AeroVee performance issues

[Onex107]

To get the full performance from the Aerovee you need good compression on all cylinders. If you don't have 70/80 you are loosing what you are talking about.

[mike.smith]

To get the full performance from the Aerovee you need good compression on all cylinders. If you don't have 70/80 you are loosing what you are talking about.

Nearly 80/80 on all my cylinders. I'm really at a loss to figure this out. I don't have a heavy plane, I'm NOT draggy, I fly with the ball centered, I'm turning descent RPMs, I have a climb prop, but my climb sucks.

[mike.smith]

With lots of input from many sources (thanks everyone!) and some tinkering and tweaking I have been making improvements. Here is where I am at now, with comments in no particular order:

I ran the suggested in-flight test of the secondary and primary ignitions, but I wasn't noticing a difference in CHT's as you would see if the secondary ignition was advanced. But when WOT, or close to it, if I turned off the secondary ignition I would get a 100 rpm rise. It does not show up during a ground run up, where I can only get up to about 2,700 rpm before the brakes start letting me inch forward. So I retarded the trigger cap a little bit, and during the next flight I noticed only about a 30 rpm increase with the secondary off. With the secondary turned off my temps did go up. So I'm going to retard it a little more and see what happens.

My oil has always run too COOL, so I have been experimenting with the block-off plates I use in the winter to make the oil cooler opening smaller. With 50% of the opening covered I still don't get oil over 180-185 degrees on even a warm day, so I'm going to try covering up a little more, for two reasons. 1) the oil needs to get hot enough to boil off the water, and 2) I am planning to go to the top-mounted oil cooler and am planning to cover much of the oil cooler opening to limit drag and pressurization the inside of the cowl.

During the annual last week I of course reset all the valve gaps. I have also been experimenting with a larger cowl exit by making (2) hinge pieces that I have been mounting across part of the horizontal pins of the bottom cowl. Essentially they spread the cowl wider across the width of the cowl bottom to let more air out. I did it a little and did not seem to do much. I did it a lot and it did have an impact, though I need more flights to verify, and I'm going to wait until I have the top mounted oil cooler before I make any permanent changes to the lower cowl opening, but for the time being it seems like an enlarged exit is in order.

I haven't had time to try my fixes one at a time, but between the larger cowl exit, making sure the valves were set, less drag at the oil cooler inlet and retarding the trigger cap, my Sunday flight went REALLY well. I loaded me and 50 lbs of extra weights, plus full fuel and a half gallon of smoke oil to get up to 1,012 lbs. Taking off with a 90 deg cross wind and both ignitions on, I was getting 2,950 rpm with 350-400 fpm climb, and all my temperatures were way into the green even at WOT with a touch of leaning. If I turned off the secondary ignition I would get about 3,050rpm on climb out.

During level flight at 3,050 rpm I was at 98-100 kts IAS, 104 kts TAS. My hottest cylinder is #1 and it was at 1270 EGT/340 CHT. That is WAY better than I have been getting. I was leaned out about 1 to 1-1/2". After 2.4 hours of flight time, including two take-offs and two landings, I burned 3.95 gph! I was running lean during cruise, but even so that seems rather low. But my perception when I have run rich is that the engine seems to bog down a bit. Maybe it's just perception so more testing is in order.

So all in all things are much better after those few tweaks :-) If you are having issues with power and/or temperatures maybe some of these things will help. But remember that 80 hp can only do so much, so keep your expectations in line with reality.

Oh, and during my compression test (cold) I got 79/80, 80/80, 79/80, 80/80 :-)

[Sonex1517]

Mike

Thanks for the update. I was wondering how it was going.

Good to hear things are going better and I look forward to hearing about your trip at Oshkosh!

It's funny you mention a bit of bogging down when rich. I am now convinced I had a set screw that was not holding in my AeroInjector mixture adjustment and I was experiencing a similar feeling. Let's compare notes over a beverage.


Sent from my iPad using Tapatalk

[gammaxy]

Mike,

Any reason you don't go wide-open-throttle during level flight?

I'd guess that 100rpm rise when turning off the secondary would be good for an extra 2.5 hp (from the Aeroconversions dyno chart)

[mike.smith]

Mike,

Any reason you don't go wide-open-throttle during level flight?

I'd guess that 100rpm rise when turning off the secondary would be good for an extra 2.5 hp (from the Aeroconversions dyno chart)

Saving fuel. Traveling out to OSH I want to get 3 hour legs with a comfortable reserve. I don't see much increase in speed between 85% and 100% throttle, so why burn up extra gas for an extra 2 knots? If I get the secondary set right then I should get that 2.5 horsepower at my 85% setting. The only time I really need WOT is in a climb (including take-off).

[kmacht]

Mike,

What speed were you climbing at? The rpm numbers during climb still seem a bit low but you are certainly moving in the right direction.

Keith

[mike.smith]

Mike,

What speed were you climbing at? The rpm numbers during climb still seem a bit low but you are certainly moving in the right direction.

Keith

2,950 rpm at 350 fpm at about 78 kts. But I did not do multiple tests and did not write everything down, so I need to do a few more to get a better base line.

[mike.smith]

I retarded my secondary ignition a little more and went for a flight today. Retarding the ignition got me to the point where I can leave the secondary turned on and I get the same rpms as if I turned it off (maybe 10 rpm difference, but that's close enough). It was 90 deg F on the ground and 78 deg F OAT during flight. Temperatures were all well in the green, with my hot (#1) cylinder at 1250 EGT/338 CHT when I was running WOT. Oil was at 174 deg F.

On take-off I had to lean about 1/2" or the fuel system skipped a beat at WOT. During flight it was fine at WOT, but I can see several rpm drop when I go to full rich.

On take-off the numbers bounced a bit, but at first 60 kt/ 455 fpm / 3060 rpm, then 68 kt / 500 fpm / 3068 rpm.

During cruise, when I climbed I saw 86 kt / 400 fpm / 3074 rpm, or 74 kt / 480 fpm / 2985 rpm.

I was at about 965 lbs including full fuel. Considering I have only 80 hp to work with I'm fairly happy at the moment.

[Sonex1414]

Mike

Have you tried taking off your air cleaner? When I went on K&N website and checked their formula it showed that the standard air cleaner that comes with the AeroVee is not large enough to produce enough air to create 80 hp. I modified my air cleaner. At WOT I am turning 3550 RPM and showing 150 mph. Just a thought .