Nissan Titan Forum - View Single Post - Ya get some, ya lose some? You gotta be kiddin me?!?

PHOEBISIS · 11-05-2004, 10:22 AM

I've never been clear on why a loss of "backpressure' would cause a loss of low RPM power or torque.
Tell me why this is wrong.
Very low restriction exhaust-low RPMS-Open Exhaust valve at 120 degrees ATDC on the power stroke-all the gases stream out immediately,and I am left with no pressure to push the piston for the last 60 degrees of the power stroke
High restriction exhaust-low RPMS-Open exhaust valve at 120 degrees-gases flow out more slowly,leaving more high pressure gas to push the piston the last 60 degrees.
Shouldn't this scenario mean that you do lose low end torque with a very low restriction exhaust?
Don't the Motorcycle Manu build adj exhaust restrictors into their pipes for just this reason??
Correct me on this-I'm just not clear on it,Charlie PS I am clear that as the time to empty decreases,and the volume emptied per unit of time increases-then the low restriction exhaust will "pay for itself".

11-05-2004, 10:22 AM	#15 (permalink)
PHOEBISIS Registered User iTrader: (0) Join Date: Apr 2004 Posts: 1,535 Thanks: 0 Thanked 0 Times in 0 Posts	Never clear on backpressure loss of low rpm power I've never been clear on why a loss of "backpressure' would cause a loss of low RPM power or torque. Tell me why this is wrong. Very low restriction exhaust-low RPMS-Open Exhaust valve at 120 degrees ATDC on the power stroke-all the gases stream out immediately,and I am left with no pressure to push the piston for the last 60 degrees of the power stroke High restriction exhaust-low RPMS-Open exhaust valve at 120 degrees-gases flow out more slowly,leaving more high pressure gas to push the piston the last 60 degrees. Shouldn't this scenario mean that you do lose low end torque with a very low restriction exhaust? Don't the Motorcycle Manu build adj exhaust restrictors into their pipes for just this reason?? Correct me on this-I'm just not clear on it,Charlie PS I am clear that as the time to empty decreases,and the volume emptied per unit of time increases-then the low restriction exhaust will "pay for itself".