Dyno Tuning: Where Power Meets Efficiency
We're using Auto Meter's NV...
We're using Auto Meter's NV series 21 16-inch gauges to monitor boost (PN 7307; $70.00) and fuel (PN 7363; $200.00). The boost gauge is mechanical and gives us accurate readings of both vacuum and boost at the top of the rpm band. The fuel gauge is an electric, full-sweep unit that measures pressure up to 100 psi. This photo shows the "night-vision" green illumination of the gauges, which works well with the factory dash lighting. The NV's brightness is strong, so we recommend giving yourself some adjustability with Auto Meter's LED lighting dimmer (PN 9114; $30.00).
Extreme Automotive's Evolution 4000 dynamometer and our '02 GT got an extreme workout during our three days of extensive testing. Again, while we recognize the numbers-horsepower and torque-are the highlights of any time spent on the dyno, we wanted to get a better sense of how the numbers are achieved when a supercharger is installed on a slightly modified Two-Valve.
One of the popular sayings about horsepower is, "You can have all the horsepower in the world, but it doesn't mean anything if you can't get it to the ground." While this is true, we also think that having gobs of power is equally as useless if it hasn't been achieved by extensive tuning. Without a proper tune, your stuff is eventually gonna go boom!
When it comes to a blown-Mustang's performance results on the dyno, having less horsepower is sometimes theoretically viewed as having more in the long run-a good-running, efficient overall package that isn't on the ragged edge.
We tested our '02 in three separate configurations: naturally aspirated, with only the SLP PerformancePac added (240.58 hp and 266.78 lb-ft); blown, with the P-1SC installed and ProCharger's factory tune (365.50 hp, 365.90 lb-ft, and 9.43 psi boost); and blown, with an Accufab 75mm throttle body and plenum, a DiabloSport MAFia, and an Extreme Automotive custom tune Saul created, using a baseline program we received from DiabloSport (383.52 hp, 372.32 lb-ft, and 9.10 psi boost).
Once we started working with the blower, running the car on the dyno became a lot more involved than simply gunning the engine. Creating a good dyno tune doesn't happen in a matter of minutes or within the first two pulls. One of the keys to success is taking small steps toward making power and keeping safety in mind when changes are made. With that, Saul stuck with an "increments" attitude-not a throw-everything-at-it-at-once mentality.
This is the spark-advance...
This is the spark-advance table Saul uses to help create our custom tune, as seen through DiabloSport's "Chipmaster Revolution" software. Saul starts with information in this table and, through incremental testing on the dyno, is able to modify our blown Mustang's spark timing to increase power while maintaining a safe buffer from detonation.
Fuel was one of the main areas of concentration. In both of the blower tests-ProCharger only, and with new throttle body/plenum, MAFia and DiabloSport tune-the first order of business was to see where things stood with the air/fuel ratio. Using Innovate's new digital air/fuel gauge helped, as we quickly saw that our mixtures were a little leaner than we preferred, in both cases, when we made short, 2,500-rpm tests to see which way we needed to go. With a blower, as boost increases, so does the demand for fuel. On the dyno, we saw improvements in performance after Saul went into the fuel tables for each program and made adjustments.
Naturally, our max-power effort was with the car in ProCharger/DiabloSport/Accufab trim. Saul spent the most time setting up a custom tune for this configuration, starting with some of the parameters that DiabloSport included in its tune. And he had to start with numbers that were below our P-1SC/factory-tune results and work upward. Again, after getting the initial air/fuel parameters set, a combination of fuel, timing, load, and other changes were made throughout the course of our final session. We saw progress every step of the way.
Octane, or California fuel's lack of higher octane, proved to be Saul's major challenge when we started seeing numbers that eclipsed where we maxed out with ProCharger's tune. Because we were limited to the 91-octane fuel-as opposed to using higher-grade race gas-there were definite timing concerns that prevented creation of a tune that would show us 400-plus horses at the rear tires. While we could have pushed the envelope and attempted to get "the number" by trying 18-degrees timing advance, which probably would have put air/fuel in dangerous territory, Saul opted for efficiency and safety. We made great horsepower and torque (383.52 hp and 372.32 lb-ft) on our final pull of the experience at air/fuel levels that never eclipsed 11.94. That's plenty safe, and with 142.94 more horsepower and 105.54 lb-ft of torque beyond the naturally aspirated totals we had going into this project, it's definitely plenty of performance for a daily driven Mustang.
 This is the DiabloSport open-loop...  This is the DiabloSport open-loop fuel table. When the ECM is operating under open-loop conditions, the O2 sensor works in conjunction with this table, the mass-air transfer file, and signals sent to the processor from other sensors-such as coolant temp and air-charge temp-to maintain the desired air/fuel ratio. |  Here Dorian points out the...  Here Dorian points out the peak gains the new ProCharger netted on the dyno pull. |  Since our 'Stang is now putting...  Since our 'Stang is now putting out street-credible power at the rear wheels (we set the bar at 350 hp and 350 lb-ft), we think it's worthy of wearing Performance Parts' bitchin' new "4.6 Interceptor" badges (www.performancepartsinc.com; $8.99/each). The factory "GT" tags were removed from the fenders and rear panel, and these babies now let folks know the real deal. |