Turbo Normalized IO-360 vs. NA

[RocketGnome]

Hello all, long time lurker, first time poster.

I am planing on buying a M-20C thru M-20F hopefully in the next month or two inventory on the market willing. I've been looking for the past year since a little before a deployment though the deployment and the two extra months of deployment, thanks for nothing corona virus. I understand the differences between models and don't rally have any questions save for one.

What is the lowest fuel flow in GPH can you cruise in a TN IO-360? I know how the turbo works, and what it gives me thanks to a few post on here and their links to great AvWeb articles for more in depth information. 

 

Background:

My mission primary is to build hours over the next year or two so bringing GPH down while cruising is an important aspect of the plane search (not the only aspect otherwise I'd be looking at anything with a C-85 engine.) With a NA IO-360 I know I can cruise at 6.9 GPH or better. But what i don't know is if I get a plane with a Rayjay TN and a manual waste gate control will I be close to that as well? My thought is if I chose to not use the boost and open the wastegate i should get close to NA GPH, though with the impeller blocking a bit of the intake and the turbine in the exhaust flow I'm thinking some efficiency will be lost and everything being equal the Turbo engine will require more GPH, but is that .5 more or 5 more? My guess is less than 1? having read all the posts on this forum I know that 69% of the responses will say "Mooney zoom" and "WOT all the RPM!" and while I love the enthusiasm and will join you doing that from time to time, I'm kind of looking for the practical low GPH setting in a Turbo. Yes I also understand the temperature sensitivities of the system as well in regards to TIT, EGT, and CHT. 

Lastly, with the turbo working boosting away what kind of GPH does one typically see in the flight levels, like FL200?

Proof reading this, I feel like I could word things a bit more softly or diplomatic, but I'm starting to see cross eyed and need to go re install my 9 yo in his bed so apologies if I am less than as coherent as I should be, and thanks to all in advance for knowledge I know I will receive from this fine community. 

 

Neil

[Shadrach]

30 minutes ago, RocketGnome said:

Hello all, long time lurker, first time poster.

I am planing on buying a M-20C thru M-20F hopefully in the next month or two inventory on the market willing. I've been looking for the past year since a little before a deployment though the deployment and the two extra months of deployment, thanks for nothing corona virus. I understand the differences between models and don't rally have any questions save for one.

What is the lowest fuel flow in GPH can you cruise in a TN IO-360? I know how the turbo works, and what it gives me thanks to a few post on here and their links to great AvWeb articles for more in depth information. 

 

Background:

My mission primary is to build hours over the next year or two so bringing GPH down while cruising is an important aspect of the plane search (not the only aspect otherwise I'd be looking at anything with a C-85 engine.) With a NA IO-360 I know I can cruise at 6.9 GPH or better. But what i don't know is if I get a plane with a Rayjay TN and a manual waste gate control will I be close to that as well? My thought is if I chose to not use the boost and open the wastegate i should get close to NA GPH, though with the impeller blocking a bit of the intake and the turbine in the exhaust flow I'm thinking some efficiency will be lost and everything being equal the Turbo engine will require more GPH, but is that .5 more or 5 more? My guess is less than 1? having read all the posts on this forum I know that 69% of the responses will say "Mooney zoom" and "WOT all the RPM!" and while I love the enthusiasm and will join you doing that from time to time, I'm kind of looking for the practical low GPH setting in a Turbo. Yes I also understand the temperature sensitivities of the system as well in regards to TIT, EGT, and CHT. 

Lastly, with the turbo working boosting away what kind of GPH does one typically see in the flight levels, like FL200?

Proof reading this, I feel like I could word things a bit more softly or diplomatic, but I'm starting to see cross eyed and need to go re install my 9 yo in his bed so apologies if I am less than as coherent as I should be, and thanks to all in advance for knowledge I know I will receive from this fine community. 

 

Neil

NA Turbo does not “boost”. It merrily maintains SL mp.  Compression ratio does not change. Roughly speaking Fuel flows should be close to book numbers at book mp. The difference is with the rayjay is you can set 24inHg at 12,000 feet where without it you’d be at 18inHg. 

[MIm20c]

The rayjay setup on my o-360 does not change the NA efficiency when the manual waste gate is off. The intake air for the turbo comes off the side of the air box, is pressurized, and is piped back in right before the carb intake. When the turbocharged air overpowers the ambient a door closes to force feed the engine. Because it’s TN vs TC the compression ratio / efficiency remains close to the same. Most of my flying lately has been 6-7 gph and the engine doesn’t mind. 
 

I haven’t been above 14k yet but I get an extra 13-15 kts for an extra 2.5-3 gph. My setup is certified for 25k, I’ve always been a little curious what numbers it could put down at that altitude. 

[RocketGnome]

Thank you gents, that’s what I thought it would be, just couldn’t find the answer anywhere. And thanks for the additional info, wasn’t quite sure where the intake lived and makes sense that I can look at the POH numbers for the “normal” performance numbers For the given settings. Think I’ll plan on not passing over a plane just because it is TN.

[carusoam]

Welcome aboard Mr. Gnome...

See if we can clear up your mission a bit...

It sounds like...

1) you want to build time...

2) Use as little fuel as possible...

3) Go quickly while doing so... (hours don’t care if you traveled near or far...)

4) The turbo only adds to your expense... unless going faster at higher altitudes is your thing.... but that costs additional fuel...

 

So...

Once around the pattern... what are you trying to accomplish with this bird?

Low fuel burn when you want?

Fast speed at altitude on the odd days of the month..?

Adding a TN will get you there.... for a few hundred thousand more... you can get two TNs on an IO550 in your acclaim...

For fun, look up Vz or Carson’s Speed... for ultimate efficiency... while Mooney flying...

Unfortunately, that Much attention to efficiency is relatively slow flying for what a Mooney is capable of...

 

just be sure... turbos cost extra... turbos add to the maintenance and OH costs... turbos add to the performance...

If you get a turbo accidentally, you may not be very happy about it... if you choose the turbo because it makes sense... it is really good...

Go Mooney!

Best regards,

-a-

[Shadrach]

1 hour ago, RocketGnome said:

Thank you gents, that’s what I thought it would be, just couldn’t find the answer anywhere. And thanks for the additional info, wasn’t quite sure where the intake lived and makes sense that I can look at the POH numbers for the “normal” performance numbers For the given settings. Think I’ll plan on not passing over a plane just because it is TN.

I have no personal experience but most owners seem to like them. I’m sure @KLRDMD can offer a dissenting opinion. @M20F can give you his long term operational observations.

[gsxrpilot]

20 hours ago, MIm20c said:

I haven’t been above 14k yet but I get an extra 13-15 kts for an extra 2.5-3 gph. My setup is certified for 25k, I’ve always been a little curious what numbers it could put down at that altitude. 

Come on up. The air is nice up here.

[Ross Taylor]

What’s your location or field elevation? That could be an important factor in your calculation. For example, we’re at almost 7000’ in Arizona...so we get density altitudes of 9-10k. TN is more of a boost (punny...) here than if you’re coastal.

Having said that, our E is NA and performs well for us (two rather light people).

[M20F]

I do around 10.2 GPH / 100 ROP / 70% power and generally cruise 9-12K seeing 140KTS.

FL190 is 160-170KTS depending on ISA and generally run around 11-11.2 GPH as you need the fuel to cool.  F190-210 is the happy altitude block.  At FL210 the controls get really mushy and you will start losing speed (you lose 100% power give or take around FL180).  

The other issue I have is the heater set up on a M20F is not really geared for -30F.  If the sun is out it is nice.  If the sun isn’t out you will be very cold and the windows will frost.  If it is winter and you descend the defroster may need a lot of time to clear (or you pull a credit card out and scrape). 
 
There really is no additional cost you can overhaul the turbo for $2K I want to say (Main Turbo).  Very bullet proof.  
 
Like all things it boils to mission.  I like traveling and do things like KLZU to KCMX/KJMS/KTOR a couple times a year.  I commuted weekly for almost 2yrs 47N to KDPA.  I currently have a hanger in KLZU and KDPA and commute back and forth (not so much under COVID).  I flew about 300hrs one year for work all up and down East coast.  The bottle and the turbo give you some options in terms of speed (100+ knot tail winds) and getting over weather.  
 
I rarely use the turbo though for much more then climbing to 9-12K.  O2 is a hassle (you can fill your own but still a hassle).  You also take a lot more time to climb.  When I went to FL250 it took @50 mins at 100-120 IAS so you have an hour where you are going 30 knots slower.  You need to make that up with a long leg and a good tail wind.  You also will burn 20 gallons getting there.  
 
For my mission and the flexibility it was what I wanted.  I can always take my turbo off and go back to a stock M20F, but I also bolt it back on.  That is not an option to anyone else as the STC no longer exists.  I wouldn’t pay a crazy premium for it but it is definitely worth having, just for the STC alone.  Hell if I found one and didn’t want the RayJay, I would buy it and put the RayJay in a box.  Very little expense to swap back exhaust. 
 
Last thing is you really have to watch CHT at altitude. The air is so thin and thus not much cooling.  Have to work the flaps and red knob.  Boot strapping at altitude is an issue as well.  You have to be micro delicate on the controls. 
 
Happy to answer any other questions but if your mission is to build time for the lowest possible cost as a first time owner, buy a C150.  Cheapest operating cost you will find and you can sell it for close to what you paid for it after putting 1000hrs on it.  

[KLRDMD]

19 hours ago, Shadrach said:

I have no personal experience but most owners seem to like them. I’m sure @KLRDMD can offer a dissenting opinion. @M20F can give you his long term operational observations.

My recollection on my Ray Jay turbo F model was that it was allowed to maintain MP up to 27” until it couldn’t which was about 15k feet on my airplane. Realistically, it was a benefit in the 10,000-15,000 ft range. Below 10,000 ft it offers little benefit over NA and about 15,000 is starts to lag as well. But I haven’t had that airplane in about 15 years so my recall may be a bit off.

[Shadrach]

6 hours ago, KLRDMD said:

My recollection on my Ray Jay turbo F model was that it was allowed to maintain MP up to 27” until it couldn’t which was about 15k feet on my airplane. Realistically, it was a benefit in the 10,000-15,000 ft range. Below 10,000 ft it offers little benefit over NA and about 15,000 is starts to lag as well. But I haven’t had that airplane in about 15 years so my recall may be a bit off.

My recollection was that it never lived up to your expectations.

[Shadrach]

14 hours ago, M20F said:

I do around 10.2 GPH / 100 ROP / 70% power and generally cruise 9-12K seeing 140KTS.

FL190 is 160-170KTS depending on ISA and generally run around 11-11.2 GPH as you need the fuel to cool.  F190-210 is the happy altitude block.  At FL210 the controls get really mushy and you will start losing speed (you lose 100% power give or take around FL180).  

The other issue I have is the heater set up on a M20F is not really geared for -30F.  If the sun is out it is nice.  If the sun isn’t out you will be very cold and the windows will frost.  If it is winter and you descend the defroster may need a lot of time to clear (or you pull a credit card out and scrape). 
 
There really is no additional cost you can overhaul the turbo for $2K I want to say (Main Turbo).  Very bullet proof.  
 
Like all things it boils to mission.  I like traveling and do things like KLZU to KCMX/KJMS/KTOR a couple times a year.  I commuted weekly for almost 2yrs 47N to KDPA.  I currently have a hanger in KLZU and KDPA and commute back and forth (not so much under COVID).  I flew about 300hrs one year for work all up and down East coast.  The bottle and the turbo give you some options in terms of speed (100+ knot tail winds) and getting over weather.  
 
I rarely use the turbo though for much more then climbing to 9-12K.  O2 is a hassle (you can fill your own but still a hassle).  You also take a lot more time to climb.  When I went to FL250 it took @50 mins at 100-120 IAS so you have an hour where you are going 30 knots slower.  You need to make that up with a long leg and a good tail wind.  You also will burn 20 gallons getting there.  
 
For my mission and the flexibility it was what I wanted.  I can always take my turbo off and go back to a stock M20F, but I also bolt it back on.  That is not an option to anyone else as the STC no longer exists.  I wouldn’t pay a crazy premium for it but it is definitely worth having, just for the STC alone.  Hell if I found one and didn’t want the RayJay, I would buy it and put the RayJay in a box.  Very little expense to swap back exhaust. 
 
Last thing is you really have to watch CHT at altitude. The air is so thin and thus not much cooling.  Have to work the flaps and red knob.  Boot strapping at altitude is an issue as well.  You have to be micro delicate on the controls. 
 
Happy to answer any other questions but if your mission is to build time for the lowest possible cost as a first time owner, buy a C150.  Cheapest operating cost you will find and you can sell it for close to what you paid for it after putting 1000hrs on it.  

I think the heater issue is unique to the TN birds. The stock heater in my F model would likely heat a tea kettle

[wcb]

14 hours ago, KLRDMD said:

My recollection on my Ray Jay turbo F model was that it was allowed to maintain MP up to 27” until it couldn’t which was about 15k feet on my airplane. Realistically, it was a benefit in the 10,000-15,000 ft range. Below 10,000 ft it offers little benefit over NA and about 15,000 is starts to lag as well. But I haven’t had that airplane in about 15 years so my recall may be a bit off.

Mine has maintained mp up to 17500 (have not gone to FL yet).  Remember even if for some reason your set up cannot maintain the full 27" of MP and say you are only getting 24 or 25" of MP that is still a ton better than say 15" mp when flying higher with NA (I think around 20- 30 kts better).  I normally run mine under 27" (I will climb at 27 and cruise at 25 or 26) because I choose to not because it won't.

[M20F-1968]

I have a RayJay TN F model.  The TN version is great in that you maintain Manifold pressure up to at least 18,000 ft, retain the efficiency of high compression pistons, and have a relatively simple system to allow all that to happen.  Airspeed in my F below at lower altitudes is about the same as a NA engine.  My airplane is now essentially a J model aerodynamically.  at 10,000 ft, 75% power = 160 kts, 10,000 ft, 98% power = 168 kts, 17,000 - 18,000 ft, 75% power = 175 - 180 kts.  In a Mooney you will use the 10,000 - 15,000 ft altitudes all the time.  The turbo makes it easy. No real cooling issues, but my plane is not at all stock.

John Breda

[M20F-1968]

Also, to answer your GPH question.  100 ROP at 18,000 = 11.5 gph, 175 kts, LOP 8.5 GPH, subtract about 5 kts.

John Breda

[RocketGnome]

Thanks again for all the responses! To clarify the mission, yes primary I am  looking to build a bunch of hours, but sub missions include routine trips between Boise and north of Seattle to pick up my parents on a regular basis, or drop off my kids from time to time. So, I need 4 seats and I don't want to stop for gas or take all day to do it on those occasions. I've made the flight a few times in a C-150 which with the fuel stop only saved an hour or so over driving. The Mooney speed even pulled back is still cheaper than other airplanes in the same class, I could get a 172-182 for close to the same price as a Mooney, burn the same gas and go slower, but I'll pass. Besides, with as much time as I want to build, I may as well cross the county a few times and see all the sights. Another reason is safety, in a 150-172 the safety margin is reduced because now you can't climb over weather as well, or you have less loiter time to go to an alternate, or your alternate needs to be closer and may not have as nice weather. If I'm flying to someplace IFR and the weather is going to be close to mins, now I have a radius that potently I just fly to an area that is VFR instead of just a little better IFR. All this to say, I'm pretty sure a Mooney fits my needs and mission best, I just wasn't sure how something that had a TN on it would compare to the base line. Sounds like it won't affect it, and indeed provides more options. I think my decision with all the new info and help provided from all of you is that while I won't go out looking for a TN, I won't avoid it either. Glad to have a good community like this around to help out!

[M20F]

On 7/16/2020 at 11:44 PM, Shadrach said:

I think the heater issue is unique to the TN birds. The stock heater in my F model would likely heat a tea kettle

Mine does ok as well when it is “cold” out at 8000 feet .  A little 2” by 4” opening though isn’t going to warm a cabin at -12F (ISA) at FL200 especially as the airframe cold soaks and there is no sun shining on you.  Especially given how any 50+ year old plane leaks air like a sieve.  

Where life is good is twins with a nice Janitrol heater.  I flew a C320 at FL280 in the winter, in the jet steam, at -40F, in my shorts, all the vents blowing, and I was still hot....

[M20F]

Just now, RocketGnome said:

Thanks again for all the responses! To clarify the mission, yes primary I am  looking to build a bunch of hours, but sub missions include routine trips between Boise and north of Seattle to pick up my parents on a regular basis, or drop off my kids from time to time. So, I need 4 seats and I don't want to stop for gas or take all day to do it on those occasions. I've made the flight a few times in a C-150 which with the fuel stop only saved an hour or so over driving. The Mooney speed even pulled back is still cheaper than other airplanes in the same class, I could get a 172-182 for close to the same price as a Mooney, burn the same gas and go slower, but I'll pass. Besides, with as much time as I want to build, I may as well cross the county a few times and see all the sights. Another reason is safety, in a 150-172 the safety margin is reduced because now you can't climb over weather as well, or you have less loiter time to go to an alternate, or your alternate needs to be closer and may not have as nice weather. If I'm flying to someplace IFR and the weather is going to be close to mins, now I have a radius that potently I just fly to an area that is VFR instead of just a little better IFR. All this to say, I'm pretty sure a Mooney fits my needs and mission best, I just wasn't sure how something that had a TN on it would compare to the base line. Sounds like it won't affect it, and indeed provides more options. I think my decision with all the new info and help provided from all of you is that while I won't go out looking for a TN, I won't avoid it either. Glad to have a good community like this around to help out!

It sounds like you have made your decision and you are looking for validation.  A Mooney is objectively not the right plane for your mission.  
 

Private airplane ownership is however not cost effective or logical.  Do what you want, but if the intent is logic then you are picking the wrong plane based upon all the information you have provided. 
 
Enjoy!

[Shadrach]

3 hours ago, M20F said:

Mine does ok as well when it is “cold” out at 8000 feet .  A little 2” by 4” opening though isn’t going to warm a cabin at -12F (ISA) at FL200 especially as the airframe cold soaks and there is no sun shining on you.  Especially given how any 50+ year old plane leaks air like a sieve.  

Where life is good is twins with a nice Janitrol heater.  I flew a C320 at FL280 in the winter, in the jet steam, at -40F, in my shorts, all the vents blowing, and I was still hot....

Mine has 4 outlets. 2 for each foot well, a large center blower for the back and the window defrost.  Size really is not the issue, the issue is volume. Since insulating the cabin,  heating has not been a problem. Don’t know how cold it would need to be to overwhelm the heater but I’ve yet to do it.

Edited July 18, 2020 by Shadrach

[M20F]

22 minutes ago, Shadrach said:

Mine has 4 outlets. 2 for each foot well, a large center blower for the back and the window defrost.  Size really is not the issue, the issue is volume. Since insulating the cabin,  heating has not been a problem. Don’t know how cold it would need to be to overwhelm the heater but I’ve yet to do it.

1967.  I have 2 footwell, 2 defroster, and 1 center blower the same as you (though you really can’t blow them all together at 100%).  Heating at 9000 feet in Maryland isn’t exactly the same as flight levels from KJMS to 47N in January (or night time in August) riding the 100kt polar vortex.  Your heater isn’t awesome it just isn’t having to work very hard.

I have spent a lot of years flying  back and forth from China.  As anyone who has sat on the window seat, a lot of insulation on modern jetliner.  TOD the cold soak has the wall a little more the  nippy.  In a GA plane the cold soak is even more evident. 
 
In short you are comparing apples (9000 feet) and oranges (Flight Levels) for heater capability.

 

[Shadrach]

1 hour ago, M20F said:

1967.  I have 2 footwell, 2 defroster, and 1 center blower the same as you (though you really can’t blow them all together at 100%).  Heating at 9000 feet in Maryland isn’t exactly the same as flight levels from KJMS to 47N in January (or night time in August) riding the 100kt polar vortex.  Your heater isn’t awesome it just isn’t having to work very hard.

I have spent a lot of years flying  back and forth from China.  As anyone who has sat on the window seat, a lot of insulation on modern jetliner.  TOD the cold soak has the wall a little more the  nippy.  In a GA plane the cold soak is even more evident. 
 
In short you are comparing apples (9000 feet) and oranges (Flight Levels) for heater capability.

 

Yup, neve left Maryland with the Mooney... hoping to expand our horizons soon. I left the pattern just last week!  Even so, I have taken off (albeit rarely) when the temps are single digits at my 701ft home airport. I’ve only been cold during ground ops. Never worn gloves in the plane after the cabin has warmed (but certainly on ground take off and initial climb). Maybe I was just dressed more appropriately because ground temps were cold so not as big of a delta from start up to cruise. Passengers are a challenge in real cold, less so now that the plane has been so thoroughly insulated.

[kortopates]

On 7/14/2020 at 10:23 PM, MIm20c said:

The rayjay setup on my o-360 does not change the NA efficiency when the manual waste gate is off. The intake air for the turbo comes off the side of the air box, is pressurized, and is piped back in right before the carb intake. When the turbocharged air overpowers the ambient a door closes to force feed the engine. Because it’s TN vs TC the compression ratio / efficiency remains close to the same. Most of my flying lately has been 6-7 gph and the engine doesn’t mind. 
 

I haven’t been above 14k yet but I get an extra 13-15 kts for an extra 2.5-3 gph. My setup is certified for 25k, I’ve always been a little curious what numbers it could put down at that altitude. 

How does your set up work in climb at high power and slower IAS? I ask because of the many C's I see, many are CHT challenged in climb and as we get higher in altitude the thinner air only compounds the problem. I assume you are able to find a high enough MAP to keep you climbing at a good rate without getting too hot? I'd assume that is the biggest operational challenge?

[MIm20c]

3 hours ago, kortopates said:

How does your set up work in climb at high power and slower IAS? I ask because of the many C's I see, many are CHT challenged in climb and as we get higher in altitude the thinner air only compounds the problem. I assume you are able to find a high enough MAP to keep you climbing at a good rate without getting too hot? I'd assume that is the biggest operational challenge?

I most certainly have high cylinder temps if I keep everything full forward. If I come back to 25 squared temps immediately drop to 360 ish and remain healthy for my climb (have not taken it above 14k yet). At that altitude the 25 squared power setting translates to around 65% power according to the stc paperwork. 
 

To answer your question I find the climb rate acceptable at my reduced power setting and the turbo maintains that easily to the mid teens. To be honest going forward with a 1 and 4 year old I’m not sure how much time I’m going to spend up there. I’ll probably just use it in the climbs to get to 8-10k keeping the system exercised. 

[Oscar Avalle]

On 7/14/2020 at 11:23 PM, MIm20c said:

The rayjay setup on my o-360 does not change the NA efficiency when the manual waste gate is off. The intake air for the turbo comes off the side of the air box, is pressurized, and is piped back in right before the carb intake. When the turbocharged air overpowers the ambient a door closes to force feed the engine. Because it’s TN vs TC the compression ratio / efficiency remains close to the same. Most of my flying lately has been 6-7 gph and the engine doesn’t mind. 
 

I haven’t been above 14k yet but I get an extra 13-15 kts for an extra 2.5-3 gph. My setup is certified for 25k, I’ve always been a little curious what numbers it could put down at that altitude. 

Hi there, I have been looking into the option of installing a turbo on my M20C. It seems you have one installed. I was wondering if you could share with me some information about the installation and of course who has the STC now... Thank you...

[MIm20c]

1 hour ago, Oscar Avalle said:

Hi there, I have been looking into the option of installing a turbo on my M20C. It seems you have one installed. I was wondering if you could share with me some information about the installation and of course who has the STC now... Thank you...

Questions about the stc should be directed to @tomgo2  

I do like the turbo. However, I’m not convinced it’s worth the upgrade cost to add on.  It’d probably add $5k to the value and cost $25k to install.  I’d be looking for a 231 or a C with it already installed.