IO-550-G Cylinder Availability

[TGreen]

Starting to look into an overhaul for my IO-550-G. Some shops have said they won't even quote or commence an overhaul because the cylinders (I think the part no. is 655474) are not available and they don't really know when they will become available. Has anyone else encountered this? Any advice?

[Bolter]

Following, because it is only a matter of time before I will contemplate overhaul.  

Does rebuilding the cylinders avoid any of the supply chain issues?

[rickseeman]

Rebuild? You mean like everybody did for 50 years before they got cylinder-replacement-happy? You would have to grind the valves and seats. Isn't it easier to just open the box on a new one and charge the customer $1,700 extra?

[Alan Maurer]

Is there more to rebuilding a wearing out cylinder than  grinding the valves and seats. What about restoring the honing on the cylinder walls 

or checking the valve guides? I find myself adding more oil than a year ago. Good question to wonder about?

Alan

[Niko182]

Is there a difference in availability with the N compared to the G cylinders? Maybe it may be worthwhile going the N route.

[rickseeman]

1 hour ago, Alan Maurer said:

Is there more to rebuilding a wearing out cylinder than  grinding the valves and seats. What about restoring the honing on the cylinder walls 

or checking the valve guides? I find myself adding more oil than a year ago. Good question to wonder about?

Alan

He will check the guides too. If it needs guides I wouldn't think that would be a big deal. I hone a lot of car cylinders. A guy that rebuilds cylinders it set up for this and can do it in a few minutes. In the old days people didn't just "buy new cylinders" You just fix it. It wasn't rocket science.

[Bolter]

10 hours ago, Niko182 said:

Is there a difference in availability with the N compared to the G cylinders? Maybe it may be worthwhile going the N route.

As a fellow 310 HP STC holder, I wonder about this.  Can you put an N to replace the G?  I did not research it, but it seemed to me that the G with the higher rpm is the approved engine, not an N with 2700 rpm and 310 HP.  The N should fit and work, but it is not the same engine.  

-dan

[StevenL757]

9 hours ago, Bolter said:

As a fellow 310 HP STC holder, I wonder about this.  Can you put an N to replace the G?  I did not research it, but it seemed to me that the G with the higher rpm is the approved engine, not an N with 2700 rpm and 310 HP.  The N should fit and work, but it is not the same engine.  

-dan

I’ve replaced two “G” engines with the IO550N.  As long as one possesses the 310hp STC and your governor has been adjusted to the T20 standard, you’re approved to install the “N” engine (out of the box as 2700RPM / 310BHP) either as factory-new or factory-reman.  Both have 2200-hour TBOs and zero-time logbooks, and are considered “approved”.  The “N” engine is actually flat-rated to nearly 338hp, but is de-rated to 310.  It is considered slightly more powerful than the “G”, per Minnis Aviation’s test criteria back when Bob Minnis established that STC.

The “G” cylinder baffles are straight; whereas, the “N” baffles are tapered; the latter requiring a couple of sheet metal wedge pieces to fill gaps left behind that the “G” cylinders take up naturally by their straight baffle design.

Steve

Edited April 22 by StevenL757

[Bolter]

1 hour ago, StevenL757 said:

I’ve replaced two “G” engines with the IO550N.  As long as one possesses the 310hp STC and your governor has been adjusted to the T20 standard, you’re approved to install the “N” engine (out of the box as 2700RPM / 310BHP) either as factory-new or factory-reman.  Both have 2200-hour TBOs and zero-time logbooks, and are considered “approved”.  The “N” engine is actually flat-rated to nearly 338hp, but is de-rated to 310.  It is considered slightly more powerful than the “G”, per Minnis Aviation’s test criteria back when Bob Minnis established that STC.

The “G” cylinder baffles are straight; whereas, the “N” baffles are tapered; the latter requiring a couple of sheet metal wedge pieces to fill gaps left behind that the “G” cylinders take up naturally by their straight baffle design.

Steve

Excellent information.  Great to have more options.  

[Niko182]

1 hour ago, StevenL757 said:

I’ve replaced two “G” engines with the IO550N.  As long as one possesses the 310hp STC and your governor has been adjusted to the T20 standard, you’re approved to install the “N” engine (out of the box as 2700RPM / 310BHP) either as factory-new or factory-reman.  Both have 2200-hour TBOs and zero-time logbooks, and are considered “approved”.  The “N” engine is actually flat-rated to nearly 338hp, but is de-rated to 310.  It is considered slightly more powerful than the “G”, per Minnis Aviation’s test criteria back when Bob Minnis established that STC.

The “G” cylinder baffles are straight; whereas, the “N” baffles are tapered; the latter requiring a couple of sheet metal wedge pieces to fill gaps left behind that the “G” cylinders take up naturally by their straight baffle design.

Steve

How is the N variant de rated from 340hp? Just max rpm?

Edited April 22 by Niko182

[PMcClure]

On 4/22/2024 at 8:56 AM, StevenL757 said:

I’ve replaced two “G” engines with the IO550N.  As long as one possesses the 310hp STC and your governor has been adjusted to the T20 standard, you’re approved to install the “N” engine (out of the box as 2700RPM / 310BHP) either as factory-new or factory-reman.  Both have 2200-hour TBOs and zero-time logbooks, and are considered “approved”.  The “N” engine is actually flat-rated to nearly 338hp, but is de-rated to 310.  It is considered slightly more powerful than the “G”, per Minnis Aviation’s test criteria back when Bob Minnis established that STC.

The “G” cylinder baffles are straight; whereas, the “N” baffles are tapered; the latter requiring a couple of sheet metal wedge pieces to fill gaps left behind that the “G” cylinders take up naturally by their straight baffle design.

Steve

Hi Steve - we are in the process of replacing our G with a new N with the STC. Is there a drawing for the metal wedges? The STC mentions drawings but we could not find them. 

 

[PMcClure]

On 4/11/2024 at 6:18 PM, TGreen said:

Starting to look into an overhaul for my IO-550-G. Some shops have said they won't even quote or commence an overhaul because the cylinders (I think the part no. is 655474) are not available and they don't really know when they will become available. Has anyone else encountered this? Any advice?

I am replacing my G with a N. After working with TCM for months we found it was the only viable option as TCM is phasing out several G series engines. I took off the G series cylinders that only had about 400 hours and replaced them with the original ones to send back with the core. Only later realizing that I could not use them on the new G. So now I have a set of G cylinders with 400 hours on them. 

[PMcClure]

On 4/21/2024 at 11:40 PM, Bolter said:

As a fellow 310 HP STC holder, I wonder about this.  Can you put an N to replace the G?  I did not research it, but it seemed to me that the G with the higher rpm is the approved engine, not an N with 2700 rpm and 310 HP.  The N should fit and work, but it is not the same engine.  

-dan

Part of the STC includes a "N" engine plate to attached to your G engine after making the required changes. 

 

[Phil EF]

Ram has a range of overhauled new and repaired cylinders for the 550C. 
May have something for other variants. 

[StevenL757]

13 hours ago, Phil EF said:

Ram has a range of overhauled new and repaired cylinders for the 550C. 
May have something for other variants. 

The 550C is not an approved engine model for the Ovation.

[StevenL757]

20 hours ago, PMcClure said:

Hi Steve - we are in the process of replacing our G with a new N with the STC. Is there a drawing for the metal wedges? The STC mentions drawings but we could not find them. 

Yes.  Bob Minnis would be a starting point for the drawings.  Brian Kendrick can lend a hand also.

1.  Bobminnis@comcast.net

2.  Brian@mooneysupport.com

[William Munney]

I just bought a factory NEW IO550G from Continental last Winter.  They had factory remanufactured engines available also.  Cornering the market on G cylinders?

[TGreen]

Got a call from Air Power during Oshkosh saying they had six new cylinder assemblies available. Bought them on the way home and will be starting overhaul at Western Skyways soon!

[Fly Boomer]

2 hours ago, TGreen said:

Got a call from Air Power during Oshkosh saying they had six new cylinder assemblies available. Bought them on the way home and will be starting overhaul at Western Skyways soon!

How long did you wait?  Your last post in April said you were trying to figure out what to do.

[TGreen]

A long time. Think I placed an order with Air Power in April or May. Never really got comfort that Continental was producing any cylinders for the IO-550-G, but then six of them showed up at Air Power.