (when, um, some idiot put in a
can of Stop-Leak to handle a pinhole in the radiator and the Stop-Leak
decided that the thermostat looked just like a REALLY BIG leak).
When the coolant finally gets hot enough to spew through the gap that the
steam creates between the intake manifold and the head, it sounds just
*exactly* like a 260-cubic-inch teakettle that's started to boil. It's A
below middle C, if memory (and my usually fairly accurate sense of pitch)
serves...
> So, is this the secret to making your race car run cooler?
It's functionally similar to the blanking sleeve Jim and I are talking
about. Take your thermostat. Cut the strap that holds the spring-
actuated plunger and disc to the body of the thermostat. Drop the
body of the thermostat into the housing in the head (or manifold),
observing the passage or passages that circulate coolant through the
head(s) when the thermostat would have been closed if you hadn't
dissected it.
I was reading some interesting articles a year or three ago about
reverse-plumbed cooling systems. The principle there is to run the
coolant from the radiator *directly into the head*, where there is
the highest temperature differential and therefore the fastest cooling
rate. The coolant then runs through the block, through the pump and out
into the radiator, where it's cooled. The article reporting tests with
this system said that they could reduce the size of the radiator by
something like 20%, with a resultant savings in weight and drag (as you
need to push air past the radiator). I don't remember whether this was
intended as something that could be retrofitted into any race car,
and of course if you're with me thus far, you'll realize that it would
require a different thermostat location, as simply reversing the
direction of the impeller would burst the top hose from the radiator
in a few minutes unless you made some other changes. I would guess
that you'd almost have to re-engineer the entire system to make it work
(thermostats, bypasses, passages for the bypassed coolant, etc.), but
it's an appealing idea.
--Scott
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