Boring Cylinders on a C Model

[LevelWing]

Are there any advantages to boring out the cylinders on a C Model (O-360A1D)? I've heard it will give you a faster climb rate and a bit more power but I'm not sure if it's actually worth doing. Feedback is appreciated.

[Oscar Avalle]

Never heard that you are allowed to do this. Is there an STC for it?

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[carusoam]

Increased diameter could...

increase volume for increased mixture for increased power... With increased heat and no way to dissipate the excess beyond the same surface area and airflow through the dog house...

Sometimes the oversizing of cylinders is a maintenance thing to improve the surface of the inside of the cylinders.

for improved power and cooling, C's got STCs to add the E's engine and J's cowling.

significant changes like these are done with large chunks of AMUs.  Sounds like an interesting project, but may take a dose of wishful thinking...?

Flying in the cold winter may not require additional cooling.   Additional power is a Concern of cylinder cracking by being over pressured. Making the cylinders thinner would not improve their strength.

PP Thoughts that come to mind,

-a-

[Hank]

Yeah, me too. Oscar and Anthony. I agree with both.

More power would be nice, but an airplane aint a Chevy small block that you can play with all you like. Blow up your Chevy, you just coast to a stop, tow it home and start over. Blow up your Lycoming, it's a whole different ball game . . . not to mention, they sure do cost a whole lot more!

[orionflt]

actually you have cylinder wall limitations that would keep you from being able to bore out the cylinder. some engines have STC to change the compression ratio (different pistons) to increase the amount of HP being created but none for the Mooney. 

 

Brian

[carusoam]

Somebody put higher compression helicopter pistons into an STC for a Mooney.  At least one Owner wasn't happy.

best regards,

-a-

[goterminal120]

Actually there is an stc for J models to install 10:1 pistons from a helicopter engine. The pistons are $600.00 apiece, before the cost of the stc.    

[BDPetersen]

When asked what the funny yellow paint on my cylinders meant, we quickly determined it meant .020 oversize. I guess it must be souped up!!

[pinerunner]

I think its just way to get extra hours out of scuffed-up out of round older cylinders. You have to get slightly oversize rings to match them. I know you can do this for cars but didn't know it was approved for aircraft. It would be a tiny percent increase in the volume and so the power output.

[N201MKTurbo]

Boring cylinders oversized is a bad idea. You can get oversized pistons and rings up to 0.020 oversized. The problem is if you have nitrided cylinders, which most are, you will compromise the hardened surface and get rapid cylinder wear. If the cylinders are chrome, nickel or ceramic coated you don't want to grind through that either. You may find a cylinder shop that would grind them and chrome them to 0.020 over, but that is a lot of work for little benefit.

The additional displacement is hardly worth it for performance.

This is usually a CB move to extend the life of a dying engine. 

[LevelWing]

Thanks for the replies. Perhaps he was trying to extend the life of the engine, as others have said. I may have misunderstood him. I'll leave mine alone.

 

[gsxrpilot]

Lasar has an STC to put an IO360 in the C model. I thinking to do that when my O360 is used up.

[LevelWing]

27 minutes ago, gsxrpilot said:

Lasar has an STC to put an IO360 in the C model. I thinking to do that when my O360 is used up.

I've seen that before. I've got a while to go on mine. Will it allow you throw in a turbo of some sorts with it?

[KSMooniac]

2 minutes ago, LevelWing said:

I've seen that before. I've got a while to go on mine. Will it allow you throw in a turbo of some sorts with it?

There aren't any active STC's to add a turbo to a Mooney as far as I know.  You might be able to find a take-off Rajay system to transplant on to a C, but that is about it.  (John Breda on this forum has such a system for sale.)  The M-20 Turbos system (now out of business) was for an IO-360, but only on the E/F & J models.  The E/F installation required fitting a J cowl, so that adds a lot of expense to the equation.

[N201MKTurbo]

2 hours ago, daver328 said:

If your cylinders are "boring," maybe get them interested in reading, discussing art, or in hobbies - like long cross country flights to exciting destinations, take them out - maybe to a comedy club? Get them a tall glass of CamGuard and show them how to loosen up and have a good time! Take them to the Mooney Summit where they can get to know other Mooneys, make new friends and learn interesting material while next to the beautiful beach?

I had a long talk with my auto correct about that.... It got bored and fell asleep!

[BDPetersen]

Yes, I was toungue-in-cheek with souped-up comment. Realize oversize is not optimum, but it's what it came with and it is still running strong. 

[cliffy]

Boring cylinders (although a dull subject :-) is/was a standard aircraft engine process. The cost delta value between new, good used and bored cylinders is something only the owner can value in his application.

There is no horsepower increase ever noted with bored cylinders in aircraft. 

[Raptor05121]

O-390?