The Acura Integra Type R (ITR) remains one of the most revered front-wheel-drive cars ever built. Its B18C5 engine, a masterpiece of Honda’s golden era, came from the factory with 195 horsepower—an impressive figure for a naturally aspirated 1.8-liter four-cylinder. But for many enthusiasts, that number is just the beginning. With the right combination of bolt-on parts and calibration, the B18C5 can be coaxed well beyond 200 hp, and a popular, proven target is 280 wheel horsepower. Achieving this requires a well-matched setup, and the Skunk2 intake manifold is often at the center of the build, paired with a thorough ECU tune. This guide covers every detail: why the Skunk2 manifold works, what other parts you need, how much it costs, how to install it, and what real-world owners actually see on the dyno and at the strip.

The Skunk2 Intake Manifold: Design and Benefits

Skunk2 Racing is a well-known name in Honda performance, and their intake manifolds are engineered to address the airflow bottlenecks of the factory unit. The stock B18C5 intake manifold is designed for broad torque and emissions compliance, but its small plenum volume and restrictive runner geometry limit top-end power. The Skunk2 Pro Series manifold (the most popular choice for 280 hp builds) increases plenum volume by roughly 40% compared to stock. This larger air reservoir helps maintain intake velocity at higher RPMs, while the shorter, smoother runners reduce flow resistance. The manifold also uses a 70mm throttle body opening versus the stock 62mm, which alone can add 5-8 hp when paired with a matching throttle body.

The manifold is constructed from cast-aluminum alloy, which is both lighter and more durable than the stock plastic unit. The runner length and taper are optimized for the B18C5’s VTEC crossover—roughly 5,800-6,000 RPM—so that when the high-lift cam lobes engage, the manifold is ready to feed the extra air demand. Importantly, the Skunk2 manifold also offers larger plenum ports for nitrous or water/methanol injection, should you want to push further later. For a naturally aspirated build, this manifold alone can contribute 10–15 hp increase (depending on other mods), but its real value is unlocking the potential of other upgrades.

Building the 280 HP Package: Required Modifications

No single part gets you 280 hp on a B18C5. The Skunk2 intake manifold is a cornerstone, but it must work in concert with a set of supporting modifications. Below is a breakdown of the necessary components and why each matters.

Fuel System Upgrades

The stock ITR fuel injectors are 240cc/min, adequate for about 220-230 hp. To reach 280 hp, you need more fuel volume. High-performance fuel injectors in the 440cc–550cc range (e.g., RDX 410cc or Precision 550cc) are common choices. They must be paired with an upgraded fuel pump—a Walbro 255 lph or AEM 340 lph is typical—to maintain pressure at high flow rates. Many also add an adjustable fuel pressure regulator (AFPR) to fine-tune the base pressure when tuning with a wideband. These fuel upgrades ensure the engine doesn’t lean out under WOT at redline, which can cause detonation and engine failure.

Exhaust System

A restrictive exhaust is a serious bottleneck. The factory ITR exhaust has a 2.25-inch diameter and a crush-bent route. For 280 hp, you need a full 3-inch or at least 2.5-inch system from the header to the tip. A 4-1 or 4-2-1 header (Skunk2 or similar) with a 3-inch collector is recommended. The header should be ceramic coated or wrapped to reduce underhood temperatures. Pair it with a high-flow catalytic converter (or test pipe for track use) and a cat-back exhaust that maintains the 3-inch diameter with a free-flowing muffler. The exhaust system alone can add 15-20 hp over stock when tuned.

ECU Tuning

Tuning is the linchpin. Without proper calibration, the other parts are wasted. The B18C5 uses a OBD2 ECU, but for full control, most builders switch to Hondata S300 (a piggyback system that replaces the stock ECU’s chip) or a standalone like Hondata K-Pro (if converting to OBD1). The tuner adjusts fuel maps, ignition timing, and VTEC engagement points. A street tune with a wideband O2 sensor can get you close, but a dyno tune is essential for extracting the last 10-15 hp and ensuring a safe air/fuel ratio (typically 12.5-13.0:1 under load). Expect to pay $300–$600 for a reputable dyno calibration.

Cost Analysis: What to Budget

Building a 280 hp ITR isn’t cheap, but it’s far less expensive than forced induction setups. Prices vary by region and whether you DIY or pay a shop. Below is a realistic parts cost range (USD).

  • Skunk2 Pro Series Intake Manifold: $600–$800
  • Skunk2 70mm Throttle Body: $250–$400 (recommended to match the manifold)
  • High-performance fuel injectors (440–550cc): $300–$500
  • Upgraded fuel pump (Walbro 255 or AEM 340): $100–$200
  • Adjustable fuel pressure regulator (optional but recommended): $100–$200
  • 4-1 Header (Skunk2 or similar): $400–$800
  • 3-inch cat-back exhaust: $500–$1,200 (depending on brand and materials)
  • Hondata S300 or K-Pro ECU and conversion harness: $500–$700
  • Dyno tuning session: $300–$600
  • Miscellaneous gaskets, bolts, fluids: $100–$200

Total parts cost: $3,150–$5,800. Labor for installation (if you’re not a mechanic) can add $500–$1,500 depending on hourly shop rates and whether you do the simple work yourself. Some shops also include the tune in their labor quote.

Installation Walkthrough

Installing the Skunk2 intake manifold and supporting fuel/exhaust parts is a weekend project for an experienced DIYer. Below is a high-level sequence; always consult the manufacturer’s instructions for torque specs and sealing tips.

  1. Disconnect battery and drain coolant – The stock manifold has coolant passages; you’ll lose some.
  2. Remove the stock intake system – Unbolt the factory manifold, throttle cable, and hoses. Be careful not to damage the VTEC solenoid wiring.
  3. Replace the fuel injectors – Swap them out while the manifold is off; it’s much easier. Use new O-rings and grease them.
  4. Install the Skunk2 manifold and throttle body – Use a new intake manifold gasket. Torque the bolts in a crisscross pattern to spec (around 20 ft-lbs).
  5. Mount the fuel pump and regulator – Drop the fuel tank (or access the pump via the rear seat) and swap the pump. Adjust the regulator to 50-55 psi base pressure.
  6. Install the exhaust – Start at the header and work back. Use new gaskets and anti-seize on bolts. Most 3-inch systems require some clearance adjustments.
  7. Reconnect everything – Coolant hoses, vacuum lines, throttle cable (may need slight adjustment if the new manifold is taller). Refill coolant.
  8. Load a base tune – If using Hondata, upload a base map from their database to get the engine idling and driveable for the dyno session.

If you are not comfortable with wiring or soldering (e.g., installing an OBD1 conversion harness), have a professional handle the ECU side. A wiring mistake can cause a no-start condition or damage the ECU.

Real-World Performance Results

Dyno results and owner feedback confirm that 280 whp is attainable with the Skunk2-based package. A stock ITR puts down about 160-165 whp at the wheels (due to drivetrain loss). After the modifications and a good tune, owners report 270–285 whp and 170-180 lb-ft of torque. This represents a 65–70% gain in power, which transforms the car’s acceleration. Quarter-mile times drop from mid-14s to low 13s (or even high 12s with slicks), and the car pulls hard to its 8,500 RPM redline. One owner on Honda-Tech shared a dyno sheet showing 274 whp and 173 lb-ft with a Skunk2 intake, full exhaust, and Hondata S300 tune.

Throttle response is noticeably sharper, especially in VTEC. The engine no longer feels flat above 7,000 RPM; instead, it surges to redline. Many drivers describe the sensation as “each gear feels longer” because power doesn’t drop off at higher RPMs. However, noise increases—the intake honks aggressively, and the exhaust may drone on the highway. That’s the trade-off for big N/A power.

Tuning for Power and Reliability

Achieving 280 hp is one thing; making it last is another. The B18C5 is robust, but pushing it to the limit requires careful tuning. The tuner should target an air/fuel ratio of 12.5–13.0:1 under wide-open throttle. Leaner mixtures risk detonation; richer mixtures lose power and foul plugs. Ignition timing is advanced until knock appears, then retarded a few degrees for safety. Most builds end up with around 24–26 degrees of total timing at high RPM.

Oil temperature management is often overlooked. With added power, the stock oil cooler (Honda’s oil-to-water unit) may struggle; adding an aftermarket oil cooler or a larger radiator is recommended for track use. Also upgrade the engine mounts—the stock rubber mounts allow excessive movement under hard acceleration, which can cause drivetrain vibration and wear.

Alternative Paths to 280 HP

The Skunk2 intake manifold is not the only route. Other options include the BLOX Racing or Edelbrock Performer X manifolds, which offer similar gains. Some builders use a modified stock manifold with a larger plenum, but results are inconsistent. For forced induction, a turbocharger at 8-10 psi would easily surpass 280 hp, but at higher cost and complexity. The naturally aspirated route keeps the ITR’s legendary throttle response and lighter weight, making it a favorite for track days.

Frequently Asked Questions

Will the Skunk2 intake hurt low-end torque?

Yes, slightly. The larger plenum can reduce intake velocity at low RPMs, costing maybe 5–10 lb-ft below 4,000 RPM. But the VTEC crossover and a proper tune can mitigate that. Most drivers find the trade-off acceptable for the top-end gain.

Can I achieve 280 hp without tuning the ECU?

No. The stock ECU cannot compensate for larger injectors, altered air flow, or higher fuel pressure. Running without a tune will cause a rich or lean condition, potentially damaging the engine. Tuning is non-negotiable.

Do I need to upgrade the cams?

For a solid 280 hp, stock ITR cams (intake 12mm lift, exhaust 10.5mm lift) can get you there with a good exhaust and tune. However, upgrading to Skunk2 Pro 2 or Tuner 1 cams will add another 10–15 hp and push you safely above 290 whp. That comes with increased cost ($400–$600) and some loss of idle quality.

Conclusion

Reaching 280 horsepower in an Acura Integra Type R is a well-documented, achievable goal. The Skunk2 intake manifold is a proven component that, when combined with proper fueling, exhaust, and ECU calibration, unlocks the B18C5’s upper potential. The parts cost is reasonable for the power gain, and the installation is straightforward for someone with moderate mechanical skill. The real-world rewards—instant throttle response, an exhilarating VTEC surge, and a car that can keep up with modern sports cars on tight roads—make this build a favorite among Honda enthusiasts. For more information on parts and tuning, consult Skunk2 Racing, Hondata, and reputable tuning shops like K-Tuned.