AC Ace (30's) & 16/hp Sports Models
The 6 cylinder cars started in earnest with the Tourer. This is also the period during which the name Ace was first used in conjunction with AC Cars. Engines of the 16/56 and 16/66 class continued to be shipped thru 1933. Many were built in a sports format, 2 seaters with open coachwork. Records of the period indicate there were approximately 650 cars of the various models (16/56, 16/60, 16/66, 16/70, 16/80 and 16/90) manufactured thru the period of 1934 thru 1940.
Those of you who aren't British might be wondering, like I did for some time, just what the 16/56, 16/66 etc means. There seems to be some obscure (to us non-British) means of calculating horsepower for the purposes of taxing cars. I think this may be common in many European countries, so maybe I shouldn't limit this to just the British among us. Anyway, using something called the RAC formula, the horsepower rating for this 6 cylinder car comes out to be 16hp for tax purposes, while the actual power delivered from the engine is the second number. If anyone would like to send me an explaination of how this really works I will be more than happy to include a more detailed explanation here.
NOTE: I have received the following comment from former AC owner, automotive enthusiast and artist, Miles Fenton . It hopefully sheds some light on how these HP figures were derived. Thanks Miles!
"The British taxation on cars was based on the bore diameter only. The stroke was not considered in the designation of horsepower (typical beaurocratic stupidity!) As as result, most British manufacturers made small bore, long stroke,and consequently low revving, engines to get the rated horsepower figure lower.This meant that the buyers could get away with a lower taxation. As a result, this held back the development of the square and oversquare engine designs in favour of the long stroke and put Britain behind in development for many years."
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