Volkswagen Beetle Forum : “1969 vw engine,how can i tell what cc and what horsepower it is”

Without taking it apart, this is practically impossible if the engine's been modified. However, if you believe that your engine is stock, then you can decode the engine number to find out. The engine number is stamped on the crankcase just below the generator stand. The two letters at the start of the engine number will tell you what it is.

The original engine in a '69 Beetle should have an engine number starting with H5, which is a 1500cc engine, which I think should be rated at 44hp. If your bug has had an engine swap, it would most likely be to a 1600cc engine. Out of these, B6 means a single-port 1600, whilst AE, AH and AJ are all twin-port 1600s. You can find plenty of information if you google search for VW engine letter.

Even at that, you can only help but assume its stock.  I have a 1641 dual port in what should indicate a 1500sp case.  Especially with the slip-ins unless you pull the heads and measure you really have no way of telling.