Back pressure; was Re: got my 2.5" centre pipe!

[sfwilliams@comcast.net (Scott F. Williams)]

Andrew Basterfield wrote:
> Gas motors need back pressure because the factory fuelling
> and ignition maps are set up with the standard air intake and
> exhaust system.

Let's amend that statement to say: "Factory fueling and ignition maps are
set up [to work with] the standard air intake and exhaust systems." -in
other words with some backpressure. It is a fact, however, that gas motors
do *NOT* need back pressure ultimately speaking.

It is certainly plausible that reducing backpressure may result in a power
loss if the resulting operating conditions are not compatible with the
engine management's factory tuning.In general, however, maximum power will
be extracted from any properly-tuned internal combustion engine when there
is zero or even negative pressure in the exhaust system.

We battled about this very subject sometime last year. In fact, the infamous
fuel injector controversy reminded me of the "back pressure wars" that came
several months before. In contrast to that thread's outcome, the powers of
good triumphed over the grim forces of evil. (chuckle)
--
Scott F. Williams
NJ Scirocco nut
'99 Subaru Impreza 2.5 RS
Mazda 323 GTX turbo "assaulted" vehicle
Golf GTI 16v "rollycar"
ClubVAC: "Roads found. Drivers wanted."