sperry How does pipe diameter effect this sound wave assitance?
I'm specifically interested in the exhaust side of things, because I'd like to replace my exhaust from the headers back with 2.25" pipes, two high-flow cats, a 2 into 1 resinator, split back out to two mufflers, and out through the stock tips. If I change my exhaust diameter, and/or the location/flow of the cats, how do I need to move the resinator to keep the flow assistance designed into the stock exhaust?
And back to the intake side of things, how does forced induction change the IRIS's effectiveness? I'm assuming that the change in the length of the intake pipe resulting from tossing a turbo in there will effect at least the resonance side of the IRIS.
'Course, with forced induction, you would think that the IRIS system becomes useless, and that intake manifold is less important, but I read a quote from the guy that designed the intake manifold on the WRX/STI and he said that's what he assumed when he started working on the manifold, but it turned out the opposite was true, and that it was very important to design the mainifold to match the turbo application.
I wonder if going to forced induction and short ram intakes, etc, is really just hobbling the motor and undoing a lot of creative engineering on Subaru's part.
Quote.
1. The dia. affects the amplitude of the wave, the larger the pipe dia, the lower the energy delivered to the cylinder.
2. You are really duplicating the standard set-up, with larger header pipes. The problem is that the tuned length that it has now, is the results of all of the componets that are in the system, they all affect the final tuned length. So it is hard to just build the same length and hope it will resonate at the same rpms.
3. The IRIS will still operate, with a turbo, or a positive displacment blower. The added length for the turbo won't affect it. The tuned length for the resonate rpms, ends at the plenum, about 15" from the inlet valve. Past that is not in the resonate length.
4. Yes the inlet design for a turbo, is mainly centered around the low end of the rpm range, when the boost is not there.
Harvey.
