[Vwdiesel] ECO -- VW ----( Hagars ECO -- Bunny Bondo )

Val Christian val at swamps.roc.ny.us
Thu Apr 14 11:02:44 EDT 2005


The problem is that the tuning is limited to a certain frequency, which
means a certain RPM.  In the case of my 91 NA, I believe that the 
tuned system is for about 50 MPH.  I haven't measured and done the calculations
yet.  But after the rebuild, I will.  Because I want to quiet the system
for operation at 70 to 75 MPH, which is more the norm on the highway
at commute time.

Putting a turbo inline can simplistically be considered the introduction
of a DC injection point in a tuned circuit, which changes the impedance 
of that circuit.

Of course, its possible to put multiple resonances into a system. 

"Yep, 78 miles to the gallon in this puppy at 48 MPH, and 73 at 63 MPH.
At 55 MPH, it's down to 30 MPG."

In 91, I bought one of the last NA diesels VW sold, because I didn't 
want the added complexity of a turbo, and the attendant reduction in 
reliability.  I called that one wrong.


> Check out the long intake runners on N/A motor. These are a tuned length to create positive wave pressure at the time intake valve opens. Wave tuning actually stuffs incoming charge into cylinder, rather than relying on vacuum to suck it in. 
> Waves are created in runner when intake valve slams shut on incoming charge, and another when intake opens. These waves travel backwards, up through runner and are reflected back down from the open end. The length of runner determines the rpm at which the positive wave arrives at intake valve opening.
> N/A two stroke motors barely run without wave tuning in the form of an expansion chamber.
> Bob 
> *********
> And opening that intake
> valve at 5 psi overpressure is different --- than opening it at a slight 
> underpressure.
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