Re: forced induction theory question: why is boost more at front than at r
I must be missing something - pressure and/or vacuum are no different as it relates to fluid dynamics, air is merely opposed by the friction of the long circuitous route of the cross ram intake manifold, it just becomes more noticeable under boost. This could be why the rear cylinders on the Roe SC have had the problem with the plugs. I would have thought this was strange if there was no difference.
Another clarification about nitrous. On nitrous there can be an issue with the front cylinders trying to grab more than their share of nitrous. That may or may not be an issue, the amount of charge that can be consummed by any one cylinder is determined by the that cylinder's volumentric efficency. A more likely explanation for nitrous related failures is the fact that not all nozzles totally disperse the fuel into the nitrous. In this case a failure to a rear cylinder is even more likely because the the fuel is heavier and it falls out of the mixture as it travel to the rear.
Although there is a slight advantage to placing the nozzles further away from the throttle bodies, that can lead to fuel fallout. On most nozzles it is better to get closer to the throttle bodies, therefore, using them (collision )to further mix the nitrous and fuel.
As an after thought, the manifold is developed for a certain flow, at or near no pressure, once you start increasing that flow (and pressure)you will hit a point where you hit hydraulic resonance. I am not saying that is what is happening, but, partial resonance could be possible, at that point the impedance of the system (manifold)goes up and the flow drops. Nitrous overcomes this problem because the manifold flow is not changed, now the problem is on the exhaust side, that is why a nitrous car without a good exhaust has such peaky torque.
