Which is a better engine?

[Colonel Sanders]

This is a subject which comes up with
amazing regularity, and we're not talking
Garrett vs PT-6. Franklin (PZL) isn't on
the menu, either.

No, we're talking Lycoming vs Continental.
Everyone wants to know (or say) which is
the "better" engine.

A difficult question, because they are simply
different.

I'm reasonably unbiased - I have many years
with both engines.

Lycoming Advantages:
- indestructible in the hands of a ham-fisted pilot
- very rare carb ice after oil warms
- will start/run better at colder temps

Continental Advantages
- less internal corrosion
- more power
- runs smoother

Lycoming Disadvantages
- very susceptible to internal corrosion
- less power
- rougher running

Continental Disadvantages
- cylinders crack with hamfisted pilots
- carb ices more easily
- doesn't like cold temps for starts (plugs easily ice)
or carbureted running (will cough in the cold)

For an airplane that flies every day at the
hands of ham-fisted pilots, the Lycoming
is the hands-down winner.

But privately-owned aircraft often don't
fly very much. Their biggest problem is
internal engine corrosion, which is such
a severe problem with Lycoming, that
they went to roller lifters. Still won't
help the nitrided cylinders rusting out,
though.

At my airport - no salt - an old Bonanza
was parked for 15 years. Owner didn't
preserve the engine. Changed the oil
and closed the hangar door and walked
away. AME recently did an internal
inspection. NO CORROSION after 15
years of neglect and no pickling. Started
up and ran just fine. Compressions
were good. Only a Continental would
take that kind of abuse.

Contrast that with an IO-540 engine
that sat in a nearby hangar - both
unheated - and was trash after 11 months:



Another IO-540 engine, same airport
that doesn't fly much but had 2F oil in it:



Both privately-owned Lycoming engines,
trashed from lack of use. If they had
Continental, it would take that kind of
abuse.

But not the abuse from a ham-fisted pilot.

My conclusion:

FTU: Lycoming (eg 172)
Private: Continental (eg 182)

NB: a frequent poster here bought a 182
in the USA which had not flown for years,
which is typical of used aircraft sales - owner
dies, or loses medical, or interest, and aircraft
sits for years untended before it sells. His
engine, at flight time TBO, is perfect. If it
had been a Lycoming, it would have been
trashed.

NB: a poster here bought an aircraft with
a Lyc angle-valve IO-360 that had sat for
a while. Made metal after he bought it,
of course. Expensive overhaul required.

NB: a guy at the airport here bought a
AA5B with a Lyc O-360 out of the US,
that had sat for a while. He just found
out it's making metal. Overhaul required.

As I said, they are different. One is not
"better" than the other.

I know lots of people don't think I'm too
bright, but if you choose to fly a Lycoming:

1) run Camguard
2) fly it every week


If you fly a Continental

a) pre-heat it even when it's not very cold
b) don't be afraid to use the carb heat when it's cold
c) watch out for carb ice
d) don't crack the cylinders

Basically, it takes more brains to run a
Continental, but you can neglect it for
months, as Canadian owners typically do.

[Rookie50]

Good advice on the camguard. I have an 0-540, I fly a fair amount and use it, like the previous owner did, (who flew often too). So far so good, last oil change filter was clean as a whistle.

[Colonel Sanders]

Yup. The thing to remember is that Lycomings
and Continentals tolerate different forms of abuse.

Lycomings tolerate amazingly hamfisted pilots.

In the FTU environment, they don't learn proper
engine handling, because they don't need to.
But when they try to fly something like a TCM
GTSIO-520, they destroy that $55,000 (overhaul)
engine in less than 100 hours. Note that this is
true not only of FTU pilots, but of airline pilots as
well. Something about that white shirt and a
lack of knowledge.

Continental engines tolerate the abuse of neglect
far better than a Lycoming. Pilots don't realize it,
but not frequently using a piece of machinery with
moving parts is terribly hard on it, and a TCM will
tolerate that abuse incredibly, where a Lycoming
will start making metal if you just give it a dirty
look. Continental engines are superbly suited
for private ownership because of this. However,
if it has a carburetor (I vastly prefer fuel injection)
you will have to use the carb heat. Carb heat
use is NOT optional, as it is on Lycoming.

There are privately-owned TCM engines with
50 years since new, never been majored out
there in the fleet. You will not find a similar
Lycoming.

I know a lot of people like to stick with Lycoming
because that's what they learned at the FTU,
but it's not always the best choice for a private
aircraft, which sits for months without flying.

[ReserveTank]

I fly a twin with Continental TSIO-520s on it, and I used to fly a twin with Lycoming TIO-540s.
I would say from a daily operator's standpoint that I prefer the Continentals. They seem to run a bit smoother and are very easy to start, hot or cold weather. Engine management (power reduction, cooling) is a little simpler as well. Rather that 1" MP per minute reduction for the 540, the 520 can do 4" MP at a time. Much better for the hamfists as you put it.

[iflyforpie]

That pretty much echoes my opinions of the engines as well...

Some are better/worse than others... it comes down to the engine type, not engine manufacturer.

Four cylinders are the best, because they don't have any counterweights and are much more simply built. This automatically stacks things in favour of Lycoming since they have the four cylinder O-320 vs the six cyl O-300, and the four cyl IO-360 vs the six cyl IO-360. Counterweights are not very tolerant of throttle (or propeller) monkeys... and will clang back and forth with rapid changes in RPM. If you ever have a chance to see a six cyl engine with jugs off... have a feel of the counterwieghts... they are very loose, only held in place by oil and centrifugal force (go easy on me there, physicists ).

Continentals can have internal corrosion too... an O-300 I worked on that hadn't flown in three years the rust in the jugs was beyond second oversize... The magnesium oil sumps of the small Continentals are also very susceptible to corrosion.... I've seen a few pin holes as a result of that.

Continentals tend to be a more 'leaky' engine too... in more ways than one. Compressions will almost always be lower on Continental even after operating it by the book... whereas the most abused Lycoming ( flight school then years of private ownership) will always be mid-70s.

Continental came out with SB03-3 which establishes the minimum acceptable leak down number--not the age old 60/80... but whatever the Master Orifice Tool reads on the tester that day--usually about 43/80 where I am--and the condition that it does not include exhaust valve leakage. It also calls for a borescope inspection of the interior of the cylinder... which in Continental's, Mike Busch's, and my own opinion is a much better indicator of the health of a cylinder. You could have 70/80 with it all going out the exhaust valve... but it would be good to go until it ate a valve 50 hours later.

The other leakiness is of course oil... which rivals round engines. Lycs tend to not have as many problems... probably because things like pushrod tubes are higher up. This is why we use straight grades only in our Continentals (we call 15W50 the 'leak finder') but we can get away with it since we live on the warm side of the Rockies.

[Rookie50]

Ok -- while we are on the subject of running engines -- here's a really dumb question.

So I'm coming in to land the other day -- on short final as is my custom, I set full rich (not before). I notice; a small drop in power, which is normal I believe. Made me get to thinking: After start up, I lean out; and do run-up; leaned to peak RPM, then take off full rich (I'm at 600 MSL) So the dumb question is -- even near a DA near zero feet -- obviously the engine is running more optimally leaned out a little -- why exactly do we take off full rich?

2 Possibilities I can think of -- Obviously in a full power climb; the engine requires the cooling of full rich;

Second would be; at Full rich / Full power, the carb accelerator pump is giving you "max power" (unlike the drop at low power I noticed on final approach)

Just try to learn how things actually work vs blindly following POH

[iflyforpie]

The accelerator pump only works when you are advancing the throttle. Once it is at the stop, the accelerator pump does nothing.

Yes, a rich mixture is required for cooling. Most (all?) carburetors have what is known as an economizer valve which opens to enrich the mixture at full power. This is why using full power for takeoff with piston engines is so important (boosted engines will enrich based on manifold pressure... even if you are only part throttle).

But as with all carbs, it is only based on pressure altitude, not density altitude... so adjustments with the mixture are needed to provide optimum fuel flow. This is easy with injected engines, since you have a fuel flow gauge and often recommendations for leaning at certain density altitudes. With carb engines, it's more of a guess. I lean to peak RPM static and then enrichen a bit more than I do in cruise. Here at 3000 ASL, leaning the mixture is much more critical to prevent fouled plugs and to get as much power for takeoff and climb. Even the humble 172 gets about 50-100RPM by leaning in the climb... which makes a world of difference.

[Shiny Side Up]

Just opinon wise, I think I'm fondest of the TCM O-470. It seems to be the least troublesome of the bunch. Of all of them it starts the best, hot or cold, its only bad characteristic seems to be its propensity for making ice. The 520 is also nice, though they tend to bit more difficult starting hot I find. Never had any real issues with either.

Of note, although its a rarity, the oil dilution on the one O-470 I operate works like a charm.

The valve sticking issue with the Lycomings seems to be somewhat of a demon. I'm not convinced all the AMEs I know are up on the rope trick.

Otherwise it would be really hard to pick. They're engines. Giv'er. They only live when they run.

[Colonel Sanders]

Exhaust valve sticking due to lead and
carbon deposits on the guide and valve
is a huge problem with both Lycoming
and Continental, as the hours build.

AME's here get pretty angry when I discuss
the rope trick. They prefer to remove the
cylinder and send it off to an engine shop.

However, if you spend a little time, you
can get a very smooth running engine,
regardless of hours since major. When
people fly in my aircraft, they always
remark upon how smooth the engines
run. I guess I'm just lucky.

[iflyforpie]

There's one AME who doesn't.....

Of course... I've checked myself out in airplanes too....

[Colonel Sanders]

Rather that 1" MP per minute reduction for the 540, the 520 can do 4" MP at a time

"inch a minute" is an urban myth unsupported
by any documentation. Both Lycoming and
Continental say you can reduce power 5" MP
at a time.

Contrary to popular belief, you don't crack
cylinders with the throttle. You crack them
with the control column (pitch attitude ie airspeed
ie CHT) and mixture control. Throttle can be hard
on turbocharger (read Lyc doc).

http://www.avweb.com/news/maint/182883-1.html

WRT life of a cylinder, far more important:

- keeping the CHT below 400F (high CHT's kill cylinders)
- don't jam the mixture in for descent (see TCM engineers)

Both of the above kill more cylinders than anything
you do with the throttle. I have done thousands of
instant full-power-to-idle throttle back and power off
landings with no distress whatsoever from any of the
engines I have flown for many years.

People "shock" their engines every time that they take
off, when they advance the throttle to full from idle.
Next time you take off with a fully instrumented engine,
watch how fast the CHT's climb in the first minute. It's
impressive. No one worries about "inch a minute" on takeoff.

Here is a quote from the Lycoming Operations Manual
for the turbocharged engine:

The descent power reduction should be accomplished in several steps. Ideally, the descent should begin by nosing the aircraft over slightly while engine power and mixture remain at the cruise setting. The added speed will initiate a gradual cooldown.

When the CHT has stabilized, reduce the manifold pressure to 25" Hg, and relean the mixture to maintain 1,350F exhaust gas temperature, which will prevent rapid cooldown.

After a period of at least one minute, a further reduction of manifold pressure to 20" Hg and 2000 RPM can be made, if necessary.

Again, mixture should be leaned to maintain 1,350F exhaust gas temperature. Cowl flaps should not be used as an aid in slowing the aircraft during descent.

Note the 5" MP changes. And the attention Lycoming
says to give to pitch attitude (airspeed) and mixture
which no one could give a sh1t about. Lyc mentions
mixture THREE TIMES IN FOUR SENTENCES.

Also note that the reason for the 5" MP throttle changes
(read above in Lyc doc) is for the turbocharger. TCM
says the same thing.

For completeness sake, I should mention that poor,
deteriorating engine baffling (resulting in excessive
CHT's) has resulted in a HUGE number of cracked
cylinders, during climb. You don't even know there's
a problem, if you have a single CHT, which might
indicate ok.

No one gives a sh1t about crappy engine baffling,
but they don't mind replacing cylinder$$$.

[ReserveTank]

Maybe the 1" per minute was a company thing on the 540...it's been a while. For the 520, the manual says to avoid reductions of greater than 4" at a time. Mixtures don't move forward 'til the FAF. Getting a 2700 TBO with this.

[Colonel Sanders]

Mixtures don't move forward 'til the FAF.

Getting a 2700 TBO

Coincidence? No.

Does anyone give a sh1t? No.

Do people like paying for premature overhauls? Yes.

[Colonel Sanders]

(compression test) does not include exhaust valve leakage

Yup. Any kind of leak past the face of
the exhaust valve is really bad news.

However, a lot of the time, leaking past
the exhaust valve is simply carbon and
crap not allowing it to seat.

"Staking" the exhaust valve - basically
wailing on it with a mallet, trying to
break off carbon deposits - is to be
expected as the time builds on the engine.

If it's a bottom jug on a radial, one quick
trick I like to do is pour solvent into the
cylinder and let it sit for a while, then
stake the exhaust valve.

Of course, there is simply no substitute
for removing the valve spring and dropping
the exhaust valve into the cylinder, and
mechanically removing the carbon and
lead from the valve stem and guide.

But as I said, many AME's are not big
fans of that procedure, which is too bad.

If you spend a day and do it, gosh, the
engine runs a lot smoother. And no
more sticking valves or bent pushrods,
which I guess is no big deal for most
people with a fixed-wing aircraft, but
is no fun with rotary-wing.



Guy with a 4 cyl Lyc at my airport ignored
the "morning sickness" warning signs of
valve sticking, and bent a pushrod and
shroud last summer.

Many years ago, a woman I know bought
an old buck fifty with an O-200 and insisted
upon running 100LL. I suggested look at
mogas which was cheaper and didn't have
all the lead that her engine didn't need, but
I'm not too bright, and she didn't listen.

She got a stuck valve and landed in a live
rifle shooting range.

No one cares, but 100LL is a comprimise
between the old 80/87 and 100/130. For
any low-compression engine designed to
run on 80/87, 100LL has far too much lead
in it, causing sticking valves as the hours
build.

[Rookie50]

Few questions about stuck valves;

What is the cause of them // what operating conditions lead to them,

What are the warning signs / symptoms? I think lycomings are a little prone -- correct?

[Colonel Sanders]

Rough running engine, esp right after startup
(when valve stems heat up and expand faster
than guide in head) and at higher RPM.

Caused by carbon deposits on exhaust valve
stem, and lead deposits on inner part of
exhaust valve guide at top. Results in
insufficient valve stem-to-guide clearance
and valve sticking.

Avblend will soften the carbon on the stem,
but nothing except mechanical will touch
the lead on the guide.

Download the Lycoming Operations Manual.
If you are hardcore, also Lyc SI 1425A and
SB 388C which most AME's don't know about.

I have the sneaking suspicion that just like
tailwheel skills have been bred out of the
white-shirt pilot population over the decades,
so have "rope-trick" skills have been bred
out of the AME population over the decade.
If they don't have a step-by-step procedure
in the airframe maintenance manual for it,
they can't do it.

PS Continentals are horrible prone to valve
sticking, same as Lycomings. The problem
gets worse if the aircraft is allowed to sit for
a number of months. Not that anyone in
Canada would ever do that.

The root cause is too much f__king lead in
the gas. You really don't need the octane
of 100LL unless you are running more than
30 inches of MP (or high-compression pistons,
which are not exactly common in Canada).

As always, my advice is worth precisely what
you paid me for it. Less than that, according
to the gold bars.

[Rookie50]

Are the deposits that cause the problem, caused by running too rich a mixture? I've been told by my Ame, (and certainly is apparent to me) that my engine runs very smooth. Ive done some reading, and I try to run lean. Lean on the ground, lean above 3000 in the climb, (at reduced climb power), lean on descent....

However my engine is well over mid-time. I do also try to fly pretty often, at least every 2 weeks.

[Colonel Sanders]

Sort of. You can slow down the rate of deposits
by leaning the mixture as Lycoming suggests,
which keeps the temps up a bit.

I lean on the ground all the time. Right after
start and during the landing rollout. Max RPM.
If I have to idle, I do it at 1100-1200 as suggested
by Lycoming with mixture leaned. First minute
of operation after a cold start (esp if sitting for
a while) I like minimum RPM as suggested, to
allow for oil to circulate.

I lean in the descent. See Lyc notes. I lean in
cruise. I lean in climb at higher density altitudes
(e.g. not winter at sea level).

my engine is well over mid-time

That's kind of meaningless. I once flew a twin
with an engine 5500 SMOH in Florida. No cold
starts. Flew every day. They just kept changing
jugs and accessories as required.

What will kill your Lyc 540 is LACK of use. Not
too much of it.

Don't cold start it.
Don't overtemp it.
Don't let it sit and rust.

Your cam & lobes will rust out long before the
engine wears out.

[Rookie50]

I have a JPI, and pay attention to it. I start the way you do and am quite careful right off startup about RPM's especially this winter where i flew a good 50 hours.

I have noticed by leaning my engine -- the way that guy writes about -- mike Busch I think his name is -- I'm getting higher egt temps, which are hard to see as harmful, but lower CHT's across the board than a richer mixture, and smooth operation. I would think rationally, lower Chts generally are a good thing -- especially as we move into the warmer months.

My highest cylinder Cht this way is 370-75 in the summer, cowl flaps half cracked on warm days. #1, port front, strangely enough. I have new baffling and seems to cool the rear side better.

My oil filters have been very clean -- so far.

[Colonel Sanders]

My highest cylinder Cht this way is 370-75

Sounds good.

Just fly it regularly to keep burning the
condensed water out of the oil, and it
will last forever. You want to see oil temp
150F for this, which is generally not a
problem in the summer, but can be in
the winter.

From Lyc SL 180B:

Engines in aircraft that are flown only occasionally may not achieve normal service life because of corrosion. This occurs when moisture from the air and products of combustion combine to attack cylinder walls and bearing surfaces during periods when the aircraft is not used.

Our experience has shown that in regions of high humidity, active corrosion can be found on cylinder walls of new engines inoperative for periods as brief as two days.

Engine temperature and length of operating time are very important in controlling rust and corrosion. The desired flight time for air cooled engines is at least one continuous hour at oil temperatures of 165°F to 200°F at intervals not to exceed 30 days, depending on location and storage conditions. This one hour does not include taxi, take-off and landing time. If recommended oil temperatures are not obtainable, contact aircraft manufacturer for availability of oil cooler winterization plates.

The oil cooler system needs to be of the proper size for the engine and airframe installation. Oil coolers that are sized incorrectly can cause over-heating or below minimum temperatures. Low temperatures are just as harmful as high temperatures due to build-up of water and acids.

Ground running just won't cut it.

As an aircraft owner in Canada, you should
also read Lyc SI 1505:

Avoid rapid acceleration after a cold start.

Do not exceed idle RPM, recommended in the engine Operator’s Manual, until oil pressure is stabilized above the minimum idling range.

Allow up to one minute for oil pressure to stabilize, since lines to the gage may remain cold.

I cringe when I hear twats immediately
hit 1500 RPM right after a cold start, and
I know the aircraft has been sitting for
a long time. All the oil has run off, and
it's scrubbing metal on metal. A great
way to quickly ruin a very expensive engine.

[Rookie50]

Do higher Egts burn off lead deposits on the exhaust valves?

[Colonel Sanders]

Yes - the higher temps keep the
spark plugs and exhaust valve cleaner.

Have you had the joyous experience
of cleaning lead out of your bottom
plugs yet?

[Rookie50]

Yes!

[Colonel Sanders]

Well, lean the mixture on the ground all
the time, and idle at 1100-1200 RPM and
you can extend the time between the joyous
experience.

PS Run 40's instead of 38's. They're hotter.

PPS 37BY's kick @ss, but you didn't hear that
from me. Usual twits will run to Enforcement.

[CpnCrunch]

Not sure why this is in the training forum.

Anyway, here is an interesting article about which engine is 'bulletproof':

http://www.avweb.com/news/maint/best_ai ... 683-1.html

The consensus seems to be that the 180hp lycomings (O-360 and IO-360) are the most bulletproof, although you could get corrosion in the cams and lifters if you don't fly it enough.