Why turbo normalizer?

"Dave S" wrote in message
k.net...


Robert M. Gary wrote:

Am I missing something?

-Robert

Heavily turbocharged engines dont have short TBO's because of inlet
plenum failure due to air pressure fatigue.. they have short TBO's (when
operated improperly) due to cracked cranks, overheated cylinders,
excessive wear type stuff.

So.. no.. its not a marketing gimmick. Turbonormalizing an engine isnt
as big a deal, because the engine is not intended to exceed its original
"normally aspirated" sea level power rating.

A popular engine mod for the Beech B36TC is to swap the TSIO-520-B for a
TNIO-550.

Better performance and TBO goes from 1600 to 1700 hrs.

I"m still confused...
1) Why not just put a regular turbo on and agree to not over boost it?
2) If compression increases inside cylinder pressure about 8 times
wouldn't taking MP up to 30" cause a MUCH higher inside cylinder
pressure than 20" (its a mutiple scale). If the outside of the cylinder
is 20" its going to have a significantly higher difference in pressure
than running out the outside 20" in MP. I just don't see how a cylinder
could crack and stress relative to 30" when its only 20" outside. Isn't
the cabin of the space shuttle under more stress when in space than
when sitting on the ground at sea lever?

-Robert

1) Why not just put a regular turbo on and agree to not over boost it?

That's what a turbo normalizer is - except that the agreement is made
with the Grand Canonical Ensemble, which enforces the agreement for you.

If the outside of the cylinder is 20" [pressure]

I don't think the outside pressure matters. Unlike with (say) the cabin
of a jetliner, the outside pressure is =not= helping to hold the engine
together. The strength and thickness of the material is. There could
be a vacuum outside and it wouldn't matter. (well except to the extent
that there's no oxygen in a vacuum

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

"Robert M. Gary" wrote in message
oups.com...
I"m still confused...
1) Why not just put a regular turbo on and agree to not over boost it?

Why do you think that's not what they do?

In fact, my airplane was originally sold with "turbo-normalization". After
the type was certified, the manufacturer went back and tested at higher
horsepower, allowing for recertification at 20 hp higher. All they changed
was an adjustment on the turbo controller. The planes built prior were all
retroactively given the benefit of this change. I still have "250" stitched
into the interior, even though the airplane is 270hp (and says so in big
letters on the engine cowl ).

Turbo-normalization is JUST LIKE regular turbo-charging, except that the
maximum induction pressure is limited to 30".

2) If compression increases inside cylinder pressure about 8 times
wouldn't taking MP up to 30" cause a MUCH higher inside cylinder
pressure than 20" (its a mutiple scale). If the outside of the cylinder
is 20" its going to have a significantly higher difference in pressure
than running out the outside 20" in MP.

Well, first of all, the difference between even 240" and either 20" or 30"
ambient is hardly significant (220" vs 210"). I don't understand why you
are comparing 30" times 8 with 20" times 8, while at the same time arguing
that the pressure differential between the inside and outside of the
cylinder is important (it's not).

As Dave explained quite well, differential pressure isn't relevant. It's
like worrying about your soda can exploding at altitude. The can is capable
of dealing with far greater pressures than it might experience, and the
difference between 15 psi (sea level) and even 0 psi is insignificant
compared to the pressures the can is designed to tolerate. A 15 psi change
in that case just doesn't mean anything, nor would a 10" or even 30"
difference matter for an airplane engine (or any engine, for that matter).

What does matter are all of the load-bearing components in the engine, but
that load is determined not by the difference between internal and external
cylinder pressure, but rather simply by how much horsepower the engine is
making.

I just don't see how a cylinder
could crack and stress relative to 30" when its only 20" outside.

Who says it could? No one here has, and prior to the above statement, you
haven't even implied anyone else has.

Isn't
the cabin of the space shuttle under more stress when in space than
when sitting on the ground at sea lever?

What's that got to do with the price of tea in China?

Pete

Robert M. Gary wrote:

I"m still confused...
1) Why not just put a regular turbo on and agree to not over boost it?

It IS a regular turbo. There is a device attached called a wastegate to
limit the boost. A turbonormalized application has a wastegate that is
set to limit pressure to what would be found at sea level on a standard
day.. approx 30 inches. Some are automatic, some are manual and some are
fixed. Deakin's colums explain this. They have pictures too.

2) If compression increases inside cylinder pressure about 8 times
wouldn't taking MP up to 30" cause a MUCH higher inside cylinder
pressure than 20" (its a mutiple scale). If the outside of the cylinder
is 20" its going to have a significantly higher difference in pressure
than running out the outside 20" in MP. I just don't see how a cylinder
could crack and stress relative to 30" when its only 20" outside. Isn't
the cabin of the space shuttle under more stress when in space than
when sitting on the ground at sea lever?

Throw this line of thinking out the window... its not doing you any
good. The forces inside the cylinder are the same for a given power
setting. If you are making 200 hp, the forces are ESSENTIALLY the same
at sea level as they are at 20,000 feet with turbo-normalization. Yea,
you went from 30 inches ambient to somewhere in the mid-teens (like 15"
ambient)... but when you look at the pressures the cylinders endure on a
POWER stroke (not a compression stroke, like you are describing, the
pressure difference is miniscule.

The Shuttle analogy is a poor one. Fatigue is the result of pressure
cycles. Launching an orbiter into space, then orbiting for a week, and
then landing is ONE cycle. I want to say they run around 10 PSI or so,
not the 15 PSI ambient that we experience here at sea level. A four
stroke engine undergoes one cycle per two rev's (a compression and power
stroke.. im "ignoring" the intake and exhaust strokes for this
argument). At 2000 rpm, that engine cylinder has just exceeded the
entire shuttle program's accumulated cabin pressure cycles in a FEW
SECONDS. And the pressure differential is MUCH greater (exponentially
so, in fact), especially on the power stroke, immediately after combustion.

Looking at the graph ( http://www.avweb.com/news/columns/182084-1.html )
on Deakins article that I mentioned shows that simple compression
without ignition (compression stroke without spark/burning) causes the
combustion chamber pressure to approach 350 PSI. Ordinary, properly
timed combustion results in a combustion chamber pressure of close to
800 PSI. A detonation event in the combustion chamber event can push
this pressure to over 1000 PSI. Now.. compare those pressures.. 350...
800.. 1000... to what the atmospheric pressure is at sea level (30"/15
psi) and in the low flight levels (15" or so/7.5 psi or so) and you see
how little a difference 7 or 8 or 9 inches really is.. and that 800 psi
is where your POWER generation is.. 800 psi is 800 psi is 800 psi. It
doesnt really matter (in a statistically significant kind of way) what
altitude you are at when you generate it.

Which brings us back to where the problems with turbocharged
installations lie: The crankshafts, the bearings, the turbo itself
sometimes, the lubrication breaks down due to high heat in the turbo,
the engine makes more power than can be adequately air-cooled and you
scorch a cylinder or two..etc... If you dont exceed the rated power of
the original engine, but only use the turbo to GET that rated power at
altitudes you couldn't before... you are getting the best of both worlds
- power AND some semblance of reliability as compared to the normally
aspirated version of that engine. BTW, The earlier limitations/
disclaimers I mentioned about cooling air mass still apply at altitude.

Dave S

If differential pressure it now what wears out cylinders in turbo
engines are you implying that its over boosting? In the Mooney
community is mostly agreed that a 201 (non turbo) will give you twice
the cylinder life as a 231 (turbo). Other wear factors (heat, less air
over the cylinders) are the same for turbo-norm vs. regular turbo. The
only difference I can see is the "idiot" difference of accidently over
boosting.

The difference in engine life is that the turbonormalized engine is
producing more average power over its lifespan. The only time that a
normally aspirated engine pruduces rated power is on takeoff at sea level, a
rare occurance. The turbonormalized engine produces full power a lot of the
time and at higher altitudes where the engine doesn't cool as well.
Additionally the turbonormalized engine will run hotter since the inlet air
is always going to be hotter (even with an intercooler)..

Mike
MU-2



"Robert M. Gary" wrote in message
oups.com...
If differential pressure it now what wears out cylinders in turbo
engines are you implying that its over boosting? In the Mooney
community is mostly agreed that a 201 (non turbo) will give you twice
the cylinder life as a 231 (turbo). Other wear factors (heat, less air
over the cylinders) are the same for turbo-norm vs. regular turbo. The
only difference I can see is the "idiot" difference of accidently over
boosting.

I owned a 1962 Mooney with a manual Ray-Jay turbo retrofitted.

Live in Houston (sea level) and just used the normal engine 29-30
inches for take off here.

Also had built in Oxy (retrofitted) and at altitude I could crank in
the Turbo and get sea level cruise power or the 29"-30" take off power
between 15K and 20K (forget just where turbo started to give out).

When I went to Denver I would put in full throttle (23-24 inches as I
recall) and then cranked in the tubo until I had the 29-30 inches
(availabel at sea level) and got full horse power for take off and
climb.

Never pulled over 29-30 inches max so engine went to TBO without any
problem.

Big John
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On 14 May 2005 14:25:57 -0700, "Robert M. Gary"
wrote:

This started on a Mooney list. I cannot for the life of me (and an
engineering degree) figure out why a turbo normalizer would be any
easier on an engine than a regular turbo. Is this just marketing crap
from the turbo normalizer people? Turbo'd engines cost more to run
because of the increased stress on the cylinders, rings, etc do to the
pressure. Running an engine at 30MP when outside is 20" is just as much
pressure difference as running at 40MP when outside is 30". It seems
like the turbo norm crowd is trying to confuse people. Unless the
entire engine was pressurized to 30", you should expect turbo style
stressed on your engine when running 30" when outside is 20". This is
*much* different than running 30" when outside is 30" (down low). Am I
missing something?

-Robert

"Robert M. Gary" wrote in message
oups.com...
[...] In the Mooney
community is mostly agreed that a 201 (non turbo) will give you twice
the cylinder life as a 231 (turbo). Other wear factors (heat, less air
over the cylinders) are the same for turbo-norm vs. regular turbo. The
only difference I can see is the "idiot" difference of accidently over
boosting.

Exactly what Mike said. Any kind of turbocharging will shorten the lifespan
of a given engine. The whole point of a turbocharger, even
turbo-normalizing, is to allow the engine to produce more power in certain
situations than it otherwise would have. More power means more wear and
tear.

Turbo-normalizing isn't as hard on an engine as "non-normalized"
turbocharging, but it still makes more power some of the time than the same
engine without a turbocharger would (and on top of that, the increase in
power is in situations when the air is less dense, making cooling more
difficult...again, more heat, more wear). That time spent making more power
results in more wear and tear.

Pete

Peter

Let me pose some what if's.

I have a turbo normalized engine. Going cross country I cruise at 5K
and 65% power. Turbo is off.

I then go on another XC and cruise at 15K and use turbo to pull 65%.

Are you saying that cruising at 65% with turbo on will do more damage
to engine than pulling 65% with turbo off??????

I'll agree that the turbo will require more maintenance it used but
engine no if run within engine manufacturers specs.

Big John
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On Mon, 16 May 2005 14:36:27 -0700, "Peter Duniho"
wrote:

"Robert M. Gary" wrote in message
roups.com...
[...] In the Mooney
community is mostly agreed that a 201 (non turbo) will give you twice
the cylinder life as a 231 (turbo). Other wear factors (heat, less air
over the cylinders) are the same for turbo-norm vs. regular turbo. The
only difference I can see is the "idiot" difference of accidently over
boosting.

Exactly what Mike said. Any kind of turbocharging will shorten the lifespan
of a given engine. The whole point of a turbocharger, even
turbo-normalizing, is to allow the engine to produce more power in certain
situations than it otherwise would have. More power means more wear and
tear.

Turbo-normalizing isn't as hard on an engine as "non-normalized"
turbocharging, but it still makes more power some of the time than the same
engine without a turbocharger would (and on top of that, the increase in
power is in situations when the air is less dense, making cooling more
difficult...again, more heat, more wear). That time spent making more power
results in more wear and tear.

Pete