Turbo Charging an O-360

[DeltaRomeo]

Maule made 10 M5 210TC's equipped with Lycoming TO-360 F1A6D's. There are maybe 6 of those still flying. I believe there is one that is my neighbor in NM that is here on the forum.

I LOVE the O-360 we have but we do fly high altitudes because of the mountains we have in NM. As I have stated before, I never really wanted to feed an O-540 but a turbo on an O-360 would give you the best of both worlds: power when you need it and economy when you don't. I ran across an ad that has STC to add turbo chargers to Bonanzas which got me thinking. Upon investigating the possibility of retrofitting a turbo like the units on the 210TC's that Maule made, I discovered that the turbo charged 360's have 7.3: 1 compression ratio pistons (ours is 8.5:1). I didn't look past that as we have a healthy engine and digging that deep would add considerable cost to a "like" to have tweak. Such a feature would allow us to fly above summer turbulence and diminish some of the DA influence during take off, etc. For those of you that prefer carbs over injection, I believe the turbo option eliminates the carb icing dynamic as well. The F1A6D is carbureted. I will say I don't like the dual mags that it comes with.

My question is with such a seemingly good combination that the 210TC's had, why were only 10 made, and why was it not employed in any subsequent models?

Also, I noticed that Maule has a Mod Kit #80 that retrofits an O-360 C1F to the 200's, 210's, 210TC's, and 235's to make it an M5 180C. There is currently not a mod listed to convert an M5 180C to M5 210TC.

[Outback]

Dave and Kim:
The TO-360 used on the M5 210 tc is not a close relative to the rest of the o-360 line. It is more like 2/3 of a TIO-540 which was 315 hp. The cylinders have the exhaust port out the top, are very expensive to replace, and the engine is rated at 42 in hg. The Rajay turbo on mine is, by todays standards, way too big. It won't be all the way spooled up at lift off, and maintains full power way higher than I will ever go. Lycoming says 19,000 ft. I think that you want to look at turbo-normalizing, which has been done on some twin commanches with the o-360. Would likely work well, but getting it approved might be your lifes work.

[DeltaRomeo]

Thanks for the reply. That really spells out why it would not be a feasible retrofit. As you mentioned, turbo normalizing may be an option as it really doesn't boost above sea level pressures, and might not entail so many changes. Its an interesting discussion either way.

[chazdevil]

Yup.
My 0-540 is normalized, not turbo-charged.
Holds sea level to 24k.
Manual waste gate.
Magic.

[DeltaRomeo]

Chaz, what kind of cruise (ground) speeds do you see at high altitudes? And, what did the install entail as well as the approval?

[chazdevil]

I typically see 165-170mph over the ground in the very low teens.
21 to 22 squared gets 12.5-12.9 GPH.
The install is pretty straightforward. It does use a good size cowl flap. We added Cessna “gillsâ€￾ to add increased cooling without as much drag.
An additional fuel pump is employed over 8,000 while engaging turbo. Same model Duke’s as stock.
METO allows for 28â€￾ for two minutes. Normal 24/24 continuous. I seldom run it that hard for long.
No reduction in TBO.
Fairly straightforward exhaust. Single tailpipe obviously.
Been trouble free for the 400ish hours I’ve been flying it.
Thankfully the he hours should get to accumulate a bit faster this year.
I purchased it with the turbo already installed, so I’ve little to add about the difficulty in certification. It was originally done in 1980. The first two owners barely flew it.
Thanks for that!

[DeltaRomeo]

What phase of the take-off run do you see the turbo finally spooled up and fully operational? Is the charge air cooled (intercooler installed)?

[Outback]

I guess I was misleading when I spoke about turbo spool up. What happens is that the MP keeps increasing during the take-off run and in the initial climb. If I am not real heavy I just shoot for 35" for take-off and climb. If I use 40-42" I have to pull back the combined throttle/waste gate knob as I gain speed. The one knob opens the throttle and then begins closing the wastegate. There is a blow off valve in the intake which is supposed to open somewhere between 47 and 52". I understand it makes an awful racket and causes the engine to stumble. Never tried it. There is no intercooler. The turbo blows through the carb and lycoming says that carb heat is mostly unnecessary.