Quote:
Originally Posted by Oldsman
I know your theory does not apply to all motors and every setup out there.
So unless you have built every motor known to man and every setup possible and dyno tested all of them, your chickenyness is only that.
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Regardless of which engine we're talking about, and my apparent "chickenyness", you still want the least amount of backpressure possible.
Quote:
Originally Posted by Oldsman
however if you hit max torque in this range and normally your going to launch in this range.....well as any drag racer knows torque wins races.
So if he is launching a 455 the above applies and if on the dyno he produces more torque with closed high flow exhaust rather than open headers or straight pipes this would lead that person to believe that a little bit of back pressure is better than none because it works best for his setup.
This is where the confusion and back and forth comes from.
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It may lead someone to believe that backpressure is making more torque, but in reality the setup that makes less torque doesn't maintain high velocity to maximize the scavenging effect.
Quote:
Originally Posted by Oldsman
Because my buddy with his GN has a 3.5" downpipe to a muffler right under the passanger seat so it is basically no back pressure and he produces more power than a closed high flow exhaust system so in this case it is the opposite.
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Throwing a turbo in the exhaust stream is a different story. You want large piping to get all the restriction and backpresure off the turbine wheel so it'll spool faster and make more power by staying spooled longer. The largest, straightest, shortest exhaust pipe is the best for a turbo.
Quote:
Originally Posted by Oldsman
Another example...........3" exhaust straight pipes on a N/A alero isn't going to produce more power or better ET than that same alero with a SLP exhaust system.
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Again, this goes back to velocity. The 3" system will make more power, but it'll peak higher up in the rpm band. With smaller piping, yet still free flowing mufflers, the exhaust will have higher velocity and therefore make more low end torque, with the possibility of slightly lower peak, high rpm horsepower.