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While I couldn't agree more with the comments concerning the inadvisability
of using a Chevy V8 as an aircraft engine, I and 7 other LIV-P builders
have come to a different conclusion: Given enough money and talent, a
liquid cooled aircraft V8 engine can be designed and built with reliability
and long service life. The following is a summary of why we elected to go
with a completely new aircraft designed engine. Bear in mind that this
engine has not flown yet, however we have done everything possible to
engineer in reliability and light weight while at the same time generating
a high power output regardless of cost.
Many aircraft builders are innocently unaware of the differences in the
mission statement of high performance aircraft engines and high performance
auto-marine engines. Each application has its own particular needs, and
design consideration must be understood for them to perform well and
survive for an expected amount of time
First, most high performance after-market components were developed for the
Chevy V-8 because the market here is the largest. The greatest amount of
component development took place in the drag racing arena, again the
largest market. Marine use was another market albeit smaller. As a
result, it would be safe to say that most components for either of these
application is life limited. The next issue is that of average load and
rpm. Most high performance engines do their best at rpm's above 4000.
Naturally aspirated or with reasonably conservative turbo-charging, the
life expectancy is not typical of an aircraft engine application which
requires a minimum TBO of 1200 hours, and preferrably 2000 hours.
The duty cycle is the most important issue. A racing engine of a given
horspower, let's say 500 hp, has a lower average bearing load at 7-8,000
rpm than an aircraft engine would have at 3000 rpm and the same 500
horspower. To understand this, let's look at the relative torque (energy
applied) between these two applications. At 8,000 rpm the rods,
crankshaft, and bearings would have to sustain at torque of 328.25 ft. lbs.
and the 500 hp aircraft engine at 3000 rpm would sustain 875 ft. lbs. of
torque. That is more than two and one half times the energy produced by
the racing engine. At 4500 rpm with a propeller reduction gear the engine
would see 583.55 ft. lbs. Small block Chevy engines would have to go
through a considerable development program to sustain this energy for 2,000
hours. Coming out the back of this development we would see an entirely
different engine design. Spinning the engine faster would reduce these
load and effect the life limit of the engine. Another issue to keep in
mind concerning this is that an aircraft engine is expected to live through
three to four overhauls without replacing all the critical components.
Another issue is the oiling system. Most passenger cars, race cars and
boats operate in a single plane invironment. Exclusive of going up and
down hills the dropped sump of the passenger car oil pan is sufficient for
these moderate climb angles. In aircraft, the oiling system
The Thunder engine project, now called the Orenda Engine, out of Canada and
Nova Scotia, began its life as a 496 Can-Am Chevy block and heads. It
underwent several developmental changes which ultimately resulted in the
depletion of funds. Orenda purchased what they thought was a flight ready
V-8 engine from the Thunder owners only to find that it required a
complete re-engineering program to come up with something adaquate for
certification. This is a good engine, however it required millions of
dollars to develop.
So, if there isn't anything wrong with a V-8 as an alternative engine,
then what needs to be done to properly design one.
The answer is to engineer an aircraft specific design. This means
increased bearing areas on the crankshaft and connecting rods. Cooling is
everything and low cooling drag systems are also important. Thermal
dynamics and aero-dynamics must be a mutual consideration. In turbo
applications, this means cooling the piston tops with oil spray which
carries heat away. The cylinder heads are the next on the design list. To
provide adaquate cooling (which should include flight to 30,000 ft for
turbos) it is essential that exhaust ports and spark plugs be surrounded
with coolant. Exhaust gas temperature in excess of 1600 degrees F are
common place in turbo-charged engines. The port design should accomodate
the rpm spectrum that the engine will see, and not ported heads for 7-9,000
rpm. This has a major effect on fuel efficiency. The head bolt pattern
should completely surround the cylinder with no bolts emminating from
inside the intake port. Manifolding should be low profile and accomodate
ram tuning frequencies to optimize the climb and cruise rpm spectrum. The
fuel system and ignition system should be as fail-safe as possible. Most
after-market electronics would fail the scrutiny of FAR requirements.
Compactness, strength and weight must be addressed in every aspect of the
design. Carrying along "dumb iron" that does nothing is absolute waste.
If gear reductions are used, tooth contact ratios should be maximised in
the design and a tuned, ENGINEERED torsional vibration coupling is a must.
.
For the above reasons I encouraged the formation of American Engine LLC,of
which I am not an owner, and to began such a development project. By mutual
agreement they kept the project underwraps until the development produced
the results they wanted. Starting from a clean sheet of paper, and taking
advantage of all the latest development learned and technology available,
the "Magnum Project", as it was called, began. A proof of concept engine
was developed which produced an outstanding 860 horsepower at 3500 rpm. It
was then that the "real" development began. If a turbo-charged V-8 could
develop that kind of power at normal manifold pressures, a highly effecient
de-rated design could be even better and outperform all its competors in
the flight levels. With "critical altitudes" ( where the engine stops
making sea level horsepower) in the range of 24,000 ft.MSL, even the
turbine engines in this same power range could be out performed.
Full computer management was another of the design requirements which
optimises power and fuel burn for all power settings and altitudes, placing
this engine in a catagory all by itself. Tuned induction, redundant
computers, full time data acquisition, electronic engine monitoring,
turbine smoothness, compactness and light weight are just some of this
engines attributes. A totally new gear reduction unit, rivaling the finest
helicopter transmission, and containing some patentable contruction process
makes for what gear engineers refer to as an "infinite life" gear box
design.
All that was needed was a seven figure check book required for this
ambitious undertaking and the selection of the right personnel with the
capability of marrying a V-8 design to an aircraft application. To these
visionaries, the sacrifices were well worth it, and with painful patience
and with the eagerness of a student pilot anticipating his first solo the
"EAGLE 540" reached completion. One hundred fifty pounds lighter than its
nearest competitor made the use of the more expensive aero-space alloys
well worth it. The "Eagles" compactness make it applicable in the small,
lightning fast Lancair IV, as well as many other applications. With cost
of development being that last consideration, the American Engine
leadership put together the right mix of engine and airframe design
engineers to produce a powerplant and firewall forward package that will
redefine the Lancair IV and IVP's performance numbers. The best news is
that more than one Lancair IVP will be in the air as soon as the multiple
quantity engine and installation parts become available. This is not a one
off project. We look for the 8 builders to be assembling and and at least
2 flight testing in '99. Then debugging and redesigning where necessary.
We'll keep every one posted as development continues.
Marshall Michaelian (SQL, 75% completed LIV-P, Eagle 540 V8)
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