Subaru EA-81 vs Continental O-200
Charles K. Scott
magazine to get the facts straight. The author is Reiner Hoffmann from
Seattle, Washington and he assembles Subaru engines for Experimental
Aviation. He calls his engines "Stratus". He installed the engine in
a Cessna 150 and used the same cowling so the airplane looks like any
other 150.
Here are the figures
Displacement: 1781 cc or 109 cu in.
Power output: 100 hp
Fuel: Unleaded
Weight: 182 lbs
Ignition: Single electronic, single spark plug
Fuel consumption: .48 lb/hp/hr/ at 75% power
Performance comparison to O-200 Cessna 150
Stratus EA-81 Continental O-200
Continuous 690 FPM 610 FPM
rate of climb
at sea level
Top speed 130 mph 120 mph
Indicated
Fuel Burn 4.0 GPH 5.5 GPH
at 100MPH
indicated
Here's a paragraph from the article that describes the trip he took
with this aircraft from Seattle to Sun 'N Fun this past Spring:
"This spring, fellow pilot Jerry Dietz and I flew our Cessnas to the
1994 Sun 'N Fun Fly-In Convention. His Cessna has a Bolen Taildragger
conversion and is powered by an O-200. Although my three point Cessna
is quite a bit dirtier, my fuel consumption averaged 4.3 GPH compared
to Jerry's consumption of 5.9, a 27 percent fuel savings (looking at it
from the auto engine perspective the fuel burn of the 0-200 is 37
percent greater!). Overall the performance of my Cessna was quite a
bit better. Jerry radioed me several times to say, "Slow down!""
Hoffman made one more comparison: he mounted a three blade Warp Drive
prop on his 0-200 and ran it at full throttle to record the max rpm.
He then mounted the same prop on his EA-81 and did the same. The EA-81
turned the prop 140 RPM faster.
He used a belt drive PSRU of his own design which he sells along with
the engine. He uses Bing altitude-compensating carburetors of 32mm
bore, part no. 62-32-94.
For those who may be interested in contacting him:
Reiner Hoffmann
Stratus Incorporated
7750 Twelfth Avenue N.W.
Seattle Washington 98117
(206) 783 3845
Corky Scott
Petrah
Charles...@dartmouth.edu (Charles K. Scott) writes:
"I re-read that article I mentioned yesterday that I'd seen in "CONTACT"
magazine to get the facts straight. The author is Reiner Hoffmann from
Seattle, Washington and he assembles Subaru engines for Experimental
Aviation. He calls his engines "Stratus". He installed the engine in
a Cessna 150 and used the same cowling so the airplane looks like any
other 150."
I'm Reiner Hoffmann, president of Stratus, Inc., and want to add to
Corky's report that our Cessna has flown 330 hours to date--all of them
trouble-free. At the beginning of next year, we will replace the EA-81
engine with a Subaru Legacy engine, which we will bring up to 160-180 hp.
I am really looking forward to the Legacy's additional power. We hope to
have all the testing done by summer and to have it in production soon
thereafter.
The Stratus-powered Cessna will be featured in an upcoming issue of Sport
Aviation.
I'd be happy to answer any questions regarding our engines.
Ed Wisch
writes:
>I'd be happy to answer any questions regarding our engines.
Great!
1. Have you done the FAA full power test?
2. The 330 hours on the C-150: what maintenance did that involve besides
oil and filter changes? (tune ups, plugs, valves, any of that?)
3. What SFC numbers are you seeing? (full power, cruise power)
4. What is your highest time engine (without any "real" maintenance)? How
much of that is on the dyno, how much in flight?
5. What is TBO? How many engines have been tested to TBO on the dyno? How
many engines have gone to TBO in flight?
6. What is your ignition set up?
7. What power do you see on the dyno, tested the same way the O-200 is
tested?
Looking forward to your answers!
Thanks
Ed Wischmeyer
Petrah
writes:
1. Have you done the FAA full power test?
>>no
2. The 330 hours on the C-150: what maintenance did that involve besides
oil and filter changes? (tune ups, plugs, valves, any of that?)
>>I checked the valve clearance at 100-hour intervals. Other than that, I
haven't had to perform any maintenance.
3. What SFC numbers are you seeing? (full power, cruise power)
>>Our numbers are as follows:
Full power .52
Cruise power .44
4. What is your highest time engine (without any "real" maintenance)? How
much of that is on the dyno, how much in flight?
>>500 hours--all in flight
5. What is TBO? How many engines have been tested to TBO on the dyno? How
many engines have gone to TBO in flight?
>>our TBO is not known yet, but we estimate 1,000.
6. What is your ignition set up?
>>regular automotive pointless distributor
7. What power do you see on the dyno, tested the same way the O-200 is
tested?
>>100-106 hp at the prop at 5,400 engine rpm
Let me know if I haven't fully answered any of your questions!
Reiner Hoffmann
Gregory R. TRAVIS
>3. What SFC numbers are you seeing? (full power, cruise power)
>>>Our numbers are as follows:
> Full power .52
> Cruise power .44
vs. a Continental O-200s cruise power rating of .46 SFC
>5. What is TBO? How many engines have been tested to TBO on the dyno? How
>many engines have gone to TBO in flight?
>>>our TBO is not known yet, but we estimate 1,000.
Can you let us know what you think may end up being the limiting
factor? Bottom end reliability? Cylinder wear?
>6. What is your ignition set up?
>>>regular automotive pointless distributor
What's your estimate on the cost to go to a dual ignition?
>7. What power do you see on the dyno, tested the same way the O-200 is
>tested?
>>>100-106 hp at the prop at 5,400 engine rpm
How does this square with the previous claims of improved climb and
speed over the O-200? Different prop? Can the same prop be fitted
to both the O-200 and the EA-81 and the tests repeated?
greg
Aeronca11c
writes:
(Gregory R. TRAVIS) Writes >
Reiner Hoffmann writes >>>
>3. What SFC numbers are you seeing? (full power, cruise power)
>>>Our numbers are as follows:
> Full power .52
> Cruise power .44
vs. a Continental O-200s cruise power rating of .46 SFC
>5. What is TBO? How many engines have been tested to TBO on the dyno? How
>many engines have gone to TBO in flight?
>>>our TBO is not known yet, but we estimate 1,000.
I have mentioned before of our experience as a maintenance officer in a
flying club
for the last ten years not many engines go to TBO unless they are flown at
least once
a week min. of the four aircraft Valley Flyers owns, ONLY one went to TBO
without
removing one or more cylinders. this engine however did need mags carb
overhaul
starter alternator & miss small stuff. Anyone out their have any numbers
as to the
average hours the GA fleet goes between overhaul Ill bet it is a lot less
than 1800-2000 hrs
that Cont & Lyc advertise.
>Can you let us know what you think may end up being the limiting
>factor? Bottom end reliability? Cylinder wear?
>6. What is your ignition set up?
>>>regular automotive pointless distributor
>What's your estimate on the cost to go to a dual ignition?
>7. What power do you see on the dyno, tested the same way the O-200 is
>tested?
>>>100-106 hp at the prop at 5,400 engine rpm
Did you know the FAA only requires 150 hours of test stand running to
certify
a NEW ENGINE. Ford runs their new engines 3500 hr at rated HP. If it
fails
back to the drawing board.
>How does this square with the previous claims of improved climb and
>speed over the O-200? Different prop? Can the same prop be fitted
>to both the O-200 and the EA-81 and the tests repeated?
Since the AD or service bulletin what ever it was on the O200 to reduce
the ignition timing to 24-25 deg, the O200 doesn't put out 100 Hp.
We lost 50 rpm when we reset ours. That's almost like taking off with
carb heat. This AD was the result of several engines blowing off
cylinder heads or cylinders I don't remember for sure which. I know
of a case of a student pilot on his long cross country in a C150 and
cylinder
blew off. Before he could reach the ground he was burned alive.
I have a friend that had a cylinder blow off a C182 On climbout.
He was able to glide back to the airport.
Northwest Aero Products "Pioneers Always Take The Arrows"
Roy D. Johnson Pvt, Instrument, ASEL, ASES EAA, AOPA, SPA
email aer...@prostar.com Ph # (206)735-5022 Fax # (206)939-1578
Gregory R. TRAVIS
>I have mentioned before of our experience as a maintenance officer in a
>flying club
>for the last ten years not many engines go to TBO unless they are flown at
>least once
>a week min. of the four aircraft Valley Flyers owns, ONLY one went to TBO
>without
>removing one or more cylinders. this engine however did need mags carb
>overhaul
>starter alternator & miss small stuff.
The engines in my car run between three and ten times a DAY. The engine
in my plane is lucky if I get it running twice a week. Frequency of
use has a lot to do with engine longevity.
I've never, yet, had a car engine that didn't outlast both its water
pump and its alternator and/or starter. I don't really expect my
aircraft engine to turn in any worse performance. What's your point?
Should I ask the manufacturers to reduce engine TBO to a point where
the accessory manufacturers can come in?
>as to the
>average hours the GA fleet goes between overhaul Ill bet it is a lot less
>than 1800-2000 hrs
>that Cont & Lyc advertise.
Here's $500 that says you're simply wrong for engines flown at least 40
hours a month. Get your engineering right.
>>Can you let us know what you think may end up being the limiting
>>factor? Bottom end reliability? Cylinder wear?
>>What's your estimate on the cost to go to a dual ignition?
Answer?
>Did you know the FAA only requires 150 hours of test stand running to
>certify
>a NEW ENGINE. Ford runs their new engines 3500 hr at rated HP. If it
>fails
>back to the drawing board.
We were not asking how Ford tests their new engine designs. We asked if
them Subaru engine had been run according to the FAA protocol and
what were the results? I am quite familiar with FAA certification
requirements. Has the Subaru engine met those requirements? Is
it certified?
>>How does this square with the previous claims of improved climb and
>>speed over the O-200? Different prop? Can the same prop be fitted
>>to both the O-200 and the EA-81 and the tests repeated?
>
>Since the AD or service bulletin what ever it was on the O200 to reduce
> the ignition timing to 24-25 deg, the O200 doesn't put out 100 Hp.
> We lost 50 rpm when we reset ours. That's almost like taking off with
>carb heat. This AD was the result of several engines blowing off
>cylinder heads or cylinders I don't remember for sure which. I know
>of a case of a student pilot on his long cross country in a C150 and
>cylinder
>blew off. Before he could reach the ground he was burned alive.
>
>I have a friend that had a cylinder blow off a C182 On climbout.
>He was able to glide back to the airport.
Ok, have you tested your engine against an O-200 with the
Superior cylinders? They should allow a reset to the original
cam and mag timing. By the way, I can guarantee that even a
Subaru conversion will "burn alive" several individuals during the
course of the product's lifetime. Do you really want to talk this
way?
greg
Charles K. Scott
gr...@silver.ucs.indiana.edu (Gregory R. TRAVIS) writes:
> By the way, I can guarantee that even a
> Subaru conversion will "burn alive" several individuals during the
> course of the product's lifetime. Do you really want to talk this
> way?
Greg, what do you mean by "burn alive"?
Corky Scott
Gregory R. TRAVIS
Just that any engine, no matter how good it is, is going to fail at
some point. Put enough of them out there, accumulate enough hours,
and, statistically, someone is going to die behind it. I objected to
the poster's insinuation that, somehow, the O-200 was a home immolation
kit while the Subaru engine would never let you down.
I believe that well over 100,000 O-200s have been produced - a HUGE
number for an aircraft engine. It's by no means a perfect engine and
with production numbers like that there are bound to be some very
large horror stories.
Don't get me wrong - I have absolutely NO objection to research
into alternative aircraft engines including derivative engines. What
really irks me though are some of the claims of instant milk and honey.
greg
Larry Elie
>From: aeron...@aol.com (Aeronca11c)
>Subject: Re: Subaru EA-81 vs Continental O-200
>Date: 11 Dec 1994 20:55:17 -0500
>In article <3ca048$2...@newsbf01.news.aol.com>, pet...@aol.com (Petrah)
>writes:
>(Gregory R. TRAVIS) Writes >
>Reiner Hoffmann writes >>>
>
>>3. What SFC numbers are you seeing? (full power, cruise power)
>>>>Our numbers are as follows:
>> Full power .52
>> Cruise power .44
>
>
{deletions}
>Did you know the FAA only requires 150 hours of test stand running to
>certify
>a NEW ENGINE. Ford runs their new engines 3500 hr at rated HP. If it
>fails
>back to the drawing board.
I probably shouldn't, but I will. I know this was in one of the aircraft
mags., but I have checked and it is not at present true. An accelerated
testing of the engine is done, with longer and more extensive testing of new
families of engines and truck/industrial, but I won't divulge the details. It
is claimed to be somewhat equivilant to the above as far as wear, but I can
tell you it isn't 3500 total hours.
{deletions}
Reinerh
gr...@silver.ucs.indiana.edu (Gregory R. TRAVIS) writes:
"vs. a Continental O-200s cruise power rating of .46 SFC"
>>In cruise, a Subaru EA-81 engine burns at least 25% less fuel than an
O-200. On a flight to Sun & Fun this year, I averaged 4.3 GPH vs. the
O-200 Cessna 150 that flew next to me burned 5.9 GPH.
"Can you let us know what you think may end up being the limiting
factor? Bottom end reliability? Cylinder wear?"
>>Probably the valve train.
"What's your estimate on the cost to go to a dual ignition?"
>>Dual ignition, single plug is about $200 dollars.
"How does this square with the previous claims of improved climb and
speed over the O-200? Different prop? Can the same prop be fitted
to both the O-200 and the EA-81 and the tests repeated?"
>>The O-200 develops only about 90 hp.
Note that you can now reach me at Rei...@aol.com. Thought that alias
might be a little easier to recognize.Let me know if i didn't answer you
questions completely,
Reiner Hoffmann