| Its been a long time myth that people have advocated the 1996 Twin-Turbo rating at 280HP because of the lack of Variable Valve Timing. This simply is false. If you know how Nissans VVT(NVCS) works in the Z you would know that it shuts off at 6100RPMs. The Z makes its peak HP at 6400RPMs, there for VVT is not in effect thus leaving 96 TTs at the same peak HP rating as every other Z. The difference is that the 96TTs will generate less low end power. Heres a basic run down of Nissans NVCS system: Light Load
At light loads and below 6100 rpm, NVCS is OFF with the intake valves retarded. This helps to promote a smooth idle and engine stability. Medium to Heavy Load, < 6100 rpm
At higher loads but lower RPM's, it is possible for air that has flowed into the cylinder to bounce back out again. This decreases volumetric efficiency and therefore an earlier valve closure is desired. So under these conditions NVCS is ON and the intake valves are advanced by 20 degrees. Doing this can increase engine torque in this range by close to 20 lb-ft. Medium to Heavy Loads, > 6100 rpm
Now at higher RPM's, whereas before the problem was that air was bouncing back out through the intake port, now the problem is that not enough air has had a chance to flow in yet. In order to take advantage of inertia effects, a later valve opening is preferred, even if it is the same duration. So at high revs, NVCS is now switched OFF and the intake valves are retarded back 20 degrees to their original position. Hoped this clears things up :)
|
