Re: [alfa] RE: Spica vs Carb

[webb.p@xxxxxxxxxxx]

Runner length and plenum volume (airbox in this case) have a direct relationship to torque.  It's called a Helmholtz chamber.  A net search should return some descent information on it.  Good reading here:

http://www.autospeed.com/cms/article.html?&A=0122

It's an integral part of the TBI vs. ITB debate.   

ITB in the case of Spica and Webers can vary the runner length pre and post throttle but the chamber can only be modified pre throttle.   The chamber should be 2x displacement.   Longer post throttle runners generate torque due to air velocity.   A larger chamber acts as an air reserve to give better inital throttle response.   New cars do this in conjunction with a non-linear throttle to give that "peppy" feel, but run out of power in the top end.  

I guess this is useful to get to that good parking spot at Walmart before the next Focus or Cavalier.

-Peter

> My carbed (true euro-spec) Berlina's airbox doesn't have any room for 
> 'ram-tubes' inside the airbox. The airbox on carbed vehicles is truly 
> round while on the Spica cars it's oval shaped (to fit the tubes). I 
> have no idea if modifying a carbed box would improve performance at 
> all. I'm inclined to say no as the factory generally knew what they 
> were doing.
> 
> I'm sure others know more than I do about this though...
> 
> Damian
> 
> magista@domain.elided
> 1750 Berlina
> Seattle, WA. <-- raining finally
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