Morgans wrote:
"Charles Vincent" wrote

I will bet that many of the un-certified engines being marketed out there
couldn't finish the endurance test without swallowing an exhaust valve.

Time for someone to trot out the GM stress test for new engines.

It makes the FAA tests look like a walk in the park.

Anyone got a copy of that handy?

I have the GM Automotive Test Code for 1967 (the FAA test regime was
codified in 1964). It specifies a two hundred hour durability test,
whereas the FAA is one hundred and fifty hour endurance test for
reciprocating non supercharged engines or reciprocating single speed
supercharged engines. Two speed supercharged and helicopter engines are
longer as I recall. The GM test code requires the engine to complete a
200 hour test schedule "without major failure". The engine is cycled
between peak torque rpm and peak hp rpm +200 rpm (max rpm not to exceed
4600)on five minute intervals. Every five and a half cycles, speed to
be reduced to idle from max test speed by closing throttle for two
minutes, after which engine speed is brought up to maximum upshift speed
within 10 seconds +/- 5 seconds, the speed is then reduced again to the
peak torque rpm and the normal cycle is continued again. The engine is
inspected every twenty five hours for cranking compression, blowby, belt
tension and ignition timing. I don't have the current testing codes for
GM, and since GM isn't selling an uncertified engine for aircraft use, I
don't know the relevance and doesn't effect my belief that many of the
un-certified engines being marketed out there couldn't finish the
endurance test without swallowing an exhaust valve.

Charles