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

[Jim Harper]

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.

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. It would seem that I am missing around
25 or so horsepower. Oh yeah, the engine SOUNDS like it is running
great, starts great. It is somewhat less great starting hot, and idles
badly, when hot...not something that one can't work around, but not as
good as it should. I have written that off as typical fuel-injected
lyc problems, but perhaps not. Oh yeah, the performance hasn't
deteriorated...pretty much what it was from the start. You might ask
why I have tolerated it up to now, but I really didn't consider that I
was limited until I flew with another RV 8A...which just walks away
from me. Makes me look like I make purt' much everybody ELSE look! :-)
The two aircraft are nearly identical in appearance, so I became
concerned.

The most common cause for missing hp is clogged fuel
injection/injectors. Now, this is a real possibility, given that the
fuel pressure misbehaves (I thought it was just a monitor problem, but
I am starting to wonder. I am also dealing with the afore mentioned
idle problem. The airplane also really doesn't run well without the
boost pump on. I was originally told that the boost pump thingy was
"the way that one works" but in the face of my power loss, I wonder,
now. Mitigating against that is that the airplane still burns 10-11
gallons per hour, and I would think that if I was fuel limited I would
burn less...but that is my speculation. Final point is that the
cylinders all run reasonably close both in CHT and EGT...so again,
speculating, I think that the injectors per se are OK.

Cause number 2 (or so) is a 1 tooth misalignment on the valve timing.
It would seem that such a phenomena occurs more regularly than one
would think. It is pretty easy to check...you just put the engine at
#1TDC and then, with the #2 valve cover off, rock the prop. If the
lifters of #2 don't move within 20 or so degrees...that's the
diagnosis. Certainly this one is possible, and easily checked.

Another possiblility is retarded timing. I have little speculation on
that.

Tuesday, I am going to go to an A&P who is a bud and we are going to
go through things. We'll start with the valve timing, given that it is
a trivial exercise. We'll clean out the injection system, 'cause it
likely needs it anyway. Of course we'll check the timing.

Any of y'all have any OTHER suggestions? The intake manifold would
look to be OK, no holes or the like.

Thanks for sharing my quandry.

Jim

[Ed Wischmeyer]

Other possibilities for perceived low power:
* engine instruments out of calibration (how does the fuel burn compare
with expected?)
* bad propeller (wrong helix angle or blade pitch)
* airframe with excess drag

Good luck with your debugging!

Ed Wischmeyer

[JFLEISC]

>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. It would seem that I am missing around
>25 or so horsepower

I had a similar situation with my RV-4 when I bought it. Climbed OK but was
substantially slower than other O-360 powered RVs. It had a Sterba fixed pitch
wood prop at the time since metal fixed was not available yet. Tried a Sterba
cruise pitch prop with no difference. Got a Sensenich fixed metal 'cruise' prop
when they became available and it was like magic. 15 more MPH on the same RPM.
Climb RPM was 200 less but the rate of climb was the same. I always thought I
needed more power but now I'm not sure. On slightly cooler than standard days
my indicated speed is right next to Vne (215 if I remember). If your RPM and
manifold vacuum is similar to other make and model RVs with that engine then
the engine should be OK. Like mine, it could be the prop airfoil.

Jim

[Nathan Young]

On 4 Jul 2004 19:26:44 -0700, (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.
>
>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. It would seem that I am missing around
>25 or so horsepower. Oh yeah, the engine SOUNDS like it is running
>great, starts great. It is somewhat less great starting hot, and idles
>badly, when hot...not something that one can't work around, but not as
>good as it should. I have written that off as typical fuel-injected
>lyc problems, but perhaps not. Oh yeah, the performance hasn't
>deteriorated...pretty much what it was from the start. You might ask
>why I have tolerated it up to now, but I really didn't consider that I
>was limited until I flew with another RV 8A...which just walks away
>from me. Makes me look like I make purt' much everybody ELSE look! :-)
>The two aircraft are nearly identical in appearance, so I became
>concerned.
>
>The most common cause for missing hp is clogged fuel
>injection/injectors. Now, this is a real possibility, given that the
>fuel pressure misbehaves (I thought it was just a monitor problem, but
>I am starting to wonder. I am also dealing with the afore mentioned
>idle problem. The airplane also really doesn't run well without the
>boost pump on. I was originally told that the boost pump thingy was
>"the way that one works" but in the face of my power loss, I wonder,
>now. Mitigating against that is that the airplane still burns 10-11
>gallons per hour, and I would think that if I was fuel limited I would
>burn less...but that is my speculation. Final point is that the
>cylinders all run reasonably close both in CHT and EGT...so again,
>speculating, I think that the injectors per se are OK.
>
>Cause number 2 (or so) is a 1 tooth misalignment on the valve timing.
>It would seem that such a phenomena occurs more regularly than one
>would think. It is pretty easy to check...you just put the engine at
>#1TDC and then, with the #2 valve cover off, rock the prop. If the
>lifters of #2 don't move within 20 or so degrees...that's the
>diagnosis. Certainly this one is possible, and easily checked.
>
>Another possiblility is retarded timing. I have little speculation on
>that.
>
>Tuesday, I am going to go to an A&P who is a bud and we are going to
>go through things. We'll start with the valve timing, given that it is
>a trivial exercise. We'll clean out the injection system, 'cause it
>likely needs it anyway. Of course we'll check the timing.
>
>Any of y'all have any OTHER suggestions? The intake manifold would
>look to be OK, no holes or the like.

Verify your airspeed. If you have access to a GPS, you can derive
true airspeed by flying the cardinal headings, noting the
groundspeeds, and plugging the values into this applet.

http://www.reacomp.com/true_airspeed/

This way you have a solid number to compare/contrast any changes you
make to the engine/prop/airframe combo.

I would also suggest doing some timed climbs (noting density altitude)
to compare/contrast against.

-Nathan

[Kyle Boatright]

"Jim Harper" > wrote in message
om...
> 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.
>
> 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. It would seem that I am missing around
> 25 or so horsepower.

<<<snip>>>

> Any of y'all have any OTHER suggestions? The intake manifold would
> look to be OK, no holes or the like.
>
> Thanks for sharing my quandry.
>
> Jim

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

[Joe Maj]

You are missing more horsepower than that. You are in the regime where
the cube rule applies: to go 11.5% faster (182 to 210) on hp alone,
you'll need 55% more horsepower!


(Jim Harper) wrote in message >...
>
> 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. It would seem that I am missing around
> 25 or so horsepower.

[Kevin Horton]

On Mon, 05 Jul 2004 13:19:04 +0000, JFLEISC wrote:

>If your RPM and manifold vacuum is similar to other
> make and model RVs with that engine then the engine should be OK. Like
> mine, it could be the prop airfoil.
>
> Jim

The engine could be way down on power, yet still have the normal rpm and
manifold pressure. For example, if you have a constant speed prop and you
shut down the engine at high speed using the mags or mixture, it would
windmill at the rpm as before, and the manifold pressure would be
unchanged. Of course the rpm would fall off once you slowed down, but it
illustrates the fact that rpm and MP are not guarantees of power if you
have a constant speed prop.

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

[Jim Harper]

(JFLEISC) wrote in message >...
>
> I had a similar situation with my RV-4 when I bought it. Climbed OK but was
> substantially slower than other O-360 powered RVs. It had a Sterba fixed pitch
> wood prop at the time since metal fixed was not available yet. Tried a Sterba
> cruise pitch prop with no difference. Got a Sensenich fixed metal 'cruise' prop
> when they became available and it was like magic. 15 more MPH on the same RPM.
> Climb RPM was 200 less but the rate of climb was the same. I always thought I
> needed more power but now I'm not sure. On slightly cooler than standard days
> my indicated speed is right next to Vne (215 if I remember). If your RPM and
> manifold vacuum is similar to other make and model RVs with that engine then
> the engine should be OK. Like mine, it could be the prop airfoil.
>
> Jim

Is a constant speed propellor, so all bets are off there. Nice idea, though!

Jim

[Jim Harper]

"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!

Thanks again, all.

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

Jim

[JFLEISC]

>shut down the engine at high speed using the mags or mixture, it would
>windmill at the rpm as before, and the manifold pressure would be
>unchanged.

good point.

Jim

[jls]

"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

[[email protected]]

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

[Jerry Springer]

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

[jls]

> 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.

[[email protected]]

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

[Kevin Horton]

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/rv8/phplinks/index.php?&PID=48
http://go.phpwebhosting.com/~khorton/rv8/phplinks/index.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

[Jim Harper]

Jerry Springer > wrote in message et>...
>
> 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

[Jerry Springer]

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

[Simon Smith]

> > 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

[jls]

"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.

[Jim Harper]

Kevin Horton > wrote in message >...
>
> 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/rv8/phplinks/index.php?&PID=48
> http://go.phpwebhosting.com/~khorton/rv8/phplinks/index.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.

First to Jerry: Yep, am a member of the RV-8 list. Got a couple of
great ideas from them.

Now to Kevin: Yer right. I am currently using TAS from a Blue Mountain
Efis compared to GPS ground speed. The two seem to match up pretty
well. I am fully cognizant that the the GPS ground speed is affected
by wind, but over a hundred hours or so I am recognizing that the two
track quite well. This ain't science, yet. :-)

Climb rate is absolutely based on VSI and again, agree that there is
substantial error present...possibly.

What started this quest was more of a global sense that we were way
off from the standards...followed by a flight with an acquaintence's
RV-8 with ostensibly the same set-up as mine (well, different prop,
and no nose wheel)...and he made me look like I pretty much have been
making everyone ELSE look.

As I said, we went through everything on Tuesday and are replacing the
gas filter for one that is less restrictive and tuning the prop
governor for FULL take-off power. I am quite a lot more confident that
there are no subtle engine problems, and it is likely going to be a
fix each aerodynamic detail at a time to get it to where I want it to
be.

We have also fixed the fuel-flow indicator, and between that and the
BMA EFIS's ability to record flights, I am going to be able to
actually generate some data. My first two projects will be actual
time-to-climb vs fuel usage and the leaning exercise needful to work
with the GAMI folks so I can further tune my fuel system.

I will be (after I have some better data (as opposed to
impressions...hey, impressions are good enough for newsgroups, I need
data to dicker with manufacturers)) talking with the aerocomposites
folks to make sure I have the right prop. They are advertising an RV 8
with fairly spectacular performance with one of their props (but a 74
inch prop, mine is considerably shorter, but with (I think) a
considerably wider chord). We'll compare and contrast and see if we
can gain from the prop losses that I suspect are occuring.

Then on to the nickle-and-dimers...off with the tie-down rings, better
seals at the various interfaces, maybe have a look at a different
cowl/induction system.

I have an outstanding airplane. It is fast, climbs very well, and is
more airplane than I have ever flown. And a great deal of fun. Now I
just want more! :-)

Jim

[Orval Fairbairn]

In article >,
(Jim Harper) wrote:

> Kevin Horton > wrote in message
> >...
> >
> > 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/rv8/phplinks/index.php?&PID=48
> > http://go.phpwebhosting.com/~khorton/rv8/phplinks/index.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.
>
> First to Jerry: Yep, am a member of the RV-8 list. Got a couple of
> great ideas from them.
>
> Now to Kevin: Yer right. I am currently using TAS from a Blue Mountain
> Efis compared to GPS ground speed. The two seem to match up pretty
> well. I am fully cognizant that the the GPS ground speed is affected
> by wind, but over a hundred hours or so I am recognizing that the two
> track quite well. This ain't science, yet. :-)
>
> Climb rate is absolutely based on VSI and again, agree that there is
> substantial error present...possibly.
>
> What started this quest was more of a global sense that we were way
> off from the standards...followed by a flight with an acquaintence's
> RV-8 with ostensibly the same set-up as mine (well, different prop,
> and no nose wheel)...and he made me look like I pretty much have been
> making everyone ELSE look.
>
> As I said, we went through everything on Tuesday and are replacing the
> gas filter for one that is less restrictive and tuning the prop
> governor for FULL take-off power. I am quite a lot more confident that
> there are no subtle engine problems, and it is likely going to be a
> fix each aerodynamic detail at a time to get it to where I want it to
> be.
>
> We have also fixed the fuel-flow indicator, and between that and the
> BMA EFIS's ability to record flights, I am going to be able to
> actually generate some data. My first two projects will be actual
> time-to-climb vs fuel usage and the leaning exercise needful to work
> with the GAMI folks so I can further tune my fuel system.
>
> I will be (after I have some better data (as opposed to
> impressions...hey, impressions are good enough for newsgroups, I need
> data to dicker with manufacturers)) talking with the aerocomposites
> folks to make sure I have the right prop. They are advertising an RV 8
> with fairly spectacular performance with one of their props (but a 74
> inch prop, mine is considerably shorter, but with (I think) a
> considerably wider chord). We'll compare and contrast and see if we
> can gain from the prop losses that I suspect are occuring.
>
> Then on to the nickle-and-dimers...off with the tie-down rings, better
> seals at the various interfaces, maybe have a look at a different
> cowl/induction system.
>
> I have an outstanding airplane. It is fast, climbs very well, and is
> more airplane than I have ever flown. And a great deal of fun. Now I
> just want more! :-)
>
> Jim

One possibility is that one or more of your hydraulic lifters is not
pumping up properly, thus inhibiting valve opening (and proper fuel/air
charge). One sure sign of this ailment is a loud tapping noise when the
engine is idling. You can also check the tappet clearances and make sure
that they are within tolerance.

[Jan Carlsson]

Jim,

Just to eliminate all errors, I guess you don't misstake knots with mph, but
210 mph is 182,45 knots, what units is your ASI and GPS reading?

Jan Carlsson
www.jcpropellerdesign.com

"Jim Harper" > skrev i meddelandet
om...
> 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.
>
> 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. It would seem that I am missing around
> 25 or so horsepower. Oh yeah, the engine SOUNDS like it is running
> great, starts great. It is somewhat less great starting hot, and idles
> badly, when hot...not something that one can't work around, but not as
> good as it should. I have written that off as typical fuel-injected
> lyc problems, but perhaps not. Oh yeah, the performance hasn't
> deteriorated...pretty much what it was from the start. You might ask
> why I have tolerated it up to now, but I really didn't consider that I
> was limited until I flew with another RV 8A...which just walks away
> from me. Makes me look like I make purt' much everybody ELSE look! :-)
> The two aircraft are nearly identical in appearance, so I became
> concerned.
>
> The most common cause for missing hp is clogged fuel
> injection/injectors. Now, this is a real possibility, given that the
> fuel pressure misbehaves (I thought it was just a monitor problem, but
> I am starting to wonder. I am also dealing with the afore mentioned
> idle problem. The airplane also really doesn't run well without the
> boost pump on. I was originally told that the boost pump thingy was
> "the way that one works" but in the face of my power loss, I wonder,
> now. Mitigating against that is that the airplane still burns 10-11
> gallons per hour, and I would think that if I was fuel limited I would
> burn less...but that is my speculation. Final point is that the
> cylinders all run reasonably close both in CHT and EGT...so again,
> speculating, I think that the injectors per se are OK.
>
> Cause number 2 (or so) is a 1 tooth misalignment on the valve timing.
> It would seem that such a phenomena occurs more regularly than one
> would think. It is pretty easy to check...you just put the engine at
> #1TDC and then, with the #2 valve cover off, rock the prop. If the
> lifters of #2 don't move within 20 or so degrees...that's the
> diagnosis. Certainly this one is possible, and easily checked.
>
> Another possiblility is retarded timing. I have little speculation on
> that.
>
> Tuesday, I am going to go to an A&P who is a bud and we are going to
> go through things. We'll start with the valve timing, given that it is
> a trivial exercise. We'll clean out the injection system, 'cause it
> likely needs it anyway. Of course we'll check the timing.
>
> Any of y'all have any OTHER suggestions? The intake manifold would
> look to be OK, no holes or the like.
>
> Thanks for sharing my quandry.
>
> Jim

[Jim Harper]

"Jan Carlsson" > wrote in message >...
> Jim,
>
> Just to eliminate all errors, I guess you don't misstake knots with mph, but
> 210 mph is 182,45 knots, what units is your ASI and GPS reading?

Good thinking, good question. Knots. :-)

Jim

[Jan Carlsson]

I was typing in the figures for the RV8 in my program when notis that 210mph
was 182 knots.

by the way, with all settings at standard it gave an optimum diameter of 72"
but there are many but's.

Jan Carlsson
www.jcpropellerdesign.com

"Jim Harper" > skrev i meddelandet
om...
> "Jan Carlsson" > wrote in message
>...
> > Jim,
> >
> > Just to eliminate all errors, I guess you don't misstake knots with mph,
but
> > 210 mph is 182,45 knots, what units is your ASI and GPS reading?
>
> Good thinking, good question. Knots. :-)
>
> Jim