{"product_id":"polini-thor-303-evo","title":"Polini Thor 303 EVO 38 HP Aircraft Engine | Mini-Max USA","description":"\u003ch1\u003ePolini Thor 303 EVO\u003c\/h1\u003e\n\u003ch3\u003e38 HP | 281cc | Liquid Cooled | Electric + Flash Start\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong\u003ePolini Thor 303 EVO\u003c\/strong\u003e takes Polini’s largest-displacement Thor engine and gives it a major update focused on reliability, durability, smooth power delivery, and thermal management.\u003c\/p\u003e\n\u003cp\u003eProducing \u003cstrong\u003e38 HP at 8,000 RPM\u003c\/strong\u003e and weighing approximately \u003cstrong\u003e47.4 lbs including the radiator\u003c\/strong\u003e, the 303 EVO delivers an excellent power-to-weight ratio for lightweight aircraft applications.\u003c\/p\u003e\n\u003cp\u003eThis isn't simply a renamed Thor 303. Polini redesigned many of the engine’s key components for the EVO, including the cylinder, cylinder head, exhaust, ignition and starting system.\u003c\/p\u003e\n\u003ch2\u003eWhat Changed With the EVO?\u003c\/h2\u003e\n\u003cp\u003eThe new Thor 303 EVO features:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eCompletely redesigned cylinder\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eEnlarged exhaust port and transfer passages\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNew \u003cstrong\u003e5-bolt cylinder mounting flange\u003c\/strong\u003e for improved sealing\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eRevised combustion chamber and squish geometry\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eImproved combustion and thermal management\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNew optimized exhaust system for smooth, linear power\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eRedesigned spherical exhaust joint to improve sealing and isolate vibration\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNew ignition system\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eDual Spark ignition available\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNew electric starter motor\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eElectric start now standard\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003ePolini Flash Starter backup starting system\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe result is a smoother, more refined version of Polini’s high-output 281cc engine built for demanding light-aircraft applications.\u003c\/p\u003e\n\u003ch2\u003ePower Without the Weight\u003c\/h2\u003e\n\u003cp\u003eThe Thor 303 EVO produces \u003cstrong\u003e38 HP from only 281cc\u003c\/strong\u003e while maintaining a complete engine weight of approximately \u003cstrong\u003e47.4 lbs including the radiator\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eWith the appropriate propeller and reduction configuration, Polini reports maximum static thrust of up to approximately \u003cstrong\u003e265 lbs\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eFor builders looking for strong two-stroke performance without the weight of a larger four-stroke installation, the 303 EVO offers an impressive combination of power, compact size and simplicity.\u003c\/p\u003e\n\u003ch2\u003eTwo Reduction Ratios\u003c\/h2\u003e\n\u003cp\u003eChoose the reduction ratio that best matches your aircraft and propeller installation:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.8:1 Reduction\u003c\/strong\u003e\u003cbr\u003eDesigned for installations using smaller or higher-RPM propeller combinations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2:1 Reduction\u003c\/strong\u003e\u003cbr\u003eAllows the engine to turn larger propellers at lower propeller RPM.\u003c\/p\u003e\n\u003cp\u003ePropeller selection must be matched to the aircraft, reduction ratio and intended operating RPM.\u003c\/p\u003e\n\u003ch2\u003eStandard or Dual Spark\u003c\/h2\u003e\n\u003cp\u003eThe Thor 303 EVO is available with Polini's standard electronic CDI ignition or the optional \u003cstrong\u003eDual Spark ignition system\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eFor aircraft builders looking for additional ignition redundancy, the Dual Spark version provides an additional level of redundancy within the ignition system.\u003c\/p\u003e\n\u003ch2\u003eElectric + Flash Start\u003c\/h2\u003e\n\u003cp\u003eUnlike earlier configurations of the Thor 303, \u003cstrong\u003eelectric start is standard on the EVO\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003ePolini also retains its mechanical \u003cstrong\u003eFlash Starter\u003c\/strong\u003e, giving the engine a secondary method of starting without relying solely on the electric starter.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eSpecifications\u003c\/h1\u003e\n\u003cp\u003e\u003cstrong\u003eEngine Type:\u003c\/strong\u003e Single-cylinder, 2-stroke\u003cbr\u003e\u003cstrong\u003eCooling:\u003c\/strong\u003e Liquid cooled\u003cbr\u003e\u003cstrong\u003eDisplacement:\u003c\/strong\u003e 281cc\u003cbr\u003e\u003cstrong\u003eBore × Stroke:\u003c\/strong\u003e 76 × 62 mm \/ 2.99 × 2.44 in\u003cbr\u003e\u003cstrong\u003ePower:\u003c\/strong\u003e 38 HP @ 8,000 RPM\u003cbr\u003e\u003cstrong\u003eMaximum RPM:\u003c\/strong\u003e 8,400 RPM\u003cbr\u003e\u003cstrong\u003eMaximum Static Thrust:\u003c\/strong\u003e Up to 120 kg \/ 265 lb with 160 cm \/ 63\" propeller\u003cbr\u003e\u003cstrong\u003eCompression Ratio:\u003c\/strong\u003e 9.5:1\u003cbr\u003e\u003cstrong\u003eCylinder:\u003c\/strong\u003e Aluminum with Gilnisil coating\u003cbr\u003e\u003cstrong\u003ePiston:\u003c\/strong\u003e Two trapezoidal chrome-plated rings\u003cbr\u003e\u003cstrong\u003eIntake:\u003c\/strong\u003e Crankcase reed valve\u003cbr\u003e\u003cstrong\u003eCarburetor:\u003c\/strong\u003e Dell’Orto VHST 28mm\u003cbr\u003e\u003cstrong\u003eAir Filter:\u003c\/strong\u003e Airbox\u003cbr\u003e\u003cstrong\u003eIgnition:\u003c\/strong\u003e Electronic CDI with variable advance\u003cbr\u003e\u003cstrong\u003eDual Ignition:\u003c\/strong\u003e Dual Spark version available\u003cbr\u003e\u003cstrong\u003eCharging Output:\u003c\/strong\u003e 40W @ 5,500 RPM\u003cbr\u003e\u003cstrong\u003eStarter:\u003c\/strong\u003e Electric Starter + Polini Flash Starter\u003cbr\u003e\u003cstrong\u003eClutch:\u003c\/strong\u003e Centrifugal, oil bath\u003cbr\u003e\u003cstrong\u003eReduction Drive:\u003c\/strong\u003e Helical gears in oil bath\u003cbr\u003e\u003cstrong\u003eReduction Ratios:\u003c\/strong\u003e 2.8:1 or 3.2:1\u003cbr\u003e\u003cstrong\u003eExhaust:\u003c\/strong\u003e Expansion chamber with aluminum silencer\u003cbr\u003e\u003cstrong\u003eEngine Weight:\u003c\/strong\u003e Approx. 21.5 kg \/ 47.4 lb including radiator\u003cbr\u003e\u003cstrong\u003ePropeller Rotation:\u003c\/strong\u003e Clockwise\u003cbr\u003e\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Polini Motori\u003cbr\u003e\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e Italy\u003c\/p\u003e\n\u003ch3\u003eFuel \u0026amp; Oil\u003c\/h3\u003e\n\u003cp\u003ePolini specifies:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eE5 unleaded gasoline, 95 RON with no more than 5% ethanol, or\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e100LL aviation gasoline\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eMixed with \u003cstrong\u003e2.5% fully synthetic 2-stroke oil\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eAlways follow the current Polini operating manual for approved fuel, oil, mixture and operating requirements.\u003c\/p\u003e\n\u003ch3\u003eFuel Consumption\u003c\/h3\u003e\n\u003cp\u003ePolini reports approximately \u003cstrong\u003e3 liters\/hour \/ 0.8 gallons\/hour while producing 30 kg \/ 66 lbs of static thrust\u003c\/strong\u003e under its test conditions.\u003c\/p\u003e\n\u003cp\u003eActual fuel consumption will vary with propeller, aircraft installation, RPM, atmospheric conditions and operating power.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eCarburetor Options\u003c\/h1\u003e\n\u003cp\u003eThe Thor 303 EVO is offered by Polini with both:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDell’Orto VHST 28mm\u003c\/strong\u003e\u003cbr\u003eTraditional float-style carburetor configuration.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eTryton Diaphragm Carburetor\u003c\/strong\u003e\u003cbr\u003ePolini also offers the EVO with a Tryton diaphragm carburetor, designed to provide stable carburetion, optimized fuel consumption and easier transportation.\u003c\/p\u003e\n\u003cp\u003eAvailability may vary. Contact Mini-Max USA if you would like a specific carburetor configuration.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eRecommended Applications\u003c\/h1\u003e\n\u003cp\u003eThe Thor 303 EVO is designed for lightweight aviation applications where strong power-to-weight performance is important.\u003c\/p\u003e\n\u003cp\u003ePotential applications include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eExperimental aircraft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eAmateur-built aircraft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eThree-axis ultralights\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eLightweight sport aircraft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eTrikes and weight-shift aircraft\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eParamotor and powered-paraglider applications\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eCustom light-aircraft projects\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor Mini-Max builders, the Thor 303 EVO is an excellent engine to consider when your aircraft and mission call for approximately \u003cstrong\u003e38–40 HP of two-stroke power\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eEngine suitability ultimately depends on the aircraft model, completed aircraft weight, center of gravity, engine mount, cooling installation, propeller and reduction ratio.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eWhat's Included\u003c\/h1\u003e\n\u003cp\u003eYour Thor 303 EVO is supplied in the configuration selected when ordering.\u003c\/p\u003e\n\u003cp\u003eThe engine package includes the major factory-supplied engine systems applicable to that configuration, including the engine, reduction drive, starting system, exhaust and cooling components.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePropeller is not included unless specifically stated with your order.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eBecause Polini periodically updates engine packages and supplied components, contact Mini-Max USA if you need confirmation of exactly what is included with your specific configuration before ordering.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eManufacturer Warranty\u003c\/h1\u003e\n\u003cp\u003ePolini states that the Thor 303 EVO is covered by a \u003cstrong\u003e24-month manufacturer warranty\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eWarranty coverage, exclusions, maintenance requirements and eligibility are governed by Polini Motori's current warranty terms and conditions.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eOrdering \u0026amp; Shipping\u003c\/h1\u003e\n\u003cp\u003ePolini engines are typically \u003cstrong\u003especial-order engines\u003c\/strong\u003e and may ship directly from the manufacturer or through Mini-Max USA depending on availability and the configuration ordered.\u003c\/p\u003e\n\u003cp\u003eLead times vary.\u003c\/p\u003e\n\u003cp\u003eInternational freight, customs fees, duties and import tariffs may apply. If an import tariff or duty is assessed on an engine, that charge is the responsibility of the purchaser and may be collected by the carrier or billed by Mini-Max USA.\u003c\/p\u003e\n\u003cp\u003eNeed help choosing your ignition, reduction ratio, carburetor or propeller combination?\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eContact Mini-Max USA before ordering and we'll help you configure the engine for your aircraft.\u003c\/strong\u003e\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eImportant Engine Notice\u003c\/h1\u003e\n\u003cp\u003ePolini Thor engines are intended for appropriate recreational, ultralight and experimental aviation applications. Engine selection, installation, propeller selection, fuel system, cooling, weight and balance, maintenance and operation are the responsibility of the aircraft builder, owner and operator.\u003c\/p\u003e\n\u003cp\u003eEngine failure can result in serious injury or death. Always operate within the manufacturer's limitations and maintain a safe landing option whenever practical.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eShopify Short Description\u003c\/h1\u003e\n\u003cp\u003e\u003cstrong\u003e38 HP from just 47.4 lbs including the radiator.\u003c\/strong\u003e The new Polini Thor 303 EVO features a redesigned cylinder and combustion chamber, improved exhaust, updated ignition, standard electric start plus Flash Starter, and optional Dual Spark ignition. Available with 2.8:1 or 3.2:1 reduction.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch1\u003eProduct Highlights\u003c\/h1\u003e\n\u003cp\u003e\u003cstrong\u003e38 HP\u003c\/strong\u003e\u003cbr\u003e@ 8,000 RPM\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e281cc\u003c\/strong\u003e\u003cbr\u003eSingle-cylinder 2-stroke\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e47.4 lbs\u003c\/strong\u003e\u003cbr\u003eIncluding radiator\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eUp to 265 lbs Thrust\u003c\/strong\u003e\u003cbr\u003eWith 63\" propeller*\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eElectric + Flash Start\u003c\/strong\u003e\u003cbr\u003eStandard\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDual Spark Available\u003c\/strong\u003e\u003cbr\u003eOptional ignition redundancy\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.8:1 or 3.2:1\u003c\/strong\u003e\u003cbr\u003eReduction options\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eLiquid Cooled\u003c\/strong\u003e\u003cbr\u003eOptimized thermal management\u003c\/p\u003e","brand":"Polini Motari","offers":[{"title":"Standard Ignition \u0026 Electric Starter \/ 2.8:1 \/ Standard Dell’Orto VHST 28mm","offer_id":50108880584927,"sku":"928.000.110","price":4899.99,"currency_code":"USD","in_stock":true},{"title":"Standard Ignition \u0026 Electric Starter \/ 2.8:1 \/ Upgraded Tryton Diaphragm Carburetor","offer_id":51365134467295,"sku":null,"price":5199.99,"currency_code":"USD","in_stock":true},{"title":"Standard Ignition \u0026 Electric Starter \/ 3.2:1 \/ Standard Dell’Orto VHST 28mm","offer_id":50108880617695,"sku":"928.000.111","price":4899.99,"currency_code":"USD","in_stock":true},{"title":"Standard Ignition \u0026 Electric Starter \/ 3.2:1 \/ Upgraded Tryton Diaphragm Carburetor","offer_id":51365134500063,"sku":null,"price":5199.99,"currency_code":"USD","in_stock":true},{"title":"Dual Ignition \u0026 Electric Start \/ 2.8:1 \/ Standard Dell’Orto VHST 28mm","offer_id":50108880650463,"sku":"928.000.120","price":5499.99,"currency_code":"USD","in_stock":true},{"title":"Dual Ignition \u0026 Electric Start \/ 2.8:1 \/ Upgraded Tryton Diaphragm Carburetor","offer_id":51365134532831,"sku":null,"price":5799.99,"currency_code":"USD","in_stock":true},{"title":"Dual Ignition \u0026 Electric Start \/ 3.2:1 \/ Standard Dell’Orto VHST 28mm","offer_id":50108880683231,"sku":"928.000.121","price":5499.99,"currency_code":"USD","in_stock":true},{"title":"Dual Ignition \u0026 Electric Start \/ 3.2:1 \/ Upgraded Tryton Diaphragm Carburetor","offer_id":51365134565599,"sku":null,"price":5799.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0805\/1045\/1935\/files\/THOR_303_maxi.webp?v=1781238609","url":"https:\/\/www.flyminimax.com\/products\/polini-thor-303-evo","provider":"Mini-Max USA","version":"1.0","type":"link"}