IO-360 vs IO 390

[kaba]

Ruminating….

Replacing IO -360 with now certified IO-390

Possible new prop

 

Anyone with experience

Benefits/Downside

 

Cost out of the equation

 

 

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[carusoam]

14 hours ago, kaba said:

 

Ruminating….

Replacing IO -360 with now certified IO-390

Possible new prop

 

Anyone with experience

Benefits/Downside

 

Cost out of the equation

 

 

Sent from my iPad using Tapatalk

 

How many responses would you like?

They are expensive…

They are great…

They have roller cam followers…

They don’t produce a stunning amount of extra power…

Was there anything in particular you wanted to know?

Best regards,

-a-

https://mooneyspace.com/search/?q=IO-390&quick=1

[Bartman]

I would consider factory rebuild or exchange and install the IO-360 with roller cam followers. Cheaper, easier, equivalent horsepower, far fewer headaches and potentially more reliable with the roller cam followers. 

[jetdriven]

If I recall, the Hartzell top prop BA prop is required for the STC which adds 10 or 12 grand to the price of a new power plant installation.   If you already need a new prop then it’s probably not that big of a deal but if yours is good it’s quite a shock of extra cash. 

[flyboy0681]

Briefly looked at this when I was at overhaul, but the posts here set me straight.

[Shadrach]

I’ve always felt like the IO390 answered a question that no one really asked. 5% more horsepower on take off... maybe 1 to 2% more horsepower in cruise. Likely no perceptible difference in cruise speed. 
does anyone have an idea of the current cost of IO390 cylinders?

Edited September 29, 2021 by Shadrach

[ZuluZulu]

@bmcconnaha to the white courtesy phone...

 

[Ragsf15e]

On 9/28/2021 at 7:12 AM, kaba said:

 

Ruminating….

Replacing IO -360 with now certified IO-390

Possible new prop

 

Anyone with experience

Benefits/Downside

 

Cost out of the equation

 

 

Sent from my iPad using Tapatalk

 

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?

[EricJ]

The IO-390 is pretty popular in the experimental community with many RV-14 builders using them.    My understanding is that part costs, including cylinders, is now comparable to the IO-360.   It looks to me like the tide is turning to perhaps favor the IO-390, but that's just my observation.   I think if/when my engine needs removal it'll be a seriously considered option.

 

[kaba]

We love our 1993 M20J MSE.

12 years ownership.Paint and interior and TLC on our airframe,we now have invested.

We like the lower glare shield.

At 1500 hours on our IO-360 A3B6 we are starting to plan engine work.

Who does not like a little more power for our forever plane.

Suggestions and thoughts are all appreciated…


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[pirate]

Not the same as a Mooney but I was in a RV7 with a IO-390 and It climbed and flew like a bat out of hell compare to the RV7 With a IO-360 I was in prior. 

[ArtVandelay]

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

[kaba]

Artvandalay
Based on your comments….I like the idea of moving forward with
IO-390.
We do intend this to be our forever plane.

My wife and I have flown many aircraft….
Nothing like a MOONEY………………..


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[ZuluZulu]

Was 210 the most HP they could wring out of four cylinders?  Going from 200 to only 210 is just so disappointing.  Something between 220-250 would have been amazing; a good compromise between the big-bore 300 HP IO-550 and the economical 200 HP IO-360.

[kaba]

Not sure how the 6 cylinder MOONEY feels….
Never flown one….
But 2000 hours in our plane feels right……….


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[carusoam]

 When it comes to extra HP…

10% is a lot!

5% should be plenty measurable…

mostly because it is excess HP that we use for T/O acceleration, and climb rate…

So 10% of the total HP doesn’t shine as much on paper as comparing the extra HP to the baseline of how much Excess HP was available originally…

 

Take the example of the Standing Ovation… Born with 280 hp, updated to 310hp… about 10%.

• T/O distance went from 1200’ to 800’ lightly loaded…
• Initial climb rate exceeded 2kfpm…
• The extra excess hp doesn’t often get used in cruise… it can, but the fuel penalty is climbing with speed squared…

With the 390, expect a similar type of improvement… adjusted for about 5% more HP not the full 10% used in this example…

 

If you like short fields… or fly on high DA days… or have to climb over a mountain of Class B airspace in a short distance….  All the excess HP you can get will always be appreciated…

Note: If you are using the excess HP in cruise… expect to see an equivalent increase in FF…  HP comes from somewhere more than increasing the volume of the cylinders…   

 

Go Excess HP!

Best regards,

-a-

 

[ZuluZulu]

7 minutes ago, carusoam said:

 When it comes to extra HP…

10% is a lot!

5% should be plenty measurable…

mostly because it is excess HP that we use for T/O acceleration, and climb rate…

So 10% of the total HP doesn’t shine as much on paper as comparing the extra HP to the baseline of how much Excess HP was available originally…

 

Take the example of the Standing Ovation… Born with 280 hp, updated to 310hp… about 10%.

• T/O distance went from 1200’ to 800’ lightly loaded…
• Initial climb rate exceeded 2kfpm…
• The extra excess hp doesn’t often get used in cruise… it can, but the fuel penalty is climbing with speed squared…

With the 390, expect a similar type of improvement… adjusted for about 5% more HP not the full 10% used in this example…

 

If you like short fields… or fly on high DA days… or have to climb over a mountain of Class B airspace in a short distance….  All the excess HP you can get will always be appreciated…

Note: If you are using the excess HP in cruise… expect to see an equivalent increase in FF…  HP comes from somewhere more than increasing the volume of the cylinders…   

 

Go Excess HP!

Best regards,

-a-

 

But haven't people who switched to the IO-390 in the M20J said they didn't notice any difference?

[Ragsf15e]

40 minutes ago, kaba said:

Artvandalay
Based on your comments….I like the idea of moving forward with
IO-390.
We do intend this to be our forever plane.

My wife and I have flown many aircraft….
Nothing like a MOONEY………………..


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He was quoting these guys stc, not performance data from an io-390 Mooney… I actually haven’t heard or seen quoted data from a -390.

https://firewallforwardengines.com/stc/

[Ragsf15e]

http://gnaircraft.com/wp-content/uploads/2017/08/mooney_stc_2017.pdf
 

this site has a little info on performance data with a -390.  We need someone who’s done it to chime in.

[carusoam]

6 minutes ago, ZuluZulu said:

But haven't people who switched to the IO-390 in the M20J said they didn't notice any difference?

Those people would have to describe in a technical format what they measured…

Don’t expect to feel, or notice much…. Some people’s seat of the pants aren’t as calibrated as others…

 

Using my example… if my T/O run went from 1200’ to only 1000’… it would only be noticeable if I were measuring it…

If I didn’t have Byron next to me while climbing out… You can’t really feel the awesome climb rate… Byron took a pic of the VSI… 

If you don’t have a class B  nearby to climb over… How would anyone notice a great climb rate?

 

Now… If the IO390 doesn’t really have any HP improvement… and you only get IO360 performance… there woukd be a lot of disappointed people out there…. It isn’t just roller cam followers people are interested in…

If you haven’t measured these performance numbers for your plane… all it takes is a WAAS source and CloudAhoy app….

 

Yes… I measured actual before and after performance and the performance of Cris’ Screamin’ Eagle before deciding on Engine and prop upgrades…

Expect some Marketing Hyperbole / puffery to always be at play…

Until you get to know the resource… ubiquitous people said…. SGOTI said…

You kind of have to find somebody to measure this stuff…

Fortunately… on MS… you can get to know a lot of people that have some really interesting experience to share…

The data you are looking for is probably around here somewhere… and somebody knows where it is…

Go MS!

Best regards,

-a-

 

[carusoam]

20 minutes ago, Ragsf15e said:

He was quoting these guys stc, not performance data from an io-390 Mooney… I actually haven’t heard or seen quoted data from a -390.

https://firewallforwardengines.com/stc/

If the FWF STC is the one using the 10:1 compression pistons… we have at least one MSer that really likes it…

Improving the CR is a real thermodynamic change in the engine operation…

Like increased ignition timing… managing CHTs becomes slightly more important…

 

There are Mooniacs with engine monitors… and Mooniacs that enjoy downloading data out of their engine monitors…

If you are downloading data and sending it to the Savvy website… you will easily see the differences in the graphs… 

 

For the Mooniacs without an engine monitor… capturing this level of data is a whole extra level of work….  
 

PP thoughts only, my first Mooney didn’t get an engine monitor…

Best regards,

-a-

[Ragsf15e]

1 minute ago, carusoam said:

If the FWF STC is the one using the 10:1 compression pistons… we have at least one MSer that really likes it…

Improving the CR is a real thermodynamic change in the engine operation…

Like increased ignition timing… managing CHTs becomes slightly more important…

 

There are Mooniacs with engine monitors… and Mooniacs that enjoy downloading data out of their engine monitors…

If you are downloading data and sending it to the Savvy website… you will easily see the differences in the graphs… 

 

For the Mooniacs without an engine monitor… capturing this level of data is a whole extra level of work….  
 

PP thoughts only, my first Mooney didn’t get an engine monitor…

Best regards,

-a-

Yeah I read the FWF data and still had no idea what the actual stc was for, but the performance improvement sounded good!

[ZuluZulu]

Just now, Ragsf15e said:

Yeah I read the FWF data and still had no idea what the actual stc was for, but the performance improvement sounded good!

This old thread is not encouraging...

 

[carusoam]

26 minutes ago, ZuluZulu said:

This old thread is not encouraging...

 

that thread has some extra baggage as well…

There was something funky going on in their history at FWF, that not everyone liked…

When it comes to bad reviews… we get to do our homework…

When it comes to good reviews… we still get to do our homework…

Reviews are good at pointing out the good and the bad…

But, to be able to use the reviews…. We need to know who wrote it and why…. 

 

There was even a mistake that used up some of the thread… with an apology posted later down it…

 

Not mentioned in the threads…. 
 

With extra HP…. Mooney pilots have choices…

We can fly with efficiency, or speed, or somewhere in the middle…

Flying in Flaming Dragon Mode is super fast… it is a safe operation, but the long term cost is going to be a set of cylinders at the halfway point… or sooner…

So…

When you are reading somebody’s review… see if you can capture how they use their mod…

Excess cash is similar to excess HP…. A good stack of excess cash can OH a lot of cylinders….

If you are in the CB club because you have to be… that excess cash can be hard to come by…

 

CHT control is everything for maintaining cylinder health…. <380°F is a guideline used around here for long cylinder life…

Climbing out at 2-300°F ROP is a way to minimize CHT in the climb…

 

All stuff to discuss when considering adding excess HP…. To some Mooniacs, the extra juice isn’t worth the squeeze…

PP thoughts only,

-a-

[bmcconnaha]

On 9/29/2021 at 3:42 AM, Bartman said:

I would consider factory rebuild or exchange and install the IO-360 with roller cam followers. Cheaper, easier, equivalent horsepower, far fewer headaches and potentially more reliable with the roller cam followers. 

That wasn't the case when I ordered my 390 last year.  390 was less money.  

Edited September 30, 2021 by bmcconnaha