MOTORES ULTRAVAIR

 

 

 

Introducing the UltraVair 2 cylinder opposed, four stroke ultralight engine.

• attractive aircraft appearance.
• low cost to build.
• balanced, smooth running 35 hp.
• weighs 80 lbs with intake and magneto ignition and only 27.5" wide.
• cradle or firewall mount configurations.
• lightweight, rugged design achieved by stock displacement.

Stock configuration includes:

• hydraulic valve lifters.
• down-facing exhaust.
• hardened valve seats.
• strong, forged crankshaft.
• well-finned heads for cooling.
• machinable, weldable aluminum case and heads.
• stock flywheel main seal serves as excellent propeller flange seal.

The UltraVair engine is made from a 6 cylinder General Motors Corvair engine cut down to 2 cylinders similar to the way the VW engine is converted to an ultralight engine. The prototype produces an estimated 35 hp at 3,500 rpm. It produces this power with stock pistons, crankshaft and camshaft. The stock Corvair has hydraulic lifters and strong through-bolts holding the case halves together. It also has the exhaust ports facing down and a removable top cover and oil pan. No special head or case boring is needed. This eliminates expense and the removal of material that weakens engine components

The prototype has single ignition using a 2 cylinder Fairbanks Morse magneto from a Wisconsin engine. The carburetor is a side-draft Bendix from a Harley Davidson motorcycle. The engine only weighs 80 pounds dry and runs very smooth due to the fact that the stock pistons and rods are very light, reducing reciprocating weight and the tendency to shuffle. The crankshaft is modified with weld-on counterweights.

UltraVair cylinder heads are extremely simple to modify and both heads can be made out of one stock Corvair head. A simple aluminum plate is welded in to complete the rocker box area and no modification is required for the rocker arms. The valve covers are cut down from stock covers and bolt on. The stock Corvair heads are very rugged and well finned. When cut for two cylinder use, the heads retain fins all the way around.

Stock pistons, cylinders and rods can be used. On the prototype, the best two cylinders out of the six were honed and re-ringed. The block is completed with basic machine work. Welding on the block is not required, but can be done to improve cosmetic appearance. Corvair parts are readily mavailable from several suppliers and total engine cost is perfect for the homebuilder budget.

Specifications:

Future changes include, battery ignition, charging system, dual ignition, fuel pump, and electric starter.