Aerocarb

Sonex's Aerocarb TBI

The Aerocarb is a throttle body injector or TBI made by Sonex. (It is not a carburetor) It is a product used for the Corvair by several of the builders, with positive feedback.

Joe Horton's setup

The following summary is provided by Joe Horton, who has a 38mm Aerocarb on a 3100cc Corvair engine on a KR-2 with a gravity feed system. A factor in his selection was because it allows for a smaller frontal area by comparison to the MA-3SPA. The MA-3 carb would have required a large bump under the cowl. He says he has encountered CarbIce at least twice, but on both occasions, CarbHeat solved the issue within a few seconds. It should be noted that on Sonex's website, they say that carb ice should not be an issue on their product, but their FAQs deal with applications related to their VW-based engine, not the Corvair. Their website also states that the product can be set up for carb heat. Additionally, it should be noted that they have discontinued making the 38mm Aerocarb and are now making a new product, the AeroInjector , which is also a TBI. The aeroinjector comes in only two sizes, 32mm and 35mm.

His solution to carb ice is as follows: He has added a carb throat temp monitor to provide an indication of a problem before it happens. The days he developed carb ice were very high humidity days with temperatures in the 70's F.

The Aerocarb works effectively. Mileage is good, although not as good by comparison to MarkLangford who has the same aircraft type. His aircraft returns very close fuel burn rates by comparison at high altitude but Mark's is better at lower altitudes. His carb pulls all its air from the cowl interior. I have recently added a full air filter box and has found that it breaths better now. His carb heat box may not be as effective as Mark Langford's as his rise in intake temperatures is in the 40 to 50 degree range, which is lower than Mark's, but this is offset by using warmer air from inside the cowl where temps are higher to begin with.

The fuel tank is gravity feed to the Aerocarb with about 18 inches of head pressure at the low fuel level. He has his header fuel tank vent piped to the exterior of the fuselage and turned into the slipstream to add some ram pressure to the tank. This provides a fuel pressure of about 8 tenths of a pound static but increases to around 1.1 pounds in flight. All the fuel lines slope to the carb and all the lines in the cowl are insulated. The gascolater has a direct fresh air cooling line to it. He said his goal was to keep constant temperatures on the entire fuel delivery system so that all adjustments could be done from a consistent starting point.