FlyWalt Posted July 2, 2017 Report Share Posted July 2, 2017 (edited) Hi guys, It has been a while since I posted. One thing I love about this forum is I come back for an engine issue and find myself considering doing a full interior replacement due to the posting on PP price reduction. This place is not good for my checkbook :-) Anyway, we have something that going on with our motor. During that last annual in January, the prop governor was sent out for repair. There was an AD on it. I have put about 30 hours on it since. And it does not seem to be overly responsive to power changes. Prop speed correction seems to lag a good bit. Another issue that may be related is that MP does not hold steady. I cruise at 31/2500 with mixture at 50 degrees ROP. I have to constantly correct MP to keep it near 31. It seems to want to vary as much as 1 inch either way. I am wondering if I have a loose induction hose in the fuel system or couplings in the turbo system. Perhaps even worse, I problem with the turbo. We have all of 130 hours SMOH. Thank you in advance for your wisdom. W Edited July 2, 2017 by FlyWalt Added humor Quote Link to comment Share on other sites More sharing options...
Yetti Posted July 2, 2017 Report Share Posted July 2, 2017 Lever/knob friction lock? Quote Link to comment Share on other sites More sharing options...
FlyWalt Posted July 2, 2017 Author Report Share Posted July 2, 2017 It is definately tight. Quote Link to comment Share on other sites More sharing options...
jlunseth Posted July 2, 2017 Report Share Posted July 2, 2017 Does the engine have a Merlyn wastegate controller or not? If it has a Merlyn, that is the place to look for the MP variance. If it does not, I am not much help but I have a pure guess. The non-Merlyn engines are known for bootstrapping. That is a process where the turbo and the engine itself, change each others operating parameters. When the engine puts out more power, it also puts out more exhaust, which drives the turbo harder, which spins harder and puts out more MP. Then they try to settle down into a medium, but it is not perfect. I have always gotten small changes in my engine (360LB), it is not a perfectly stable system even with the Merlyn. 1" is probably too much though. As for the prop controller, that sounds as though the prop controller was not properly repaired. I would let the A&P know right away. They usually have a shop warranty for repairs, but it is always usually short, like 90 days. Quote Link to comment Share on other sites More sharing options...
cliffy Posted July 2, 2017 Report Share Posted July 2, 2017 The two issues may be concomitant IMO. If the RPM is moving the flow through the turbo is moving thus a change in MP. Get the gov fixed first and the MP issue might resolve it self. Quote Link to comment Share on other sites More sharing options...
FlyWalt Posted July 2, 2017 Author Report Share Posted July 2, 2017 It is not a merlyn wastegate. I tend to agree with you Cliffy. The prop governor is way too unresponsive at certain points to be operating correctly. Quote Link to comment Share on other sites More sharing options...
KLRDMD Posted July 2, 2017 Report Share Posted July 2, 2017 5 hours ago, FlyWalt said: I cruise at 31/2500 with mixture at 50 degrees ROP. Probably not related to this issue but you may want to read up on LOP operations. 50º ROP is second only to 40º ROP as the absolute worst place to run your engine. If you insist on ROP, consider at least 100º ROP, but since you have a turbo and won't lose any airspeed by running LOP - why wouldn't you ? 2 Quote Link to comment Share on other sites More sharing options...
FlyWalt Posted July 2, 2017 Author Report Share Posted July 2, 2017 I would need gami injectors to do that safely. However, both IA' at my two Mooney shops have been happy with the numbers on my JPI logs. I can inquire further though. Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted July 2, 2017 Report Share Posted July 2, 2017 You only need GAMI's if your lean spread is to great. Many of our planes already have very well balanced injectors and don't need GAMI's at all. 1 Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 2, 2017 Report Share Posted July 2, 2017 1 hour ago, KLRDMD said: Probably not related to this issue but you may want to read up on LOP operations. 50º ROP is second only to 40º ROP as the absolute worst place to run your engine. If you insist on ROP, consider at least 100º ROP, but since you have a turbo and won't lose any airspeed by running LOP - why wouldn't you ? I don't fly a turbocharged engine so take this for what it's worth, but I would think it would be hard to set LOP while having to constantly adjust the throttle. I would not trust it. Quote Link to comment Share on other sites More sharing options...
KLRDMD Posted July 2, 2017 Report Share Posted July 2, 2017 7 minutes ago, Bartman said: I don't fly a turbocharged engine so take this for what it's worth, but I would think it would be hard to set LOP while having to constantly adjust the throttle. I would not trust it. It is easier than flying a normally aspirated engine. 1 Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted July 2, 2017 Report Share Posted July 2, 2017 2 hours ago, KLRDMD said: It is easier than flying a normally aspirated engine. Ken... What percentage of power are you at when you make the big pull to LOP? I'm starting all over with my 252 with all new instrumentation and wondering what others are doing. Thanks, Quote Link to comment Share on other sites More sharing options...
KLRDMD Posted July 2, 2017 Report Share Posted July 2, 2017 20 minutes ago, gsxrpilot said: Ken... What percentage of power are you at when you make the big pull to LOP? I'm starting all over with my 252 with all new instrumentation and wondering what others are doing. Anything at or below 65% power is fine on the TSIO-360 series engines. It goes faster at 75% power but you'll be doing at least one and probably two top overhauls before TBO. 65% power = 10.0 GPH, 62% power = 9.5 GPH and 59% power is 9.0 GPH. I fly 9.0 GPH since the true airspeed increase as a percentage increase is 50% of what the fuel flow increase is as a percentage based on starting at 9 GPH, as follows: At 10,000 ft I get: 9.0 GPH - 160 KTAS 9.5 GPH - 165 KTAS (3% increase in airspeed for a 5.5% increase in fuel flow) 10.0 GPH - 170 KTAS (6% increase in airspeed for an 11% increase in fuel flow from 9.0 GPH) Add 2 KTAS for every 1,000 ft in altitude above 10,000 ft, on the same fuel flow. Ain't turbocharging and LOP operations great ? 3 Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted July 2, 2017 Report Share Posted July 2, 2017 Thanks! Quote Link to comment Share on other sites More sharing options...
Parker_Woodruff Posted July 3, 2017 Report Share Posted July 3, 2017 Paul, I was able to run higher power settings safely LOP when I got the Tempest Fine Wire spark plugs. I ended up finding a happy home at 11.2 - 11.6 GPH LOP when I was in a hurry to be somewhere. Ken's numbers work in any TSIO-360 and are a great rule of thumb for that engine. Towards the latter part of my M20K ownership I really had that engine dialed in and happy. One cylinder (#2, IIRC) was always the hot one and never quite settled in as well as the others. That one was started losing ground on the compressions. my speeds were comparable to KLRDMD's mine would get 174 KTAS no problem at 11.5 GPH at 10K. same fuel flow would get me 183-185 KTAS at 15,000 2 Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted July 3, 2017 Report Share Posted July 3, 2017 Thanks @Parker_Woodruff, I'm gonna try this out on the way home in a couple of weeks. Quote Link to comment Share on other sites More sharing options...
milotron Posted July 3, 2017 Report Share Posted July 3, 2017 7 hours ago, KLRDMD said: Anything at or below 65% power is fine on the TSIO-360 series engines. It goes faster at 75% power but you'll be doing at least one and probably two top overhauls before TBO. 65% power = 10.0 GPH, 62% power = 9.5 GPH and 59% power is 9.0 GPH. I fly 9.0 GPH since the true airspeed increase as a percentage increase is 50% of what the fuel flow increase is as a percentage based on starting at 9 GPH, as follows: At 10,000 ft I get: 9.0 GPH - 160 KTAS 9.5 GPH - 165 KTAS (3% increase in airspeed for a 5.5% increase in fuel flow) 10.0 GPH - 170 KTAS (6% increase in airspeed for an 11% increase in fuel flow from 9.0 GPH) Add 2 KTAS for every 1,000 ft in altitude above 10,000 ft, on the same fuel flow. Ain't turbocharging and LOP operations great ? Very helpful. Have you found a preferred rpm/MP combination for this? My 262 modded 231 performs similar to this and I tend to run LOP in the 9-9.5 GPH range most of the time. According to the POH fuel flow for a given %HP varies with RPM, such that lower RPM for the same HP give greater range. The endurance charts support this too. Any empirical evidence showing this too? 2200 RPM LOP vs 2400 RPM LOP at a given HP? Quote Link to comment Share on other sites More sharing options...
milotron Posted July 3, 2017 Report Share Posted July 3, 2017 1 hour ago, Parker_Woodruff said: Paul, I was able to run higher power settings safely LOP when I got the Tempest Fine Wire spark plugs. I ended up finding a happy home at 11.2 - 11.6 GPH LOP when I was in a hurry to be somewhere. Ken's numbers work in any TSIO-360 and are a great rule of thumb for that engine. Towards the latter part of my M20K ownership I really had that engine dialed in and happy. One cylinder (#2, IIRC) was always the hot one and never quite settled in as well as the others. That one was started losing ground on the compressions. my speeds were comparable to KLRDMD's mine would get 174 KTAS no problem at 11.5 GPH at 10K. same fuel flow would get me 183-185 KTAS at 15,000 +1 for the fine wires. They helped LOP at altitude for me. Quote Link to comment Share on other sites More sharing options...
KLRDMD Posted July 3, 2017 Report Share Posted July 3, 2017 Just now, milotron said: Have you found a preferred rpm/MP combination for this? My 262 modded 231 performs similar to this and I tend to run LOP in the 9-9.5 GPH range most of the time. According to the POH fuel flow for a given %HP varies with RPM, such that lower RPM for the same HP give greater range. The endurance charts support this too. Any empirical evidence showing this too? 2200 RPM LOP vs 2400 RPM LOP at a given HP? LOP, only fuel flow matters. Pick anything you want as long as you're LOP and hit the fuel flow numbers. Personally, I fly at 30" MP and 2500 RPM. 1 Quote Link to comment Share on other sites More sharing options...
exM20K Posted July 3, 2017 Report Share Posted July 3, 2017 Jlunseth probably has it right WRT bootstrapping. A few knots of IAS will do this to MP. I'd be very conscious of CDT in the 231 running high MP especially at high altitudes. Quote Link to comment Share on other sites More sharing options...
FlyWalt Posted August 3, 2017 Author Report Share Posted August 3, 2017 Issue has supposedly been resolved. A 40 year old prop governor that had been "repaired" in January 2017, was the cause. It has been replaced with an "Overhauled Unit".I am picking her up tomorrow. Thank you again for all the input, W Quote Link to comment Share on other sites More sharing options...
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