Quinton Oliviero

There's a performance mod shop not far from me that is known for breaking horsepower records with their sleds. I had found them from a news article about their 650HP Yamaha Apex. Come to discover in talking to "Hurricane Dave" that was years ago, and their more recent efforts are in the 1000s. Of course, these are Yamaha engines in name only at this point. Virtually every part is custom made, specially mixed racing fuels are used, and *insane* boost pressures. Like 60+ PSI (Edge Performance, by contrast, uses only a ridiculous 40+). I definitely wouldn't trust a monster like that trans-pacific, it was obviously built to go fast, not to last long. Interestingly though, he says the one part they've never had fail, even at those insane power levels, is the crankshaft. Tip of the hat to Yamaha for building a crankshaft that can take six times the force of its design spec! Anyway, all this to say I think you could pull 180-200HP out of one of those engines naturally aspirated easily, and since they were designed for long treks at 75%+ power I don't think you'd have any issue. I personally would love a turbo just for altitude compensation, but the added complexity probably isn't worth it.

Power to weight for marine engines tends to be not great, and since waverunners tend to use the water they're immersed in as coolant they're not really a viable option. Snowmobile engines are better, but quite a few Aussies have been trying to get some sort of marine engine to work since they have a lot more of those, and not so much with the snowmobiles. To my knowledge none have been successful. There's a fairly sizable community for Yamaha snowmobile engine conversions for aviation on Facebook. Most of the ones flying are in Gyrocopters and STOL type aircraft. There are actually a couple of groups, but there's a fair bit of overlap. There was some community split around a guy named Greg Taylor Mills, who runs a company called Mohawk. He's a bit of an outspoken "salesman" type personality and it caused some drama, but he and his group are still a pretty good source for information. Want to see something truly amazing? Look up Edge Performance and their EPeX 300Ti. It's a converted Yamaha Apex engine with Teal Jenkins' "SkyTrax" gearbox. 300 HP, and I think they're already pushing it up into the 400s. Pretty sure it's what Steve Henry is flying in his "YeeHaw" Highlander for STOL competitions. Not sure what the installed weight is, but a few guys are reporting their Apex installations at ~140lbs ish. I'd bet with the turbo, custom intake/exhaust, coolant system and whatnot this thing is probably closer to 200. Andrew: To answer your question they're 4 strokes, and then reduced at the gearbox for propellers. Peak power is something like 9500-10500 engine RPM, but reduced at 3.83:1 in the case of the Apex. Some of the older/smaller engines (RX1, Phazer) the gyro guys have been using converted Rotax C gearboxes for a while now with a fair bit of success.

Hopefully I'll be editing this space with some details soon, but a friend of mine from my time in Quebec is selling his beautiful Cozy III, C-GDSB. He had a few ads up for a while, but mostly in French-language or Canadian/Quebec specific publications. All I can remember off the top of my head is that it's got an O-320, Catto 3 blade with nickel leading edges, dual EFIS/EMS. I'd buy it myself, but I need every spare cent to get my Cozy IV build done, and I'm afraid that my wife will definitely enforce her threatened "Plane to Pony ratio" if I get a third plane! More to follow.

Oh, by the way, if you're planning to use the formulas from the article to calculate pitch don't be a weirdo. Please use knots, not mph. Why would you use mph for aviation? It bothers me, like when Europeans express altitude in meters. Don't even get me started on altimeter settings in millibars... Anyway, the conversion factor is different for knots. Pitch is expressed in inches of forward motion per revolution of the prop, but we want nautical miles so: 6080 feet in a nautical mile, and 12 inches per foot is 72960 inches per nautical mile. Likewise RPM is per minute, and we want hours (for nautical miles per hour) and there are 60 minutes per hour. 72960 / 60 = 1216 so if you want to go speed V at rpm R, the desired pitch is P. P = V x 1216 / R or alternatively if you turn a prop of pitch P at rpm R you will get speed V V = P x R / 1216 where P = pitch in inches V = speed in kts R = prop speed in rpm Just be aware that these are what I would call "glossy brochure" numbers. You may not be able to achieve a speed of V because of drag, or an rpm of R because your engine doesn't produce enough torque. But it'll help you get a good sense of whether a prop is a good fit for your aircraft. Vne is 191 kts, so P = 191 x 1216 / 2700 gives you 86 inches at max power could theoretically rub just up against it. I'd call that the upper limit for a cruise prop. There are, of course, other factors. That 86" pitch might not turn at a sufficient RPM (2200 at a minimum, I'd be more comfortable with 2400) at static to give you enough takeoff power. Rule of thumb I learned is that subtracting an inch of pitch will give you an extra 40 RPM at static. I've got no math to back that up though, so take that for what it's worth.

Welcome Rafael! I'm in pretty well the same boat you are, minus your education and experience with composites. What could possibly go wrong? LOL I want to echo the other guys sentiments on the Mazda rotary. I loved that engine in my RX-8, but years of running down internet rabbit holes has taught me that it's probably just not meant to be a viable aircraft engine. A lot of the auto conversion guys in the Vans world either tried and failed at it, or found out that it was more trouble than it was worth, and that was back when there was a community! They always came in heavier than a suitable (if not comparable) lycoming after the gearbox, liquids, and radiators were factored in, and they seem to run hot. Plus there's no support out there anymore. Even Mazda doesn't make them anymore! PSRUs are hard to come by, ECU issues abound, etc. I had read that Atkins Rotary might still put together a FWF kit if you want to take the chance, but I can't confirm that. Good luck with your build and keep us updated with how it's going!

CS, maybe not. But in-flight adjustable options are getting better. IVO Prop and Airmaster have been known around here for a while. There are also a lot of props coming out of Ukraine and Russia these days. Their thing is mostly ground-adjustable props for <130hp and they seem to be marketing their products more toward the STOL guys so I haven't paid them much mind, but if you look at this link (http://www.airtrikes.net/propellers.shtml) you can see that one of the companies, calling themselves Kool has an in-flight adjustable option. If you go this way though, it's worth making sure that they understand that you'll be using a direct-drive engine. Apparently they're not as common outside North America and there have been some blade failures over the misunderstanding. Ground adjustable models run about 1200 USD, in flight adjustable models go for 1800. Another option, sure to stir up some controversy, is the Aeromatic propeller. It was a precursor to the modern constant speed propeller and was kind of a thing for a while on certified aircraft in the post-war era. Air pressure against the blades pushes the pitch toward fine, but centrifugal force on a set of counterweights in the hub as the prop speed increases forces the pitch toward coarse, ideally finding an equilibrium. Univair quit making them I think in the 60s, and the propeller went out of style, but a guy named Kent Tarver revived them a few years back. Reviews are mixed to say the least. Some people love them, saying they're the next best thing to a CS prop at half the price, and others say they hate them and would never fly behind one but I can never find much specificity to the haters issue. I have turned up that the prop hubs will leak a little oil, and that in certain flight regimes the prop will seem to "hunt" back and forth rather than settling on a pitch for the RPM it's at. Used ones don't seem to be easy to come by, but no telling if that's good or bad. Tarver used to make claims like "60+ years without a single AD" or something like that (the first ones were built in 1946 and some are still flying apparently), but I haven't seen that in a while and the claim is gone from his website. It also seems he got tired of wrestling with the FAA and gave up on the certified market. I haven't seen any crashes or anything relating to the failure of one of these things, but it also looks like they were never all that popular, so who knows? If you want to see what all the fuss is about a new one will cost you about 5400 USD.

I knew I recognized that SQ2000. Dave showed me pictures of it, as part of his "portfolio" if you will, to convince me to let him finish the build on my Cozy. I've got to say I'm surprised to hear it's had the issues that it has, as he'd built at least a Varieze and a Long by 2005, and from what I can tell this thing was built in 2011 (though I'm just guessing based on the timestamp of the photos he sent me. I can't make out the N-number)

I do! Though that looks like a homegrown solution. Looks like a tight fit in there, and is that a Ballistic gearbox? That thing looks and sounds like a monster, and he claims 495 HP! Electric Supercharger do you think? Oh I'm with you on the LS3. Cheaper, and better P/W. Definitely would have to put in a little more nose ballast though, eh? The titan guys are just up the road from where my project is right now in Ohio. Might be worth going to have a look!

The Supermarine V8 LS2 looks beautiful, but at 48k AUD it's a little out of my price range. (http://www.campbellaeroclassics.com/sitebuildercontent/sitebuilderfiles/spittybrochure.pdf) The Titan LS3 kit though, wow. 300 HP and it's only $6250 USD? They say their gearbox and conversion kit aren't included, so conservatively add another $10k for that? They've also got suzuki engine kits to directly rival Aeromomentum. Assuming my $10k estimate is right they slightly undermatch price, horsepower, and weight but their gearbox ratio is far more attractive than AM's 2.588:1 (who wants peak horsepower at 2240 prop RPM?). I also really like the look of that Honda. (http://www.titanaircraft.com/engines.php)

I appreciate the offer, but after consulting quite a few other people's experiences I have to pass on an auto conversion that's not already a FWF kit. Even experienced guys are saying it's taken them 400 hours to get things right, and given my schedule that's 2 years of work. I love the rotary engine, as I myself used to have an RX-8 and it was a great car, but there just aren't enough rotaries flying anymore for me to be able to get the help I would certainly need. Man, the idea of that power to weight ratio though... From what I gather nobody was ever really able to keep their 13B builds much below 280 lbs, but putting a turbo on it could be an easy 350HP+! And the 20B? I've seen street cars that were able to make it over 900! Obviously I don't think you'd want to run those kind of boost pressures to have any kind of life on that engine, but it's still really impressive.

Yeah, the numbers I'm getting are between 72 and 77 g/hp/h or about 0.16 lb/hp/h Way too low. I expect real world consumption should be like triple that!

In consideration of the wise words of people like Chris (and a few others) I've decided to limit my search for powerplants to complete FWF (or in our case FWR?) kits. I like tinkering, but I like flying more. Having a unique engine setup means having unique problems. Much as the price of a roll-your-own automotive conversion is attractive I just don't have the mechanical knowhow at this point to treat that as a realistic option. That and there's no way my wife will get in if I do! A few more engines on my watchlist: Aeromomentum has added a couple of engines to their selection. A naturally aspirated version of the AM20T which at 170HP might be right for a Cozy. There's also an AM24 now, which depending on weight could be very nice as well. No details on these new models as of yet, but the AM20T is advertised as 260HP for 285 lbs with a price tag of 19k, so that should give some indication. Any fears I had about the engineering of these machines have been put to bed after digging through forum posts and youtube videos of Mark Kettering. He's done his homework, and he doesn't seem the type to overpromise and underdeliver. Tons of testing, and seemingly nothing but happy customers. The balkanization of experimental aviation never ceases to astound me, as I just discovered that the gyroplane guys have been flying Yamaha snowmobile engines since about 2013 and fixed wing guys are just getting in on the action! Mohawk Aero Craft has made a kit from the 998cc Genesis Turbo engine from the Yamaha Sidewinder snowmobile. I gather the power clocked in at over 200HP sub-200lb weight (I remember reading 204HP and 170 lbs, but I can't find the source now). Only one flying right now, though about 20 more with other Yamaha engines. Greg Taylor Mills seems very knowledgeable and enthusiastic, and I think has a genuine desire to advance the state of experimental aviation. My concern with this one is that there hasn't been a lot of testing, and none of the guys flying these things seem to have more than a couple hundred hours. Ten years ago the auto conversion True Believers like all the Subie guys (and I'm not talking about the Egg ones here, that's another story) thought they were launching a revolution until a few hundred hours later crankshafts started to fail... Scared a lot of people off. No failures on this one as of yet, and it is definitely one to keep an eye on. A > 1.0 P/W ratio is a big deal! I'm still keeping the Diesel dream alive. P2M, an italian company, is advertising a line of diesel engines and is trying to get certified. Actually saw one bolted to a LongEZ on another forum (there's that balkanization again). All of their specs on their website are in metric, but the translation is this: The JPE01 engine is 150HP and weighs 220 lb, burns about 3.7 GPH at full power, and closer to 2 in cruise. The JPE03 is 220HP and weighs 345 lbs, burns 5 GPH at full power and 3.7 in cruise. I would avoid the 02 and 04 models as they are Hybrids. They bolt on 88 lbs of electric motor and battery to give ~30 minutes of 80 extra HP. Juice that in my opinion is not worth the squeeze. That's a lot of added weight and complexity for extra power at takeoff. Anyway, these seem like "glossy brochure" numbers and I'm sure the price tag will be astronomical, but they're supposed to be at Oshkosh this year, so we'll know more in July. They have a distributor in western Canada but it sounds like they'll have an American one this year.

The engine is interesting, but at nearly 100 lbs over plans weight I feel like it would really complicate w&b. Also that prop is pitched on the short side. You'd have to spin it at 2800 rpm to get maybe 150-155 kts. As for the body? If he's not an aerospace engineer the changing of the fuselage dimensions is a hard pass for me.

Just for those who aren't tracking, 3000 CAD is only 2281 USD.

I gather Aeromomentum uses Suzuki engines? They look pretty good! That being said their unbelievably cheap gearbox gives me pause. A Powersport PSRU is like $9k, which fits pretty well with what guys like Marcotte and Crook were charging back when they still made theirs. I found a company that is making their own gearbox for aviation (specifically to transmit 250HP for Mazda rotaries) that is charging $5500. The fact that the Aeromomentum gearbox is only $1600 is a serious red flag for me. Plus to get the 260HP out of a 2L engine it looks like they needed a turbo and 10.5:1 cylinders. I wonder if a turbo could be put on the AM15 147HP version to get it to ~180? These guys are definitely worth watching. Hopefully not another Viking. The Lycoming O-320 and O-360 are bulletproof by just about any definition(minus the infamous O-320-H2AD). Flight schools all over Canada and the US have racked up millions of hours on these things over the years, and it's the odd one that doesn't make it to TBO. I've seen some pretty gnarly failures - a friend of mine had to land on Virginia Beach after part of his O-320 decided to depart the aircraft by way of blasting itself right through the crankcase - but those stories are exceptional in part because they are so rare. It's just a shame that being the big name in the market means they still command such high prices for carbureted, magneto driven, early 20th century technology when others are offering FADEC for much less. I've kept my ear to the ground on the alternatives, I even really considered Diesel for a while there, but the offerings are still too slim and those that are out there are far too expensive. Deltahawk, if they ever become a thing, is apparently asking $65k. Not 100% sure WAM is still producing? And Continental still doesn't seem that friendly to single purchases, more looking to power a new fleet of certified aircraft. I'd considered a Subaru EE20, but they got infamous for crankshaft failures that Subaru disavowed. The availability and relatively low cost of Jet-A keeps the dream alive though. I'd really love to see someone succeed in this area, I just feel like it's going to have to be someone much richer's passion project.