Jim F

Agreed jlunseth, I have my JPI830 on the Pilot side right above the throttle quadrant. It is easy to keep the 830 in my scan. As Kortopates teaches, on my take off roll my scan is all JPI data in the green, and again mid takeoff roll ~63MPH when I am checking that I have 50% runway remaining, I scan the 830 before liftoff.

Hi Don, What Paul said. That is why I said full power and not full throttle. With the manual waste gate if I push more throttle, I get more power. The popoff valve (upper-deck over pressure valve) looks like it opens at 43-44in based on the max MAP readings that I have seen in the past and they can stick. I set 37in on the takeoff roll and adjust during my scan during my takeoff roll. I see 38-41in during my climb to altitude. The manual wastegate makes MAP part of the primary scan. The JPI830 is blinking red at any MAP over 40.1in so it gets my attention pretty quick. Jim

Great writeup jlunseth thank you I think I can add to this discussion. I have an 81 231 with a GB, fixed waste gate, no intercooler, and 1961 hours since new. I purchased the AC in 2010 with 1200 hours and it had two cylinders swapped out in that time. In the 761 hours that I have put on it, I replaced one cylinder due to a crack in the exhaust port that started at a void in the aluminum that was the stress pint to start the crack. I have always taken off at full power and climbed to cruise altitude at full power. Full power adds the extra fuel to aid in lowers CHTs in the climb. If you pull back to a cruise climb you will not get the extra fuel added for cooling. Fuel is cheaper then and top overhaul. With in the first year, I installed a JPI830, and I believe that for my AC the 830 is required equipment. It is just too easy to overheat the engine with the single point factory installed instrumentation. Can you keep a GB cool enough to get to TBO, yes. How to do that, well you need a little luck that the previous owner didn't hurt it too bad. If there is an engine analyzer on now grab the historical data. The LBs have a larger opening throttle body and the front intake tubes from the throttle body to Cyl #5 & #6 are a different part number and i believe they have a larger ID. I believe that both larger IDs must be to reduce the restriction is air flow. I reason I say it this way is that I have heard on this forum that LB run cooler, and I have a list of the GB to LB differences, but I have never seen an explanation from continental as to why these changes make the LB run cooler. At overhaul mine will be converted to an LB. I am blessed that I am the A&P/IA for my 231 and I am an engine guy. Back in the day I have overhauled >500 GA engines and maybe 30ish TSIO-360s, I have set >1000 Continental fuel flows. To dos: Engine baffle seals must be tight with NO leaks. All cooling air must go through the cylinder fins. You can have these replaced with new seal material. Fuel flows must be set correctly by a mechanic that in experienced with fuel flows. To set the fuel flows correctly I first ultrasonically clean the fuel injectors to remove the buildup on the metering orifice, once the injectors are reinstalled, I pressurize the intake and exhaust system with the pressure side of a clean shop vac to look for leaks. I spray soapy water to find, and leaks and I fix any leak. Now I set the fuel flows with a reference to SID97-3G low unmetered fuel pressure to at 700rpm to 6.5 +/-.1psi and at full RPM(2700) and max MAP(~40ish) the metered fuel flow of ~26.7gpm and this gives me ~1400df TIT. You can see that the metered max fuel flow I use has the added 1GPM to aid in reducing the CHT in full power takeoff and climb. I first heard about the added 1GPM from kortopates on this forum. This is the best single change that I have made to keep my engine cool at high power. (SID97-3G TSIO-360-G, GB 700 2700 40.0 6.25 - 6.75 45.0 - 49.0 16.7 - 19.3 135 - 145 23.0 - 24.7) I would recommend that you use Savvy to review your engine data. They do a great job giving input as to what areas need to be looked at. Enjoy Jim

Hi T.Peterson, I am in a similar position and am planning an overhaul mid 2025. I have an 81 231 and apparently the only 231 left without a Merlyn or intercooler. I am planning to install a Merlyn wastegate and a Turboplus intercooler before I do the overhaul so that I can do a PIRP on both. My position on the Merlyn is that a higher critical altitude would be helpful and allow me to fly 75% power in the flight levels at 2500RPM. Currently I need to be >2600RPM to get enough MP out of the turbo for 75% power. On the intercooler, my thought process is why did Mooney not put an intercooler on the 231 and why did Mooney add an intercooler to the 252/Encore (I know the engine is TCM). The 231 was a low-cost entry into the turbo market and in general the industry considers the 231 a hot running engine. After market feedback Mooney decided that the addition of an automatic wastegate and intercooler was what customers wanted, and I do think that was a great decision. Everyone with a 252 or Encore raves about their Mooney being the best option for their mission. On our 231s the compressor discharge pressure can get very warm, and that warm air charge can really push the CHTs up in the 400s on hot days with a slow climb. I look at any aftermarket add-on to see if the manufacture released a similar solution in later years. With the wastegate the fixed wastegate is a pain to deal with and has a low critical altitude, so the automatic wastegate makes sense. On the intercooler, the hot running 231 when you add an intercooler it has a much better CHT margin from red line. For me these are reliability decisions, the Merlyn will not be spinning the turbo at as high of an RPM so in theory it should last longer. The intercooler will have a cooler air charge and should lower the CHTs ~20d and the cylinders should last longer when running cooler. Remember after the engine change and intercooler add, if your aircraft is faster, you are producing more horsepower. Also, make sure the fuel system is set correctly once the intercooler is installed. The intercooler cools the air charge and at that lower Max MP(~36in) you need about the same FF as MP 40in on your non intercooled engine. Refer to the Merlyn and intercooler documents. I fly 75%HP, 100d rich of peak at 17.5/16.5ft, 13.9FF, ~30.0in MP, 1550TIT and I see 181Kn. After I added fine wire plugs, I am now able to run lean of peak, but I don't very often. Also, I love the fact that I can pick up ~2kn TAS per thousand feet, so I cruise high almost always. At 17.5 65%HP, 12.4FF I get 170kn. Fly fast, Jim

Hi Bigmo, Yes, I have a smaller Peltier unit (semiconductor chip that cools) that clips to the back/top of my mini. The only times in the past where i had my mini overheat was when it had direct sunlight on it for a long period of time. With the cooling unit i have not had an overheat and it is powered from a USB cigarette lighter adaptor. I purchased off Amazon two plus years ago.

Hat rack: plexus, clean rag, paper towels, spare headsets Baggage: tool kit in a 4-inch-high suitcase (w/spare spark plug), sidewinder power tug, dry bag w/emergence supplies (water filter, signal mirror, spare clothes), Bruce's cover, Plastic shoe box w/ oil and an oil filler shutoff, hand tow bar Cabin: In winter I keep the dry bag behind the pilot seat. Most of my flying crosses the Sierra Navada mountains, in the winter a frozen lake might be the best option for an off field landing. I want my best options to survive the off field and not freeze to death. handheld radio, Neck string under shirt(so I don't have to find in a rough landing): Spot, pulse O2, small emergency led light

You're talking to the right guy, Paul knows what he is talking about. I would add that you still should verify your fuel flows. I would also think your data would show fuel flow fluctuations 1-2 seconds before your EGT starts to rise because the flow transduce is up stream. It's odd to me that I have never seen this as i fly high all the time.

I have over 700 hours in my 231 and set the fuel flows on 1000s of engines and I have never needed the boost pump in flight. I have never had any symptoms that resemble cavitation. Is this real or instrumentation? You did not mention EGTs when this happened. Do you have an engine monitor? I don't think my engine will stay running at 6gpm. Does it happen on both tanks? If you have a restriction in fuel flow that causes the fuel pump to cavitate I would suspect that to happen at full power and max fuel flow. What engine and addon's do you have? First, is this instrumentation? Hard to believe that the cowl flap position could affect anything. The fuel pump main cooling has to be the fuel going through it. I would look at the fuel flow sender wiring that might(?) be affected by changes in air flow. Second, I would have the intake pressurized and look for leaks in the upper deck lines and fuel pump Aneroid. Third, check all fuel screens. Forth, have the fuel flows set by someone with experience. If the fuel flows are off, check the fifth item before setting the fuel flows Fifth, verify that the fuel return line is not blocked. This is the line on the top of the fuel pump that send a small portion of the fuel back to the tank and any vapor. If it's blocked the vapor would be pushed into the engine (long shot). Not sure how you would get the fuel flow set correctly if this line is blocked. Jim

Hi Fred, I have done this same fix. My head liner had some #4 screws in from the top on the fwd. section to the aft section. Basically, where the head liner won't release there is a fastener. I cut all the way around the square plastic box that is pop riveted to the black 90 fitting. Go shallow on the cut. I drilled out the rivets and then I could get to the back of the Wemac eyeball. I found a tiny clip ring that had popped out and jammed the Wemac eyeball. Once the Wemac was back together I put one drop of Loctite on the clip and lubed her up and riveted the Wemec back into the square plastic piece. I used some scrap ABS sheet and i cut the rectangular pieces and glued the eyeball assembly back into the head liner with the ABS glue. I think Mooney started assembling the plane with the Wemac vent, crazy PITA

Hi Skip, Four or more years ago, I saw someone post here a pic of a Lycoming with a crack in the case right under the lifting eye. At the time, I thought the only possible reason for the crack was jacking the nose of the aircraft with the engine lifting eye. Jim

Hi Wingover, I don't have the part number but you can measure the tube OD and the opening in the baffling. Then search the web or a hardware store. When you get the new grommet just cut and roll it in place. Jim

Agreed Ross, just my 2 cents

Hi Shadrach, I have seen problems with CHT cooling and the only thing found on inspection was detached seal from the aluminum baffle. Reattached and the CHT came down. My take away was that the airflow is dynamic inside the cowl during flight and must have vibrated or folded over. Back in the day I replaced cowl seals two times a week on average. I have said before in other threads, I look at the baffling and cowl seal like a water radiator, no air lead are expectable.

The red oval shows the missing rivets

There should be a rubber grommet in the area in red, one to seal the air gap and two to keep from chaffing through the line. jim