Libbybapa at wmconnect.com Libbybapa at wmconnect.com
Mon Dec 12 10:46:33 EST 2005

Okay, I got very clearly that an engine just pumping air will not produce 
boost and so dropped the idea of underfueling when accelerating with boost in a 
TD.  But the idea just wouldn't play dead in my head.  The fact is we're not 
just pumping air.  Obviously the volume of gasses leaving the engine compared to 
that entering the engine is far greater.  That volume of gasses is what spins 
the turbine.  Even at idle with an extremely minimalal fueling for the amount 
of air, the turbine will spin.  The VNT turbo with vanes closed will actually 
produce boost at idle on a 1.6.  Although there is no throttle plate, there 
still would be pumping losses when pushing that air in and pushing the gasses 
out especially considering the losses of some of the gasses passing the rings.  
I understand that fuel makes boost, but still feel that a condition could 
exist where the amount of boost air entering the engine is above that where any 
benefit in work is achieved and therefore a detriment to fuel economy.

I understand Svend's claims to high economy in "ECO mode".  I also have 
talked to others that tried "ECO mode" with a significant drop in fuel economy 
accompanying the abysmal drop in performance.  I have also heard from several 
folks that the 1.9TD ECO (not sold in North America) had resultant lower fuel 
economy.  That is second hand and unconfirmed by me.  Also, if I remember 
correctly, the most recent Fuel Economy numbers produced by Svend resulted in mid to 
high 40's (US gallons), figures that my '86 N/A Jetta could easily beat with 
300,000 miles on the engine, horrendous compression (400, 320, 320, 230) and 
200,000 miles on the injectors.


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