A lot of people focus,
On the
peak power gain when talking about tuning.
This should be put into perspective.
An engine only makes peak power for less than a second when accelerating, the rate at what it is accelerating at (mechanical power-wise, not gearing or car weight) is what gets the engine to peak power.
Indicating the average power increase, and not only the peak output, is a better way to illustrate how the car will behave with tuning. During acceleration, for example when overtaking, it’s the
area under the power graph in the current rpm interval that determines how fast the car will accelerate. The average power generally tells more about the acceleration than the stated peak output.
e.g. A car with a 2.5litre engine (manual box and rwd) was dyno'd and gave 137rwhp (corrected to J607 and exactly as advertised by the manufacturer, which is unusual).
It was then re-chipped, dyno'd again and showed a 6rwhp gain after atmospheric correction; 143hp.
6rwhp translates to about 7 or 8hp at the crank in a manual rwd car. That doesn't seem worth it at face value.
This doesn't mean it wasn't any different to drive though.
If you looked closely at the car's dyno graph; with the performance chip fitted, the car was making the same power as it did with the o.e. chip, but it was all happening 250rpm earlier.
i.e. if it was making 100rwhp @ 3000rpm on the o.e. chip, it was making 100rwhp at 2,750rpm with the aftermarket one; and this was happening all the way from 1500rpm through to 6,200rpm.
The
average power (from 1500 all the way to 6,200rpm) had jumped up considerably and it was noticeable on the road. It improved the 30-70mph acceleration by approximately 0.5 seconds. That, is not to be sniffed at.
The car felt livelier and more responsive to the throttle.
It was money well spent in that particular case.
A good explanation about average power here:-
http://www.impulsengine.com/performance/moreav.shtml
