Exhaust debate 2

[Islander]

am having a friendly debate.

if you have a 3" y pipe tied into a
3.5" peice of straight exhaust pipe...no muffler..6' long..

would it have any advantage over a 3" y pipe tied into a
3" pipe of same configuration.

ie...would not the restriction at the 3" collector cancel any advantage of the 3.5" pipe.

ie...my "opponent" states it will require more HP with the 3" pipe.

thanks.

 

[Islander]

Thanks for the reply(s).


Anyhow..I have installed headers and 2.5" true duals.(gsmotorsports.com).lessening backpressure, increasing torque/hp.(even at low rpm)..maybe the x-pipe synched the pulses feels like a nice gain..have'nt dyno'd yet.

 

[Rob45]

One other not-so-minor point: some engines have a much greater sensitivity to exhaust backpressure than others.
In general, the higher the specific output(and therefore the greater the valve overlap) the greater will be the power loss per unit increase in backpressure.
More backpressure produces more charge dilution and/or reduced scavenging during the valve overlap period.

For this same reason, 4-valve engines are generally much less sensitive to exhaust backpressure.
Ford produced an excellent but not widely-disseminated internal-only paper on this topic during the MN-12 program.