Re: It's a Gas

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: Ken Ames <ameskg@xxxxxxxxx>
" 
" Quoting Tom Jennings <tomj@xxxxxxx>:
" 
" > On Mon, 19 Sep 2005 farna@xxxxxxx wrote:
" > 
" > > The electric turbo looks neat, but boost goes DOWN with speed.
" > > Starts at 5-6 psi, goes down to 3 psi at higher speeds. Takes to
" > > much juice to spin it up at high speeds. I think I'll stick to the
" > > remote setup -- can do that with mostly salvaged parts too.
" > 
" > Why is this a problem? Except for race conditions, boost at low
" > speeds, and less so at cruise, would seem perfect. A small
" > displacement engine is fine flat-and-level, but lacks torque for
" > accelleration.
" > 
" > The real advantage to the electric supercharger would be software
" > control -- essentially the times when you'd be lugging it, you
" > boost the hell out of it, and back off at highway cruise.
" 
" 
" Isn't this kinda the opposite of what you might want? Lots of boost at low speed
" will _really_ stress an engine, you want more boost at higher rpm where the
" engines volumetric efficiency drops off. 

in one important way it doesn't.  dynamic forces on the rotating
assembly go up as the square [or is it cube?] of rpm, so at 5000rpm
they're 4x what they are at 2500.  that's a fair bit of headroom for
boost.

the water and oil pumps are still spinning slowly though, so this is
one situation where high volume parts are definitely needed.  it'd be
nice to decouple them from strictly rpm-controlled volume and make
them somehow demand regulated, but the increase in complexity - and
potential for failure...
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen

adh@xxxxxxxxxxxxxxxxx                       and think what none thought