Standards for H.P. corr. factors ??

Peter Dohm wrote:

I don't know of anything that is necessarily specific to any one automotive
brand, but a test procedure from some time in the 1990s has been posted to
this NG a couple of times. As of this time, I can't find it; either because
I can't remember the file name or because it died with an older computer.

There is an article from Contact magazine that has been posted here
before. It states that GM runs at max hp rpm with max load for 265
hours as one test and does the cyclic test I described for 400 hours,
along with the thermal testing you mentioned. However, I have not seen
the actual formal test regime, whereas I have a copy of the 1967 test
regime. In the end, it still doesn;t matter as GM is not to my
knowledge selling reciprocating aircraft engines certified or otherwise
and I have not seen any evidence many of the uncertified engines for
sale are testing their engines at this level.

Charles

"Charles Vincent" wrote

In the end, it still doesn;t matter as GM is not to my knowledge selling
reciprocating aircraft engines certified or otherwise and I have not seen
any evidence many of the uncertified engines for sale are testing their
engines at this level.

I guess the point that we were making, is that although GM is not selling
uncertified engines for airplanes, a number of them do find their ways into
experimental airplanes, thus the reaction about the reliability of auto
engines.

Interestingly, it is most always not the core auto engine that experiences
failure when an auto engine conversion has problems, but the prop speed
reducer, or fuel system, or non original fuel system, or whatever else has
been added or re-engineered by the experimenter.

I hope this sheds light on why your comments got such a swift and
enthusiastic rebuttal by some here. It sounded as if you were condemning
those that used auto engines for airplanes, as a unsatisfactory, not as
tough engine as what is made as a certified engine.

After all of the major metallurgical crankshaft problems that some of the
certified engines have had as of late, it is hard to accept that just
because it is certified, it is completely reliable.
--
Jim in NC

"Morgans" wrote in message
...

"Charles Vincent" wrote

In the end, it still doesn;t matter as GM is not to my knowledge selling
reciprocating aircraft engines certified or otherwise and I have not
seen
any evidence many of the uncertified engines for sale are testing their
engines at this level.

I guess the point that we were making, is that although GM is not selling
uncertified engines for airplanes, a number of them do find their ways
into
experimental airplanes, thus the reaction about the reliability of auto
engines.

Interestingly, it is most always not the core auto engine that experiences
failure when an auto engine conversion has problems, but the prop speed
reducer, or fuel system, or non original fuel system, or whatever else has
been added or re-engineered by the experimenter.

I hope this sheds light on why your comments got such a swift and
enthusiastic rebuttal by some here. It sounded as if you were condemning
those that used auto engines for airplanes, as a unsatisfactory, not as
tough engine as what is made as a certified engine.

After all of the major metallurgical crankshaft problems that some of the
certified engines have had as of late, it is hard to accept that just
because it is certified, it is completely reliable.
--
Jim in NC


I interpreted the comment as pertaining to uncertified engines, or engined
certified to a different standard, originally manufactured and sold for
aircraft use.

Peter

"Charles Vincent" wrote in message
et...
Peter Dohm wrote:

I don't know of anything that is necessarily specific to any one
automotive
brand, but a test procedure from some time in the 1990s has been posted
to
this NG a couple of times. As of this time, I can't find it; either
because
I can't remember the file name or because it died with an older
computer.

There is an article from Contact magazine that has been posted here
before. It states that GM runs at max hp rpm with max load for 265
hours as one test and does the cyclic test I described for 400 hours,
along with the thermal testing you mentioned. However, I have not seen
the actual formal test regime, whereas I have a copy of the 1967 test
regime. In the end, it still doesn;t matter as GM is not to my
knowledge selling reciprocating aircraft engines certified or otherwise
and I have not seen any evidence many of the uncertified engines for
sale are testing their engines at this level.

Charles

I believe that you have summed it up rather well.

I remain undecided whether I might or might not adapt an automotive engine
for aircraft use, but I would cdertainly avoid any of the changes which
would negate the laboratory and field testing which had already been done.
Changing or removing flywheels, driving from the accessory end, and changing
cams and timing are all high on that list--as is nearly anything else that
does not let the engine "believe" that it is still doing what it always did.
If that makes it too heavy, then it is simply the wrong engine for the job.

Peter

Morgans wrote:
"Charles Vincent" wrote

In the end, it still doesn;t matter as GM is not to my knowledge selling
reciprocating aircraft engines certified or otherwise and I have not seen
any evidence many of the uncertified engines for sale are testing their
engines at this level.

I guess the point that we were making, is that although GM is not selling
uncertified engines for airplanes, a number of them do find their ways into
experimental airplanes, thus the reaction about the reliability of auto
engines.

Automotive engines today are exceptionally reliable. No where did I
impugn automotive engines. It is also obvious that all readers are not
clear on the use of the adjective "many". Many does not mean all or
even imply a majority, it at most implies more than "several".

Interestingly, it is most always not the core auto engine that experiences
failure when an auto engine conversion has problems, but the prop speed
reducer, or fuel system, or non original fuel system, or whatever else has
been added or re-engineered by the experimenter.

What the heck does that have to do with it? "Why, its the best most
reliable 200hp airplane engine you can buy, unless you insist on hanging
a prop on it -- have you considered building an ornithoper?" If it is
not reliable when configured for use in an airplane, it is not a
reliable airplane engine. The FAA endurance test requires "a propeller
ordinarily used on a similar engine" be installed, it is also required
for the vibration survey, which is another specified test. The FAA
tests and certification has specific requirements of the fuel,
lubrication and ignition system with aviation necessities in mind. I
believe the reduction unit would be part of the equipment tested, as the
type sheets list the geared and ungeared varieties as separate engines.


I hope this sheds light on why your comments got such a swift and
enthusiastic rebuttal by some here. It sounded as if you were condemning
those that used auto engines for airplanes, as a unsatisfactory, not as
tough engine as what is made as a certified engine.

It may have been enthusiatic, but it was not a rebuttal. I opined that
many (not all) un-certified engines being marketed (not built in
backyards from automotive sources) would be unable to complete the
endurance test. People responded with evidence that automotive
manufacturers did endurance testing of automotive engines configured
with accessories required for automotive use (i.e. transmissions etc)
which has nothing to do with my statement.

I am not a certified engine bigot and I believe experimental aviation
should be experimental ( I also believe homebuilts should be homebuilt
as well) I was more specifically aiming at the vendors targeting the
experimental market with uncertified engines that make outlandish claims
regarding reliability, fuel burn and most especially power. The first
two tests --

(1) A 30-hour run consisting of alternate periods of five minutes at
takeoff power and speed, and five minutes at maximum best economy
cruising power or maximum recommended cruising power.

(2) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 75 percent maximum continuous
power and 91 percent maximum continuous speed.

--- would highlight the fact that just camming and carbing an engine to
produce 100hp on the dyno isn't going to be enough to get it through
thirty hours of five minute 100hp bursts with a five minute cooling
period at what, 75HP?. The second test is just going to further
highlight any deficiencies in cooling. There is often a vast difference
between dyno results and useful power.

After all of the major metallurgical crankshaft problems that some of the
certified engines have had as of late, it is hard to accept that just
because it is certified, it is completely reliable.

No one said it was, but do you honestly think an honest comparison of
certified engine installations with uncertified engine installations on
a reliability basis is going to make certified engines look bad? You
would have to compare incidents per hour of operation for all certified
engines vs incidents per hour of operation for all uncertified engines.
The data I doubt exists and the data that is there is probably
not proportionate i.e. certified installations are more likely to be
reported than uncertified. As I understand it the Lycoming debacle
affected 3000-5000 engines and resulted from a combination of a change
in alloy used for the crank and the jobber forging the cranks not
holding to the forging temps required. Small details that resulted in
the crank not being up to the job of carrying prop loads at power. So
do you think uncertified engines are more immune to this than certified?
As immune? So how does some relatively low volume uncertified engine
company with parts sourced from everywhere from chinese made bubble pack
hot rod stuff, to custom machined assemblies going to track things at
that level? Particularly when most of the parts where never intended
for aviation and the part vendor is continually trying to optimize his
costs for his intended market? And your backyard assembler/builder?
Even though I am not really talking about automotive manufacturers, I
will point out that the number of auto recalls and TSB's issued on a
monthly basis is not insignificant even with their endurance testing.
Anyway, this is not intended as a diatribe against un certified engines.
I think they are great. I was really just addressing the original
poster's question on the standard day used for certified engines. I
assumed he was going to be using that information to compare his
favorite certified engine to some recently dyno'd uncertified variant
being marketed. My point was just that as I said before in this post,
there is often a vast difference between dyno results and useful power
and an endurance test ala FAA is more useful than a dyno run.

Charles

Wow, big post. I'll just hit a couple points to respond to. ;-)

Automotive engines today are exceptionally reliable. No where did I
impugn automotive engines. It is also obvious that all readers are not
clear on the use of the adjective "many". Many does not mean all or even
imply a majority, it at most implies more than "several".

I may have jumped in without fully understanding the response to the OP.
That never happens around here, does it? g

Interestingly, it is most always not the core auto engine that
experiences failure when an auto engine conversion has problems, but the
prop speed reducer, or fuel system, or non original fuel system, or
whatever else has been added or re-engineered by the experimenter.

What the heck does that have to do with it?

I was making a point that the experimenter that builds his ow PSRU does so
at much risk, unless it is really well engineered. There are comercial
units out there that have very good reliability records. People get into
trouble when they try to improve on the standard conversion, usually. You
are correct though, the engine and PSRU and any other additions that make
the whole package is what really counts in the end.

I am not a certified engine bigot and I believe experimental aviation
should be experimental ( I also believe homebuilts should be homebuilt as
well) I was more specifically aiming at the vendors targeting the
experimental market with uncertified engines that make outlandish claims
regarding reliability, fuel burn and most especially power.

I get a kick out of the 100 HP VW's, especially.
--
Jim in NC

I get a kick out of the 100 HP VW's, especially.
--
Jim in NC
-------------------------------------------------------------------------------------------

Even 80hp should have you rolling on the floor :-)

After waving the magical 80hp flag at a tent-full of round-eyed
admirers the next kerchief out of his sleeve is usually "3.3 gph"
followed by a round of patting himself on the back in routine worth of
a French circus. Are we great or what?

Truth is, if you know engines and want some serious fun, get a bunch
of real engine guys together and show them the Aero-vee assembly
video. I swear to God it's the funniest thing I've seen in years.
Seriously. Most guys assume it's a put-on. When they realize it's
being sold as a 'expert advice' their reactions range from blowing
beer out their nose to simply sitting there in stunned amazement.

-R.S.Hoover

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?
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Morgans, no need.

You're outclassed no matter what you wave at the crowd. :-)

I am sooooo glad that I have no dogs in this hunt.....

YET!


- Barnyard BOb -

"Barnyard BOb" wrote
Morgans, no need.

You're outclassed no matter what you wave at the crowd. :-)

I am sooooo glad that I have no dogs in this hunt.....

YET!

I know, I know. Keep flying those ancient tractor engines, and be quiet!
g

I had not sighted you around, for a while, so I thought it would be safe to
throw out the conversion engine testing bit.

Next time, give me a 3 day warning before you pop in, so I know whether to
post stuff like that, or to wait until you are gone! ;-)
--
Jim in NC

"Morgans" wrote in message
...

"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?
--
Jim in NC


IIRC, the one who used to post that article was Corky Scott and it has been
quite some time since I have observed any posts from him. OTOH, I have
never been sure which manufacturer's stress test that may have been. A
frequent contributor to another NG, who was retired from one of the other
automobile companies, occasionally wrote in the same style as the article
that I recall; but that style may very well be generic to the industry.

However, I am glad that you brought the subject back up; because there are a
couple of points which I neglected to make in an earlier post in a branch of
this thread.

1) The certification test for aircraft engines really does apear to be
directly related to the actual use and performance of aircraft engines, as
installed, using real propellers and an acceptable simulation of real
aircraft cooling systems--with all of the efficiencies and inefficiencies
which all of that might imply.

2) The automotive engine stress tests could very well be exactly what the
name implies--Stress Tests. In other words, they may well be very carefully
designed tests to predict certian common warranty problems on new engine
models--as used in automobiles where they commonly operate between idle and
20% power, with occasional bursts of full power and occasional demands for
maximum power from cold engines. Based on that possibility, it would be
very usefull to know the engine coolant outlet *and* inlet temperatures and
flow rate as well as the oil outlet *and* inlet temperatures and flow rate
during the sustained high power run. (Remember that they have chillers on
line which probably have far more capability than the engines under test.)
There are a few other things I would like to know, specifically for any
engine which I might consider for conversion, such as any additional steady
speeds which might have been tested; but those temperatures and flow rates
would tell whether the engine showed any promise when using any plausible
cooling system in an aircraft.

There are still several automotive engines that I believe have a lot of
promise, and I would really enjoy such a project. However, it would save a
lot of effort if a few more data points happened to be published.

Peter