IO-360 vs IO 390

[bmcconnaha]

19 hours ago, Ragsf15e said:

These guys covered the issues… new prop required, significant initial investment over io-360, insignificant change in horsepower, and the cylinders were cost prohibitive if they need replaced.  I’m not sure if that last one has changed.  
 

Now the engine is “newer” but I’m not exactly sure what that means.  SR20s now have them, so maybe that has changed the cost issues.  Still, if you cruise at 65%, you’ll see 6 more hp there.  Maybe it’ll climb better?

I thought there were very few (or only one) place authorized to do the stc?

Unfortunately some common misconceptions.  

1-Cylinders cost the same.

2- I did the swap right there in my hanagr in Coeur D alene.  Didn't have to take it to a special location.

3- the prop.  I think most people should agree  that at engine overhaul, the prop should get one to.  At min, an IRAN.  The 390 was less money from Lycoming than an IO360A3B6.  I was ditching the single drive mag anyways.  The D engine was more money from Lycoming than both. I paid 9700 for a top prop.  Sold my other prop in a day for 3.  So, 6700 out of pocket for the prop, and I didn't have to pay to overhaul a 30 year old prop, and I saved several thousand on the engine vs either 360.  

4- the 360 was certified in a day when rounding up was allowed to rate an engine, the 390 certified in more modern times,  it makes as much or more than the rated 210. The factory test sheet showed it developed rated HP at 27 inches and some change manifold pressure.  

5- after 100 hours, I can confidently say cruise is 4 knots faster on average vs my old 360 according to all the data I've downloaded (have each flight for both engines)

6-climb is substantially better.  I find myself cruising in the low teens regularly, and even a short hundred mile hop, I'll climb to 10k no problem if I need to.  

7- the install is almost identical to converting to the split mag io360 a3b6.  

Edited September 30, 2021 by bmcconnaha

[bmcconnaha]

Couple screen grabs from a video I took yesterday, coming home at 14500.  

Initial cruise was at 10500.  It was 167kts true there.  

The bumps got bad, so I tried 12500, no change, so up to 14500.  It was light, still seeing 700fpm climbing to 14500, 90-95 knots indicated.  

Nice tight CHT spread, this is 100 ROP.  Just over 9 gallons an hour.  

[kaba]

Impressive…..
Thanks for the update


Sent from my iPad using Tapatalk

[OR75]

lots of misconception because of how the STC was launched :

• IO-390 WAS initially more expensive (today, same as IO-360-A3B6 and less than the IO-360-A3B6D)
• Cylinder WERE initially more expensive 
• When launched, Lycoming was requiring to go through a Lycoming Service Center (not any more required)

  The Hartzell top prop IS required and that adds a significant cost

 

Other considerations: the Top Prop is ~ 10lbs heavier (consider a SkyTek lightweight starter to make it a wash)

The IO-390 accessory panel is the same as the IO-360-A3B6  (so different than the IO-360-A3B6D) , so you will be a few brackets and fluid hoses   

 

[ZuluZulu]

2 hours ago, bmcconnaha said:

Unfortunately some common misconceptions.  

1-Cylinders cost the same.

2- I did the swap right there in my hanagr in Coeur D alene.  Didn't have to take it to a special location.

3- the prop.  I think most people should agree  that at engine overhaul, the prop should get one to.  At min, an IRAN.  The 390 was less money from Lycoming than an IO360A3B6.  I was ditching the single drive mag anyways.  The D engine was more money from Lycoming than both. I paid 9700 for a top prop.  Sold my other prop in a day for 3.  So, 6700 out of pocket for the prop, and I didn't have to pay to overhaul a 30 year old prop, and I saved several thousand on the engine vs either 360.  

4- the 360 was certified in a day when rounding up was allowed to rate an engine, the 390 certified in more modern times,  it makes as much or more than the rated 210. The factory test sheet showed it developed rated HP at 27 inches and some change manifold pressure.  

5- after 100 hours, I can confidently say cruise is 4 knots faster on average vs my old 360 according to all the data I've downloaded (have each flight for both engines)

6-climb is substantially better.  I find myself cruising in the low teens regularly, and even a short hundred mile hop, I'll climb to 10k no problem if I need to.  

7- the install is almost identical to converting to the split mag io360 a3b6.  

Did you go with the two-blade or three-blade prop?  Any thoughts on the trade-offs (if any) between the two?

[bmcconnaha]

7 hours ago, ZuluZulu said:

Did you go with the two-blade or three-blade prop?  Any thoughts on the trade-offs (if any) between the two?

Two blade.  I don't see the point of any more weight on the nose.  I had the plane at 17500 today, and it climbed fine.  Coming through 17000 was still 400-600fpm.  I'd rather have the faster cruise of the two blade.  

[201Mooniac]

If only I could use my MT prop on an IO-390 I would seriously consider it when I change the engine.  MT said it will work fine but there is that paperwork thing...

[bmcconnaha]

26 minutes ago, 201Mooniac said:

If only I could use my MT prop on an IO-390 I would seriously consider it when I change the engine.  MT said it will work fine but there is that paperwork thing...

I've been talking about a field approval for one from their DER.  

[201Mooniac]

2 hours ago, bmcconnaha said:

I've been talking about a field approval for one from their DER.  

Please let me know how it goes.  I would be very interested.

[jetdriven]

On 9/29/2021 at 8:21 PM, ArtVandelay said:

I wonder how 390 compares to firewall forwards stc:

9mph Increase in T.A.S.@8000′
Rate of climb increase 220 fpm at Vy
12% Reduction in fuel consumption
13% Increase in both range & endurance
No decrease in TBO

You forgot the part where the cylinders overheat and the rings lose tension in 500 hours and you have to redo it again. Same as the sparrowhawk 152 conversion.

[bradp]

44 minutes ago, jetdriven said:

You forgot the part where the cylinders overheat and the rings lose tension in 500 hours and you have to redo it again. Same as the sparrowhawk 152 conversion.

Isn’t there a thing about roller reports needing replacement every time the case is split, if using a repair station ? 

[bmcconnaha]

1 hour ago, jetdriven said:

You forgot the part where the cylinders overheat and the rings lose tension in 500 hours and you have to redo it again. Same as the sparrowhawk 152 conversion.

 No thanks.  I briefly looked at FWFs stc. Not for me.

[jetdriven]

9 hours ago, bradp said:

Isn’t there a thing about roller reports needing replacement every time the case is split, if using a repair station ? 

every time the engine is overhauled or a prop strike, yes they must be replaced.  But not if the case is split, per se

 

[bradp]

19 minutes ago, jetdriven said:

every time the engine is overhauled or a prop strike, yes they must be replaced.  But not if the case is split, per se

 

Gotcha thanks Byron 

[John Mininger]

I changed out my IO360 A3B6D with a factory re-built 360 A3B6 in 2019. I lost a (another) cylinder and had to make an emergency landing at an airport 200 miles away from my home field. The engine change was done there. My McCauley only had about 300 hours on it at the time, and I didn't want to deal with a new prop on top of everything else; with my J 200 miles from home. If it wasn't for my existing low time prop, I would have seriously considered the 390.

If I had to do it again, and my prop was closer to TBO, I would go with the IO 390 and an MT propeller. The MT isn't specifically STC'd for the 390, but Peter Marshall at MT-Propeller USA in Deland FL says they do field approvals for the 390 all the time. 

If you like MT Props, and you want to replace your IO 360 with a 390, that's the route that I would pursue.

And for what it's worth, I was going through some of my notes from a few years ago. Back when I thought I would actually have some time to plan out the engine change. Using the part numbers, I looked up what Air-Power is currently quoting for cylinder kits. $2301 for the Lycoming 05K21120 cylinder kit for an IO 360. And $2155.81 for 05K26625 cylinder kit for an IO 390. 

[John Mininger]

And incidentally, I would love to see Mooney Corp (or someone) do a new carbon fiber cowling around an IO390 with cold air induction and an MT prop for the E, F and J.

Cold induction is how the new SR20 and the newer RV14s get 215ish HP.

 

[Ragsf15e]

Has someone done this to an F and can comment on required changes?  IE - does the oil cooler move?  Does the intake change? Maybe RAM air goes away?  Those are possible, but definitely changes to the cowling.  Any other changes?

[AerostarDriver]

For what it is worth, here is my thinking.

An IO-390 is worth it if you have the following conditions:

• RPM limitations on a non-counterbalanced motor (E & F)
• If you have a mid body (F & G)
• If you already have a top prop
• If you are replaced a single mag drive motor (J)

When I am due for a engine which I hope wont be for a long time I am seriously considering an IO-390 for my E, I have the top prop, I have pretty severe RPM limitations, and I have a J cowl which I plan to put on. The other option is to rebuild my A1A as a counter balanced motor, but when you look at the cost, its about equal to a new 390.