328 e46 exhaust valve

[bikerz]

hi, i just plug out the hose for exhaust valve. after test drive, i can say my pick-up increase while my mid-end power decrease. have anyone done the experiment before? is it true it reduce mid-end or my psychology thinking only?bcoz, according to e46fanatics.com, the valve is only to reduce noise. the prove is after market exhaust doesn't have valve. so why is it i feel my mid-end power reduce? or do i need to wait for my ECU to calibrate with the exhaust??

 

[Tom328]

If i'm not mistaken, i read somewhere that the valve will improve mid range torque... i haven't tried it personally... for the E36 328i, the valve opens at around 2500rpm... not sure bout E46...

 

[pussy]

very simple theory here...

if the back pressure is high, meaning the gas is restricted, you will have more torque cos of the back pressure helps on the mid range(this is good for autocars).. the flap stays closed under a certain rpm within the vacuum set by the bmw engineers to aid a less back pressure to have a more power hp to move the car faster, flap opens..it's where the max torque achieved and hp moves up till 5600rpm(i think)..

it's like the smaller diameter straw and a larger diameter ones..

 

[bikerz]

so, if i change to aftermarket like eisenmann, no valve, my car will experience this kind of power graph?

 

[pussy]

most likey the torque ould be lesser...

 

[Crymson]

What if repack existing original exhaust but still maintain the valve and double barrel tip?