Turbo performance vs non-turbo

Matt Barrow wrote:

I believe that's a Turbo Alley turbonormalizer, not a Turbo "supercharger".
If not, I suspect the STC might require some "beefing up" of certain parts.

According to the article, it's a RCM turbonormalization package which contains a
turbocharger. The turbocharger is made by Kelly Aerospace. They say they have
over 1600 hours on one Commander with it.

This unit keeps the manifold pressure at or below 28 PSI. I take it you were
describing systems that do not have this limitation.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.

"George Patterson" wrote in message
newsUm0f.35172$wb3.22707@trndny03...
Matt Barrow wrote:

I believe that's a Turbo Alley turbonormalizer, not a Turbo
"supercharger". If not, I suspect the STC might require some "beefing up"
of certain parts.

According to the article, it's a RCM turbonormalization package which
contains a turbocharger.

That sounds like being "sorta pregnant". A TN system has a TC, but the
popoff keeps it from running beyonf normal sea level pressure internally.


The turbocharger is made by Kelly Aerospace. They say they have over 1600
hours on one Commander with it.

This unit keeps the manifold pressure at or below 28 PSI.

That's about typical for a TN system. Mine keeps MP at or below 31.5 inches.

I take it you were describing systems that do not have this limitation.

A TN system will been a TC Lite :~)


--
Matt

---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

Right. A turbonormalized engine never sees any more pressure than one
that is normally aspirated - it just sees it up to a high altitude.
Cooling (at high altitudes) may be an issue, but not cylinder pressure.

jmk wrote:
: Right. A turbonormalized engine never sees any more pressure than one
: that is normally aspirated - it just sees it up to a high altitude.
: Cooling (at high altitudes) may be an issue, but not cylinder pressure.

Actually, technically speaking, running the same MP at higher altitudes will
produce a little more power than at lower altitudes. The lower ambient pressure
reduces backpressure on the exhaust, so there's more scavanging and a bigger intake
air/fuel charge for the same MP.

I saw that in the performance specs on a friend's normally-aspirated
PA-24-250. Something like equal power is between 1-2" different MP at 12000' vs. sea
level (RPM constant). I don't remember the exact numbers, but that's in the ballpark.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
jmk wrote:
: Right. A turbonormalized engine never sees any more pressure than one
: that is normally aspirated - it just sees it up to a high altitude.
: Cooling (at high altitudes) may be an issue, but not cylinder pressure.

Actually, technically speaking, running the same MP at higher altitudes
will
produce a little more power than at lower altitudes. The lower ambient
pressure
reduces backpressure on the exhaust, so there's more scavanging and a
bigger intake
air/fuel charge for the same MP.

I saw that in the performance specs on a friend's normally-aspirated
PA-24-250. Something like equal power is between 1-2" different MP at
12000' vs. sea
level (RPM constant). I don't remember the exact numbers, but that's in
the ballpark.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************


It doesn't work that way with a turbocharged engine since the ingested air
is heated by compression.

Mike
MU-2

Mike Rapoport wrote:

: It doesn't work that way with a turbocharged engine since the ingested air
: is heated by compression.

I would argue that it still works that way. In addition, however, the heating
of the intake air reduces the effective mass on the intake charge. Whether one or the
other dominates or they cancel each other out depends on lots of factors... in
particular an intercooler.

I'm not being argumentative... just sharing info that I'd never thought of
before. It doesn't make a huge difference, but it does make a difference. Running
24/24 doesn't *always* make the same power or burn the same fuel. Altitude and
mixture both have 10-20% adjustment fudge factors in there.... throw in a turbo with
heating and there's another 10-20% in the mix as well.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
Mike Rapoport wrote:

: It doesn't work that way with a turbocharged engine since the ingested
air
: is heated by compression.

I would argue that it still works that way. In addition, however, the
heating
of the intake air reduces the effective mass on the intake charge.
Whether one or the
other dominates or they cancel each other out depends on lots of
factors... in
particular an intercooler.

I'm not being argumentative... just sharing info that I'd never thought of
before. It doesn't make a huge difference, but it does make a difference.
Running
24/24 doesn't *always* make the same power or burn the same fuel.
Altitude and
mixture both have 10-20% adjustment fudge factors in there.... throw in a
turbo with
heating and there's another 10-20% in the mix as well.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************


The heating of the intake and the consequent reduction in density is the
reason that I think it will take more MP to produce the same HP at higher
altitudes with a turbocharged engine. At the same MP/RPM a tubocharged
engine is effectively running at a higher density altitude than a normally
aspirated one. The turbocharged engine is also running at a higher density
altitude as altitude increases at the same PM becasue there is more
compression required, therefore more heating. The intake air is heated
*substantially* and its density is reduced substantially. Natually, the
effect is strongest at high manifold pressures and high altitudes. I agree
that reduced pressure at the exhaust helps and an intercooler certainly
helps too.

I don't have a flight manual for a turbocharged airplane here but hopefully
somebody here does.

Mike
MU-2

: The heating of the intake and the consequent reduction in density is the
: reason that I think it will take more MP to produce the same HP at higher
: altitudes with a turbocharged engine. At the same MP/RPM a tubocharged
: engine is effectively running at a higher density altitude than a normally
: aspirated one. The turbocharged engine is also running at a higher density
: altitude as altitude increases at the same PM becasue there is more
: compression required, therefore more heating. The intake air is heated
: *substantially* and its density is reduced substantially. Natually, the
: effect is strongest at high manifold pressures and high altitudes. I agree
: that reduced pressure at the exhaust helps and an intercooler certainly
: helps too.

: I don't have a flight manual for a turbocharged airplane here but hopefully
: somebody here does.

I agree completely. The heating can be quite substantial from what I've read.
If there's no intercooler, I suspect that you probably always lose the added
scavanging HP to lower density incoming air at the elevated temperature as you
suggest. If there's an intercooler, things might trade off differently and equiv
MP/RPM combination at altitude might be less than, more than, or equal sea-level power
at the same MP/RPM combination.

Between the (substantially) higher inlet air temperature, decreased cooling
due to thinner air flow over the cylinders, and the ability to maintain very long,
high-power climbs, it's no wonder turbo'd engines eat cylinders routinely. The stock
turbo Arrow system is particularly bad... throttling full boost at the inlet? Pretty
stupid to compress the intake only to throw away most of it.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

This is sort of OT, but the new Aviation Consumer this month has an
article on an SMA diesel installed in a C182. The SMA diesel uses 85"
MP on takeoff and pretty much stays there for the entire flight.

sort of OT?

"Paul kgyy" wrote in message
ups.com...
This is sort of OT, but the new Aviation Consumer this month has an
article on an SMA diesel installed in a C182. The SMA diesel uses 85"
MP on takeoff and pretty much stays there for the entire flight.