RAC or Taxable Horsepower:
Quote:
This measure was instituted by the Royal Automobile Club in Britain and was used to denote the power of early 20th century British cars. Many cars took their names from this figure (hence the Austin Seven and Riley Nine), while others had names such as "40/50 hp", which indicated the RAC figure followed by the true measured power.
Taxable horsepower does not reflect developed horsepower; rather, it is a calculated figure based on the engine's bore size, number of cylinders, and a (now archaic) presumption of engine efficiency. As new engines were designed with ever-increasing efficiency, it was no longer a useful measure, but was kept in use by UK regulations which used the rating for tax purposes.
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I never knew that...just always thought it was an industry term that loosely described a line of automobiles horsepower ratings.
Despite what some think, that's pretty much what this thread is about.
(or at least it's a huge sidebar)
Deducing a 1/4 mile time from a given HP rating.
Ding! Ding! Ding!
That's the problem. Taxable, gross, brake/net/crank, rwhp/effective horspower are all measured differently.
Oldsprepp was smart enough to ask very specifically what 1/4mile #'s
could be expected from a RWHP rating...a specific type of measurement.
Others, the more obtuse, don't really care or at the very least,
don't care to specify what type of rating they have used.