Yamaha 160 lb engine

[Royal]

Yamaha makes some amazing boat engines. Seems the Waverunner engines would be an even better airplane engine. It just insane what HP numbers they can get out of a 3 cyclinder 1000cc engine. 

160 lbs and 130 hp

I think these would be crazy fuel efficient since you wouldn't need 130 hp to cruise. 

https://www.boats.com/reviews/new-yamaha-waverunner-tr-1-ho-engine-ushers-in-era-of-compact-performance/

[macleodm3]

They 2 stroke?  Props can only spin at 3000 rpm max..... what is the hp at 2800 to 3000 rpm?

Edited July 13, 2020 by macleodm3

[Quinton Oliviero]

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.

[Voidhawk9]

The Edge Performance engines are impressive, lots of power and light weight. But RPMs and boosting like that would leave me nervous.

For me, I think, "Would I cross the pacific with this engine?"

Because I'd like to do that one day!

[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.

[Voidhawk9]

Just now, Quinton Oliviero said:

I personally would love a turbo just for altitude compensation, but the added complexity probably isn't worth it.

Yes, exactly. I was researching down this road and discussing with some very experienced and knowledgeable folks who pointed out that for the same weight, you can install a more powerful NA engine and the installation is far simpler (read - more reliable) to boot.

Now, if it were for a racing application where reliability isn't quite as important, that may change the equation, as may other mission considerations.

[BadAss Power Sports]

On 7/14/2020 at 10:20 AM, Quinton Oliviero said:

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.

We make 313 hp on 91 Oct with this motor at 15.2 Psi of boost