Turbocharged engine options for a 2 seater - what would you consider?

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thisadviceisworthles

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I'm looking at turbo engine options for a 2 seat plane, something along the lines of a Whitman W8.

The big points I would like to consider are:

Under 220lbs installed
Minimum 90hp @ 9000ft DA
Ability to run on pump gas I can buy anywhere (including E10)
Forced induction for consistent takeoff performance
Installed price of under $20K
Some proven time in the air (I don't want to be the first doing this install), with manufacturer support being ideal

My "measuring stick" is the Rotax 914, but I am looking for something with a lower cost to overhaul
My plan is to build this to be my "last plane", so I am looking at per hour cost including overhaul and with a preference for efficiency and ease of running.
 

addaon

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I think that 90 hp is just a bit small for turbocharging to be a common option. There's not a lot of engines much less than 1.5 L, which will be closer to 200 hp with turbo (assuming redrive). The 914 is unusually small for a turbo option, and runs at pretty low manifold pressure compared to the automotive world. As someone who lives at altitude I'm a huge fan of turbos, but I think you might end up happier with performance, availability, and maintenance costs to look at something that's 125 hp naturally aspirated (giving you your 90 hp at 9k); something like the ULPower UL350iS will hit your weight and power targets, significantly outperform when you're below 9k, and is a "real" airplane engine (which may or not be a pro for you).
 

addaon

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The G10? Wasn't that rated to closer to 70 hp? I also wonder how much lighter it is than a modern 1.5 L four-cylinder at 2x or 3x the power (or a heck of a lot of derating).
 

addaon

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That Yamaha is running /really/ rich at WOT if it's an 19 gph... I know a lot of automotive ECU tunes tend to get super rich above 75% power or so, but if that richness holds up it's concerning. Interesting option other than that.
 

KeithO

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Viking 90 and add turbo of your choice. You would need to re-program the controller. A lot depends on whether you are turbo normalizing or actually adding boost because that engine is good for 90hp at sea level. The logical alternate is a turbo 912, but that is a much more complex subject than a turbo normalised Mitsubishi Mirage engine (viking 90.
 

thisadviceisworthles

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I think that 90 hp is just a bit small for turbocharging to be a common option. There's not a lot of engines much less than 1.5 L, which will be closer to 200 hp with turbo (assuming redrive). The 914 is unusually small for a turbo option, and runs at pretty low manifold pressure compared to the automotive world. As someone who lives at altitude I'm a huge fan of turbos, but I think you might end up happier with performance, availability, and maintenance costs to look at something that's 125 hp naturally aspirated (giving you your 90 hp at 9k); something like the ULPower UL350iS will hit your weight and power targets, significantly outperform when you're below 9k, and is a "real" airplane engine (which may or not be a pro for you).
[email protected] 9K feet is based on having more than the design HP in an extreme DA. The line is kinda arbitrary, because I am confident I can get that out of some of the NA engine options, so it seemed like a good floor.

Before we get too far down the rabbit hole, take into consideration the power requirement for a W8. 90hp is a tad weak at sea level. Something to consider.
The W8 was designed around the C85/C90/O-200, so 90hp at sea level is within its design specs.

Having said that, I am open to more power, that is a floor not a ceiling.
 

thisadviceisworthles

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Wow, that is an awesome setup, and right along the lines I am thinking of.

I had no idea about this specific plane, all of the Yamaha conversions I have seen are on STOL planes, either running NA, or a custom turbo setup outputting 300hp.

200hp in a factory tested design sounds like a great place to start, even if the ECU tuning seems to need some tweaks.
 

rv7charlie

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It's a relatively new installation, but the guy doing it makes the reduction drives for a lot of the STOL Yamahas. Pretty sure he's proceeding cautiously since this is the 1st one known on a faster a/c like an RV.

19gph isn't out of line if it's at full power. The engine is actually rated at ~200 HP at sea level. A 200 HP Lyc will burn ~19 gph at full power. There's no free lunch, and most 4 stroke piston engines burn pretty close to the same amount of fuel at the same HP, when running at full power. (There can be significant variations at low power settings, depending on induction, timing, etc.)
 

addaon

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That's about 0.6 lbs*hp/hr... a 200 HP Lyc might burn that at full power, but it'll back down to 0.48 or so when leaned at 75%. An automotive engine should back down to 0.42 or better...
 

addaon

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Yep. Hence concern that 0.6 is high... but as Charlie mentions, that's not unusual at full power, all of these engines are basically fuel-cooled engines at full throttle; it would just be nice to see saner numbers around the torque peak to make sure that nothing weird is going on.
 

Tiger Tim

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A Yamaha powered Tailwind was living in my fantasies for a while too. Be nice to get it north of 200mph VFR at 17,500 eastbound with a rockin wind from behind and all the benefits turbo-normalizing and TAS at altitude can bring.
 

Monty

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That Yamaha is running /really/ rich at WOT if it's an 19 gph... I know a lot of automotive ECU tunes tend to get super rich above 75% power or so, but if that richness holds up it's concerning. Interesting option other than that.
Not that rich for a boosted engine. I don't think it's about cooling in a liquid cooled engine, it's about detonation margin on boost. 100LL may help, but requires dyno time to test.
 
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