Engine type

["Nolan Penney" <npenney@mde.state.md.us>]

I need a little help here.  I've got some of Vizard's books and thoroughly 
enjoy them.  But being far less then an expert on the engineering history of 
these engines, I have no idea if the Triumph 1500 engine is of a particular 
type of engine that Vizard often describes in his book.   

Do any of you folks know if the 1500 is a "type" (a type, etc), or decended 
from one, or any of that?