running straight pipes?

I've had it like this for a while but i'm just wondering if it's really hurting to have little backpressure (only from the cats)

 

where does your exhaust end? like...do you have tailpipes? or is it dumped after the last cat? if dumped after last cat, holy hell batman, gas chuggin' loud obknoxious gutless wonder.

 

oh yeah, hahahah it's dumped right after the cat. the loudness doesnt bug me anymore, idk it never really was loud to me to begin with, i liked the sound too personally

 

i had dual tail pipes and one broke from four wheeling and i lost power...cut the other one off so its dumped after the cat and i got more low end power. its loud as hell but i love it.

 

You dont lose power from reducing backpressure.

This has been a PSA.

 

that isn't completely true. you need balance in everything. not enough or too much pressure will make it hard to evacuate exhaust gases.

 

having some "backpressure" helps with low-end responsiveness.

 

well isnt there still backpressure from the cats?

 

Yes there is back pressure from the cats, but if you dump it right after the cats, or a muffler for that matter, the exhaust gasses are just "tumbling" out of the pipe. To make the most power, you need about 18" of pipe after a muffler or cat to smooth the airflow back out, and regain some of the "scavenging" effect.

 

Back pressure is never good for an engine. What is good for an engine is to get the exhaust gasses out as efficiently as possible. A smaller pipe can deliver more torque than a larger pipe and that is usually mistaken as back pressure. Internal combustion engine exhaust gasses flow in pulses due to the individual firing of the cylinders. If a pipe is too large, these pulses in the exhaust pipe can stop or even instantaneously flow in the wrong direction. This results in inefficient flow of the gas and poor performance along with intermittent back pressure. Exhaust velocity is what is important, not back pressure.

If you use a pipe that is too small it will result in back constant back pressure and will choke the engine. The velocity of the gas will be high but will not be high enough to let the engine breath.

Every engine has an exhaust pipe size that is optimal for it. An open exhaust will usually let the engine breath better but sometimes a muffler can enhance low end torque by smoothing out the exhaust pulses along with other issues that are more complex.

I run an open exhaust in my race car, when I can, to maximize top end horse power. However, when I am required to run a silencer (single camber race flow master), I do get a slight increase in mid range torque to slightly offset the decrease in top end power. This has been confirmed on the dyno and has nothing to do with back pressure. I have been building my own race engines for over 20 years and have learned a lot from some very knowledgeable people during that time.