| That's a great question but I can only give you a subjective answer. Ideally the turbos would spool up exactly in parallel and the wastegates would manage the boost pressure of both turbos exactly the same. Reality is no two turbos are exactly alike, and although the wastegates are very accurate, sloppy automotive production tolerances and necessary differences in kinematics result in the two turbos spooling up differently. This problem was mitigated in the design by incorporating the balance tube on top of the intake plenum. The pressure downstream of both turbo compressors is about the same. Always! These real world inaccuracies manifest themselves in differences in airflow coming out the driver's side turbo versus that coming out of the passenger side. So any imbalance is dealt with by moving required airflow from one bank to the other via the balance tube. Passing air through the balance tube imparts additional pressure losses, intake temperature increase, and local turbulence going into the rear cylinders... notably 5 & 6. How big are these losses? That depends on the amount of imbalance but I rationalize the size of the OEM balance tube was engineered to accommodate a "reasonable" amount of production-type imbalance plus margin without noticeable changes in performance. Probably your sport500s were configured good enough such that you'll not notice either. But if you want to get the absolute max performance out of your configuration you'll make sure the wastegates are exactly balanced... not only by balancing the wastegate crack point but also quantifying the flow difference across the balance tube during wide open throttle across the whole rpm range and adjusting the wastegates to trim out all the variables (it's actually not that hard to do). The reason I posted this is because halfway into my build up I realized that the exhaust housings are indeed different left to right (I had them on backwards), and balancing through my simple method is extremely sensitive to changes in compressor housing/WG actuator orientation. 1 degree makes a big difference in the balance point -- a very shocking result for me! I'm wondering if anyone else picked up on how these seemingly minor changes in the OEM orientation result in noticeably different wastegate angles... which guarantee a certain bias in the turbo work balance.
OverZealous (CT) My General posts (click)
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