Quote:
Originally Posted by Varn
I remember a post by aerohead where he quotes an 1986,SAE Paper 860211 showing that a 15deg hood slope can reduce cd by .0475. That is pretty huge! It is from the technology of cars of the era that my car comes from. When I made the hood splitter I shot for that angle, 15 deg.
So if my car has a cd of .36 stock that and the paper says 16% less wind drag, that makes it about .31. If half of my drag is from aero that means that I might have 8% less overall drag. My previous tank was 47.7 mpg. An 8% increase says 51.5 mpg My car got 50.1 over 500 miles.
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Yes if the hood is too horizontal and the front end too blunt and sharply radiussed then the hood experiences non-laminar flow so it stands to reason if changes are made such that flow over the hood straightens out then drag goes down.
I'm sorry, don't take it personally, but to use that to leap to your second paragraph makes no sense. Look at any Rabbit in a wind tunnel, or Hucho's book, and you'll see that VW did angle the hood and radius the leading edge of the hood properly so too bad, I'd wager you are stuck with .36, blister or not.