Operating a turbo-charged engine like a turbo-normalized engine.

R

RhinoDrvr

Pre-takeoff checklist
Joined
Nov 7, 2013
Messages
149
Display Name
Display name:
RhinoDrvr
Hi all,

I’m in the beginning stages of searching for my first “family airplane”. I’ve flown a Vans RV-8 for a few years, and have a significant amount of piston single experience.

I’ve been looking at Mooney’s, mainly due to their ease of CG loading (compared to Bonanza’s) as well as the efficiency. I’ve been looking at M20J’s (201/205) but recently started researching the M20K (231/252) as I do a large portion of my flying out West around the Sierra Nevada’s, Cascades and Rockies.

I don’t know the first thing about turbocharging. I understand the basic concept, but the execution is still foreign. I understand maintenance costs can be increased, and as more power is available for longer, there is more stress on the engine.

Here are my questions;

1. If you operate a TSIO-360 as if it were turbo-normalized, I.E. limit max power to 30” vice 41”, and regulate throttle to maintain 30” through the whole climb, are you doing anything to reduce stress on the system? Power should be comparable to a normally aspirated IO-360 at that point, with the advantage of maintaining that power into the flight levels?

2. What are the increased wear items with the turbos, and the TSIO-360 in general?

3. I’ve heard the 252 is a much better airplane than the 231. Is that the case even if the 231 has intercoolers and a Merlyn wastegate?

4. What are everyone’s thoughts on the M20J vs M20K? I currently do okay with the RV-8, but the thought of being able to go high with O2 to top weather, and have a little more clearance from the rocks is appealing.
 
The turbocharged engines are designed to be operated as turbocharged engines - they have lower-compression than the normally-aspirated engines and will not produce the same power at lower manifold pressures as the similar-displacement, NA engines.
 
@RhinoDrvr Mike Bush had a pretty good primer on Turbo's which might be a helpful start.


Look closely at the turbo set-up for a given model of Mooney. A number of them have fixed waste gates.
 
Last edited:
Trade offs. Agree with flying the plane as it was designed. That doesn’t mean one can’t back off the cruise power to 70%, or limit altitude to put less stress on the engine. I love Mooneys, but not the turbo IO360 in a tightly cowled engine. If I wanted the turbo charging and was going to fly in 13-17T range a lot, breathing Oxygen, I would look at the T182RG with the IO 540 and a pretty simple system and derated engine. If I wanted a plane to fly 10-12T I would look at ovation, IO550 Bonanza, Comanche 400, ie normally aspirated but with extra horsepower. I fly outwest, but prefer 8T when possible, so I follow roads in the mornings when the winds are calm and it’s cooler.
 
Pilot here. Mooney owner here. Also own a 252.

It all depends on your mission. 201's are awesome because of their speed to cost ratio. 150+ on 4 cylinders and the related cost of overhaul? All day.

231 drivers virtually always want to be 252 drivers - one less knob to turn, better cooling, etc.
252 drivers want to be Encore drivers because of the additional Gross Weight, but those are rare and priced as unobtanium. And then, those that have them often look at the larger bodied Bravo's but you're talking about a whole different price bracket.

Flying 252's by the book isn't ideal necessarily. They do run a bit warmer, which drags you into ensuring that you at least attend Gami's Advanced Pilot School. It will help you keep your engine alive longer - and at $40-50k for an overhaul, that isn't cheap. Valves and Jugs will go if you fly them "not rich enough" and if you're not as careful with balanced injectors - you can either throw gas at the problem, or gami's with an engine monitor and look at lean of peak, which is better and cooler.

If you fly in the low teens, a 201 is fine. If you go above the mountains, there's not much better than a 28,000 turbocharged 252. Now, you can step up to the cost and insurance of a Bonanza with six seats...but do you really want to?





RhinoDrvr said:
Hi all,

I’m in the beginning stages of searching for my first “family airplane”. I’ve flown a Vans RV-8 for a few years, and have a significant amount of piston single experience.

I’ve been looking at Mooney’s, mainly due to their ease of CG loading (compared to Bonanza’s) as well as the efficiency. I’ve been looking at M20J’s (201/205) but recently started researching the M20K (231/252) as I do a large portion of my flying out West around the Sierra Nevada’s, Cascades and Rockies.

I don’t know the first thing about turbocharging. I understand the basic concept, but the execution is still foreign. I understand maintenance costs can be increased, and as more power is available for longer, there is more stress on the engine.

Here are my questions;

1. If you operate a TSIO-360 as if it were turbo-normalized, I.E. limit max power to 30” vice 41”, and regulate throttle to maintain 30” through the whole climb, are you doing anything to reduce stress on the system? Power should be comparable to a normally aspirated IO-360 at that point, with the advantage of maintaining that power into the flight levels?

2. What are the increased wear items with the turbos, and the TSIO-360 in general?

3. I’ve heard the 252 is a much better airplane than the 231. Is that the case even if the 231 has intercoolers and a Merlyn wastegate?

4. What are everyone’s thoughts on the M20J vs M20K? I currently do okay with the RV-8, but the thought of being able to go high with O2 to top weather, and have a little more clearance from the rocks is appealing.
Click to expand...
 
Turbo Bonanza owner here. I watched Mike's video...and he's spot on with all (4) accounts. Although I don't fly cross country much...that is the beauty for the turbo. It really makes flying much more pleasurable. Smoother ride and lots of options being high.
 
Checkout_my_Six said:
Turbo Bonanza owner here. I watched Mike's video...and he's spot on with all (4) accounts. Although I don't fly cross country much...that is the beauty for the turbo. It really makes flying much more pleasurable. Smoother ride and lots of options being high.
Click to expand...

Meh. I spent over 2,000 hours flying naturally aspirated piston twins all over the eastern 2/3 of the US before we got the 414, and a few hours in an M20F and some other naturally aspirated singles. Very few times that turbos really would have made those trips better. There were benefits to the turbos but unless you live or frequently travel to the mountain areas, it adds weight, maintenance expense, and fuel burn. A bigger naturally aspirated engine will ultimately cost less to own, may weigh less (depending on what you're comparing it to) and will get you some of the turbo benefit at altitude with extra benefits down low.

Were it me, I'd look for a nice J model, Missile (550 converted J), or one of the later Mooneys with a 550 in it and buy that instead of a 231/252 with the TSIO-360 (which is not a good engine) unless travel plans include routinely flying west of Denver. And even then, I'd evaluate what exactly was in the plans before going turbo. The OP has said mountain areas for flying, but even then a 550 can offer a lot at altitude.

Turbos? De-ice? BTDT and paid the bills. No thanks, I'd rather have a plane without any of those.
 
DSC_02472.jpg

but....I don't "prefer" Mooneys. lol :D
 

Attachments

  • 098C8616-7121-419E-851A-7893FC7AC51B.jpg
    098C8616-7121-419E-851A-7893FC7AC51B.jpg
    101.6 KB · Views: 24
Google “Pelican’s Perch Those Fire Breathing Turbos” and get to reading. Trust me, you’ll thank me later.

Yes, running turbo’ed engine at reduced power settings in climb will not be good for the engine. Yes, you will appreciate a turbo on the West Coast. Yes the 252 is considered preferable for the intercooler and wastegates, but also for some cooling and cowl changes and a bit of drag cleanup as well (IIRC) but no, the 231 is no slouch either and can be operated just fine with a little attention to detail, as I understand it. The increased wear items for a turbo are.. the turbo. But also the exhaust, and to the extent the turbo causes you to overheat cylinders, the cylinders.

I have always wanted a turbo’ed Mooney, but they really don’t meet my mission and I can hardly get my shoulders in them. The M20J and M20K are both great planes, but the Ks are really a significant step up in terms of performance as far as I can tell.
 
Since you like a Mooney and you like a turbonormalized engine, why not look for a turbonormalized Mooney? There is an STC so there may be some around. The article I looked at said you lose about 30 lb of useful load and you lose a little bit of sea level performance, but that performance loss comes back quickly as you climb.

Also... Since there is an STC it could be possible to add a turbonormalized system to an existing airplane that you already like. So you could buy your airplane and add a TN system to it. I haven't done any serious research on this so I don't know which kits are available if any. But in theory it could work.

Just a thought.
 
Last edited:
RhinoDrvr said:
1. If you operate a TSIO-360 as if it were turbo-normalized, I.E. limit max power to 30” vice 41”, and regulate throttle to maintain 30” through the whole climb, are you doing anything to reduce stress on the system? Power should be comparable to a normally aspirated IO-360 at that point, with the advantage of maintaining that power into the flight levels?

2. What are the increased wear items with the turbos, and the TSIO-360 in general?

3. I’ve heard the 252 is a much better airplane than the 231. Is that the case even if the 231 has intercoolers and a Merlyn wastegate?

4. What are everyone’s thoughts on the M20J vs M20K? I currently do okay with the RV-8, but the thought of being able to go high with O2 to top weather, and have a little more clearance from the rocks is appealing.
Click to expand...

231 owner (with intercooler + merlyn wastegate)

1. That's take off power. And 30" will not get you off the ground fast enough, so no, just do what the POH tells you to do: 100% power, full RPM, mixture rich. Same for climb, on an intercooled TSIO-360-LB, climb power is around 33"/2600 RPM - can you climb with less, sure (cruise climb for instance), but it'll be slow, and might not do your engine much good anyway (try driving up a hill on 5th gear...). In cruise, do whatever you want, as long as the temperatures are in check, especially TIT. I personally like to cruise at 28-29"/2500 RPM - at 8-12000ft that setting will give me 160-170 KTAS at 12.5GPH The higher you go, the better it gets (but also hotter, so again, watch those temps)

2. as many pointed out, the turbo is the obvious item

3. the original 231 with the -GB engine was a handful. once you add an intercooler and a merlyn wastegate controller things get better - engine runs cooler and critical altitude increases to like 18000ft. the 252 incorporated those improvements and a few more. on a 231, you can NEVER firewall the throttle - you'll blow the engine. and even with the merlyn there's a little extra engine management you need to do, but you'll get used to it. Just be careful not to overboost the engine on go-arounds...

4. can't comment - never owned a J.
 
Hmm, interesting. I didn’t know turbo engines didn’t produce the same power as their NA counterparts at less than full power. That’s good to know.

I’m leaning at this point towards sticking with the Lycoming in the M20J. Seems to have a better overall reputation than a 231 or 252.

Thanks for the education and insight!
 
RhinoDrvr said:
I didn’t know turbo engines didn’t produce the same power as their NA counterparts at less than full power
Click to expand...
Yeah that's not obvious but with the different compression ratios and the engine designed to operate at a higher MP it makes sense that running at 30 inches, vs 40 inches, would map out differently than its NA counterpart

For what it's worth, having flown both T and TN Cirrus (okay, not a Mooney, but it relates) the T planes consistently felt slower by about 3 to 6 knots. The T technically has more HP, and yes the G5 weighs more.. but when just one or two people in the plane and comparable weights at 29-30 inches the TN consistently moved along 3-6 knots faster. Made me an advocate for TN haha
 
You must log in or register to reply here.
Back
Top