| As the car comes from the factory, DS turbo feeds PS bank and PS turbo feeds DS bank. This is due to the crossflow intake plenum design. The plenum was designed this way to maximize the torque output of the motor. But is also has a built in protection for the motor. With the twin turbo setup, if one turbo were to go bad or one were to overboost, you'll like do less damage, or delay it longer, to you motor with the crossflow design. Let's say the PS turbo seizes during a hard run. This means that the DS bank of cylinders is not getting boost and the PS bank is. Now, since the DS bank is not getting boost, it has less exhaust output thus slowing down the DS turbo and dropping boost to the PS bank of cylinders. If this cross flow design were to be eliminated by the instal of an FMIC, this situation could be catastrophic. The ECU controls all 6 fuel injectors based on the air metered from the MAFS. But it does not control them individualy. They all get the same signal to deliver x amount of fuel. If the PS turbo is now feeding the PS bank and seizes up, the DS turbo feeding the DS bank keeps going. So now the DS side is seeing boost while the PS side is not. But the ECU is alotting the same amount of fuel on both sides. The DS bank will not get enough fuel for the boost it is getting, and the PS bank will get too much fuel for the air it is drawing in. Bad things will happen soon enough. Yes, there is a balance tube on top of the plenum, but in a situation such as the one I described above, I don't think it is of adequate size to flow enough air to balance the manifold pressure. Again, this is my understanding of it. I could be wrong. I would appreciate anyone who knows to correct me where I am wrong.
Later,
Spencer
AIM: sbsTT14 PETZ member #4 '91 300ZX TT Stage IV+
'96 Jeep Cherokee Sport
"also tired of ppl driving in a straight line for 1/4 mile and thinkin they're hot shit" - hey GotBo0st 22:17:26 09/26/04 JAMChitlen (8:01:35 PM): I vote to ban anyone who uses "hot" to describe anything other than a chick
sbsTT14 (8:01:48 PM): 2nd "You are stupidier than dirt." - AzHeat 21:23:10 08/05/04 "Welcome, and I'd listen to Spee" - BigTDogg (MA) 18:21:41 02/17/04 "SCORE: Spee=1 The rest of us=0 (n/m)" - jaymztt(seWA) 19:17:12 07/23/04 |
