I happens to have a lot of faith in GM engines. They , like everything
else, are not perfect. Chevy had camshaft problems in the distance
past,and the timing chain is the first thing you dump when you hop
up the engines, gears are much more reliable.However it is the Chryslers
that like to jump teeth with their plastic gears etc. Fords had problems
in their V8's a decade ago with too few threads holding the spark
plugs.Aircraft engines are made with the finest steel and
techniques available...................in the 1940's!! If I have
such a high opinion of the word "certified" I would not be looking
at alternate engines.They published my letter in the latest Flying
mag. on that subject. Another reason for the nickel content is for
a bit better corrosion resistance, which a/c have more than many
cars. The nickel content also add some toughness, but I don't think
they have any where near as much as in amour plating.
Auto engines had incremental improvements through the years,
while aircraft engines are at a stand still, and still have lead
in the gas. The auto industry, easily 100 times the size, within a
time span of 3 years, had the lead removed starting in
1975?Basically with hardened valve seats and to get the necessary
octane with more refining without the lead. Now they use
ethanol.They had incentive from governments, especially Calif.
A 400 HP engine only use a small fraction on the highway, that is
no indication of the engine's toughness. A Chevy small block 350
cubic inch can easily put out twice that or even more in dragster applications
where the engine life is 1 mile.
I heard of how they pushed these engines during endurance
testings, some with pictures of the turbo glowing red hot.So a
race modified 400 HP Chevy LS engine at 350 HP cruise would easily
outlast the standard 2000 hr. TBO , the TBO times could rival that
of a PT-6! I think the % of certified engines that made it to TBO
is around 5% or less. But the piston engine do have several inherit
disadvantages, compare with rotary and turbines, more part count,
liquid cooling, and the re drive, one more thing to go wrong.
The re drive I think is only troublesome for the smaller HP
applications, where there are more space, weight and budget
constraints. Even Rotex, with their engineer resources available
to them, had their shares of AD's.By the time you get to 300 HP,
I don't hear as much complaints.All turbines have re drives, for
prop, fan or accessories, yet the PT-6 have a reputation for reliability.
One thing the Viking engines(and Rotex) taught me, they use Evans
coolant. This stuff boil at 375F, a significant margin in
borderline detonation cases in boosted engines. That means I only
need a minimal amount of pressure (0-5 Psi?) to aid circulation and
to forget the pressure for raising the boiling point.That increase
reliability. The engine may run a bit hotter. Tony Lam
A race modified V8 is lucky to last a 24 hour race.
It took GM several years on a Le Mans programed dyno to get a
Chevy V8 to last 24 hours. We had to back off on the sprint car
power red line. As it was, GM used all aircraft qulity parts. The
engines were then worth over $100,000 in today's dollar. The
fundamental problem is inadequate bore spacing and the V8
configuration,
http://www.rotaryeng.net/DS-smith-art.pdf
Smithsonian Air & Space magazine article "Power Struggle" by Don
Sherman, January 1997, page 72. Excellent ten page article (with
many pictures) about auto engines in airplanes. A brief history of
all auto engines in airplanes and a more detailed history of the
twenty year, twenty million dollar development of the Chevy V8
based, all aluminum Orenda liquid cooled aircraft engine. At this
time (Jan 1997) and well after the article was written the engine
failed its FAA 150 hour full power certification test due to a
crankshaft problem after 20 years of very expensive development.
It was finally certified in 1998 by Transport Canada.
Extensive changes have been made to the basic Chevy big block
engine including a parallel cooling system with dual coolant pumps
as opposed to the serial cooling system with single pump as
typically found in automotive engines. Parallel cooling systems
were considered to be essential in the 1920's on liquid cooled aircraft
engines.
Engine length is almost everything to a car designer. Engine
cooling compromises are made by simezing the cylinder walls in automotive
engines. Crankshaft life at high continuous power is compromised
by shortening the length, leaving too little room for adequate
size journal fillet radii. In my opinion this engine will not be
successful until it is re-designed from a clean sheet of paper to be
a real aircraft engine. If that happens they might as well go to a
horizontal opposed configuration for lighter weight.
Orenda is now in the process of moving the project to Nova Scotia
and injecting another 32 million dollars of mostly Canadian
government money. They are also attempting to market the engine to
the homebuilt market. I don't expect many takers at over $100K per
engine.
Recently Lancair gave up after spending a lot of money installing
the engine in a special airplane called the Lancair Tigress.
The engine and the Tigress were donated to the EAA museum as
a tax write off.
The Orenda company is now bankrupt.
http://www.rotaryeng.net/DS-smith-art.pdf
Paul Lamar
A few years back, NASA had an LS 1 engine put through FAA aicraft
engine certification testing. With only minor problems, it passed.
They were operating at a low power of about 280 hp max at 4000rpm
if I recall, as they intended it to direct shaft drive a ducted
prop; no gearing. When they told the GM engineers of the details of
the certification test, they laughed. "We torture them alot harded than
that." Many current auto engines could be developed into
satisfactory engines for experimental aircraft. I agree that the
rotary is the best choice in most cases.
Murry I Rozansky
I remember that project. It never got off the ground let alone a
prototype. All a paper study. NASA proposed a ducted fan pusher
powered by a Corvette engine at OSH in 2004-2006. The people they
had on that project were idiots led by Mark D. Moore. Mark Moore did
not even have a pilots license at the time. Ducted fans don't work
in that power/speed range. The duct itself creates a lot of drag.
Don't get me started on ducted fans :) Surprisingly and ironically
Francesco Iannetti, developer of the ceramic apex seals for the
rotary, did the dyno test of the LS1 V8 in 2003.
The whole project was a typical federal government gross waste of money.
No results. No hardware. No airplane. No flight. The program was an
out and out failure.
-----------------------------------------------------------------------
Next Generation NASA GA Advanced Concept
Quote the NASA pdf on that project:
"Historically,
most automotive engine conversions to aircraft use have
been failures. The basic reason appears to be that the
developers try to get aircraft engine performance out of
an engine that is at a fundamental disadvantage
because it has not been designed with similar
compromises. For example, liquid cooling is heavier
than air cooling, particularly when the whole system is
taken into account. This [UTF-8?]doesn’t mean that there [UTF-
8?]aren’t advantages to liquid cooling that may make it
attractive, but to expect the liquid cooled engine to have the same
power to weight ratio is unreasonable. The temptation to [UTF-
8?]“hop [UTF-8?]up†the automotive engine to get a comparable
power to weight ratio is difficult to resist, and usually
results in a series of escalating decisions that both raise
the cost of the engine and lower the reliability. It is just
not possible to get aircraft engine performance and low
cost out of an automotive engine at the same time.
There have been four certified aircraft engines that have
started as automotive engines. They are the Orenda
OE-600, the Porsche PFM, the Toyota FV4000, and the
Thielert Centurion 1.7. Of these, only the Thielert is
currently being installed by an OEM on new airframes."
"The Porsche PFM is a typical example of what happens
when an automotive engine is retrofitted onto an
airframe designed for an aircraft engine. Even after
replacing most of the components for enhanced
durability at high power levels, the engine added 91 kg
(200 lb) to the empty weight, 13 kW (17 hp) to the
power, $100,000 to the price and actually dropped top
speed by 9 km (5 kts). It is no wonder that it sold poorly
and that Porsche is buying back the engines to destroy
them to reduce liability exposure"
"The key to getting the cost benefit of an automotive
engine is to leave it as much of an automotive engine as
possible, and design an airframe to work well with it.
Because of previous experiences, there is a general
belief that the automotive engine [UTF-8?]can’t operate at the
high power duty cycles that the aircraft engine does,
which is true if maintaining the same power to weight
ratio is important. If it is not important, then the engine
can be de-rated to a point that it will function just as well
as the aircraft engine, albeit at a heavier weight. To
prove this, Iannetti ran his preferred Chevrolet LS-1
Corvette engine in a dynamometer, simulating the
Federal Aviation [UTF-8?]Administration’s [UTF-8?](FAA’s)
150-hour FAR part 33.49b engine endurance test [27] (Figure 33).
While the test did not simulate the vibratory characteristics of
the long shaft and Q-fan, it did show that the engine was easily
capable of passing the same test that all piston aircraft engines
must pass from a duty cycle perspective."
-------------------------------------------------------------------
280/400 is 70% max power to begin with. So it made 70% power for several
5 minute periods. Then it ran the rest of the test at 196 HP or 50%
power. Max HP occurs at 5500 RPM or above.
That is known as de-rating. Any auto eninge will pass the FAA test
if you de-rate it enough. Passing the test is not enough. The FAA
then grants a TBO. The Orenda engine was granted only a 1200 hour TBO.
The bare aluminum LS1 engine is 400 pounds.
To that you need to add a gear box which for a typical V8 would
weigh 80 to 100 pounds. The Orenda firewall forward came out to 1000
pounds. Typical LS1 firewall forward are 500 to 600 pounds.
Paul Lamar
My parents have a ford 302c in their luxury sedan with 550,000 ks on
it, when they bought it 500,000 ks. Ex hire car ( Kind of a luxury
taxi, and on LPG). The Cleveland design V8 was made in Oz by ford
Australia under license. They have more iron than U.S. Cleveland
engines and weigh, well, lots.(and lots) When emissions control
really got going (1980) they choked the life out of these engines.
The cams were designed for low end grunt and no power above 3750rpm.
Max power new would only have been around 150hp on gasolene. So yes
Paul is right de-rate it you will get longevity, but power to weight
is EXTREMELY poor. Good for highway cruising ( 120kph at 1300rpm)
with enough torque for overtaking, and good for boat anchors.
Aircraft? no. Don't get me wrong it's a great car and a pleasure to
drive and I do like V8's, for cars. Graeme Riley
A friend has a 1982 Pontiac Parisienne that has a Chev(GM division)
engine with 4 barrel carb. He changes oil regularly. 1500 Km's (1000
Mi). he also drives like grandma Moses. The maintainence is the big
thing but exceptionally low duty cycle contribute. He replaced the
timing chain for all metal when the nylon cam gear failed. At the
same time the camshaft was replaced with an RV style. Other than the
HO 305 in Camaros, the engineers spec'd a cam with less lift on the
intake lobe than the 350 engines for emissions reasons. They had
poor fuel economy, power and driveability.
I had one in a 1092
Blazer that cycled in and out of over drive almost continually. Both
his and mine had the cams replaced with a 350 RV cam that had split
pattern duration and more lift than factory. My Blazer almost
completely cured the shift cycle problem and driveability was vastly
improved. Fuel economy went from 15miles/Imp gallon to
19. My friend hasa also installed an overdrive auto trans and
headers. This car has 440,000Km on it now and runs like a top. It
has the typical Chev puff of blue smoke due to valve seals on
startup but does not use oil between changes.
Dale Davies
Sorry folks,
The Blazer was a 1982. Was involved in a MVA Friday night. Filled the co.
truck and washed it. Went for dinner with a friend as his BD was Monday.
8:50PM I was leaving his place and approaching a left turn onto the Hwy/road
through town. Some clown had stolen a Dodge 1/2 ton in Fox Creek 90Km away,
right in front of the police. They followed at speeds up to 150KPH. Almost
100MPH. He darted into the right turn lane and ran the red light. Struck my
co. truck just behind the LR wheel and spun me around. The stolen truck went
about 150 yards and curved to the left. It went over the center median and the
LF and RR wheels were knocked off. The RR axle sheared off at the wheel
bearing. Lots of witnesses that said he ran the red at a high speed. No
injuries and the perp jumped out the passenger side of the Dodge and ran
through the Ford dealer lot and circled around. About 8 police cars were there
in less then 2 minutes. When a witness told them he had bailed out through
the dealership they went looking for him. Caught him after he had gone behind
the police station and was apprehended behind the hospital.
I am extremely blessed as I could have been killed if the timing had been
slightly different.
Dale Davies
--Far-out Dale, what are the chances of walking away from that!!!!!! I'm
-- guessing that you had less than 50% chance of survival, much less
-- escaping without serious injury. Did you see him coming or just the
-- impact? Time for a new truck aye.
Graeme Riley.
Graeme, what email program are you using?
Paul Lamar
--
The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
You Tube key word PaulLamar2
Copyright 1998-2012 All world wide rights reserved.