The automotive community was in anticipation after Acura announced the release of a new turbocharged SUV known as the RDX in August of 2006. The RDX, deemed as Acura's first turbocharged gasoline engine, uses a 2.3L K23A1 that powers its all-wheel-drive platform to a tune of 240 hp and 260 lb-ft of torque. A top-mount intercooler similar to the Subaru WRX offers ambient airflow through a trick ducting system that draws air through the factory grille to keep temperatures optimal. Developed under the K-series family, the 2.3L engine was engineered with a lower compression ratio of 8.8:1 to cater to the new boost-friendly setup.
With much hype and anticipation, the RDX offered the aftermarket import car community a stealthier SUV-type model. The RDX, however, never seemed to catch on; sales were marginal at best. The 240hp all-wheel-drive configuration looked promising in terms of performance on paper. When driving the RDX, though, you could feel its weight (3,924 pounds) and its factory "safe" ECU tune, masking the vehicle's true potential. Hondata, located in Torrance, Calif., was up to the task to improve the vehicle's power, performance, and even fuel economy. Hondata recently developed a reflash setup that's not only simple to install, but it also offers some major bang for the buck.
I took a quick drive down to Church Automotive in Wilmington, Calif., where I met up with Doug MacMillan, Hondata co-owner, and Shawn Church, owner of Church Automotive, to testdrive and dyno test a stock '08 Acura RDX. The RDX had before and after modifications done to the ECU, along with a custom exhaust system installed before the final pull. A quick spin on the dynopack revealed baseline numbers at 210 hp and 243 lb-ft of torque. Doug and his crew at Hondata had gone through months of test and ECU analysis for the RDX before the final product was released to the general public. With laptop in hand, Doug reflashed the ECU and the RDX was ready for its next run using the new maps. A quick dyno pull showed a peak of 237 hp and 268 lb-ft of torque-a gain of 27 hp and 25 lb-ft of torque over baseline.
Acura's variable flow turbocharger minimizes turbo lag by using a valve-type unit to pinch off the exhaust pressure, increasing the turbo response and spooling characteristics at lower rpm, while at a higher rpm the valve opens to increase flow. This design works great for the average commuter, but falls short in terms of performance when it comes to making real horsepower. Boost data logging shows the RDX running a factory boost pressure of 13-14 psi consistently till 4,500 rpm, where the boost begins to taper off as it finally falls on its face by 8 psi at 6,500 rpm. The factory ECU was designed to constantly monitor knock, as it automatically advances and retards ignition timing. This rapid change in timing alters the engine's performance as variable results such as low-octane fuel, intake temperature, hard driving on boost, and higher rpm shifting will cause knock and downgrade power output. Acura has tuned the factory air/fuel ratio in the low 10s to thwart off any issues that may develop with an engine running in lean conditions. It's obvious that Acura engineers detuned this turbocharged engine to retain a more comparable margin of safety for warranty issues.
"The reflashed RDX ECU shows gains throughout the powerband as a strong increase of power (10-20 hp) is shown on the dyno graphs from low-end torque (33 lb-ft at 3,300 rpm) to a good increase in top end power (26hp peak) above 5,500 rpm," Doug says. The reflashed ECU has been altered to increase the factory rev limiter from 6,500 rpm to 7,200 rpm (sport shift mode only). Baseline air/fuel ratios were slightly altered by one point to low 11s to improve the power and torque output delivered using the reflash. With some additional massaging taking place in reprogramming the reflash maps, Hondata was able to advance the ignition, lean the A/F mixture ever so slightly, and advance the cam angle to improve power. Most importantly, the spooling characteristics on the turbo were improved over factory, as the Hondata reflash increased the boost 1-2 psi in the midrange while top end boost was altered to a safe yet noticeable 3-4 psi. "We designed the reflash to be marginal in alterations to the engine, yet deliver the maximum amount of power available for the RDX without sacrificing driveability and reliability," Doug says.
The next phase of testing consisted of removing the factory exhaust and down pipe setup to replace it with a larger 3-inch diameter prototype Church Automotive exhaust system. A custom reflash setup, available only through Church Automotive, offered some promising results as the custom exhaust netted 40-plus horsepower and torque increase over stock. Currently, Church Automotive has no plans of offering this system to the general public due to the intricate design and cost to build, but it's possible that customer demands and inquiries can sway them to build a more affordable, cost effective unit in the near future. A quick testdrive around the block offered a whole different animal in the RDX. A quick turn around the corner followed by a stomp on the accelerator broke all four tires loose as the turbo quickly spooled with every shift of the transmission. The performance gains were obvious and gave the RDX a sportier presence than what I had experienced less than an hour ago when driving the stock version.
Ordering the Hondata reflash is as quick and easy as removing your factory ECU. Drop it off at an authorized Hondata dealership, fill out a vehicle information form, and they send it off to Hondata to be programmed. Hondata doesn't require the vehicle's keys or immobilizer, which makes this a simple one-two step. At $595 for the basic reflash and the option to purchase a new ECU with reflash for $1,150, the Hondata reflash is your answer to obtaining maximum power from your RDX.
Acura RDX ECU PN RWC-A56 and A57 Hondata Reflash Pricing:
K23A1-RDX ECU flash program 7,200rpm rev limit: $595
K23A1ECU-RDX ECU and flash program 7,200rpm rev limit: $1,150
K23A1-RDX-Church ECU flash program 8,600rpm rev limit: $595
K23A1-RDX ECU flash program 7,200rpm rev limit with new ECU: $1,095