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Back Pressure

WHAT IS BACKPRESSURE?

THROUGHOUT THE COMMUNITY OF CAR ENTUSIASTS, THERE IS WIDESPREAD MISSUNDERSTANDING OF BACKPRESSURE AND HOW ELIMINATING IT MAY HELP OR HINDER PERFORMANCE.  

BACKPRESSURE IS THE ENEMY OF MAKING POWER AND PERFORMANCE, BUT THAT DOESNT MEAN YOU SHOULD JUST REMOVE ALL OF YOUR EXHAUST FOR NO BACK PRESSURE.

THERE ARE MANY IMPORTANT ASPECTS AND PARTS OF THE EXHAUST THAT ARE VITAL TO THE OPPERATION OF THE ENGINE, AND REMOVAL OF THESE CAN LEAD TO DAMAGE OR NO START CONDITIONS.

BACKPRESSURE IS THE RESTRICTION OR SLOWING OF THE EXHAUST GASSES TO THE POINT WHERE PRESSURE IS BUILDING AROUND THE EXHAUST VALVES.


THIS LIMITS THE AMOUNT OF BURNT OR USED GASSES THAT CAN LEAVE THE CLYINDER, AND STOPS NEW CLEAN AIR FROM ENTERING.  


IF YOU HAVE A CLOGGED CATALYTIC CONVERTER, YOU COULD BE EXPERIENCING MUCH HIGHER LEVELS OF BACK PRESSURE, EVEN TO THE POINT OF DECREASED GAS MILAGE AND SLUGGISH ACCELERATION.

BACK PRESSURE VS SCAVENGING

ASIDE FROM THE OBVIOUS BENEFITS OF MOVING EXHAUST GASSES FARTHER FROM THE DRIVER AND MUFFLING SOUND, THE DESIGN OF YOUR EXHAUST COULD ACTUALLY HELP ELIMINATE BACKPRESSURE!


THIS IS DONE BY DESIGNING THE HEADERS AND COLLECTORS TO PULL ADDITIONAL EXHAUST AND MAKE YOUR ENGINE MORE POWERFUL.


THIS EFFECT IS CALLED EXHAUST SCAVENGING AND THE EFFECTS CAN BE TUNED AND MODIFIED TO HELP YOUR ENGINE PERFORM AT ITS PEAK.

 

HOW HEADERS EFFECT BACK PRESSURE

"LOG" STYLE EXHAUST MANIFOLDS ARE THE EASIEST AND CHEAPEST TO PRODUCE, AND ARE EXTREMELY RELIABLE AND HEAT RESISTANT.
THESE LOG MANIFOLDS WILL MERGE THE CYLINDERS IN THE QUICKEST PATH AND WITH UN-EQUAL LENGTHS.  


LONG TUBE HEADERS WILL HAVE PIPES THAT ARE MORE EQUAL LENGTH AND HAVE A LONGER TIME UNTIL THEY MERGE AT THE COLLECTOR.
THE LONGER AND SMOOTHER THE EXHAUST PATH IS, THE MORE TOP END POWER YOU WILL SEE, WHILE SHORTER PIPES LIKE "SHORTY HEADERS" WILL GIVE A POWER BOOST IN THE MIDRANGE OF THE ENGINE.

CATALYTIC CONVERTERS AND BACKPRESSURE


CATALYTIC CONVERTERS ARE A HONEY-COMB LIKE STRUCTURE IN YOUR EXHAUST THAT LOOKS LIKE A FILTER.
OLDER CATALYTIC CONVERTERS CAN BE RESTRICTIVE IN DESIGN WHICH WILL INCREASE BACKPRESSURE, BUT NEWER MODERN CATALYTIC CONVERTERS ARE DESIGNED TO FLOW THE FULL CAPACITY OF THE ENGINE WITH NO RESTRICTIONS.

IS YOUR CATALYTIC CONVERTER HURTING YOUR HORSE POWER?


FOR MOST CARS WITH LIGHT MODIFICATIONS THAT PRODUCE 10% MORE POWER AND TUNED CORRECTLY WILL NOT NOTICE A SIGNIFICANT GAIN FROM REMOVING THE CATALYTIC CONVERTERS.
IF YOU ARE HEAVILY MODIFIED AND MAKING 20% OR MORE ADDITIONAL POWER, YOU MAY NEED TO SWITCH TO HIGH FLOW CATS OR REMOVE THEM TO NOTICE ADDITIONAL GAINS.

SO IN CONCLUSION, BACK PRESSURE IS THE ENEMY OF POWER, AND EXHAUST SCAVENGING IS A FRIEND.

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