Aerochargers etc: real back pressure numbers

[Bernd Felsche]

Jeff Meager tapped away at the keyboard with:

> yep, correct.  The bigger the turbo, the better the efficiency,
> the more lag.....

The turbo's diameter (rotating inertia) is the crucial factor in
"lag". The more efficient turbos are larger; the size allow for more
of the thermodynamic energy to be extracted by the turbine.

A variable vane can overcome the turbo lag by ensuring that the
turbo is compressing at fairly low engine speeds, yet not
over-revved at high exhaust gas flow rates.

Another method of reducing lag is to use multiple turbochargers or
multiple turbines on the same compressor shaft. The turbine area
increases without greatly increasing rotating inertia. One other
advantage is that exhaust flows can remain separated for longer,
allowing for some extraction effects (pulses) to help reduce the
back pressure.

-- 
 /"\  Bernd Felsche - Innovative Reckoning, Perth, Western Australia
 \ /      ASCII ribbon campaign | I'm a .signature virus!       |
  X       against HTML mail     | Copy me into your ~/.signature|
 / \      and postings          | to help me spread!            |
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org