i was thinking about putting dual exaust on my 92 blazer.. but will it mess with the back pressure?

or should i just get dualls exaust from the muffler, or will that still mess with the back pressure to?

suggestions would help

 

Your engine is basically an air pump. The more air you can move thru it, the better it will run (more power, better efficiency, etc.) Headers, and dual exhaust all the way back will give you a noticable improvement on the Butt-Dyno. The suggestion that you need a certain amount of backpressure, in order for things to work "right" is a Myth.

 

True dual exhaust on a v6 engine sounds pretty bad... If what you want is more performance, you can get that by increasing the exhaust diameter and putting on high flow components (cat & muffler).

While 'required backpressure' is a myth, there is such a thing as oversized exhausts which hinders performance as well.

 

Is backpressure really just a myth?

 

YES!!!!!!!

Your engine does not need nor does it want backpressure. Backpressure is a restriction to air flow. Every restriction to air flow the engine must overcome to exhuast spent gases. That effort robs you of horsepower. More backpressure = more restriction = less horsepower. It is that simple.




Most people get backpressure confused with is scavenging. Scavenging is when the exhaust pulls the air from the engine. That allows the engine to breath better. In racing engines scavenging is used to pull in the next charge of air/fuel mixture. More you can stuff into the chamber before it explodes the more power you can generate. This is why an engine is reffered to as an air pump. Teh more air it can pump, the more power it makes. If you set your exhaust up correctly it can be used to draw in more air/fuel and create more power. Backpressure has the oppostie effect, it reduces the amount of fresh air/fuel you can draw into the chamber.

 

True, Tim. 'Backpressure' is a term of convenience that I am guilty of using just for simplicity's sake, but 'scavaging' is the correct idea. As with most things, there is a point of diminishing returns and when an exhaust system is 'too large' andthe flow of gasses becomes too much in volume and too slow in speed, performance can start to suffer. This is why, for the 4.3's design, going over 2.5" for the exhaust pipe is pretty much uselesseven if you have installed headers to optimize the initial flow of exhaust gas. Staying with the stock 2.25" is probably the route to take. I also agree with Kyle that dual exhaust lines on our trucks accomplish nothing and do not have a good sound.

 

you can, however, use a 2.5in dual exhaust setup with an x-pipe. that will help equalize opposing pressure and, in turn, increase exhaust scavenging. not only will it help HP and low-end TQ, it'll sound better with an x-pipe, as well.