Turbo Saratoga Engine Management

jdfrey1

jdfrey1

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Jeff Frey
I just purchased a 1981 Turbo Saratoga (PA32R-301T). This is the first plane with a turbo-charged engine that I've owned and I wanted to get some thoughts on the best way to manage this engine. I know what the POH says but I'm looking for what people recommend for all phases of flight to manage MAP, RPM, CHT, EGT & TIT. Is lean of peak even an option or advisable in this engine? I have a JPI 830 which seems like it will be an invaluable tool to help me optimize my performance.

My goal is to find the balancing point between speed, fuel efficiency and engine life. Any recommendations would be greatly appreciated!
 
Congrats!!

I bought a 1980 Toga (PA32R-301T) last Sept. and I have been trying to come up with the same thing for my plane.

I thought I was doing well by running ROP and not going over 380 CHT but after reading a few articles from John Deakin's, I do not know what to think.
 
Ron Levy said:
Go to AvWeb and read John Deakin's articles on engine management, starting here:
http://www.avweb.com/news/pelican/P...fold-Pressure-Sucks182081-1.html?redirected=1
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I've read his articles over and over. I wish more people listened to what he has to say.

Scott@KTYR said:
Congrats!!

I bought a 1980 Toga (PA32R-301T) last Sept. and I have been trying to come up with the same thing for my plane.

I thought I was doing well by running ROP and not going over 380 CHT but after reading a few articles from John Deakin's, I do not know what to think.
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Until you understand them completely, run what the POH says.

I know how to manage a normally aspirated engine, but would not mess with a turbocharged version at this point in time.
 
Do you have an intercooler? I cannot say definitively, but I gave been told that without an intercooler, you'll be hard pressed running it LOP. My dad has a 79 Turbo Lance II and runs his per the POH. It runs hot.
 
Fearless Tower said:
Do you have an intercooler? I cannot say definitively, but I gave been told that without an intercooler, you'll be hard pressed running it LOP. My dad has a 79 Turbo Lance II and runs his per the POH. It runs hot.
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No intercooler (yet). It would be nice to upgrade to that at some point and also get rid of the fishmouth scoop at the same time.
 
Absent an Intercooler AND balanced injectors, running LOP is going to save a few bucks an hour of fuel and make your mechanic rich to the tune of thousands for changing fried cylinders.
Yes, read Deakins
And, read about Gamijectors

Let me second the post about following the POH until you know a whole lot more :D
 
jdfrey1 said:
No intercooler (yet). It would be nice to upgrade to that at some point and also get rid of the fishmouth scoop at the same time.
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Jeff,

Yesterday I checked and the LoPresti cowling and intercooler for our planes sells for $14995.00. They estimate 60 hours to install plus paint. I guess it will end up costing when complete around $25000.00
 
Dr. O said:
Absent an Intercooler AND balanced injectors, running LOP is going to save a few bucks an hour of fuel and make your mechanic rich to the tune of thousands for changing fried cylinders.
Yes, read Deakins
And, read about Gamijectors

Let me second the post about following the POH until you know a whole lot more :D
Click to expand...

I'll second the note on balanced injectors.

As others have said, don't try LOP until you are comfortable with your knowledge of what is going on with your engine.

In the mean time, learn to include MP, TIT, and fuel flow in your scan. Also include fuel flow in your "engine green" call on take-off roll. I've also learned to call mixture and prop full when turning onto the centerline for take-off.

...and keep reading Deakin...
 
Doesn't running LOP result in lower CHTs? Why would it fry the cylinders? Just trying to learn here.
 
dans2992 said:
Doesn't running LOP result in lower CHTs? Why would it fry the cylinders? Just trying to learn here.
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It won't fry valves or cylinders in a normally aspirated engine.

Don't transfer that to turbocharged engines. I don't know enough about them to give any sort of information.
 
The real issue with running LOP is running LOP above the limitation for operating at peak EGT (65% for Continentals, 75% for Lycomings.) You can do it, but you have to have very even fuel flows and very good instrumentation. At or below, no issues whatsoever, and it doesn't require a Deakinistic approach.
 
Sac Arrow said:
The real issue with running LOP is running LOP above the limitation for operating at peak EGT (65% for Continentals, 75% for Lycomings.) You can do it, but you have to have very even fuel flows and very good instrumentation. At or below, no issues whatsoever, and it doesn't require a Deakinistic approach.
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What would you be watching for on the instrumentation in this case?
 
Sac Arrow said:
Individual CHT's, EGT/TIT's, you would have to read the cited article to know what you're looking for.
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I've read the article(s). So, if you keep the CHT's at a reasonable level (i.e. under 380-400), and keep the TIT within limits, is it still possible to harm the engine?
 
dans2992 said:
I've read the article(s). So, if you keep the CHT's at a reasonable level (i.e. under 380-400), and keep the TIT within limits, is it still possible to harm the engine?
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Well, yeah, it's a little more complicated than that. The detonation box is a function of how close you are to peak EGT/TIT and power. So if you are at a high power setting, you need to run either sufficiently rich of peak, or sufficiently lean of peak so that detonation does not occur. Same as with burning cylinders. So if you keep CHT, EGT/TIT within limits and LOP numbers correct, you shouldn't damage your engine, in theory anyway.

But I personally would still do full rich climbouts per POH then worry about running LOP once I've backed down to a safe power setting at cruise. Can't go wrong there.
 
Yep. That's what I do now. Haven't dealt with a turbo though..

The rule of thumb as I understand it is that as long as your power is below 75%, you can't really hurt anything by leaning. I would assume this is the same for a turbocharged engine as long as the temps are reasonable....
 
dans2992 said:
Yep. That's what I do now. Haven't dealt with a turbo though..

The rule of thumb as I understand it is that as long as your power is below 75%, you can't really hurt anything by leaning. I would assume this is the same for a turbocharged engine as long as the temps are reasonable....
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It's the same - the people that burn up turbocharged engines prematurely do so not necessarily because of their leaning procedures, rather the fact that they can run their engines at 75%+ power settings at 10,000 feet, and do. If you regularly push an engine at 80% power for 300 NM at a stretch, it's not going to last very long, regardless of how you lean it.
 
Sac Arrow said:
It's the same - the people that burn up turbocharged engines prematurely do so not necessarily because of their leaning procedures, rather the fact that they can run their engines at 75%+ power settings at 10,000 feet, and do. If you regularly push an engine at 80% power for 300 NM at a stretch, it's not going to last very long, regardless of how you lean it.
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Gotcha. In addition to the maintenance issues, I would think that the fuel flows required at 80% power would be a strong dis-incentive to run an engine like this.

So, would you advise to run a turbocharged engine no more than 65% power or so in cruise?
 
dans2992 said:
Gotcha. In addition to the maintenance issues, I would think that the fuel flows required at 80% power would be a strong dis-incentive to run an engine like this.

So, would you advise to run a turbocharged engine no more than 65% power or so in cruise?
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75% is a normal cruise power limit, but I personally don't run past 65% in cruise, turbo or not.

Unless it's a rental.
 
I've been spending a lot of time at different power configurations and I've captured the data from my JPI 830. Would anyone be interested in reviewing my data and observations and providing me some feedback?
 
Ron Levy said:
Go to AvWeb and read John Deakin's articles on engine management, starting here:
http://www.avweb.com/news/pelican/P...fold-Pressure-Sucks182081-1.html?redirected=1
Click to expand...

:yeahthat::yeahthat:

I presume you have TIT - lean to it. I flew my Turbo Viking to 1550 or so TIT average for both sides. Engine loved it. Of course I was normalized - so ymmv. Literally.

The controlling temp in the first instance is TIT, then CHT - since EGT will in almost every situation be lower than TIT.

Also - most motors have max sustained power settings - obey that religiously.

In my case the Turbo Vik with the IO-540K1-E5 it was 27" and 2400rpm - just under 80%. I ran mine right close to 70% sustained at 26" and 2200rpm - the lower rpm was smoother and cooler. You can do 75% or even max sustained but your temps in a well-monitored engine are going to real close to limits by your max sustained limits - and you do that all the time and sooner or later something is gonna break.

Most Turbo Contis require the injector balancing magic whereas many if not most Turbo Lycs can be fixed up with the poor mans injector magic - switch hottest and coolest cylinders - fly it - do that again - fly it and then do it again - and its pretty much set to operate LOP. Just remember that LOP you will slow down - unless you restore the lost power with MP - to your engine limits.

In my case I was up against the MP limits and if I wanted to operate LOP I needed to increase my RPM to recapture some of the engine power [recall I operating at 26"/2200 with max sustained of 27" and 2400]. Which changes the LOP equation again . . . .
 
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I have read John Deakin's articles but need to re-read now that I have some practical experience. I really haven't been paying too much attention to TIT as it really hasn't gotten too high on me. I did struggle with CHTs today when I got greedy. I'm targeting keeping the hottest cylinders around 380-390 with 400 being my top end where I make an adjustment. Multiple times today I tried leaning just a bit and watched the temps creep back up. Next flight I'll try focusing more on TIT though and leaning to it to see the results.
 
TIT is dependent also on where the probes are - remember - you still need to keep your CHT as cool as you can - which means if LOP works for you - it will help on that side- just keep in mind that LOP requires alot more monitoring of engine performance and health - its not a set it and leave it alone proposition . . .

The nice thing about turbos is that even in the descent you can set your MP and fuel flow will stay the same so there is no real big work load on descent until you configure for landing . ..
 
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