Increased performance with new cylinders?

k9medic

k9medic

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ATP-H, CMEL, CSEL, CFI/CFII Airplanes and Helicopters
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Here is a question for the group to debate -

Say you have a Continental engine that has moderate to low compressions (50-55) when compared to the master orifice. The engine seems to run fine and doesn't burn oil.

Would you really see a performance improvement by replacing all the cylinders?
 
No.

50-55 with no exhaust valve leakage is a basic midtime-or-older conti situation. compressions on them aren't like the lycomings where you demand 78/80 or it's trash :)
 
Compression has little impact on power delivery, but depending on the cause of lower compression, may increase oil usage. Cylinder replacement is intended to correct issues such as valve leakage, compression ring failiure, or excessive oil usage and fouling.
 
There’s not much to debate. The engine will need to be in pretty poor health before you’ll be able to detect any real difference in performance.
 
I agree with the above^^^^
It is too bad we can't stick some higher compression pistons with maybe a performance valve job and maybe some over sized valves in these old motors. Then you might see a performance advantage? Maybe 4 barrel carb? lol
 
Gary Ward said:
I agree with the above^^^^
It is too bad we can't stick some higher compression pistons with maybe a performance valve job and maybe some over sized valves in these old motors. Then you might see a performance advantage? Maybe 4 barrel carb? lol
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I wish I could turn my O-470-U up to 2650rpm.
 
Gary Ward said:
I agree with the above^^^^
It is too bad we can't stick some higher compression pistons with maybe a performance valve job and maybe some over sized valves in these old motors. Then you might see a performance advantage? Maybe 4 barrel carb? lol
Click to expand...

That is done on the EAB world. Especially for aerobatic competition airplanes. Helicopter pistons. Flow balanced porting. Different cam.

https://www.aerosportpower.com/
 
Gary Ward said:
I agree with the above^^^^
It is too bad we can't stick some higher compression pistons with maybe a performance valve job and maybe some over sized valves in these old motors. Then you might see a performance advantage? Maybe 4 barrel carb? lol
Click to expand...

Talk to Ly-Con if you're interested in head work on these aircraft engines while playing within the boundaries. Their prices are affordable and they claim that it will add 20ish horsepower with their improvements. I've been pleased with the work I've seen come out of their shop.
 
Gary Ward said:
I agree with the above^^^^
It is too bad we can't stick some higher compression pistons with maybe a performance valve job and maybe some over sized valves in these old motors. Then you might see a performance advantage? Maybe 4 barrel carb? lol
Click to expand...

Always wanted to photoshop a B&M blower sticking out of the cowling.

And there is always a NOS alternative to be considered ... :D
 
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Daleandee said:
Always wanted to photoshop a B&M blower sticking out of the cowling.

And the is always a NOS alternative to be considered ... :D
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Oh heck yea!!
When I first learned what NOS was I remember being told it was first used by the piston fighter planes during WW2?
 
eman1200 said:
send me a pic of your plane and I'll see what I can do......
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Edit: This will likely work better ...
iu
 
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There's a RV guy running a Honda, but I think it's a water cooled model.
 
schmookeeg said:
And agile will make you doomeder but now with fibonacci numbers
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:yeahthat:


Agile can (sorta) work okay with (some) non-life-critical software applications, and (some) small subsets of hardware development. But I’ve seen Agile evangelists try to force it onto things like missile development which is insane. “Fail fast” is BS that leads to bankruptcy when each failure costs $50M or so. The cost of failures MUST be a consideration when deciding whether to use Agile.

Agile is a technique that can be used with caution in controlled, limited cases. It is NOT the universal solution that its fanatical proponents preach. It’s no substitute for thorough design and analysis methods; merely another tool in the box.
 
In my world, it seems to enable non-technical project management to feign intelligence and provide them interesting bar charts about velocity and burndown, while the engineers all work on their side projects or wordles.
 
schmookeeg said:
In my world, it seems to enable non-technical project management to feign intelligence and provide them interesting bar charts about velocity and burndown, while the engineers all work on their side projects or wordles.
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When I was at Lockheed, I used to advocate for Fermi experiments - simple, quick, cheap experiments that give fast rough answers which inform trade studies and concepts to narrow the solution space. Agile can be useful in this context. But it’s no substitute for rigorous, disciplined design and analysis practices. The chosen solution must be subjected to thorough analysis and verification.
 
MVC-574S.jpg

Real blowers have ballistic blankets and no chrome.
MVC-620S.jpg

Bolt that on to this cessna. I went from a 275mph dragster to a 125mph airplane and had a rough time learning to drive the cessna.
IMG_1605.JPG
 
schmookeeg said:
In my world, it seems to enable non-technical project management to feign intelligence and provide them interesting bar charts about velocity and burndown, while the engineers all work on their side projects or wordles.
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The value stream in SAFe is to Dean Leffingwell.
 
All that talk of Agile and Fibonacci and t-shirt sizing and burndown is giving me nightmares about exposure to software development at a previous company.

Still not as bad as Six Sigma. I was in a research environment when word came down that our group had been told they needed a Sigma Green Belt, and I was the sacrificial lamb. Nevermind that in medchem discovery, every experiment is supposed to be different. You're looking for new things, for gawd's sake. But my mentor steadfastly insisted that we had to change the process so that every experiment took the same amount of time to run...even though some reactions are over in seconds at -70C, while others take a week cooking in a high-boiling solvent, which is to say reaction kinetics don't give a fig about Six Sigma principles.

And just last month, I had to replace an over-range microwave from GE. That's relevant because GE was the first and/or largest American company to go all-in with Six Sigma, and from there it spread like an unwelcome fungal infection. I reached out to their help line to confirm if any of their six available 30" wide over-range microwaves would fit the existing mounting bracket that I had installed with the previous GE microwave. No, I was assured, all six of GE's 30" microwaves use different mounting brackets, incompatible with each other, and with all earlier models.
 
Future anthropologists will correctly conclude that agile was a cargo cult that believed the flow of value over the customer's face is maximized through ceremonial burnt offerings of MVPs to PMs, the demigods of mediocrity.
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GaryM said:
I was in a research environment when word came down that our group had been told they needed a Sigma Green Belt, and I was the sacrificial lamb.
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Was in manufacturing when the six sigma wind blew in.

Couldn't understand the point in my facility of talking about defects per million when we made 5000-25,000 of any SKU per year, meaning our denominator was much too low to be relevant to the framework. At that time we were told that the theory emanated from Motorola in their quest to builder pagers reliably enough to not have to test them before shipping. If some measured defect level was metric'd to be low enough, i.e., about 6 in a million, just ship the thing and exchange the duds.
 
Half Fast said:
Agile is a technique that can be used with caution in controlled, limited cases. It is NOT the universal solution that its fanatical proponents preach. It’s no substitute for thorough design and analysis methods; merely another tool in the box.
Click to expand...

schmookeeg said:
In my world, it seems to enable non-technical project management to feign intelligence and provide them interesting bar charts about velocity and burndown, while the engineers all work on their side projects or wordles.
Click to expand...

I am aware of a company that is getting a stealth Agile "transformation" pushed from the top down, with no actual discussion at the lower levels of the organization. The very first step they took was to fire all of the project managers with no advance warning one day. Some of them would have happily transitioned into scrum masters or whatever other role was needed. To this day no one has actually used the term Agile. I predict things are going to get a lot worse for them before they get better.
 
k9medic said:
engine that has moderate to low compressions (50-55) when compared to the master orifice. The engine seems to run fine and doesn't burn oil. Would you really see a performance improvement by replacing all the cylinders?
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As others have stated, even an engine with a 0/80 leakdown test (compression test) can make full power. It's just that there will be lots of blowby and other undesirable side effects. And you may be headed for a failure if the leakage is past the exhaust valve due to thermal distress.
The primary wear situation that affects horsepower output is camlobe wear... if the camlobes start to wear, then engine breathing is affected. The amount of power you can make is directly proportional to fuel/air mixture in and exhaust out of the cylinder. Worn camlobes limit valve lift, and allow less in/out flow, thereby reducing power.
So unless you have camlobe wear, an overhaul won't increase engine horsepower output.
BTW, you can check valve lift with a dial indicator... for most Lycomings, you're looking for 1/2" lift on both intake and exhaust valves. I'm not certain on Continental engines.

Paul
 
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