Re: Back pressure

[VW155mph@aol.com]

Back pressure refers to how exhaust freely (or not) gases flow out of the 
engine.  It is dependent on the size of the exhaust tubing, muffler design, 
cat design, number of bends in the system, etc.  I.E.  A car with a 3 inch 
exhaust system will have less back pressure than a car with a 2 inch exhaust 
if the muffler design is the same.  On the other hand, if the 3 inch exhaust 
has a chamber design muffler and the 2 inch had a straight through, this may 
not be the case.  If a vehicle is running an open header (no exhaust system), 
there is very little back pressure.  Turbo vehicles generally like low back 
pressure because it will allow a turbo to spool up quicker, thus building 
more high rpm power.  Naturally aspirated cars need a certain amount of back 
pressure because back pressure helps the torque curve of a motor.

Marc A. Brown
Speed Etc. Motorsports
Club GTI International (Northeast Region)
"Cogito Ergo Sum"
1995 Jetta GLX (well modded)
1998 New Beetle 2.0 (still stock)