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2008 Acura RDX - Power Pages

Text By: Luke Munnell, Steve Demmitt, Photography by Luke Munnell, Steve Demmitt

* Dyno And Facility:Dynojet, Courtesy Of K&N Filters
* Testing & Installation:James Yim, Nestor Cabrera, Luke Munnell

Pros
Prior to the RDX's launch in '06, if you were to ask any Honda tuner what their dream swap would be, they'd reply with something along the lines of what this modern day crossover offers straight from the assembly line: a factory turbocharged and intercooled Honda K-series engine. Marking their return to turbocharging technology after nearly 20 years since the discontinuation of the City Turbo in '87, Honda chose to boost a version of one of their most tunable engines, to a claimed 240 whp and 260 lb-ft of torque. Big power and torque, with factory reliability and potentially huge aftermarket support? What was there not to like?

Cons
In true Honda fashion, instead of boosting one of the most well-designed four cylinders of all time in the name of all-out power, and dropping it into a platform capable of challenging performance giants like the EVO, STI, and Mazdaspeed 3, the company opted instead for fuel efficiency, midrange torque and decreased emissions when designing the K23A1, and fitted it into a crossover SUV, to rival the likes of the Forrester, CX-9 and Santa Fe. Not that this completely negates the "cool factor" of a factory turbocharged Honda K-series, but... how completely badass would it have been to see the engine tweaked slightly and dropped into, say, the Mugen Civic Si?

Notes
At the rollers of K&N's all-wheel-drive Dynojet, regular 2NR contributing photographer Steve Demmitt's '08 RDX rolled out 66 whp less than its claimed flywheel hp number, indicating a driveline loss of almost 30 percent. If such a comparatively low number is a bit surprising, consider that the K23A1's power is transferred by an automatic transmission to all four wheels before our chassis dyno can measure it, and the 90+ degree ambient temperatures encountered throughout testing decreased power significantly, compared to conditions inside Honda's own climate-controlled engine dyno facilities.

Pros
Factory programming of the RDX ECU limits boost generated by its K23A1 to between 13 to 14 psi until 4,500 RPM, then decreases to 8 psi approaching the 6,500 rpm redline. Hondata's ECU reflash raises boost by 1-1.5 psi under 4,500 rpm, and 3.5-4 psi to an extended 7,500 rpm redline. Additionally, the reflash advances ignition timing, and leans out the RDX's conservative air/fuel ratio to within more ideal tolerances. The result is more power and torque across the board, with improved fuel economy to boot, provided you can refrain from driving with a lead foot. Finally, the entire reflash process is reversible, should users ever want to return their vehicles to the stock tune, or re-tune for additional modifications.

Cons
Because of Hondata's more aggressive boost, timing, and AFR adjustments, 91 octane or better gasoline must be run at all times, otherwise under instances of stress (high heat or engine load), the RDX's knock sensor will kick in and retard timing, robbing power until conditions improve.

Parts
Reflash of the factory ECU

Tools
10mm socket and ratchet, postal service

Installation Time
2-day turnaround, 5-minute removal and re-installation

Notes
Since the Hondata tune is designed to accommodate 91 octane gas, use of higher octane fuel may lead to improved power output and fuel economy. Also, the heightened redline only functions in the "Sportshift" mode; all other features are available in every mode.

Pros
Powder-coated, mandrel-bent, thin-walled aluminum tubing; a flow bench-tested and properly-sized re-usable filter; and a black powder-coated heat shield worked together to feed our K23A1 with the most efficient amount of smooth flowing, cool, clean air to improve output by more than 11 whp and 13 lb-ft of torque at points throughout its powerband - all in lightweight, aesthetically pleasing style, complete with a lifetime guarantee and CARB certification.

Cons
Mid-range and top-end power gains do come at the cost of a fraction of a horsepower and lb-ft of torque pre-boost; a small price to pay, given its advantages.

Parts
Intake filter, tubing, heat shield, MAFS hardware, coupler, clamps

Tools
10mm socket, extension, and ratchet, flat and Phillips head screwdrivers

Installation Time
1 hour

Notes
If you ever wished for your K23A1's factory bypass valve and intake to be a little more audible, you'll be happy after installing this mod. Hearing our turbo spool under throttle and its boost reccirculate at let-off prompted ear-to-ear grins with every press of the 'go' pedal, and gave our RDX just enough bark to let the punk in the next lane know we mean business!

Pros
Reducing exhaust backpressure is crucial to freeing up power in turbocharged cars. But, in vehicles like the RDX, so is maintaining a subtle appearance and sound. No one wants to outfit their $30K luxury crossover with a raspy "fart can"; that's why the ATLP unit is an attractive addition. Mandrel-bent, 2.5-inch 439 stainless steel piping scavenges exhaust gas efficiently, resists corrosion and remains durable under high-heat duress, while proprietary heat resistant packing in straight-through silencers ensures years of quiet operation, and a polished 402 stainless muffler and dual four-inch tips give a more aggressive, yet mature finish.

Cons
Again, midrange and top-end power come at the cost of a few ponies down low, but with more than 10 whp and 11 lb-ft of torque throughout the powerband from below 4,500 rpm until redline, we consider this a non-issue.

Parts
Exhaust system, gaskets, hardware

Tools
14mm, 17mm sockets, ratchet and wrenches, WD-40, hanger removal tool

Installation Time
1 hour

Notes
Unlike a lot of popular modern-day platforms, the RDX's exhaust tract doesn't include a welded-in catalyst, which means upgrading the stock exhaust won't cost your street-legality. The RDX does use two separate catalysts, the lower of which-since it neither accommodate an O2 sensor, nor requires removal of the factory downpipe-can easily be removed through the use of an optional ATLP test-pipe; a good addition for any... um, off-highway event (wink, wink).

Conclusion
Weighing the pros and cons of modifying the RDX for power, we can only see reasons why doing so can be a good thing. After the addition of three reversible, bolt-on modifications, our RDX moves with the help of nearly 40 more horses and as many lb-ft of torque at the wheels, averages better fuel efficiency during the daily commute, and retains its upscale appeal. Keep reading 2NR as we continue to dig for the bottom line as to how much power this Honda dream engine is capable of.

BANKROLL
HONDATA ECU REFLASH $595.00
K&N TYPHOON PERFORMANCE
INTAKE KIT $321.00
ATLP STAINLESS STEEL
CAT-BACK EXHAUST $939.00
MSRP Total $1,855.00
CONCLUSION
HP Level +HP TQ Level +TQ
BASELINE 175.1 179.8
HONDATA ECU REFLASH 196.3 21.2 201.5 21.7
K&N TYPHOON PERFORMANCE INTAKE KIT 203.5 7.2 215.4 13.9
ATLP STAINLESS STEEL CAT-BACK EXHAUST 206.2 2.7 219.8 4.4
FINAL 206.2 31.1 219.8 40.0
HOTBOX
K&N
P.O. Box 1329
Riverside
CA  92502
Acura Tl Parts (ATLP)
www.acuratlparts.com
Hondata
2341 W. 205th St.
Torrance
CA  90501
3-10/-782-8278
www.hondata.com
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By Luke Munnell, Steve Demmitt
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