VALLEY ENGINEERING BIG TWIN

WINNER OF THE ULTRALIGHT INNOVATION - CUSTOM POWER PLANT AWARD AT OSHKOSH, 2006 40 HP
3600 rpm
(peak) 32 HP ( consistent ) 120 lbs COMPLETE* ( Fan Cooled, 1.98 to 1 PSRU, 70" X 40" prop. 250 lbs static thrust.) *COMPLETE implies dry weght, 20 amp alternator, starter, oil cooler, oil filter AND prop. In other words... READY TO FLY!!

See YouTube Videos of the Big Twin

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The engine is a Four-Cycle, two-cylinder, 990cc, V-Twin occurring 40 hp at 3600 rpm. With a Valley Engineering PSRU and Culver prop, it will certainly do whatever and also more that the present smaller two-cylinder, two-cycle engines perform. All this through the relicapability, low rpms, smooth procedure, fuel economic situation and also throaty sound of a four-cycle engine.

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Dimensions: Height from bottom of engine to top: 19" Height from bottom of engine to facility of crank shaft: 6 1/2" Height from bottom of engine to center of PSRU: 11.5" - 12" depending on PSRU proportion. Width: 17" Depth from ago of engine to earlier of prop flange: 15" (fan cooled) Depth from back of engine to ago of prop flange. 13 1/2" (cost-free air) Prices: The premium package through Big Twin engine, Valley design Series 3 PSRU, custom manifold, Weber Carburetor, Valley Engineering practice automatic-carb-warm, electric fuel pump and also practice cut Culver propeller designed for your certain aircraft"s engine is $5495 (price excellent thru Feb 2017). Your engine package come firewall-forward, ready-to-mount and fly! (or in a pusher configuration, firewall backwards.) 50 hp Big Bad Twin!

By some changes, tweaking and tuning we"ve upgraded the 40 hp Big Twin to the 50 hp Big Bad Twin. The additional power renders a BIG difference too. All dimensions the exact same as the Big Twin via a small little bit more fuel intake... around 2 gallons an hour. The firewall forward package is the same also. Price $6195 (price excellent thru Feb 2017).

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Click HERE to read the post around the Back Yard Flyer and Big Twin engine that appeared in the December "06 Issue of EAA Sport Pilot Magazine
All the photos below are thumbnails, Just click on the thumbnail for a larger photo. (Oshkosh "06 photos by Monty Graves of Iberia, MO.)


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This view offers you a look at the custom-designed intake manifold. The original carburetor has been reput through a Weber carburetor. Also visible is the pulse fuel pump placed on peak of the right-hand cylinder.
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The Valley Engineering reduction for the Big Twin engines supplies an automatic belt-tensioning /slip-clutch (idler pulley) on a Poly-V belt to act as a one-way clutch. This substantially reduces the torsional backlash resulting in a a lot smoother operation.
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You can see the pulse fuel pump is the little black box on top of the rocker cover. The white asbestos fabric tube covers the Valley Engineering automatic carburetor warmth source..
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Here"s a great shot of the automatic slack-side tensioner on the Poly-V belt. Also visible is the starter, oil cooler and also oil filter.
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When they first gained the engine, they tested the Big Twin by mounting it on a dune buggy. Larry gained it approximately the 50 and also 60 mph variety up and dvery own hill. The buggy weighs in the 900 pounds array.
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Then the significant testing started by mounting the engine on among their WaterBug air watercrafts and also running it at full throttle for hours and also hrs on the Osage river. They hired high-school boys to do this and they all jumped at the possibility.
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With the relicapability of the engine prcooktop, the men installed it on a extremely modified Legal Eagle. This aircraft has Honcho wings and also a wing expectancy of 32 feet.They bought as a test aircraft platdevelop. They tested many various props and also PSRU ratios to arrive at simply the right one.

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Here"s an additional look at the automatic belt-tensioning slip-clutch. Also, the "piccolo" exhaust manifold that really smoothes out the engine sounds.
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The Big Twin made its Oshkosh dehowever via the brand-new Back Yard Flyer UL. It was flvery own eextremely day and at the end of the week, Gene Smith was awarded the Custom Power Plant award for his innovative new addition to the line up of power plants available for sport aircraft.
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This is a very compact engine via numerous functions not found on various other tiny engines. Eincredibly Big Twin engine package comes with a Valley Engineering custom PSRU and also Culver prop custom-built for your specific plane.
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A starter, oil filter, oil cooler, alternator and Valley Engineering"s exclusive auto carb warmth attribute are conventional through the engine. Note the little size of the fuel tank. That"s all you"re going to need because the engine only sips 5 QUARTS of gas per hour..
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The Big Twin engine will certainly essentially remove all the problems linked via two-cycle engines and also still supply the exact same performance. No oil to mix, a lot even more reliable four-cycle performance, much less noise and a lot simpler maintenance.
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Sharon Starks stands through Larry Smith just after taking delivery of her Kolb Twinstar via its fan-cooled Big Twin engine package. No even more Two Cycle woes here! The engine starts via a simple push of the button and also fires best off. Very smooth idle at 750 rpm and very, extremely quiet.
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Cock Starks runs the Kolb down the runmethod at Liberty Landing International Airport. At simply 2000 rpm, he had the ability to raise the tail. If it hadn"t been raining, he"d have actually taken her around the patch. Flight tests will certainly be began as soon as the weather breaks.
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Sharon Starks pops the Kolb off for the initially time via the Big Twin purring away. They first did a new weight and also balance to watch if tright here was any kind of adjust. (none). Then numerous "light on the gear" runs were made down the runmethod to just examine out acceleration. ( no distinction tbelow either.)
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Sharon Starks makes a low pass dvery own the runway at Liberty Landing International Airport via the Big Twin put-placing amethod behind her at 2800 rpm. They were worried that the new area of the prop; 5"greater than it had been before would affect trim. It didn"t. The aircraft flew simply choose it did prior to the engine readjust however through a LOT LESS vibration and a MUCH LOWER noise level.

Please note: While this set-up is constructed and designed for airboat usage, as you deserve to see, it can be quickly adapted for usage on Ultralight and also some smaller Light Sport Aircraft.