I was wondering if anyone has their cylinders ported and polished? Pros/Cons and any useful information.

You are not modifying anything. You are cleaning up the mess that the factory was too cheap to do right the first time.

You can over-do porting. Big NASCAR V-8's and screaming F-1 race car engines have enough airflow and velocity that hogging out a larger port is usually helpful. But the slower-turning and slower-flowing engines on airplanes make it so that the "get a bigger hammer" approach may not work.

Believe it or not, in some cylinders (O-200) adding metal into certain parts of the intake ports is more of an improvement than removing metal.

As a safe, conservative, and good-odds bet, go directly to Ly-Con in Visalia, or Monty Barrett aerobatic engines (forgot location), and see what they have to say. Between the two of them, they have the most experience doing this on airplane engines. I recommend you do NOT just go to the local race car engine builder that is not an airplane engine expert.

Polishing is likely not a big improvement because airplane engines do not flow air fast enough.

You'll get more benefit overall by reducing internal friction IMHO.

I have been curious about this also. My practical side (agrees w/ EZ)feels that these are basically a pretty slow turning tractor engines, and any improvments from porting and polishing would probly not be noticeable. My optimistic sides hopes that it make a difference and would like to do it. I have read 2-6 hp. increase per cyl. Also read the biggest noticeable difference is engine smoothness , I think due to a more equal cyl. pressure.??

I would be happy to hear if anyone has done this mod only and seen a measurerable difference in anything.

And I would agree, if it were gonna be done, certainly best to be done by one of the better shops like Ly-Con.
Gary

This is second hand, but I talked to a pilot who had his 150HP O-320 (C172) overhauled by Ly-Con and when he got it back it was putting out 190HP on their dyno. He said it didn't cost much extra during the overhaul to have the extra stuff done and he could really tell a difference in power. And it was still a certified engine in a certified plane.

I'm confused! How can an airplane traveling at 150 mph flow less air than a race car? I totally understand that NASCAR cars run 200mph or so but still... I port, polish and bore rock crawlers and there a significant improvement! Is it the intake?

SV

Airplane engines turn at 2000 rpm, versus triple that for a normal car and ten times that in a F1 engine. Same displacement turning slower flows less air. Has nothing to do with ground or airspeed. The engine doesn't care.

Most n/a aircooled airplane engines make max power around 2600-2800 RPM.

Most airplane engines are similar sized or larger than most American V-8's.

The air and fuel at stoichiometric required to make 150 hp should be the same, no matter what RPM you make that power at (we can get into efficiency at different RPMs ranging from engine to engine, but I'm assuming ideal conditions and equal BSFC across the RPM range.).

Most airplane engines have between 4 and 6 cylinders. We have fewer cylinders to divide that airflow into so each has a larger flow rate as an automotive engine, given the same horsepower level.

I think that if I was already working on the cylinders, I'd definitely get them ported by someone who knows airplane engines. Unless it was cost prohibitive, anyway. Anything you can do to minimize pumping losses (such as porting and polishing, flow-matching, etc.) will decrease the amount of power your engine requires to run, which increase the amount of power available for spinning the prop.

When my engine builder worked my new ECI cylinders on my Pponk engine he "cleaned" up the mess in the ports which made them quite smooth. He also flow balanced them on a machine that measured airflow both into and out of the ports. Both actions do 2 things increase volumetric efficiency and help with engine balance. I forget the price but it was bundled into the Pponk build seems it was around $200 per jug.
The way I understand it they adjust the air flow based on the all valves being open to the same amount allowing consistent airflow. This may buy you 10-15 hp, bundled into a build like the Pponk I believe it is well worth it.

I had my new cylinders polished and flow matched by LyCon. They can only go so far on a certified engine,
They can clean up the rough areas on the castings but not remove any material past that. The Tech I talked to at LyCon said it should give an additional 5 to 8 HP per cylinder. This is on my 032-E2D with the RAM 160hp STC and a PowerFlow exhaust. LyCon estimated the output at between 190 to 200hp.
I did not dyno the engine so I can't prove it, but my fuel burn went up and it climbs like crazy.
Charged $250 per cylinder. Big bang for the bucks!

When I had my engine built by Aircraft Cylinders & Engines, now at GXY, I asked that as much extra tweaking as was possible be done. I was told that because it was certified, the only things that could be done are porting, polishing, and balancing, so that's what Joe did. He opined that the balancing would have as much positive effect as anything (that's not flow balancing--it's making sure that the pistons/rings/rods are all very close to one another in weight). I have a honey of an engine, which I think is as powerful as an O-360 Lycoming can be. It didn't cost me any more, because I was already paying for the newly built engine.

Cary

I'm wondering about simple stuff like match porting the gaskets on the exhaust and the diameter of the intake tubes. I'm about to rebuild a set of Millennium cylinders with 258 hours.. I noticed the seat counterbores are quite a bit narrower than the ID of the seats with sharp 90 degree edges. You'd think an even chamfer to the seat ID edge would improve the air flow. What I don't know is how much would that effect the heat sink area for the seats? Not much I'd imagine...but I don't know. When I rebuilt the ECI cylinders for/on the IO520 for the Bearhawk the intake/exhaust seat counter bores matched the seat ID. I did match bore the intake and exhaust to match the gaskets on the Continental...it's experimental. The O320 is for the Pacer I'm rebuilding.... And I can't ask Dave Williams the mechanic who I was working with.....Alaska Regional did him in. So...I'm asking here. I did talk to Lycon about their pistons but felt asking about the particulars of porting was a no no.....as they wouldn't profit from giving the information.
Mark M.
Platinum Ak.

I'm usually skeptical of things like this without data. If porting really makes a difference, can someone find a dyno curve comparison of a sample of new/rebuilt polished/ported vs stock cylinders on Lycs and TCMs? If even 5% HP were easier to get at the top end, this would be a no-brainer as a standard service during rebuilds.

And yet, it isn't. Why?

I've seen things definitively work for auto hot rodders, and it can be impressive with the right combo of valve lift vs. porting...10% is a fair number to use, I hear, in extreme cases. On the other hand, I also know a fellow who spent a lot of money to get his Ford polished and ported, and *lost* about 10 hp. He bought new heads and had his chip tuned again and the HP *magically* returned. He sold his ported units very easily to someone else eager to try the same thing. It seemed to make a lot of sense, but in the end, it was lost in the noise.

Most aircraft engines produce slightly more HP than rated in general at some point after they are broken in, according to a couple engine builders I've heard it from.

Anyone have actual dyno data of modified vs stock for TCM's or Lycs?

Once upon a time I ran a shop and built performance engines, I always pushed my customers for at least what I called a stage 1(I offered up to a stage 3 cylinder head clean up, port and polish) , I never had a complaint and always got complements. (most of the time) performance changes like the ones we are looking for are not in changing the port shape or even changing the flow @ full lift, but rather increasing the flow @ low lift, that is where the lowest hanging fruit is and I a liken to giving the flow a head start, large changes in performance can be made with little removal of material, air flow is like water flow, it does not like sharp edges. A quality five angle valve grind makes a difference you can feel in seat of your pants, cutting a 30 deg. Angle under the 45 on the valve makes a big difference at low lift, going into the port, valve bowl and removing or rounding edges, matching ports helps too, another big one is CC ing the combustion chambers and adjusting them to the CC of the largest one. Not a LOT of Porting and polishing to make a big difference. Just making what is there work well. You will feel it in the seat of your pants! [facebookvideo][/facebookvideo]

fat tire bob wrote:I had my new cylinders polished and flow matched by LyCon. They can only go so far on a certified engine,
They can clean up the rough areas on the castings but not remove any material past that. The Tech I talked to at LyCon said it should give an additional 5 to 8 HP per cylinder. This is on my 032-E2D with the RAM 160hp STC and a PowerFlow exhaust. LyCon estimated the output at between 190 to 200hp.
I did not dyno the engine so I can't prove it, but my fuel burn went up and it climbs like crazy.
Charged $250 per cylinder. Big bang for the bucks!

Same on my engine, dyno was 194hp at 2700. Mine is O-320-B2B I can pull back to 2350 and get 6,8gph