Joe Jagersberger came to the USA from Austria and began working for Case Corporation in Racine Wisconsin to assist in developing a race car programme.
Whilst working for Case Jagersberger was a regular race competitor including racing at the Indianapolis 500. He continued to race until 1911 eventually becoming victim to a career ending crash after which he spent several months in hospital and resulted in an amputation of his right leg.
Despite his injuries he continued to work at Case as a consultant. He continued to design cylinder heads and other peripherals eventually starting his own company under the famous Rajo brand. The name of the brand was formed from the RA of Racine and the JO from his first name.
Rajo started off by producing spark plugs and various other items. They then moved into producing performance cylinder heads for Ford Model T and Model A cars.
The first design was the Model 30 which had 4 exhaust ports and one intake port all on the right side of the head. The Model 31 had two intakes on the right and four exhaust on the left. The Model 35C, first known as the “Improved Rajo Valve-in-Head” and later as the Model C had two intakes and three exhausts on the right. The Model A used the stock intake ports on the block. It had two exhaust ports on the right. His Model B two intakes on the right and four exhausts on the left. It came in three versions. The BB featured a higher compression ratio and the BB-R also included two spark plugs per cylinder.
He also offered a modification to the 1941-52 Chevrolet “stovebolt” L6 OHV 15 bolt head, which added another set of 3 intake ports above the 3 originals, to permit adding (an) extra carburetor(s) on a separate manifold.
Jagersberger died in 1952. The company closed in 1980.
Rajo equipment is still very much sought after and command very high prices amongst the traditional hot rod community
Here on Hemmings are some great examples of period Rajo powered racers
There are also some interesting Rajo ephemera items to be found on sites such as eBay
Sources Wikipedia, Hemmings, trackforum.com