Why Upgrade to a Skunk2 Intake Manifold?

The J-series engine—found in Honda Accords, Pilots, Odysseys, and Acura TLs—is already a strong performer, but its factory intake manifold was designed for quiet operation and emissions, not peak horsepower. A Skunk2 intake manifold replaces the restrictive OEM plastic or cast aluminum unit with a free-flowing, velocity-stacked design. The result is measurable gains in mid-range and top-end power, often 10–15 horsepower on a stock J35 with no other modifications. For a $500 budget, this is one of the best dollar-per-horsepower upgrades you can make.

The Skunk2 manifold features larger, smoother runners and a larger plenum volume. This allows the engine to breathe more efficiently at higher RPMs without sacrificing too much low-end torque. If you pair it with a mild tune, the gains become even more consistent across the rev range. This guide will walk you through the entire installation process and show you exactly how to do it for under $500, including the cost of the manifold itself.

Tools and Parts Needed

Before you start, gather everything. Trying to run to the auto parts store mid-job wastes time and increases the chance of mistakes.

  • Skunk2 Intake Manifold – Part number: 409-05-0120 (for J35/J37 applications). Verify compatibility with your specific J-series variant (J30, J35, J37).
  • New intake manifold gasket – OEM Honda gasket (Part 17106-R70-A00) or a high-quality aftermarket like Fel-Pro. Do not reuse the old one.
  • Throttle body gasket – Also replace this; part 17107-R70-A00.
  • Thread locker – Loctite 242 (blue) for manifold bolts.
  • Permatex Ultra Grey silicone gasket maker – For sealing any coolant passages if your J-series has them on the manifold (some do).
  • Basic hand tools – Metric socket set (8mm, 10mm, 12mm, 14mm), wrenches, extensions, a universal joint for tight spots.
  • Torque wrench – ¼-inch drive for small bolts, ⅜-inch drive for the manifold bolts. Accuracy matters.
  • Flat blade screwdriver and picks – For disconnecting vacuum lines and electrical connectors.
  • Brake cleaner or throttle body cleaner – For cleaning the intake flange and gasket surfaces.
  • Shop towels and rags
  • Safety glasses and nitrile gloves
  • Penetrating oil – PB Blaster or WD-40 for stubborn bolts.
  • Digital camera or labeling tape – To document vacuum line routing.

Cost Breakdown: How to Stay Under $500

The headline says $500, and that’s realistic if you shop smart. Here’s a typical breakdown:

  • Skunk2 intake manifold – $280–$320 (new, aftermarket pricing, check Skunk2 direct or major retailers like Summit Racing).
  • OEM manifold gasket – $12
  • Throttle body gasket – $5
  • Permatex Ultra Grey – $8
  • Thread locker + cleaner – $10
  • Shipping – ~$15

Total: ~$350–$370. That leaves room for a used manifold (if you find one) and still covers a basic professional tune (around $150). If you tune it yourself with a device like Hondata KTuner, you’ll already own it, so no extra cost. Alternatively, you can allocate the remaining $130 toward a better throttle body spacer or a cold air intake. But the manifold alone will get you most of the benefit.

Preparation and Safety

Work on a cool engine. A hot engine can burn you, and the aluminum manifold expands at a different rate than the block, making gasket seating tricky.

  • Disconnect the battery – Remove the negative terminal. Wait at least 10 minutes for any residual energy to dissipate. This prevents short circuits and accidental airbag deployment (some J-series use an integrated air intake resonator with sensors).
  • Drain coolant (if needed) – Many J-series engines route coolant through the intake manifold for the throttle body heater and IACV (idle air control valve). If you don’t drain it, coolant will spill when you disconnect those hoses. Place a drain pan under the car and open the radiator drain valve. Collect and reuse coolant, or use fresh 50/50 mix.
  • Remove the negative battery cable first, positive second – Always follow this order for safety.
  • Let the engine cool completely – At least 2 hours after shutdown. The exhaust manifold and headers can cause burns.
  • Take pictures – Photograph every vacuum line, electrical connector, and hose before you disconnect. This is the single best way to avoid confusion during reassembly.

Step-by-Step Installation

Removing the OEM Intake Manifold

  1. Remove the engine cover – If equipped, it’s usually a push-pin or small screws. Set aside.
  2. Remove the air intake assembly – Unbolt the intake tube, mass airflow sensor, and air filter box. Disconnect the MAF sensor connector.
  3. Disconnect the throttle cable – Locate the throttle cable bracket on the throttle body. Remove the two 10mm bolts. Carefully pull the cable end off the throttle lever. Do not kink or stretch the cable.
  4. Disconnect all vacuum lines and electrical connectors – On a J35A, you’ll find the EVAP purge valve, brake booster hose, IACV connector, TPS (throttle position sensor), and various small hoses. Label each with tape or take detailed photos.
  5. Disconnect coolant hoses – Two hoses connect to the throttle body and IACV. Have a catch pan ready. Squeeze hose clamps with pliers, slide them back, and pull the hoses off. Expect some coolant loss—about 200ml.
  6. Unbolt the intake manifold – Use a 12mm socket for the six or eight manifold bolts. They are located around the plenum and runner flanges. Do not unbolt the throttle body separately yet; it’s easier to remove the entire assembly together.
  7. Lift the manifold away – Gently rock it side to side to break the gasket seal. Some J35 manifolds have a heat shield or brackets attached. Remove those as needed. Once free, place the manifold on a clean workbench.

Cleaning the Block Side

With the manifold removed, you will see the gasket surface on the cylinder head. This must be perfectly clean. Use a razor blade gasket scraper (plastic is safer for aluminum) to remove any old gasket material. Then spray brake cleaner and wipe with a lint-free towel. Avoid getting debris into the intake ports. If the gasket stuck badly, use a brass wire brush gently. Do not score the aluminum surface. A small shop vacuum can help suck up loose particles.

Inspect the coolant passages on the cylinder head. Clean out any scale or old silicone. The Skunk2 manifold uses an O-ring or a silicone bead for these—refer to its instructions.

Preparing the Skunk2 Manifold

Unbox your new Skunk2 manifold. It ships bare (no gasket or hardware). The manifold has a smooth cast finish. Some builders choose to port-match the runners to the head for even more flow, but that’s optional and beyond this guide. Install the throttle body onto the Skunk2 manifold using the included bolts or your original hardware. Use a new throttle body gasket. Torque the throttle body bolts to 8–10 ft-lbs (check service manual for your specific model).

Transfer any sensors from the old manifold to the new one: IACV, TPS, and any MAP sensor if used. Many J-series use a speed-density system; the Skunk2 manifold usually has sensor ports pre-drilled. Use Teflon tape on sensor threads (if applicable) to prevent vacuum leaks.

Check the coolant passage alignment. Some Skunk2 manifolds have a small plug for the coolant port; if your engine does not use it, install the plug with thread sealer. If it does, reuse the brass fitting from the OEM manifold.

Installing the Skunk2 Manifold

  1. Apply a thin bead of Permatex Ultra Grey to the cylinder head’s coolant passages – Only a small dab around each coolant hole. Do not get silicone on the intake runner openings. Let it tack up for a minute.
  2. Place the new manifold gasket onto the cylinder head studs (if studs exist) or align it manually. Some J-series use M8 bolts directly; in that case, hold the gasket in place with a drop of silicone or use gasket alignment studs (long bolts with tips cut off).
  3. Set the Skunk2 manifold onto the gasket – Carefully lower it, ensuring the runners seat evenly. Do not force it. If it does not sit flush, check for interference from brackets or the coolant fitting.
  4. Hand-thread all manifold bolts – Use the original bolts or the ones supplied by Skunk2. Apply a drop of blue Loctite to each bolt thread. Hand-tighten until snug.
  5. Torque the manifold bolts in a cross-pattern – Start from the center and work outward. Final torque: 18–22 ft-lbs (check your engine’s FSM; J35 generally 22 ft-lbs, J30 sometimes 18 ft-lbs). Do not overtorque; aluminum threads strip easily.
  6. Reconnect all coolant hoses – Slide the hoses back onto the throttle body and IACV. Tighten hose clamps securely. Refill the coolant system with the drained or fresh coolant.
  7. Reconnect vacuum lines and electrical connectors – Use your photos as a guide. Pay special attention to the brake booster hose (large diameter) and the EVAP line. Mistakes here cause drivability issues.
  8. Reattach the throttle cable – Slide the cable end onto the throttle lever. Re-bolt the bracket. Adjust cable slack so there is half a millimeter of free play before the throttle opens. Tighten locknut.
  9. Reinstall the air intake assembly – MAF sensor, intake tube, air box. Torque MAF bolts lightly (8 ft-lbs).

Double-check that all bolts, hoses, and connectors are secure. Rotate the throttle by hand to ensure smooth operation with no binding.

Common Mistakes and How to Avoid Them

  • Reusing old gaskets – Always replace both manifold and throttle body gaskets. A vacuum leak will kill performance and idle quality.
  • Cross-threading manifold bolts – J-series intake flanges are aluminum. Use a tap and die set if you feel resistance. Start bolts by hand only.
  • Forgetting to plug coolant ports – If you don’t need the coolant lines (some Skunk2 users delete them to reduce heat), plug the ports with brass pipe plugs. Otherwise, you’ll have a geyser when starting the engine.
  • Skipping the torque wrench – Even torque distribution prevents warpage. Use a cross-pattern sequence.
  • Not cleaning the intake ports – Leftover gasket debris can get sucked into the cylinder and ruin ring lands.
  • Incorrect vacuum line routing – The brake booster vacuum line must be connected directly to the manifold’s largest vacuum port. Swapping it with a smaller port reduces brake assist.
  • Overtapping the IACV – Some aftermarket manifolds have undertapped sensor ports. Check that the IACV O-ring seals properly. Use a thread chaser if needed.

Tuning and Performance Gains

The Skunk2 intake manifold alone will improve airflow, but the ECU (engine control unit) will adapt only so far. The factory fuel and ignition maps are calibrated for the restrictive OEM manifold. To fully unlock the horsepower, you need a tune. Options include:

  • Hondata FlashPro – For K- and J-series, allows full control of fuel tables, ignition timing, VTEC engagement, and idle. Cost around $700 new, but can be shared among friends if they have compatible ECUs. Many tuners offer remote base maps for $50–$100.
    Hondata FlashPro – Learn More
  • KTuner – Similar functionality, often more affordable. Some J-series ECUs are supported via the V1.2 unit.
  • Dyno tune – A professional tuner will spend 2–3 hours on a dynamometer. Expect to pay $400–$600. Combined with the manifold, you’ll see an additional 10–15 hp over the untuned install.

Even without a custom tune, the Skunk2 manifold will improve top-end power. But drivability may suffer: the idle may be lumpy, part-throttle response could be rich, and VTEC engagement might feel too abrupt. A safe, off-the-shelf base tune from a reputable J-series specialist avoids these issues. If you are not ready to spend on a full tune, at least reset your ECU by disconnecting the battery for 10 minutes after the install. This forces the ECU to relearn the new airflow characteristics (idle and fuel trims).

Conclusion

Installing a Skunk2 intake manifold on a J-series engine for $500 is absolutely achievable with careful planning and buying used parts where possible. The process takes a weekend for a first-timer, but the payoff in throttle response and high-RPM pull is well worth the effort. Don’t skip the gasket prep, torque specs, and coolant management. If you can afford a tune, do it—it transforms the car. This upgrade is a proven path to making your J-series engine feel more like a genuine performance motor, and with a $500 budget, you have no excuse not to try it.

For further reading and community support, check out Drive Accord forums or the many installation walkthroughs on YouTube to see the process in real time. Good luck, and enjoy the extra revs.