Airplane engine improvements with Performance Coatings
Racers, by their nature are pretty quiet about what secrets they use to give themselves that competitive edge to win. Unless you know someone well, seldom can you just walk up to a pit crew and expect to learn much. It helps if you have a friend.
Ed Dear, pilot, A&P mechanic, neighbor, drag racer and race car builder. Ed's top-fuel racing license has two digits. He goes way back, has Don Garlits number in his phone. He's been an engine mentor to me for decades and has given me so much guidance with philosophical statements that become undeniable truths.
"...if you want to know what works, go to the track."
What "works" is what is helping winners. He always tells me the fundamentals of engines, no matter what they're installed in, have not changed.
"...it never changes, fuel-air-ignition, suck-squeeze-bang-blow."
What has changed is metallurgy, precision machining, and electronics. These day’s race engines, when allowed, are computer controlled and divulge instantaneous data to make decisions in real time or by looking back at trends. What's always changing is "the next best thing", that constant quest to find that edge. Along the way some things become cornerstones and "gotta-haves" for no matter what else you do, you can't gain that edge without them even with a new "secret stuff".
For years Ed told me "When you decide to overhaul that O-200 in yer Varieze, go see Carl." The Carl he was referring to was Carl Benton, owner of Polydyn Performance Coatings. Ed can be a persuasive character. When the O-200 got taken apart he became very persuasive and finally I made a trip to meet Carl. When I met with him I asked him "Do you know Ed Dear?" He smiled and said, "Everybody in racing knows Ed Dear". Credibility +1
Carl gave me a tour of his facility and I was intrigued but not really convinced. He'd point at things and say, "... those are NASCAR heads..." On one table were 12 neatly arranged, large pistons that are gold on the piston crowns and black on the sides. Carl noticed my gaze and said "Those are Merlin engine pistons for a P-51". He explained the gold was a ceramic coating used to contain the heat in the combustion chamber and help inhibit that heat from transferring through the piston. The black was a friction coating used to help the reduce friction as the piston traveled up and down the bore. The principle is simple he said, "Remove the friction and you remove the heat, friction taxes the engines energy. Remove the friction and the engine doesn't have to work as hard, you can transfer more energy to the crankshaft." Ok, I get that but I don't know these are really Merlin pistons or NASCAR heads.. how do I know? Then, I looked across the room and I saw a picture of an airplane I recognized with autographs all over the border of it. It was Bruce Bohannon’s record setting "Pushy Galore"! Carl explained how he'd been their Sponsor and then showed me another autographed picture, of the space shuttle! It had Hoot Gibson's autograph on it thanking Carl for the help with the engine in his Cassutt Reno racer! I asked Carl what parts of my engine I should bring him and He said; "Bring me everything. We have a coating for everything!" I knew I had some phone calls to make.
I got ahold of Gary Hunter, fellow Varieze builder and Pilot, and was crew chief for Bruce's Pushy Galore. He gave Polydyn a thumb’s up in a way only a way a racer depending on sponsorships to survive could and said "We loved it when it was free!" Being in the non-profit aviation museum business and racing at Reno now, I get it Gary! Credibility +2.
I fly for an Airline in real life and Hoot Gibson was a Pilot for us now, plus I knew of him from flying in the Navy. I tracked down Hoot at work one day and picked his brain about Polydyn. He also gave it much praise and when I asked him what parts of the engine he let Carl coat he said, "Take him everything". Credibility +3. When I got home from my trip I boxed up my entire O-200 and took it to Carl. I'd just blown my budget for this upgrade and overhaul.
So what does this stuff do? As I took each part of my beloved little Varieze's motor and handed it to Carl, he described how each part would be coated. He said " Ever heard of racers polishing the inside of their case to get the oil to flow back into sump quicker and get cooler fast? Don't bother. I have an oil shedding coating for the inside of your case." There was a specific coating for every part. An oil retention coating for the gears and cam lobes. Anti-friction coatings for everything that rubbed. He even finished the outside of the case in a bright metallic gold baked on paint that made my little O-200 look like a show cars engine and this stuff was so tough you cloud hit it with a hammer and it wouldn't chip.
Every part looked different than the way I brought it in. It was a shame to hide these parts inside an engine but the real question was, how would the engine run? I’ll proudly tell you my little O-200 ran cooler, made more oil pressure and more power than it ever had. Without a way to measure it on a dynamometer my test was to run the same prop I'd used before the overhaul and see if there were any rpm and indicated airspeed changes. Before the overhaul/performance upgrade I was turning a Sterba 60x74 prop at about 2900 rpm and getting a true airspeed of 163 knots true airspeed. After the overhaul, I was able to turn that same prop at 3200 rpm and 168 knots true airspeed, about a 3 percent increase. Later I had master prop maker Ed Sterba make me a 60x80 prop. With more pitch I could absorb some of that excess energy and push more air. My rom went down to 2900 and my speed went up to 173. A ten knot increase and 6 percent more. However, I'd done a lot to the engine. Before the overhaul/upgrade I had a homemade four pipe exhaust, one electronic Electroair electronic ignition and one Slick mag, K&N filter pointed aft and other than that inside was a stock O-200. After the rebuild, I had Venolia 9.5:1 pistons, New Style TCM cylinders with the IO-360 intake valves and seats as intake guide seals, ported, polished and flow balanced by Monty Barrett Sr. himself. The crankshaft was dynamically balanced, each connecting rod assembly and piston weights were identical, and I balanced everything that rotated. Overall it was the smoothest O-200 I'd ever flown and it ran cold! You'd think with all that power it would generate lots of heat but I had to rework to baffling to get CHTs Up! The chart below shows the cylinder head temperatures for cylinder number 2, which is notoriously the hottest cylinder on a Varieze.
The yellow line is before the overhaul, the blue line after. As shown the cylinder ran an average of 40 degrees cooler, a 12 percent improvement. That’s significant but again not real evidence that performance coatings are responsible. The only real way of knowing what they do is when you take the engine apart and measure the wear. If performance coatings do reduce friction, thus wear, then it should be measurable. When that time comes I’ll be able to make a measurable analysis.. till then all I can say is you see Polidybe stickers on every took box at the track, and this last story.
Fast forward to a few years later, I’m flying around south Florida in a Beech 18 with a friend of mine Fred Katterman, owner of Islip Avionics. We’re shooting landings at Indian Town and he suggests we take a break and meet a friend of his in a hangar at the end of the runway. We walk into the hangar of Glenn Wegman and are immediately surround by P-51’s in various stages of assembly. Amazing and never in a million years would’ve guessed this existed right here in south Florida. As we get a tour from of the place from Glenn, I see row upon row of Merlin engines. On a table is 12 neatly arranged, large pistons that are gold on the piston crowns and black on the sides. I pick one up and ask why they’re these colors and he say’s “Oh I send them to a guy in Houston and he coats the for me.” Credibility +4!
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