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2004 Acura TSX Part 1 - Power Pages

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The K24A2 engine features intelligent variable valve timing (i-VTEC) used on both the intake and exhaust cams and is factory rated at 205 hp and 164 lb-ft of torque. Its 2.4L engine is a long stroke version of the highly refined 2.0L engine found in the Acura RSX-S. With the TSX used car market being more affordable and increasingly popular among the import tuner market, we seized the opportunity to power page test three products with the goal of creating additional horsepower.

Initial dyno testing revealed the factory ECU tuning on the 2.4L engine was obviously tuned by Honda/Acura for those commuters only using their cars to and from work. The graphs showed a significant drop off in power as torque figures were adversely affected before the low- to high-cam transition of VTEC. A gradual decline of more than 27 lb-ft of torque from 172 to 145 lb-ft was recorded before the VTEC secondary lobes were finally engaged, at 6,000 rpm as it ever so slightly increased once again.

Prior to our baseline run, the TSX was given an oil change, spark plug check/replacement, and OEM intake filter replacement before strapping onto the dyno. In stock trim, the TSX delivered 186.5 hp and 172.5 lb-ft of torque.

Hondata Heatshield and OEM Throttle-Body Mod

Heatshield gasket

10, 12, and 14mm socket; 10, 12, and 14mm open-end ratchet; extension; screwdriver; pliers; and magnetic pickup (for the nuts and bolts you will drop)

Installation time
60 minutes

For $50 the Hondata Heatshield intake manifold gasket is considered the best bang for the buck in terms of horsepower. The Hondata unit is made of a special high-temperature–insulating gasket, which replaces the stock intake manifold gasket. This gasket has been proven beneficial on the TSX and its K24A2 engine as the factory intake manifold was designed with long narrow runners that are prone to experience internal heat soaking, ultimately affecting the incoming air. Keep in mind that for every 3.3 degrees C (5 degrees F) rise in intake temperature, air density drops 1 percent. The hotter the air, the less fuel the computer injects to compensate for reduced oxygen, which translates to less power. We combined the Hondata Heatshield with bypassing the coolant lines on the OEM throttle body. The TB modification is a simple DIY trick that ended up costing us nothing in the end, but was a major help in keeping intake temps cooler for additional horsepower.

Installation involves the long process of removing the intake manifold, installing the gasket and replacing the intake manifold. Be sure your engine is completely cool before attempting to remove/install the gasket, which also applies with the TB coolant bypass mod to prevent any coolant burns.

The Hondata Heatshield and TB mod delivered 8.2 peak and 7.3 lb-ft of torque over the previous run with both horsepower and torque gains throughout the entire powerband. The largest gains were recorded in the low to midrange level from 2,100 rpm to 5,500 rpm with the largest recorded gains taking place at 4,300 rpm with 12.5 hp and 7 lb-ft of torque.

Hondata FlashPro

Hondata unit/ECU, USC cables, stickers, instructions, and CD-ROM

Tools Laptop and tuning experience

Installation time
140 minutes

Hondata’s FlashPro for the ’04 -08 TSX is the latest addition to its highly successful FlashPro line, offering comprehensive tuning solutions to the late-model Honda market. The Hondata FlashPro enables the user to quickly and accurately tune the TSX engine computer parameters through the OBD-II diagnostic port for maximum performance and economy without having to use a dual harness or ECU while allowing you to retain both VSA and cruise control. Using the FlashPro manager software enables multiple features including 20 hours of onboard data logging capability, support for larger injectors, race vehicle sensor disabling, individual cylinder knock data logging, fuel trim and ignition trim tuning, along with a bevy of additional parameters.

The ’04-06 Acura TSX will need to be retrofitted with a ’07-08 Acura TSX ECU, which Honda retails for $610 U.S. and a Hondata-supplied adapter cable for $50 in order to properly tune with a FlashPro. Although this step is a bit more expensive, it is vital for optimizing the ECU for your modifications.

The FlashPro allowed us to lower VTEC engagement to 4,900 rpm, while increasing the rev limit to 7,600 rpm. The most coveted reason to purchase and tune with the FlashPro is the ability to adjust the variable timing control (VTC), which is located on the end of the intake camshaft for additional horsepower. The factory ECU limits the maximum cam angle to 20 degrees of cam movement. This is fine for a stock TSX engine, but completely inadequate for modified engine, which needs no less than 25 degrees on the high cam. FlashPro allows you to tune up to 25 degrees with the stock cam wheel and up to 50 degrees with a modified/replacement VTC cam pulley to take full advantage of larger profile camshafts, race headers, and aftermarket exhaust systems. Dyno testing following tuning the FlashPro revealed an increase in power and torque throughout the powerband, with a healthy gain in the midrange and top end from 3,500 rpm to redline.

Injen SP Series Cold Air Intake

Performance filter, two-piece intake tube, brackets, washers, grommets, nuts and bolts, silicone hose, hose clamps, instructions, stickers, and stud rubber mount.

10 and 12mm socket, 10 and 12mm open end, ratchet, extension, screwdriver, and pliers

Installation Time
40 minutes

The Injen SP Series cold air intake system is built from 6061, T6 aluminum alloy and comes in your choice of polished aluminum or black finish. The Injen intake features TIG-welded aluminum vacuum ports and brackets, stainless steel clamps, and Injen’s Purosil silicone hose. The cold air intake also includes a rubber vibra-mount used to relieve stress on the intake pipe from driving vibration. Each Injen air intake system comes with a replaceable Injen performance urethane air filter, limited-lifetime warranty, and is CARB approved.

Installing the intake system does require the removal of the driver-side wheel and tire, under panel pieces, and some clever maneuvering to squeeze your hands and fingers inside the cramped engine bay area. The TSX with its small front bumper duct proved to be a cumbersome task to remove, which requires the owner to remove the duct cover to access the reservoir box and bolts that reside under the bumper before attempting to install the new intake.

The cold air intake along with tuning increased both horsepower and torque throughout the -powerband as the TSX made gains of 6 hp and 4 lb-ft of torque at 4,500 rpm while consistent gains of 5 hp and 4 lb-ft of torque were seen from 5,200 rpm to redline.


Our final testing saw peak output improve to 213 hp and 187.7 lb-ft torque—an increase of 26.5 and 15.2 lb-ft of torque—with the largest gains of 32.2 hp and 38.3lb-ft of torque occurring at 6,000 rpm. With over 200 hp to the wheels, a quick drive around the block revealed a night- and-day difference with improved throttle response. We found this TSX a blast to drive on the street. Torque output and horsepower improved greatly in all the right places. Stay tuned for part two in our next issue as future modifications are calling our name in the form of a full exhaust system, RBC intake manifold, and aftermarket camshafts. We’re betting this engine has what it takes to eclipse the 250-whp marker.

HONDATA FLASH PRO208.013.3185.05.2
INJEN COLD AIR INTAKE213.05.0187.72.7

ACURA '07-08 TSX ECU$610.00

2840 Columbia St.
CA  90503
Injen Technology
244 Pioneer Place
CA  91768
Church Automotive Testing
300 Quay Ave.
CA  90744
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