Q The Engineer

Good post and the numbers are fuel flow for ROP and LOP. Thanks and cancel my request.

Just getting caught up, thanks for your feedback. If you're looking for best fuel economy, yes, max allowed continuous TIT should do it.

I checked the 252 POH Bob gave me. Normal is 1300-1650 deg F, 1650 deg F redline maximum limit*. * = do not exceed 1650 deg F for more than 30 seconds, do not exceed 1700 deg F under any circumstance. Yep the GB and LB's have a short runner to the head with a long log. The MB and SB's have a tuned, longer runner. MB and SB's also have a Garret turbo and an aftercooler where the GB/LB doesn't, it's a straight turbo, no aftercooler. On the short drop runner GB and LB's, the standing wave under lower speed conditions pushes injected fuel back into the long log. The air is fed front to back on the engine so as air is moved to feed the middle and back cylinders the mixture gets richer and richer causing over rich conditions on the back cylinders. The MB and SB intake runners are 4x longer than the GB/LB (haven't measured my parts yet, much longer) so the standing wave pushes the injected fuel up the runner the same amount however, since the runner is much longer, the blown back fuel never hits the common log/plenum so the fuel doesn't get pushed to the middle and back cylinders. That is the idea in theory. Bob says he proved it during 231 development which is what drove the new intake manifold on the 252. He sent me the data but I haven't had a chance to look at it yet. What are you referencing on 13.3-14.5 when Rich Of Peak and around 11 on Lean Of Peak? That is new to me. The burble on decent is definitely there! I'm not ready for TIT tuning in the pattern yet, I'm not that good. And I kinda like the burble being a race car guy. Thanks for your feedback.

I'm with you on the TIT, I'm thinking 1650 deg F for continuous is a bit high. I'll check with my guys for a check on TIT limits using inconel.

Great post, thanks for your feedback. I've not been using TIT to tune for a couple of reasons, my instructor is not good with anything not full rich until reaching pattern altitude and that coupled with me not being that good yet keeps me at full rich. I'll add the TIT tuning when everything is automatic, it's clearly not yet. I'll ask Bob about the box numbers and check the POH. Running the engine lean of peak on the run up and doing a run up lean every 3 pattern runs has solved the problem so far as Bob suggested. I wouldn't want to go 1650 deg F even with an inconel turbine/casing. No engine monitor here other than TIT, CDT, oil temp and head temp as from Mooney. We definitely got shake but no bang so it must not have been too bad. I can't tell you if it's the same plugs or not without exh port temp measurements. Bob's thought was full rich with extended rich idle times and the poor intake design on the MB loading the back cylinders is causing the issue. I've been helping my CFI with the engine management but I'm still learning stuff. I've been doing engine development/design for 32 years so I get the fundamentals. Good thoughts sir, thanks for your feedback.

I wanted to share some info on the M20K engine I've become familiar with. The engine has an intake manifold design that is less than optimum. The standing wave pushes fuel to the rear cylinders causing misfire at low speed, light load. It causes the plugs to load up and misfire. I've flown the airplane training towards my private pilots license so we've run it full rich for about 10 hours. I did a mid field crossing, hit 500 AGL and pulled back to cruise power at 33" in Hg. The engine missed hard enough to shake the plane. My instructor called my airplane to give you an idea. I talked to Bob Minnis as he was the engineer on the J to K project for continental. Bob shared you shouldn't run the engine for that long full rich. I've been leaning the engine out on run up and every 3-4 pattern runs I'll do a run up to lean it out to clean the plugs off. It's worked good so far. FYI

It is if you're into engines and managing their complexities. If you don't like engines, likely not. A J would be a better machine IMO.

Yep, that's why I kick the gear down early. And to be honest, the gear warning horn and stall horn are so close it's hard to sort them. That's the only thing I've found I don't like about the Mooney. Speed brakes would be cool. Good post, thanks for that.

I put the gear down at mid field to slow down and go to take-off flaps at the end of runway and target 105 mph. That takes about 20 in hg intake pressure. Turn to base, go additional flaps and target 95 mph. On final I go full flaps and target 85 mph. It's worked pretty ok as I've been training. The POH isn't prescriptive enough IMO.

Found them at Lasar after quite a bit of searching. I'm not sure why it was such a PITA to find but we're good now. Thanks for the help guys. https://lasar.com/misc-supplies/rat-sock-l560070-001?utm_medium=email&utm_source=customer_notification

Mike, I was able to get one made based on your dimensions. Thanks again for sharing it. I'm not sure why but my 1980 M20K is quite a bit different than your stick. When I get time to drain mine and make the measurements I'll share the results for comparison.

Thanks very much! s

Sounds like existing used or modification of what I have. Thanks for the info Todd.

The biggest piece is finding the NACA duct feeding cooling air to the aftercooler. I believe the duct can be attached to the existing cowling and then cut the appropriate hole in the outer surface. There are two aftermarket STC offerings that attach the duct to the existing cowling. I'll have to look them up, can't remember now. Thanks for the feedback A.

I would try aircraft engravers. https://engravers.net/faceplate-inserts.html

No cowling yet, it's on the look for list. I'm not sure on the propellor but I need to check. I'll check the engine mounts. Thanks!

All 100% truth. Bob is a great resource and a wealth of knowledge. And I can't write that fast which is why I type it instead.

I do have a couple of giant American cars with giant v8's. I guess it depends on who is doing the work. I build race car engines on the side, have designed and developed diesel engines for 33 years. It's not that big of deal, approval is though. I already have 80% of the parts and an A&P/IA buddy so it's doable for me. This is a forever plane for me. I've spent the last year going through it, I don't want to do that again!

Thanks!

Might have to. Any idea on material?

Same here. The visors work great! I put a set in my K a couple of weeks ago and they are awesome. Thanks @DonMuncy!

Guys, I've been looking for dust boots PN 560070-001 for a couple of hours with no luck. It looks like Lasar had a replacement part that is no longer available. Does anyone have any ideas? Thanks, Aaron

Let's hope so! I'll hit Bob up again.

Thanks

Thanks for the note and I appreciate the feedback. My buddy was the original application engineer for Continental on the 231 and 252 and is a DER with the FAA. He thinks it can be done. I'm going to dig into it more and see. Either way, he is able to sign it off. His point was we're not swinging an engine, we are upfitting an LB to an SB as described in point 1. of the service bulletin. I have 80% of the parts to complete the conversion so I'm going to dig into it further. I'll share what I find out.