On Tue, 05 Aug 2003 02:13:10 GMT, "JWS"
wrote:


Considering the conditions an airplane sparkplug has to operate in, it is
probably worth more than $1.99. Look what an airplane engine has to do
compared to a car engine. Try running your car from idle to full throttle,
hold at full throttle under load for extended time periods and repeat. Check
out some of the experimental flyers who with some degree of success use
automotive engines in their planes, very few car engines can handle the
task. Plus, Wal-Mart sells a lot more sparkplugs that your aviation parts
supplier.

The auto conversions fly just like their more expensive cousins, using
the same manifold pressures and use ordinary auto spark plugs.

I should post the article I have that describes the development of an
ordinary Chevy V-6. The number of hours the engines spend at full
throttle and the torture they go through is by FAR more severe than
the FAA's mandated testing for new aircraft engines. Here's one small
excerpt:

"Thermal cycle tests are run to define engine capability under cold
weather condition. We run the engine at full throttle at 4000 RPM,
bring it down to idle, stop it, switch the coolant valves to drain the
hot coolant, pump the chilled coolant from the chiller until the metal
temperature stabilizes at 0 degrees F. Frost forms on the outside of
the block, as the cold coolant rushes into the engine. When it
stabilizes at 0 F, we motor the engine, start it, come to full
throttle at 4400 RPM, the valves switch and the coolant temperature
starts to climb. It climbs back up to 260 degrees F. It takes 10 -11
minutes to complete one cycle. The engine must pass 600 cycles
without any sign of failure. We typically run 1200 cycles and a probe
test will run 1600 cycles. That's a (sic) excellent gasket killer
test. Head gaskets are the first to fail because of the rapid
expansion and contraction."

Chevy is only typical, all automakers butcher their engines like this
during development. They have to, if they produce a dog or
maintenance hog, their reputation will take a long time to rebuild and
money, lots of it, will be lost.

Corky Scott