Lycoming IO-390 converstion

[Indianarob]

Has anyone completed the Lycoming IO-390 STC for Mooneys?  If so I would be interested for feedback. Looking for cost and performance improvements.

 

Kindly let me know.

 

Thanks

[PTK]

My understanding is that you need a new prop, and it has to be installed by a Lycoming approved facility. Cost is ~18K > the IO360. Imo this delta is difficult to justify because the performance is just not that different.
There are threads on here if you search.

[jetdriven]

The actual IO-390 engine is about the same price as the IO-360-A3B6.   But like smiles said, you need that Hartzell BA prop for the STC.  if you need a new prop too, the math might work out.

[flyboy0681]

A lot has been written here about it and the conclusion that I come away with is that the minute performance increase is not worth the conversion costs. One Mooney driver even reported his performance actually went down.

[carusoam]

Probably makes more sense to a person that has incurred a ground strike on a high time motor.

Best regards,

-a-

[Indianarob]

Thanks guys I agree it looks like a difficult STC to justify.  The Hartzell prop is 10K.

 

Keep the wheel down.

 

thanks for your feedback.

[Jamie]

I have the 390 conversion.

 

Having never flown in a mooney without, I can't really compare. The conversion brings with it some engine upgrades (roller tappets, different mags, new starter, etc) that otherwise wouldn't be there. But that's probably not worth it if you're the one paying the full cost of the overhaul.

[N601RX]

One question I would have about the IO 390 is parts cost and availability.  Their can't be that many of them out there, so it is unlikely Superior or ECI will be making parts for them and Lycoming will be the only source.  Has anyone priced a cylinder for one?  It might make our angle vavled cylinders look like a good deal.

[fantom]

I have the 390 conversion.

 

The conversion brings with it some engine upgrades (roller tappets, different mags, new starter, etc) that otherwise wouldn't be there.

Those engine upgrades are not unique to a 390 conversion.

It would be interesting to learn your cruise settings, fuel burn and TAS.

[Jamie]

It would be interesting to learn your cruise settings, fuel burn and TAS.

 

Yes, it would.

 

I'm still trying to figure that out. I just went on my first long trip, and was playing with the engine monitor. I'm going to have to get some help from my instructor (more help) because I'm not confident in what I'm seeing. When I get it figured out, I'll post a report.

[jetdriven]

One question I would have about the IO 390 is parts cost and availability.  Their can't be that many of them out there, so it is unlikely Superior or ECI will be making parts for them and Lycoming will be the only source.  Has anyone priced a cylinder for one?  It might make our angle vavled cylinders look like a good deal.

Angle-valve cylinders can only be bought new from Lycoming. And they are expensive as hell, 2 grand each.  Unless you want second or third-run cylinders with unknown history that separate at the head and barrel at random times.

[jetdriven]

Jamie, on 17 Apr 2013 - 10:08 PM, said:

I have the 390 conversion.
 
The conversion brings with it some engine upgrades (roller tappets, different mags, new starter, etc) that otherwise wouldn't be there.

 

Those engine upgrades are not unique to a 390 conversion.

It would be interesting to learn your cruise settings, fuel burn and TAS.

All those things are the same between an IO-360-A3B6 and the IO-390-A3A6.  The only principal difference is another 3/16"  of bore.  The IO-390 also has a takeoff limit of 5 minutes at 210 HP, then 27.2" manifold pressure continuous, 200 HP.  I would suppose running 29" LOP has similar cylinder pressure as 27.2" ROP, but that's technically a violation of the engine's type certificate.

[N601RX]

The Lycoming list price for a IO 390 cylinder is a little over $4100.

[KSMooniac]

And that is another good reason not to buy one... wow.

[OR75]

in my opinion, the IO-390 can only be worth it if or when an STC is developped to use autogas, and a de- rate to 200hp.

not Lycoming route of choice right now, but a possibility if 100LL replacement proves too difficult

[jetdriven]

Pretty much all autogas is poisoned with ethanol, and will never be legal for aircraft.

[OR75]

Pretty much all autogas is poisoned with ethanol, and will never be legal for aircraft.

 

I should have been more precise: unleaded gasoline (rather than autogas)

Ethanol helps boost the octane number. But you don't need it to reach the 90s. 

[KSMooniac]

Ethanol doesn't boost octane does it?  I thought it just boosted the corn lobby's income!  Terrible idea in any case to put foodstock into fuel and distort the food markets while simultaneously screwing up engines across many industries.

[OR75]

It actually does both.

But in our leaders mind, it was mostly a way to manage the farmland ( read the votes) ... But we are drifting.

Ethanol can be probably be used in aircraft engines. Some hoses and gaskets would need to be changed.

The testing needed would be huge. We are talking FAA ( they are trying their best to leep is safe) Easier route would be to stick with petroleum based products.

[Jamie]

I could have done without seeing the io-390 cylinder price. Yikes.

 

Well, I bought it with 170ish hours on a brand new engine, so we'll see. All the more reason to take reeeeeeeeealy good care of it.

[OR75]

I could have done without seeing the io-390 cylinder price. Yikes.

 

Well, I bought it with 170ish hours on a brand new engine, so we'll see. All the more reason to take reeeeeeeeealy good care of it.

since you have been riding an IO-390 ... any hot start issues ?

what kind of starter came with the engine. ?

[201er]

I considered the IO390 when doing my engine overhaul and it worked out to be a lot more money for basically no benefit at all. It's only 10HP and only for 5 minutes... If the conversion price were equal or $1-$2k more it might be something to think about. But given just the higher maintenance price alone it's already not worth it. Would be a different story if it added 50HP or something.

 

BTW in addition to a new prop I think you need a different engine mount too if I remember right.

[jetdriven]

Nope, only a different prop and governor. The A3B6 needs the governor as well. If you were in the position of needing a new prop anyways, it becomes a clear advantage. Until you discover that new cylinders for the IO-390 are about 4 grand each.

[201er]

Is 75% cruise based on 200HP restriction or 210 max rated? Even if it is based on 210HP, that's only 7.5HP more. That's what? About 3 knots for .5gph more?

 

Too bad you can't get a missile conversion anymore... for a firewall-forward wreck I bet that would be the best way to go.

[jetdriven]

Thats what I figured, 3-7 HP at altitude, a little more gas.  We had a good prop, so we got the A3B6. How is yours running?