In this project, Andrew Totolos has installed a computerized adjustable engine-management system on a Dodge SRT-4 that will help custom match fuel and boost ratios for enhanced performance. To make the most of the new computerized system, it's time to head to the Dyno shop for some serious tuning. The Dyno is a safe and controlled environment that will give you optimum fine tuning results. In this final segment, we get some hard numbers that show why this fine-tuning can be so important in achieving peak performance.
The first thing to do in any tuning situation is to perform a base run to find out exactly how the car is running before the new modifications. If you're doing any mechanical upgrades, it's best to take two trips to the DYNO for before and after comparisons. In our baseline run, the srt-4 racked up a solid 264 horsepower and 264 pound-feet of torque, but the fuel mixture is a little rich at 16 to 1 from around 3200 to 5200 rpm.
An SRT-4 in this state of tune should be running closer to 11.8:1, so our first tuning step is to remove some extra fuel in the rich ranges and examine the results.
It's best to make adjustments in small increments to get an idea of how the engine is going to react rather then trying to overdo it and risk possible damage to the engine.
Once the air/fuel ratio is adjusted to satisfactory levels, it's safe to begin adding small amounts of boost. More boost could lean out the fuel mixture, so keep an eye on the readings and dial fuel back in as necessary to keep things on target.
The process continues until a satisfactory balance of power is achieved. Dyno Results
Until this car can receive an upgrade to the fuel system in the form of larger injectors, we decided to keep this engine running at a target boost level of about 17 psi. At those levels, the engine produced an impressive 308 horsepower and 307 pound-feet of torque with a nice level 13.5:1 air to fuel ratio across the power band.
The Bottom Line
DTEC computer $700
Wide-band tuner $400
Gaming system $90
Misc. supplies $30
DYNO time $300
Total = $1520
Important: Included in this summary are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular car or truck, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of upgrade-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.
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