Interested in hearing real world horse power numbers for continental engines that had the cylinders ported and polished.

I hear lycomings get more of a HP increase then continentals.

I'm running an IO-550. Port cleanup by Lycon. Continental cylinders. Bored .010 oversize. It's said to produce 330 hp. Haven't had it on a dyno, can't prove it, but plausible.

I run an MT prop on it.

I doesn't sound as impressive as the old IO-520 two blade! Folks who ride with me are impressed though. It's pig on amphibs. Where it shows is on wheels.

I think the returns for flow matching are most significant on factory cylinders. Superiors and in the past, Titans, not as much gain because they are better than factory to start with. Nicer castings, and we know more about induction and exhaust flow now than Continental did when they designed their castings.

Not sure I'd spend the money unless I needed every last bit of the power for a specific mission. I don't try to win any contests. I race along the lake like a speedboat until I'm flying. Both phases are fun, so I don't sweat a few seconds more or less on the water.

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Maybe this doesn't mean much to you guys but I took my cylinders to a trusted machinist that builds mostly race/high performance engines of all kinds (but not airplane engines) and asked him about porting/polishing the cylinders off my Continental IO360. He looked at them, took a few measurements, asked a few questions then told me it wouldn't be worth it. That I wouldn't notice a difference.

Whee, I believe he gave you good advice.

When I was into automotive performance, a good valve grind, three angle, could go a long way to improving performance. Shaping the valve and the seat for a good seal, but then also relieveing the valve and seat to improve flow through the open valve, made a big difference. I'm not sure if a good three angle grind is permisible on aero engines though.

Also, I should have mentioned, same as glacier, my engine runs remarkably smooth.

I have a TIO-540 from Lycon that the former owner had them Port/Polish. Lycon dyno'd it at 346hp. Another Lycon engine, a Port / Polish IO-550 on a 1968 Skywagon was measured at 330hp. Not sure how much these figures would differ from stock.


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p.s. They're both nearly turbine smooth


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whee wrote:...asked him about porting/polishing the cylinders off my Continental IO360.

Whee, are you flying a Maule?

He's building a Bearhawk