Turbo Temp/Lower pressure side heat - Optimization

[tps8903]

B Vents installed and primed. Paint tomorrow then test flight.

[tps8903]

Installed

[tps8903]

Test results with B vents and deflectors.

OAT 88F
CHT Cruise 35" MAP 340-365F
CHT Climb out 40" MAP to 1000agl Max 370F approx 40F reduction on CHT 3
Climb 35" MAP at 100mph max CHT 380F. I was unable to keep below 410F before.
Max ambient cowl temp 110F.
Max oil temp 171F.

My configuration is 1 NACA blocked. Will likely reinstall cold induction and carb heat with that vent. 1 NACA blast tube to firewall accesories to keep cool. Front smile open. Turbo blanket on. Liquid turbo cooling for shut down. B vents with deflectors. Bottom vent.

I can now climb continuous at 35" MAP without going over 380F on CHT 3. Next test I will climb at 35" to 6000+' to see if that holds. Oil Temp is 20F cooler and ambient cowl temp is 110F, about 20F over OAT. I think I finally have the cooling where I want it. To summarize, no change in cruise CHT, which was already good. But great improvement in climbing cooling, which was my issue. Also improvement in cowl ambient temps.

[Bryan Cotton]

Chris,
That's cool! Is there any noticable difference in cruise speed? I have a set of B exits but was talked out of putting them in addition to my stock A model bottom exits. Climb in high temperatures is still a killer.

[tps8903]

Chris,
That's cool! Is there any noticable difference in cruise speed? I have a set of B exits but was talked out of putting them in addition to my stock A model bottom exits. Climb in high temperatures is still a killer.

Cool indeed!

I didn't notice any appreciable difference in cruise speed. If there is a difference, I wasn't able to detect it. That's using the highly scientific TAR (Thats about Right) Method.

[builderflyer]

Test results with B vents and
My configuration is 1 NACA blocked.

ambient cowl temp is 110F, about 20F over OAT. .

Not flying behind an Aerovee but these are the numbers that really jumped out at me. My ambient cowl temp is typically 70F above OAT. Your number sounds almost too good to be true. I wonder what others have seen here for this differential.

Art,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,Jabiru 3300 #261

[Bryan Cotton]

I've never measured mine, but the cowl is too hot to leave my hand on it after flying.

[tps8903]

Test results with B vents and
My configuration is 1 NACA blocked.

ambient cowl temp is 110F, about 20F over OAT. .

Not flying behind an Aerovee but these are the numbers that really jumped out at me. My ambient cowl temp is typically 70F above OAT. Your number sounds almost too good to be true. I wonder what others have seen here for this differential.

Art,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,Jabiru 3300 #261

I don't know what it use to be. But like Bryan said it use to be too hot to touch. I would also get the occasional paint blister.

I have so much exit space now I can afford to dump a 2" NACA into the firewall area to keep things cool. I put my hand on the cowl after the flight, and for the first time it was hot, but didn't hurt my hand. I definitely can leave my hand on the cowl.

It should read 30° over OAT. Typo. It was a mid 80 day and cowl tamp was about 110-120

[tps8903]

I'll do a longer flight when I get back from out west and post results. Including an extended climb report.

[tps8903]

Today I did a 2.4 hour test of my new setup.

I'm please to announce that everything is working 100%.

Today I climbed at 35" MAP and 105mph up to 8000' msl from 70' msl on a 83F day. At 8000' the hottest cylinders were just below 370F. The cool cylinders just above 350F. Oil Temp was 176F peak and cowl firewall temp never got over 120F.

I ran the engine at 35" MAP for 2 solid hours and everything was green. When I landed for fuel I put my hand on the cowl and left it there, warm, but not hot.

My setup is a quality turbo blanket, exhaust wrap, Legacy bottom vent with B side vents with 1" deflectors. 4" round top vents and 1 NACA vent (2") blasting cool air on the coils. Front cowl smile open and the NACA vent on the left side is currently still blocked. I may reinstall my cold air induction and carb heat on that side, but for now it's working great.

I did a IAS to CAS test on the flight back. Today was a zero wind day in Central Florida, so that made it super easy and consistent. My IAS reads 2mph low in the 130-150 mph range.

32.5" MAP gets me 153 mph TAS at 3600' (5665' DA)
35" MAP gets me 164 mph TAS at 3600'. (5665' DA)

Environmental. 30.12inhg, 28C 3500 msl