Quote:
Originally Posted by G37Sam
What does the VVEL have to do with anything?
People are pushing 10 pounds of boost without even touching the VVEL..
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I was wondering the same myself. The Z comes from the factory tuned for the lowest emissions, agreed? That equates to a very lean running engine which was shown in the base run AFR's ranging from low to mid 14's. Tuners will lower the AFR which will result in a cooler running engine i.e. runs richer and at the same time advance the timing to produce the gains. I expect your particular tuner advanced the timing well in excess of 2 deg and probably throughout the load range to the brink in which the engine will begin to 'ping' at any given load/rpm. That is the point where your power is peaking. I'm not surprised that you gained 30HP which is about a 10% increase from a leaned out engine to begin with imo. I have a Screaming Eagle Race Tuner program for my Harley which lets you play with dozens of variables but basically all you need to to do to get about 90% of the performance from the engine without using a dyno is adjust timing and AFR. There is more than one way to fool the ecu into increasing the fuel into the engine depending upon the variables that allow adjustment. On Harley's, one way is to adjust the volumetric efficiency tables. Increase for an increase in fuel delivery which lowers the AFR. To get the most out of a Harley, the narrow band O2 sensors need to be changed out to wide band. Anyway, the twin cam Harley in essence is a 2 cylinder Chevy small block. Anyway, for the Harley crowd, maps are readily available for downloading free for just about any mods. These maps will get you to about 90% or better performance. I personnaly don't track my car so I wouldn't take it to a tuner and spend say $500 just to gain say 3-5 more HP (90% to 100%) using someone else's dyno tuned map in my ecu. I would be happy with a canned map and tweak by seat of the pants from there. I'm sure Nissan has built in some parameters that can't be exceeded even by a tuner such as timing advance in order to protect the engine. For those who want to tune the engine themselves go for it but you must have a good working knowledge of the inter-relationships for the different variables in the map. If you don't then don't bother with self tuning or you will probably due more harm than good to your engine.