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2004 Acura TSX Part 2 - Power Pages

The Dyno Doesn't Lie

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Given this is the second part in our two-part Power Pages series for our TSX, we’ve found that there are many different routes you can follow when building your TSX. This time around we were able to increase power by enabling the engine to breathe using a Hytech header, high-flow cat, and exhaust system; RBC intake manifold; Honda TL 64mm TB; Acura ’06 TSX intake camshaft; and VTC Cam timing mechanism mod.

None: Unless you don’t appreciate bolt-on parts that help develop additional horsepower and torque!

Before we began the second part of our testing, we concluded our previous test to the tune of 187.7 hp and 213 lb-ft of torque by outfitting our TSX with a Hondata intake head shield gasket, FlashPro; ’07 TSX ECU; Injen cold air intake; and OEM TB coolant mod. We began our initial baseline for part two with the previously mentioned mods, including an Acura ’06 TSX intake camshaft and Honda TL 64mm TB.

Hytech Exhaust Full-Setup System (Hondata FlashPro tuned)

Header, piping, brackets catalytic, and exhaust

10, 12, and 14mm sockets; 10, 12, and 14mm open-end wrenches; ratchet; extension; crescent wrench; and WD-40

Installation time
100 minutes

The Hytech Full exhaust system we tested consists of a header, high-flow catalytic, and exhaust system. The Hytech header is designed as a long-tube tri-Y 4-2-1 header and made of 304 stainless steel. Using a 2.5-inch collector, the headers are designed using their patented anti-reversion chambers. Anti-reversion chambers are placed at strategic locations in the primary pipe to tune the arrival of the exhaust wave and to diminish the effects of the high pressure in the pipes. The results are higher volumetric efficiency and increased power. Coupled to a Renault high-flow catalytic converter placed approximately 40cm further back and 2.5-inch straight-through cat-back exhaust that’s been marketed as one of the most horsepower-friendly exhaust systems sold for the TSX.

Due to the length of the header, which is longer than the standard OEM-style header, the oxygen sensor wires need to be lengthened 18 inches while also taking note that you cannot mix and match it along with a standard cat-back system. The Hytech header requires either purchasing their exhaust or customizing to fit off-the-shelf OEM-sized cat-back exhaust systems.

The Hytech header lowered the VTEC point to 4,000 rpm from the factory 6,000 rpm, which enabled us to give the new intake cam full advance timing. This gave us 10 to 15 hp throughout the powerband on the high cam with the largest gains of 18 hp and 16 lb-ft of torque taking place at 5,200 rpm.

RBC Intake Manifold (Hondata FlashPro tuned)

Intake manifold, intake/TB gasket (required)

10, 12, and 14mm socket, 10, 12, and 14mm open-end, ratchet, extension, screwdriver and Hondabond

Installation time
120 minutes

The factory RBB is a two-piece, long runner intake manifold found on the TSX. In comparison, the RBC found on the Euro Accord Type R and ’06-and-newer Civic Si is more compact due to shorter, fatter runners with less curvature and a larger plenum design. The stock RBB manifold uses long narrow runners, which is good for torque, whereas the RBC intake from the Accord Euro R uses shorter, fatter runners optimized for high-rpm breathing. The RBC intake is a direct replacement for the RBB.

Don’t expect power gains by simply installing the new intake without tuning. The RBC intake manifold with its runner design is improved for higher rpm breathing but forfeits some horsepower and torque throughout the midrange powerband compared to the RBB without proper tuning.

The newly installed RBC manifold was tuned with a Hondata FlashPro and made 249.3 hp and 193.6 lb-ft of torque—a gain of 10.8 hp but lost 2.6 lb-ft of torque over our factory manifold. The RBC manifold gained 7 hp and torque under 3,000 rpm, but showed a significant loss in torque from 3,500-5,000 rpm. The manifold showed its worth up top with its largest gains of 9 hp and 7 lb-ft of torque from 6,000 rpm to redline.

Interestingly enough, we noticed the RBB manifold tuned with VTC set at 45 degrees showed a significant gain in top end peak torque versus the RBB at 25 degrees (210 versus 203 lb-ft of torque).

VTC Cam timing mechanism (Hondata FlashPro tuned)

VTC Cam Gear Modification

Reputable machinist or tuner shop for modifications

Installation time
Two days including removal/installation

The Honda/Acura K-Series engine uses VTC (Variable Timing Control) as it continually adjusts camshaft timing with Variable Valve Timing and Lift Electronic Control (VTEC). Located on the end of the intake camshaft, the VTC mechanism, via hydraulics allows 25 (crank) degrees of continuous movement on the TSX and 50 degrees on the RSX. Engine tuners have found that 25 degrees of cam movement is fine for a stock TSX engine but completely inadequate for a modified engine with as little as race headers and intake. Modifying the factory VTC mechanism has been proven to net big horsepower gains. Advancing the camshaft to increase valve overlap allows us to use the header’s reversion pulses to draw more intake air resulting in gains everywhere above 4,000 rpm. We used a VTC mechanism machined to 45 degrees to limit the valve overlap and valve-to-piston clearance. Due to popular belief, the valves do not make piston contact at 50 degrees, but we wanted a little extra safety margin in case of accidents like a mis-shift.

Although you could probably purchase and bolt on an RSX VTC mechanism for 50 degrees cam travel, there is the danger of less valve-to-piston clearance on the TSX pistons compared to the RSX. Our measurements suggest 45 degrees maximum cam movement is much safer. Although modifying the factory VTC at home is possible, we recommend a qualified machinist or shop with prior experience to machine and remove material to increase the cam advance from 25 to 45 degrees.

The Hondata FlashPro allows you to tune up to 25 degrees with the stock cam wheel and up to 50 degrees with a replacement VTC cam pulley to take full advantage of the TSX now equipped with a larger-profile intake camshaft, RBC intake, and Hytech race headers and exhaust system. At this power level, the injectors were maxed out at 100 percent duty cycle, so upgrading to larger-sized RDX (410cc) injectors are highly recommended. Overall these changes netted 12 lb-ft of torque increase and 10 peak horsepower over our previous dyno.


What began as a two-part engine build, finished with promising results for this daily driven TSX. We began the second part of our two-part series of testing with a baseline run of 219.9 hp and 185.6 lb-ft torque and ended off with 251.9 hp and 203.2 lb-ft torque, an increase of 32 hp and 17.6 lb-ft of torque. Not only did we manage to eclipse the 250-whp marker in the end, we made an impressive 60.5 hp and 30.7 lb-ft of torque over factory baseline.

RBC INTAKE MANIFOLD249.310.8193.6-2.6

ACURA '06 TSX INTAKE CAM ($346)/TL 64MM TB ($490)$836
HYTECH HEADER ($1,300)/CAT ($395)/EXHAUST ($899)$2,594

2840 Columbia St.
CA  90503
Church Automotive Testing
300 Quay Ave.
CA  90744
HyTech Exhaust
12 Hammond St.
CA  92618
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