OHG was originally started by a group of ex-Impco employees as described in the History of OHG and the OHG product line is now part of the NGVI North America (NGVI NA) Streamline™ carburetion products for gas engines.
Nolff's Carburetion originally manufactured copies of Impco products when Impco's patents expired but Woodward acquired Nolff's Carburetion and their product line in 2002. The Woodward Governor Company, through their acquisition of Nolff's Carburetion then manufactured and sold the OHG and Nolff's products. In 2008, NGVI North America, purchased the design and manufacturing rights for the Streamline product line from Woodward Governor Company.
The OHG 450 mixer was marketed as the Streamline N-CA475 mixer as well as the MM X-450 while the OHG X-1 vaporizer/regulator is currently marketed as the Streamline N-H420 vaporizer/regulator. Although NGVI NA has an excellent guide to sizing, installing, and troubleshooting their equipment in their online catalog and the N-CA475 mixer was rated at about 250 hp for automotive applications, they gave very little information about the operation of the CA475 mixer.
The original OHG X-450 and X-1 gaseous fuel components and their current NGVI NA versions are excellent alternatives to Impco's Model CA425 and Model EB products. However, since the X-450 mixer was manufactured for NGVI NA by MM (Marilyn Miller), this product is currently not in production.
For high performance carbureted applications, the N-CA475 mixer is similar to the Impco Model CA425: 250 hp compared with 287 hp. In addition, the N-CA475 has a more sophisticated fuel metering system that doesn't rely on different air-gas valves for changing the fuel mixtures supplied to the engine and has a built-in means of enriching the fuel mixture at high loads.