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 Post subject: Piper Saratoga Lean of Peak operations
PostPosted: Mon Jan 03, 2011 12:04 pm 
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qbreland - FlightAware user avatar

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I have gotten multiple conflicting opinions/reports on this topic, so I'll throw it out to the board. Is it safe/wise/risky/etc to run a 1993 Piper Saratoga's 300hp Lycoming lean of peak? I only have one CHT gauge and an EGT gauge.

What fuel burn are others getting at altitude?


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 Post subject: Re: Piper Saratoga Lean of Peak operations
PostPosted: Mon Jan 03, 2011 3:40 pm 
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qbreland wrote:
I have gotten multiple conflicting opinions/reports on this topic, so I'll throw it out to the board. Is it safe/wise/risky/etc to run a 1993 Piper Saratoga's 300hp Lycoming lean of peak? I only have one CHT gauge and an EGT gauge.

What fuel burn are others getting at altitude?


Although I have zero experience with a Saratoga, the common wisdom I have usually heard on LOP operations is to only do so if you have a an engine anaylzer that shows CHTs for all cylinders. That way you don't chance burning out one cylinder that is running a little leaner than the one you have a CHT for.


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PostPosted: Mon Jan 03, 2011 8:10 pm 
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Do not run the TIO-540 Lean of Peak. If you want it to last run it 150 degrees Rich of peak.
what ever you do STAGE COOL, STAGE COOL, STAGE COOL.


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 Post subject:
PostPosted: Mon Jan 03, 2011 8:38 pm 
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If you install GAMI injectors & a 6 point egt/cht monitor; then it is okay, only when pulling less than 70-65% power.

The folks at GAMI have a lot of research on this and really know their stuff.
Most all the old propliners ran lean of peak in cruise (AT LOW POWER)

If you want power; then you need to burn something... & I highly suggest it be fuel and not your pistons and cylinders.

High RPM, High Temps & High cylinder pressure is what kills and engine. Keep them low and it will last longer.


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 Post subject:
PostPosted: Tue Jan 04, 2011 12:46 am 
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My $0.02 fuel is cheaper than cylinders,

I've always run rich of peak. more gas running through will keep it cooler, lessening the risk of burning a valve or head etc.


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 Post subject:
PostPosted: Tue Jan 04, 2011 2:51 am 
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The general consensus reached on another forum was not to run LOP on turbocharged engines, over 75% power and be fully equipped i.e. full CHT and EGT gauges with sensors on each cylinder. That was not engine specific, just in general. Some of the higher time pilots said they would not run lean over 65% power and a few brought up specific engines they would not do it on, though I don't remember which ones. The thread was interesting to read but since my present ride does not have a mixture control I admit I did not pay more attention to it.


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 Post subject:
PostPosted: Tue Jan 04, 2011 11:19 am 
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At AMF (Ameriflight) they are able to extend the TBO on the TIO-520 by 750 hours because they train all their pilots to lean 150 degrees rich of peak and to stage cool 2" of MP every 2min.
that extension comes from the manufacturer. I'm still a baby when it come to experience in the High Performance piston airplanes- I only have about 3,500 hours in them but I know that you don't run hot.


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 Post subject:
PostPosted: Tue Jan 04, 2011 11:59 am 
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Stage cooling for sure has a lot to do with longevity. I'm not so sure that leaning 150 ROP is that much better than 50 ROP though. On a high compression engine, or TC'd like the Navajo I would never go LOP.


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 Post subject:
PostPosted: Sun Jan 09, 2011 8:53 am 
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N117SE - FlightAware user avatar

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I would be leary of pushing temps with only one CHT reading. My Saratoga has CHT sensors on all cylinders. The temp varies from 400 (mfgr recommended max for long term operation) on cyl 2 to a low of 324 on three other cylinders. A single temp sensor on the lowest temp cylinder could result in a possible 470+ temp on the hottest cylinder. This condition is less than the 500 degree short term max temp, but well in excess of the mfgr desired long term max.

Regarding lean of peak vs rich of peak - my mechanic says that lean of peak operations improves his business sufficiently that he too can afford to fly! Many writings have been provided on this website regarding LOP vs ROP, check them out, but look to the manufacturer for sure-fire advice.


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 Post subject:
PostPosted: Mon Jan 10, 2011 12:31 am 
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porterjet wrote:
...but since my present ride does not have a mixture control...

Let's just say its runs REEEAALL rich. 8)


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 Post subject:
PostPosted: Mon Jan 10, 2011 10:37 am 
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N117SE - FlightAware user avatar

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I found that if I ran extremely rich, such as when I first got the plane, I would get a lot of plug fouling.

My instrument instructor then helped me with the math to show that running a reasonable ROP rather than extremely rich saved enough money to pay for an engine overhaul. Briefly, let's say you burn 3 gal/hr more than necessary to run overrich to keep the engine cool. At roughly $4.50 to $5./gallon over a 2,000 hour engine life yeilded a cost of $27 to $30K which is about what the rebuild cost is for the TIO 540. His point was don't burn the extra avgas when you save nothing on an engine rebuild. In short, if the manufacturer gives you a fuel burn rate of 16 gpm and you burn at 19 gpm under similar load conditions, you are wasting money.

Here are the assumptions; Lycombing recoomeds TBO at 2,000 hours, Continental is different at 1,700 hours. That the rebuild cost is a standard rebuild and doesn't include excessive damage or turbo rebuild cost. That fuel stays at $4.5 to $5/gal over the 2,000 hours, that the 16 gpm provides you with the mfgr recommended chts and tits, etc.

Lastly: no mixture control on your plane???


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 Post subject:
PostPosted: Mon Jan 10, 2011 10:58 am 
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N117SE wrote:
Lastly: no mixture control on your plane???

He drives a jet. :D


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 Post subject:
PostPosted: Mon Jan 10, 2011 11:15 am 
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It comes equipped with an automatic mixture control. :roll:


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 Post subject:
PostPosted: Mon Jan 10, 2011 12:30 pm 
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porterjet wrote:
It comes equipped with an automatic mixture control. :roll:


Especially down low. Extra, extra, extra rich. At least in terms of money being spent!


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 Post subject:
PostPosted: Mon Jan 10, 2011 1:22 pm 
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nah, it only burns a bit over 1000 Gallons per hour/per engine at takeoff power.


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 Post subject:
PostPosted: Mon Jan 10, 2011 2:55 pm 
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N117SE - FlightAware user avatar

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Well, forget my discussion of LOP vs ROP if your flying a jet. I thought we were talking about another plane.


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 Post subject:
PostPosted: Mon Jan 10, 2011 3:15 pm 
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Sorry.
Thread creep.


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 Post subject:
PostPosted: Mon Jan 10, 2011 3:26 pm 
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mduell - FlightAware user avatar

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N117SE wrote:
Well, forget my discussion of LOP vs ROP if your flying a jet. I thought we were talking about another plane.


Jets run lean.


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 Post subject:
PostPosted: Mon Jan 10, 2011 3:40 pm 
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Maybe your jet runs lean..... :)


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 Post subject:
PostPosted: Sun Jan 30, 2011 6:31 am 
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9452m - FlightAware user avatar

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GAMI and JPI. I've been running the IO-520 lean of peak as long as I've owned it. Did the flight test program with GAMI staff, which previous owner never bothered to complete. Best time ever spent as "GAMI spread" now near zero. GAMI staffers very helpful.

You guys that think rich is saving engine parts just haven't seen enough data.

Don't try this at high power, low altitude or without the right 6 cyl. data, but if you want less wear, lower fuel bills and are willing to learn, go to GAMI's website and read about BMEP and how the airliners of the 1950's did it before the jet age. BMEP was "state of the art" at the time. May I be so bold as to suggest your piston engine is 1950 technology, so use the concepts that were developed with it.


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 Post subject:
PostPosted: Tue Feb 22, 2011 10:57 am 
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rgtoga - FlightAware user avatar

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All the data about LOP does not include running your turbo charger at almost red line. The LOP operational information I have seen shows the TIT running at 1600. Heat kills, so when you are constantly running you turbo charger that hard, it will cost you an overhauled turbo charger sooner than later. What point is it if you are saving a few dollars a gallon up front, but paying that money out on an engine and turbo charger overhaul. A non turbo charged, maybe I can see it, but there are too many bad things that could bite you doing it with a turbo charged engine. How many times have you seen a pilot try to save a few dollars by skimping, only to pay a price with their life, along with their passengers too.


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 Post subject:
PostPosted: Tue Feb 22, 2011 1:35 pm 
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rgtoga wrote:
All the data about LOP does not include running your turbo charger at almost red line. The LOP operational information I have seen shows the TIT running at 1600.


1600 is a normal TIT for ROP or LOP operations. If you've ever flown a Navajo or 400 series Cessna at night you see the turbo glowing through the cowling louvers.

In 20 years all Turbo damage I've seen has been a result of shaft bearing problems from impatient idiots that don't let the engine idle long enough before shut down. Most people think of this as the "cool down" when the engine actually gets warmer due to a lack of cooling air flowing over the engine. It is actually time to let the turbo spin down to a low enough RPM that it will come to a stop before the bearings go dry when the oil pressure disappears.

The TIT is a product of egt and exhaust gas pressure. All of which run lower with proper LOP operations. With proper LOP operations internal cylinder pressures are lower, temps are lower, fuel consumption is lower, engine wear is lower, speeds are lower, performance is lower.

No mater how much fuel you put through it, if you ask for 100% you'll get it for awhile. If you ask for 75% you'll get it for a reasonable amount of time & if you ask for 60% and loaf it, it will last longer.


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 Post subject:
PostPosted: Tue Mar 01, 2011 10:52 pm 
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rsingh - FlightAware user avatar

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After landing, how long do you folks let engine cool down or what is a safe temperature to allow for shut down.
Can't seem to find a definitive answer.


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 Post subject: cool down
PostPosted: Wed Mar 02, 2011 12:38 am 
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rgtoga - FlightAware user avatar

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The cool down is not so much for the oil temp as it is for the turbo charger temp to stabilize. Give it a 3 minute cool down for the temps in the turbo to stabilize (it is about the metals, turbine, bearings, etc). If you have a low power long taxi, you can factor the time in. A decent cool down is good for the engine too.


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 Post subject:
PostPosted: Wed Mar 02, 2011 9:01 pm 
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rsingh wrote:
After landing, how long do you folks let engine cool down or what is a safe temperature to allow for shut down.
Can't seem to find a definitive answer.


TCM says 5 Minutes from closing the throttle to idle before shut down. This would be good for a Lyc as well. Keep in mind this is for the turbo, not the rest of the engine. As i stated previously temps might increase at idle on the ground. Remember to taxi with minimum power, pushing them up over 1500-2000 is not only poor pilotage but it spools the turbo back up and you've lost some of your pre-shutdown stabilization.


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