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

Area31 Research Facility stephensrw at stn.net
Thu Apr 14 12:21:16 EDT 2005

```Bob,

In my fixed speed 1800 RPM genset application with a NA 1980, 1.5 D, I am
after absolute minimun fuel consumption possible.  I thought of
experimenting with tuned intake runners as you mention as a way of improving
power and efficiency (lower fuel use).  Any idea of the mathematical formula
to calculate runner length?  Is the wave propagation at the speed of sound.
1140 ft/sec and independent of flow velocity in the pipe?

I am also interested in the potential benefit that advancing the camshaft
may have on my application as well, although I recently read that a whole
belt notch on the cam gear will cause valve piston collisions.  Not much
room upstairs in these high compression engines.  I'm used to working on
obsolete (by that I mean pretty much all of them now) gasoline engines with

Rob

----- Original Message -----
From: <slatersfb at aol.com>
To: <vwdiesel at vwfans.com>
Sent: Thursday, April 14, 2005 10:38 AM
Subject: [Vwdiesel] ECO -- VW ----( Hagars ECO -- Bunny Bondo )

> 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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```