Quote:
Originally Posted by ssmoked
Use a Mustang Dyno for true whp numbers. Most other dyno brands are way optimistic. My stock 370z achieved ~260whp on the Mustang dyno, which is in line with typical drivetrain loss (21%).
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The only way to get a "true" measure would be to unbolt the engine from the chassis and dyno it that way.
Mustang dynos are no more accurate (in this context, meaning able to yield consistent, repeatable measures) than any other dynomometer. However, like all load bearing dynos, they can be set up quite differently from shop to shop.
Your car will likely put down very different numbers across Mustang units, depending on the various starting values inputted by the shop.
Dynojets are the only dynos I am aware of that are highly consistent
across units and shops, given that all calculations are ultimately based on the rate at which the drive wheels can accelerate the known (and fixed) weight and diameter of a rotating drum.
For all dynos, there are also transient factors (e.g., various ECU trim commands) that are difficult to perfectly control for, and also correction factors that compensate (imperfectly) for ambient conditions. These too will result in some measurement variance across runs for the same vehicle, even on the same dyno.
Dynojets are somewhat less desirable for tuning under partial load, but that is another matter...
Quote:
Originally Posted by brancky3
Can you explain this? I've never heard the stock tune being limited in this way before, but I've only owned my Z a few weeks  |
The OEM tune tends to restrict full throttle opening, especially under low load. Because it is "fly-by-wire", this can be adjusted in a table that commands throttle opening in the ECU, which with some tweaking, can result in snappier throttle response. There's also a "soft" rev cut that pulls fueling as you approach redline, as another poster mentioned, that can be changed.
There are other factors that can be adjusted as well (e.g., torque restriction on gear shifts in the auto) in the ECU maps to affect how the car responds to various driver inputs.