Did you read the by-line on that paper? Enthalpy and Mattback.
They used a the nastiest of nasty, weld-els, 90's and T's, log manifold. In fact, that info is probably on TR. The paper also has absolutely zero to do with what we're talking about or external wastegates. Allow me to digress....
Originally Posted by
Z28ricer
GT2871 @ 15 psi doing 353 RWHP, but that 3082 only did 300 rwhp at 13, riiiiiiight
If you believe the story they are sellin, thats cool. But i'll pass on that load of BS
Hey, no one mentioned pushrods and long tubes. You don't get to chime in on technical stuff!
So here's the deal with that test. With a huge turbo at 13psi and a free-flowing motor with medium cams, that log is easily the biggest restriction. What you're seeing is the removal of a restriction that is far and away limiting the power. The low boost level really shows this off. On my brother's 2871 car, it only made 30whp more at 19psi with HKS cams over stock, but made 50+whp more if you compared them at 15psi. This car makes 350whp at 1 bar on stock manifolds.
So yeah, 2871 makes 350-360 at 1 bar. At 2psi more on the tubular/3082 would have made 375-380whp (10whp per 1psi is generally accepted on 2.0L). My 3071TS made 370-380whp at 1 bar on 2 different setups. Notice a trend here? It's not coincidence. It's math. Barring restrictions, if you fill the same 2.0L with 13psi worth of air and 93 octane it'll make the same power regardless of what's supplying that boost. Without flow restrictions like small exhaust housings or compressor going inefficient, the main variables are down to compression ratio and VE. That 2871 doesn't make the power that the 3082 and 3071 did in my example because of the slight VE difference from the stock manifold and the tubular (among other smaller things). The log/3082 didn't make nearly the power the tubular/3082 did because the log absolutely kills the VE of the engine.
So maybe it is like headers after all.