IO 360 Power down (danger, long, rambling post!)

"Jim Harper" wrote in message
om...
"Kyle Boatright" wrote in message
...

How about a bad camshaft or follower? You could pull the valve covers
and
plugs, then rotate the engine by hand and measure the movement of the
rocker
arms to see if you have a worn cam lobe or follower. This is a simple
way
to determine if there is a valve that doesn't get the same lift as the
others...

By the way, do you have RPM and MP data on the engine? Are you gettting
the
reduced performance you quote when running at 75% per the lycoming
rpm/mp/temp charts?

Is it possible that your tach is off or your MP is low because of a
clogged
air filter or some other induction problem?

KB


Thanks to everyone, so far for the excellent suggestions. Kyle: we are
gonna check for valve timing, and will pursue looking for a worn cam
lobe or follower. Good suggestion, thanks.

My tach has been confirmed by an optical tach, so those are both spot
on. MP? One of the things we are wondering about is an induction
problem, but so far that doesn't look likley. Regarding your comment
about RPM/MP data. Yes, I have RPM and MP data, and can cruise at the
appropriate RPM and MP for 75% power at a given altitude and
temperature. However, if the engine was somehow "derated" to 180 HP,
wouldn't I just be getting 75% of 180HP? The constant speed prop is
going to adapt to the power output to maintain the appropriate RPM,
and the MP is just the MP.

One of the things that lead me to this group was the comment elsewhere
that IO 360 were hot running engines. Mine is pretty cool running.
Hence my suspicion that I am not producing the horsepower!

I was talking about a six-cylinder Teledyne Continental IO-360 engine in
the thread about cylinders running hot because they had flashing between the
fins, if you were referring to my comment. Of course, the Lycoming IO-360
is a four-cylinder engine.

As to your engine start troubleshooting by the shop manual --- static runup,
first.

Best of luck and keep us posted on what your findings are.


Thanks again, all.

One hopes we'll have an answer in a few days!

Jim

On 4 Jul 2004 19:26:44 -0700, (Jim Harper) wrote:

Van's says a 200 horsepower RV8A will cruise at 210mph at 75% power at
8000 feet. Book says it will climb at 2500 fpm at 1500 pounds.

Mine cruises at 182mph and climbs at 1800 fpm. Now, nothing wrong with
that performance, but still and all...The airplane is straight and
slick. No unusual drag makers.

Is the prop pitch adjustable? If so, where is it set? Is the engine
building to maximum rpm? If the engine is not being allowed to
develop full rated rpm, then the engine will not produce rated
horsepower. If the engine cannot develop rated horsepower, speed will
be affected.

If the prop is not adjustable, what is the diameter and pitch? How
does this compare to the recommended propeller?

Corky Scott

Jim Harper wrote:

Hi, group. I've come to this august assembelage of persons to ask for
ideas, and to discuss a few of mine. I am the proud owner and flyer of
a lovely, new, RV 8A. Alas, I am not the builder, but as I am sure you
know, owning one begins the process of working with one...

At any rate, we have around 135 hours on this machine. Engine is an
IO-360-A1B6 with one Plasma ignition, one Bendix mag, Gami injectors,
Aero Composites CS prop, stock Van's intake with K&N filter on the
left front baffle shelf. Since the airplane started its flying life,
itsbeen power down. The engine is one of those Bulldog engines
imported from England. It has around 900 hours total, and is fresh
(just before installation) off of an overhaul. Compressions are fine,
plugs look good and I am taking good care of it.

Van's says a 200 horsepower RV8A will cruise at 210mph at 75% power at
8000 feet. Book says it will climb at 2500 fpm at 1500 pounds.

***snip***
Thanks for sharing my quandry.

Jim

Jim, while this is notexacetly the same situation you have here is a web page
with some good prop testing done by a local RV-8 builder in my area.

http://www.rv-8.com/Prop.htm


Jerry (slow flying RV-6 and love it) Springer

wrote in message
...
On 4 Jul 2004 19:26:44 -0700, (Jim Harper) wrote:

Van's says a 200 horsepower RV8A will cruise at 210mph at 75% power at
8000 feet. Book says it will climb at 2500 fpm at 1500 pounds.

Mine cruises at 182mph and climbs at 1800 fpm. Now, nothing wrong with
that performance, but still and all...The airplane is straight and
slick. No unusual drag makers.

Is the prop pitch adjustable?

In the original post, he says he has on the aircraft an "Aero Composites CS
prop." One can only infer his pitch is adjustable by a cockpit-controlled
(usually by a red knob) governor which produces pressure to increase pitch
and releases pressure to reduce pitch.

On Tue, 6 Jul 2004 11:18:40 -0400, " jls"
wrote:

In the original post, he says he has on the aircraft an "Aero Composites CS
prop." One can only infer his pitch is adjustable by a cockpit-controlled
(usually by a red knob) governor which produces pressure to increase pitch
and releases pressure to reduce pitch.

Yes, saw that later on in the post, sorry, didn't read carefully
enough. That makes me wonder if the pitch range is adaquate.

Corky Scott

On Sun, 04 Jul 2004 20:26:44 -0700, Jim Harper wrote:

Van's says a 200 horsepower RV8A will cruise at 210mph at 75% power at
8000 feet. Book says it will climb at 2500 fpm at 1500 pounds.

Mine cruises at 182mph and climbs at 1800 fpm.

Please detail how you determined the cruise speed and climb rate. If you
used the IAS and converted to TAS there are a lot of ways that errors can
be introduced. For example, I've seen reports of ASIs with over 10 mph of
instrument error, and I've communicated with builders who found that flush
static ports causing the airspeed to read over 10 mph too low. A local
RV-8 builder had that problem recently. And some of the methods that
people quote for using GPS to get TAS aren't mathematically sound,
although the error here would only be a few mph, unless you've done
something really creative.

Lots of info on how to figure out TAS from GPS data, how to calibrate ASIs
and how to measure static source position error at my web site:

http://go.phpwebhosting.com/~khorton...ex.php?&PID=48
http://go.phpwebhosting.com/~khorton...ex.php?&PID=49

If you used the VSI to determine climb rate, be aware that VSIs can have
very large errors. You really need to use an altimeter and a stop watch.
And you need to understand that the rate of climb that Van quotes is
almost certain an extrapolation down to sea level at standard temperature.
You are almost certainly at a higher altitude when you do your testing,
and the temperature may very well be warmer than standard, so your rate of
climb would be a bit less than 2500 even if everything else is sorted out.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

Jerry Springer wrote in message link.net...

Jim, while this is notexacetly the same situation you have here is a web page
with some good prop testing done by a local RV-8 builder in my area.

http://www.rv-8.com/Prop.htm


Jerry (slow flying RV-6 and love it) Springer

To you, Jerry, and Corky, the plot thickens, and you may well have the
right of it. We went through the airplane today and found:

1. The mechanical timing (valve timing) was fine.
2. The fuel system was clean. No junk anywhere. There is a military
fuel filter which seemed to be obstructive, so we removed it for a
test flight. Fixed the fluctuations in fuel pressure. No increase in
speed. We are replacing that with a known unit capable of 30ghp flows
before further flights.
3. Magneto is timed appropriately. Will likely time the lightspeed
unit in a day or two. It was in good time when installed, so is likely
not an issue.
4. Prop is an aerocomposites constant speed prop. The best rpm we
could get was 2650, so we adjusted it and took one further test
flight. ROC went up from around 900 (on a hot day in Georgia) at gross
to around 1300...and rpm was up to 2700. We're gonna get another 50
rpm or so.
5. We fixed the fuel flow sensor. At climb we are running around 20
gph. At high speed cruise (still not fast enough) we are burning
around 11.5, 12 gph. This is right on Van's book speed. This also
suggests that we are producing the hp, just not getting the speed.

We are going, as I said, to adjust the prop to get 2750 and then run a
series of tests. I still don't understand how this will effect cruise
(I would think it wouldn't...unless I cruise at 2750 rpm) but perhaps
it will help. Looks like we will get the climb performance we should.

Next step is going to be to talk to the aerocomposites folks. Now,
turns out that aerocomposites are agressively courting the RV-8 crowd.
I am sublimely confident that I can work with them and figure this
out. Oh, I am not writing all that I am thinking...If we are producing
the power, and climb and fuel flow...and the fact that the engine is
working fine...are right on, then the limitations to speed are
airframe or prop. RV's are pretty much all of a kind. Little place for
large variations. So gonna rule out the prop as a problem next.

That doesn't help, going to be thinking on a different cowling, I
guess. After I make sure the airframe is dead straight. Seems to be,
but perhaps there is some improvement available there.

I'll keep you posted and thank you for the input to date!

Jim

Jim Harper wrote:


I'll keep you posted and thank you for the input to date!

Jim

Jim are you a member of the RV-LIST? You might get some good input from the RV
crowd if you subscribe to the Matronics RV List.

Jerry

Is the prop pitch adjustable?

In the original post, he says he has on the aircraft an "Aero Composites
CS
prop." One can only infer his pitch is adjustable by a
cockpit-controlled
(usually by a red knob)

Last time I looked, the red knob controlled the mixture!

Try the blue one

Simon

"Simon Smith" wrote in message
...
Is the prop pitch adjustable?

In the original post, he says he has on the aircraft an "Aero Composites
CS
prop." One can only infer his pitch is adjustable by a
cockpit-controlled
(usually by a red knob)

Last time I looked, the red knob controlled the mixture!

Try the blue one

Simon

Thanks. Well, hey, live and let live --- some of us are colorblind.