idahoflier
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idahoflier
Thanks for all the feedback! I think I'm going to move forward with stock cylinders...
Port & Polish?
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MBDiagMan
Final Approach
I think that is a wise decision.
Good ports are good because of shape and contour. Aircraft ports are pretty good to start with so the payback for all the expensive handwork is limited. In the days of two valve car engines, there was a lot of gain that could be had because the ports weren’t very good to start with.
As someone pointed out, you’re not racing, so the power advantage is unnecessary anyway.
Good ports are good because of shape and contour. Aircraft ports are pretty good to start with so the payback for all the expensive handwork is limited. In the days of two valve car engines, there was a lot of gain that could be had because the ports weren’t very good to start with.
As someone pointed out, you’re not racing, so the power advantage is unnecessary anyway.
Stewartb
Final Approach
Whose cylinders and for what engine?
Port and polish is about flow. Flow matching and balancing the rotating weight make a smoother running engine. Do you dynamically balance your prop? Most of what you're correcting is internal to the engine. Why not correct it there? Enjoy less vibration and better cylinder temperatures. But these days many of your cylinder choices are already flow matched and balance matched. At overhaul it's easy to have the crank and rods balanced. It all adds up to a better engine.
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MBDiagMan
Final Approach
Doing port work for the purpose of a smoother running engine is a new one on me. There are too many other variables to expect a smoother running engine from the process. You are correct about it being about flow, but equalizing flow resulting in smooth running would be a side benefit, even if it were to accidentally materialize.
Flow is about power. More fuel/air in, the more power out.
Flow is about power. More fuel/air in, the more power out.
Stewartb
Final Approach
At 2700 rpm max your limit for the air pump is already determined. Like I said earlier, given a known displacement and max RPM limit the big improvement for power lies in compression.
I've had a couple of flow matched and balanced engines. Built one of them myself. It makes a difference. Once you've had one you won't want to go back. That said as I'm patiently waiting for a ported, polished, balanced engine from Lycoming's custom shop!
I've had a couple of flow matched and balanced engines. Built one of them myself. It makes a difference. Once you've had one you won't want to go back. That said as I'm patiently waiting for a ported, polished, balanced engine from Lycoming's custom shop!
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MBDiagMan
Final Approach
Over the years I’ve meticulously built several automotive race engines and I agree, but in a race car, it’s about every possible advantage. The fractional advantage of modifying an already decent flowing port in an engine not needing all out max power, seems like a poor investment of funds.
You are indeed correct about the results of increased compression. That is, of course, assuming it’s not so high as to create detonation.
You are indeed correct about the results of increased compression. That is, of course, assuming it’s not so high as to create detonation.
Stewartb
Final Approach
Are you a proponent of dynamic balancing? Does stacking washers on your prop backing plate to compensate for internal imbalance make sense to you? Treat the symptom rather than the problem?
Now that Lycoming is bringing cylinder production back under their own roof it'll be interesting to see if they incorporate the same improvements that Continental and Superior have made. Time will tell.
Now that Lycoming is bringing cylinder production back under their own roof it'll be interesting to see if they incorporate the same improvements that Continental and Superior have made. Time will tell.
MBDiagMan
Final Approach
And where did I write anything against dynamic balancing? I missed it. The subject was port work, not balancing. I’ve had several engines balanced and am a proponent.
idahoflier
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idahoflier
Lycoming cylinders for an O-360.
Stewartb
Final Approach
Have you checked availability? My engine is currently 4-1/2 months overdue from the scheduled ship date because Lycoming is having issues with cylinder production. I hope your cylinders are easier to get.
The parallel valve wide deck cylinders (and some of the narrow deck parallel valve ones) seem to be easy to get. I've never had trouble sourcing the common stuff and I would not be concerned with obtaining Lycoming cylinders for the OP's o-360. However, when you start talking about more special cylinders such as the angle valve narrow deck stuff Lycoming will tell you 4-5 weeks out and just keep stringing you along with another 4-5 week promise. Don't waste your time waiting for Lycoming parts in a situation like that, they won't materialize in any reasonable amount of time. I've heard of guys waiting for well over a year before giving up. Both times I've fallen for the trap we gave up at 6-7 months. Hopefully your engine experience is better.
Stewartb
Final Approach
Lycoming has brought cylinder production back in house and production is slow. This isn't a normal situation. My 390 experience matches a guy I know's 360 experience.
They've been playing games for a while, regardless of what the reason is. I'm not the only one who has had this experience.