Standards for H.P. corr. factors ??

Jerry Wass wrote:
To what standards are today's(and/or yesterdays) A/C engines corrected
to???

I find the older SAE J607--60°F---29.92" Hg 0% humidity
SAE J1349--77°F 29.234"Hg 0%
DIN 68°F 29.92
JIS 77°F 29.234 0%
?? J1995 77°F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry

I sincerely doubt it was the J607 standard used to rate the engines
since if you actually read the J607 standard you will see that it
clearly states that it was developed for basically lawnmower engines(
50 ci displacement and 20hp) You will also see that it allows for only
a ten percent correction to be applied. A real hoot when you see it
applied to a 500hp supercharged engine. However your question seems to
be what is the standard day used for calculations, rather than the
calculations applied, so I will say I believe the FAA uses standard day,
standard atmosphere at sea level with zero humidity calculated by the
formulas defined in the US Standard Atmosphere 1976 standard(Temperature
= 15°C, specific humidity = 0.00 kg H2O/kg dry air, and pressure =
101325 Pa). I also believe that this standard is largely in agreement
with the international standard at near sea level altitudes that you are
concerned with.

As far as what standard was in effect at the time a particular engine
was certified, I can't tell you. There are versions of the US Standard
Atmosphere going back to 1958, and I do not know what correction factors
were applied.

The FAA engine certification tests are more rigorous than the typical
dyno run and require an endurance test that includes the following regimes:

(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.

(3) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 70 percent maximum continuous
power and 89 percent maximum continuous speed.

(4) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 65 percent maximum continuous
power and 87 percent maximum continuous speed.

(5) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 60 percent maximum continuous
power and 84.5 percent maximum continuous speed.

(6) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 50 percent maximum continuous
power and 79.5 percent maximum continuous speed.

(7) A 20-hour run consisting of alternate periods of 2½ hours at maximum
continuous power and speed, and 2½ hours at maximum best economy
cruising power or at maximum recommended cruising power

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.


Charles

Charles Vincent wrote:
Jerry Wass wrote:
To what standards are today's(and/or yesterdays) A/C engines corrected
to???

I find the older SAE J607--60°F---29.92" Hg 0% humidity
SAE J1349--77°F 29.234"Hg 0%
DIN 68°F 29.92
JIS 77°F 29.234 0%
?? J1995 77°F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry

I sincerely doubt it was the J607 standard used to rate the engines
since if you actually read the J607 standard you will see that it
clearly states that it was developed for basically lawnmower engines(
50 ci displacement and 20hp) You will also see that it allows for only
a ten percent correction to be applied. A real hoot when you see it
applied to a 500hp supercharged engine. However your question seems to
be what is the standard day used for calculations, rather than the
calculations applied, so I will say I believe the FAA uses standard day,
standard atmosphere at sea level with zero humidity calculated by the
formulas defined in the US Standard Atmosphere 1976 standard(Temperature
= 15°C, specific humidity = 0.00 kg H2O/kg dry air, and pressure =
101325 Pa). I also believe that this standard is largely in agreement
with the international standard at near sea level altitudes that you are
concerned with.

As far as what standard was in effect at the time a particular engine
was certified, I can't tell you. There are versions of the US Standard
Atmosphere going back to 1958, and I do not know what correction factors
were applied.

The FAA engine certification tests are more rigorous than the typical
dyno run and require an endurance test that includes the following regimes:

(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.

(3) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 70 percent maximum continuous
power and 89 percent maximum continuous speed.

(4) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 65 percent maximum continuous
power and 87 percent maximum continuous speed.

(5) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 60 percent maximum continuous
power and 84.5 percent maximum continuous speed.

(6) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 50 percent maximum continuous
power and 79.5 percent maximum continuous speed.

(7) A 20-hour run consisting of alternate periods of 2½ hours at maximum
continuous power and speed, and 2½ hours at maximum best economy
cruising power or at maximum recommended cruising power

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.


Charles

Thanks, Charles, I'm inclined to agree with you--the 59°F temp rings a
bell in my memory.

"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

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

"Charles Vincent" wrote in message
. ..
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


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.

To the best of my recollection, the more recent engine testing includes a
rather long run, possibly 100 total hours, at 100% power. Interestingly,
the actual purpose is to verify the effectiveness and durability of the
torsion dampener. Failure of the torsion dampener will cause a failure of
the crankshaft and/or drive train--as will its absence or incorrect
calibration--which should be of considerable interest on this NG.

I suspect that the cycling test between maximum torque and maximum power is
also primarily a verification of harmonic dampening; but that is only a
presumption on my part--with the discalimer that I am not an automotive
engineer.

In addition, there was mention of a temperature cycling test in which the
engine is repeatedly run at full throttle until normal temperature is
reached, shut down and chilled to below freezing, then started and run
immediately at full throttle until normal temperature is reached, etc. The
purpose was stated to be verification of the head gaskets and related
clamping force--especially on engines that were all or partly aluminum.

There is also a cycling test including an automatic transmission, in which
the engine repeatedly runs up through the gears and then back down--as
though a driver accelerated through the gears in drive with the accelerator
to the floor, then pulled the lever into low and coasted back
down--repeating the process over and over. According to the account which
was given, an engine will usually outlast multiple transmissions. Obvoiusly
the test has value in predicting warranty costs, but the exact purpose is a
mystery to me.

Further disclaimer: All of this is from memory and the true original source
is unknown, as is the brand of engine(s) involved.

Peter

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

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

"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