High Altitude / high density altitude performance

[fastj22]

Now that we are back from Airventure with our Jab3300 birds and Carl is flying off his 40 in his turbo aerovee, maybe we can do some high altitude one on one tests. My initial impressions of the turbo Aerovee at 10000 DA, was it was at least as good as the Jab, maybe even a touch better.

[MichaelFarley56]

Let us know how things go on a comparison John. I'll be curious how the engine performs. Also how cool or warm the engine runs at those altitudes. Mine seems to run a tad warmer above 7000' DA.

[Wyo-flyer]

John,

I will definitely be following your results if you can. I flew last week at 8:30pm and DA was 9400 feet, the ol Tripacer can still get it done but it's pretty sluggish.

I don't really want to get into a "highly boosted" engine because then you get into lower compression, intercoolers, high octane and heat issues but I think we could run slightly more boost to overcome the thinner air. 7lbs of boost just brings us back to 30" of manifold so really it's not much different than running a stock engine at sea level.

Can't wait to hear the results!!!

[fastj22]

Now that we are back from Airventure with our Jab3300 birds and Carl is flying off his 40 in his turbo aerovee, maybe we can do some high altitude one on one tests. My initial impressions of the turbo Aerovee at 10000 DA, was it was at least as good as the Jab, maybe even a touch better.

Well, finally got to fly with Carl and Gary to get some performance comparisons.
We flew from KFLY to KPUB as a flight of 3 with Gary (normally aspirated VW). I had to pull back to 2600 RPM to keep on his wing. Carl was turning around 3100 RPM and pulled back to 32 in MP. His take off MP is over 40. I think Gary was full throttle and turning 3300 RPM. DA was about 8500ft.
On the return trip, we decided to see a head to head climb and speed. I led and climbed out from 5000ft MSL at 100MPH seeing 700fpm all the way to 9500ft. Carl with the turbo was keeping up with me. Gary, well, lets not talk about that here. Leveling off at cruise at 9500ft, I pulled back to 2800 rpm, 18 in MP and sped up to 135 mph indicated and about 150 TAS (my normal cruise). This is where I pulled away from Carl. He was seeing 130 mph indicated at 34 in MP and his TAS was not reading right. I did a 360 to get back on his wing and with him cruising at 34 in MP and 3300 RPM, I had to throttle down to about 2700 RPM to stay on his wing. If I goosed it and went to 3000 RPM, I walked away again. This was at 9500 MSL and about 11000 DA. I think with a better cruise prop, Carl will be close to cruise performance. HIs climb was very similar to mine. Also, I'm fully clothed. Pants, skirts, leg fairings, intersection fairings. Carl has leg fairings but no pants. And he's a bit out of rig so he has to fight a heavy wing.

[MichaelFarley56]

Thank you for the report John. It's good to hear the turbo can give you a good run for the money! Hopefully Carl is able to get his wheel pants on for a rematch!

Just out of curiosity, has Carl said how his engine likes running at those power settings and density altitudes? I've flown mine to high density altitudes and temperatures many times before and while it still does just fine, the temperatures are a little higher than at low altitudes. Just curious how Carl's is doing.

Thanks again for the report!

[fastj22]

I don't know specifics, but he did say his temps were fine. He has a fairly unconventional cowl setup. A ram air intake on the top from a grafted in Ford Mustang hood louver through the top mounted oil cooler. And the exit under the bottom is just a big open hole from the normal lip back.

[intoaircooled]

Oil Temps Average 170 to 190 (on a hot day)
CHT's 330 to 360
EGT's Range 1250 to 1320

I'm running a 54 x 50 Ed Sturba Climp Prop, changing to a cruise prop would net some gain. I'm not sold on wheel pants, it may net a couple miles per hour. Overall the performance of the Aerovee turbo is well worth the purchase.

[MichaelFarley56]

Oil Temps Average 170 to 190 (on a hot day)
CHT's 330 to 360
EGT's Range 1250 to 1320

Those are great numbers Carl! I need to run richer than you to keep my CHTs in that range. I'm jealous!

If you ever have the time I'd love to see your cowling modifications. Any chance you snap a few pics to share?

[intoaircooled]

I will take some photo's the cowl scoop. More than likely the spin on oil filter and the frame rail cooler (adds about two quarts more oil) are the biggest reason for the cooling numbers. Yesterdays outing with John and Gary, pushing it to see how it performed (MP 34" 3300-3400 rpm) the fuel burn was 6.2 gph on a 2.1 hour flight full rich mixture setting. I'm going to start closing in the bottom of the cowling to clean up the air flow and work on the heavy left wing and tweek a few more items. It should help improve the cruse speed once it's dialed in. About the only thing after that would be a cruse propeller.

It is a lot of fun to fly!!!

[Wyo-flyer]

Thanks so much for the great data! This is exactly what I've been looking for. Living at 7000 feet makes sea level airplanes and performance data nill.

I would be really happy with 150 mph tas at 9500 feet, especially having a little throttle left if needed. I take off all summer long at over 9000 da.

Thanks so much for sharing your findings