Dan Thomas wrote:

I don't see auto engines blowing a jug, or breaking a rod, or hanging a
valve at low hours, like lycosauruses.
There is no reason for all of the engine out situations that airplane
engines have, IMO.
As far as blowing jugs or breaking rods or hanging valves: Try
making an auto conversion run at 75 power for a few hours and see what
begins to happen. They weren't designed for that, and the guys who
successfuly convert and run them for several hundred hours have had to
get around a LOT of problems.


For what it's worth regarding catastrophic auto engine failure, in May of
this year I got to experience it first hand in my car. Driving down the
freeway at 70mph, I heard a God awful noise and realized it was my car. I
managed to nurse it across 3 or 4 lanes of the freeway to the shoulder. As I
coasted to a stop and turned off the engine, steam started pouring out. I
popped the hood (yes, a very dumb idea in hindsight given the potentially
scalding coolant that was loose) and saw that the engine was so hot it had
melted through a rubber emissions control hose containing fuel/air and
ignited. There were also flames down at my engine block. I was able to get
them out without hosting a car-b-que on the 91 freeway.

What happened? The engine threw a rod which punched a quarter sized hole in
the side front of my engine, donating all of my oil to the freeway below.
Perhaps some of it sprayed up on the hot exhaust manifold and caught fire -
I'm not sure what the source of fuel for the fire was. I didn't especially
care at the time. The failure also caused my radiator fan to throw a blade
(plastic) into my radiator, cracking it open.

This was in my 1991 Geo Prizm. (Ooooh...ahhhh!) It had 156,000+ miles on it
and had been used since '91 to drive LA freeways and side streets on a daily
basis. The last two years of its life were spent going from my house to my
college 35 miles away 5 days a week on freeways. So obviously, it was
pushing the end of its useful life and had been driven hard. It was meant to
be an economy car.

Maybe the failure was a fluke, maybe it was perfectly reasonable given the
car's life. But when I hear about Geo conversions for homebuilts now, I tend
to look the other way. Sure it can be done, but it was enough to keep me
away from them.


-Tony Goetz