Turbo guys...question

[KSMooniac]

Jim, I keep the throttle full-forward until setting up for an approach.  I'll run RPM ~2550 or even 2600.  (My tach isn't very accurate)  I too typically cruise 7-9000' unless winds (or ice) dictate otherwise.  As Ken mentioned, at our typical cruise altitudes you're really not going to produce enough power to hurt anything with the red knob of death, so go ahead and keep wading into the LOP pool! 

On your next XC trip, keep everything forward from takeoff to level-off, except lean in the climb to maintain a target EGT on a cylinder of your choosing.  (likely in the 1250-1300 dF range)  As you climb, every 500' or 1000' lean a little to bring the EGT back up to what you saw on takeoff, full-rich.  Once you get to cruise altitude, level-off and wait for the airspeed to build up, then set the prop to whatever you wish and then lean looking at the cylinder of your choosing.  *IF* you can lean to 50 dF LOP (or more) *AND* your engine stays smooth, then as I mentioned above you'll know all of your cylinders are safely LOP.  Now, 50 dF LOP is more LOP (less power) than you need to be to stay out of the red box, but if you can get there smoothly, you kow all the jugs are pretty close together...so go ahead an enrichen a bit and aim for 20-30 LOP if you're at 8000+ altitude.  Once you feel this out, you'll be much more comfortable and then you can do some timed cruise runs on one tank only to establish your fuel burn at that particular power setting like Ken knows for his F. 

That is pretty much my procedure, except I have a FF display that I use to cross-check my leaning, especially if I'm at low altitude.  I still cruise WOT even down low, but lean more to stay out of the red box if at 3,000 or 4,000.  In the summer I typically have to lean a bit further to keep the CHT's below 380 too.

The benefits are tremendous as we've enumerated many times...the only knock is a slightly slower cruise speed for our NA birds, but the efficiency gains more than make up for it IMO.  I'm still lusting after a TN kit for my bird so I can cruise at 85% power LOP continuously, especially in the teens, and really boogie!  185 KTAS on 11.5 GPH at 17,000 ft is where I want to be....someday!

[KLRDMD]

&n

Quote: JimR

[jlunseth]

Two thoughts, and maybe these concerns don't work the same in a normally aspirated as in a 231, but how is fuel flow alone going to equate to a specific HP?  It may do that LOP, but not ROP.  ROP you are intentionally leaving fuel unburned and using it to cool the engine.  At least a higher percentage of fuel unburned than LOP.  So it seems to me that as all our POH's seem to tell us, FF is just one factor in determining HP when ROP.   My 75% HP fuel flow is a little less than 14 when ROP, but my full throttle fuel flow is about 24, so this is plainly not a linear equation.  (I should add that "full throttle" in my 231 is not firewall throttle, not at MSL, it is about 36 or 37 with more throttle available as the plane climbs until critical altitude.  "Full throttle" is the throttle setting that develops the rated HP of the engine.) 

Second, I have tried the cruise climb and leaning during the climb, but have found it better to climb at full throttle, 2700 and full rich.  I am typically climbing to the mid-teens.  I am able to maintain full horsepower for the climb and the engine stays cool.  I pitch for about 120.  Works good.  But I have the turbo so am not losing air pressure as I go up.  I tried the cruise climb method, also climbing at 120 but with a cruise throttle setting of say 31 or 32", and leaning as I go, but the engine can get pretty warm that way.  Full throttle gets me up to cruising altitude faster and the plane seems to like to do it this way.

Leaning while climbing does seem to work in the normally aspirated Warriors, Archers, and the 201 I sometimes fly.

[seebruce]

What your saying seems to be reasonable. Here is the fuel flow vs.power chart I tried to attach earlier. If I'm understanding it correctly the best power curve is approximate and the minimum fuel is specific. Looks like the differance at 75% is about 2 gals. Note that the limitations for running in this range are quite high.

[danb35]

Quote: jlunseth

Two thoughts, and maybe these concerns don't work the same in a normally aspirated as in a 231, but how is fuel flow alone going to equate to a specific HP?  It may do that LOP, but not ROP.

[jlunseth]

Yes, I agree, some of it was, but there was a mention that the JPI algorithm for deteriming HP was based on FF alone, and I don't think that would be the case since FF does not alone determine %HP when ROP.  Of course, it is JPI's algorithm and they aren't saying, so who knows. 

[Awful_Charlie]

There is a spreadsheet for calculating HP and FF available from http://www.egtrends.com/LOPFFvsHP.xls

I'm not sure how accurate it is, but it is in the right ballpark

[KSMooniac]

jlunseth, the leaning-in-the-climb technique is for normally-aspirated planes only!  Since your turbo can maintain MP through the climb, there is no need to lean the mixture to compensate for less air...leave everything at your takeoff setting until leveling-off for cruise. 

Jim, I forgot to mention that you can descend from LOP cruise without changing the power setting....simply trim nose-down for descent and don't change anything until you really need to slow down for the approach/pattern, and then just pull back the throttle.  You will stay safely LOP (and in fact go further LOP) in the descent.  We have plenty of "headroom" in the green arc to nose over and descend at full-throttle/LOP settings without getting into the yellow, unless you do something like 1500-2000 FPM.

[CoachTom]

This has been a lively discussion!!!

Could I get any type of consensus from this august body regards power settings as well as procedures for an intercooled; Merlyn waste gate on a -LB 1 engine?

The 262 power curves are different as they are lower apparently in output as the Turbo Plus curves are more related to the actual efficiency of the coil or the "delta-T" across the coil. Hence the apparent fluctuation from aircraft to aircraft.

I was hoping to get to a good baseline of settings for climb, cruise (65%), and descent.

 

Thanks in advance to all,

Tom

 

 

[KSMooniac]

Tom, I'm strong believer in the Church of LOP as I think it is the cleanest, coolest, and most efficient way to run our engines.  If I had a 231/262 or TN-201 (my dream) I would do everything I could to run it LOP.  If you haven't already, try the GAMI Lean Test (http://www.gami.com/gamijectors/leantest.php) to see if *your* -LB will run LOP.  If you have a fuel flow gauge, then you can simply set power by fuel flow once you get comfortable with LOP OPs.  I think the multiplier for that engine is 13.7, so 75% power LOP would be 11.5 GPH at whatever MP and RPM you choose.

[KLRDMD]

Quote: JimR

[seebruce]

I beleive that if you use the best econimy fuel flow on your power setting chart it gives you your LOP HP.

[fantom]

At about 30 dF LOP, 9,000 ft., I can't stand the 5 to 7 kt. drop off.

[KLRDMD]

Quote: fantom

At about 30 dF LOP, 9,000 ft., I can't stand the 5 to 7 kt. drop off.

[fantom]

Quote: KLRDMD

Simple, get a turbo.

That was one reason I didn't consider normally aspirated airplanes, the turbo allows you to get back manifold pressure lost by going LOP at almost any altitude.

[Jake]

Anyone out there know good sources to purchase a Mooney.  I have owned 3 Mooneys and would like to upgrade to an Ovation or Bravo.  Always looking for best value, price etc.

[Jake]

Anyone out there know good sources to purchase a Mooney.  I have owned 3 Mooneys and would like to upgrade to an Ovation or Bravo.  Always looking for best value, price etc.

[Buster1]

Controller.com, ASO.com, Trade a Plane.com, Lasar, willmar.

[randypugh]

jake, pm me, I have some info 

[jlunseth]

Update.

I have had my plane back from Willmar for awhile, with the EDM 930 in it.  They also cleaned the Intercooler at my request.  I have noticed that the temp. drop with the newly cleaned Intercooler (Turboplus) is quite a bit better than what I was getting.  Up in the teens and low 20's I have seen temp drops in the 80's (Centigrade) and on one trip over 100 C.  That has to really help the engine.  However, I have also found that when I tried to fly the plane over FL200, the Intercooler is not much help.  It certainly results in a high temperature drop from CDT to IAT, but the temperature problem I have experienced is a high CDT, which the intercooler does not help with (it is downstream of the compressor). 

I have to say that under FL200, the combination of good baffling and the intercooler appears to me to make the engine much stabler from a temperature standpoint. 

Have not conquered LOP yet though.  The engine runs a little rough at 70 degrees LOP.  I don't think it will run LOP at the higher altitudes at all.  It may be that tweaking the GAMI's will help a little, my two rear cylinders run hotter than the other four.

Going to Ada in October.

[N9937c]

However, I have also found that when I tried to fly the plane over FL200, the Intercooler is not much help.  It certainly results in a high temperature drop from CDT to IAT, but the temperature problem I have experienced is a high CDT, which the intercooler does not help with (it is downstream of the compressor). 

 

The intercooler IS dropping the cdt temp by the value on the readout. Flip the switch on the intercooler guage to in ( should be the same as cdt) flip switch to out and record value. Put back to middle position for differential.  The intercooler would do nothing in front of the turbo.

larry

[jlunseth]

Semantics I think.  In a system without an intercooler CDT is the same as IAT (induction air temperature), that is, the temperature of the air coming out of the compressor section of the turbo is the same temperature as the air going into the induction section of the engine.  But in my engine, which has in intercooler, there is both a CDT and an IAT probe and readout.  The CDT is the temperature of the air coming out of the compressor section of the turbo.  It is an indication of the health of the turbo, i.e. if the turbo is running too hot.  A CDT over redline is an indication of just exactly that, that the turbo is running too hot for its own good.  The intercooler will not help that, it only cools the air after it leaves the turbo, i.e. it reduces the IAT.  That is good for the cylinders, they are not receiving an super hot induction mixture, but it still doesn't help the turbo which is running too hot. 

[N9937c]

If memeory serves me the Redline cdt is the max temperature for the tsio 360.

[jlunseth]

Yes, you are correct, the POH specifies a max or redline CDT, which is 280.  Its still an interesting question though, what the purpose of the CDT redline is in the POH, because the after market intercooler changes things a little.  If the purpose of the CDT redline is to protect the turbosupercharger from overheating, then the addition of the intercooler to the engine changes nothing.  The intercooler has no effect on what temp. the turbo runs at.  But if the purpose of the redline CDT in the 231 POH is to prevent a situation where the cylinders are jeopardized because they are being fed an induction mixture that is too hot, or there is a possibility of the induction mixture self igniting outside the cylinder, then the intercooler does make a difference.  It would be possible to run at a CDT higher than the POH redline without jeopardizing the engine, provided the IAT remains low. 

In my engine, I have seen differences between the CDT and the IAT of as much as 180 F. 

This is just a question, I am not providing any answers or advice.  Part of the reason why I am going to Ada to see what I can learn. 

[N9937c]

Am interested in what you find out. Most my trips are low to mid teens so dont see the high temps as would be 20k up.

thanks

larry