K-Swapping an S2000 for NASA TT5: What the K24a2 Actually Gives You

ByKenji Alvarez

Why the K24a2 Makes Sense When the F20 Gets Expensive

The Honda S2000’s F20C is one of the finest naturally aspirated engines Honda ever produced. 240 horsepower from two liters, no forced induction — still impressive. But the S2000 stopped production in 2009, and those engines don’t grow on trees anymore. Rebuilt F20s command serious money, an increasing number of parts are discontinued, and operational risk compounds every season you stay on the original powerplant.

The K24a2 is the answer more S2000 owners are landing on. Typically sourced as a JDM pull from an Acura TSX, it’s abundant, comparatively cheap, and responds to modifications in ways the F20 doesn’t. It’s not a downgrade. It’s a different engine with a different power character — and for a car competing in NASA Time Trial, many of those differences work in your favor.

K24a2 vs. F20C: The Honest Trade-offs

The F20C revs to 9,000 rpm and makes its power up top. That’s the car’s entire personality. The K24a2 is a 2.4-liter that produces strong midrange torque and has genuine headroom for modifications the F20 simply doesn’t. Honda engineers extracted nearly everything the F20C had to give in stock form. The K series still has room to grow.

Documented K24 builds in S2000s have shown gains of roughly 50 horsepower and 50 lb-ft of torque over the stock F20C with supporting mods. A Stage 1 K24a2 with drop-in cams and a standalone ECU typically lands in the 230–250 whp range on the dyno. The torque curve fills in where the F20 thins out, and that translates to a faster car on most track configurations even at similar peak numbers.

What you give up: the F20’s screaming top-end character and the satisfaction of keeping a rare engine alive. What you gain: parts availability, a wider modification ecosystem, and significantly lower cost per horsepower as the build develops.

The ASM Stage 1 Package

For a first-time engine swapper, a packaged solution from a shop that has done this hundreds of times removes a lot of guesswork. ASMotorsports (ASM) offers tiered K-swap packages built around the K24a2 for the S2000. Their Stage 1 kit centers on using the F-series intake manifold adapted to the K motor — an approach that keeps the parts count low and the install manageable for someone not doing engine swaps professionally.

The kit covers engine mounts, an adapter plate (F-series transmission to K-series block), clutch, flywheel, and a prepped K24 engine. Their add-on F2K OEM wiring service converts the S2000’s factory harness to work with the K-series. It ships with a base map, all factory gauges functioning, and AC pre-wired — so you can retain creature comforts without hacking the chassis harness. Cruise control retention is also achievable through this service.

One budget note: pallet delivery to a residential address requires liftgate service, which runs above the base shipping quote on the product page. Factor that in from the start.

Drag Cartel Drop-In Cams: Stage 1 Without Valvetrain Surgery

The Drag Cartel DIC (Drop-In Cams) are a Stage 1 camshaft designed to work within the K-series’ stock valvetrain. No upgraded springs, no new retainers, no followers required. OEM components handle it. The cams are 8620 billet steel with meaningfully more duration and lift than stock: intake high-speed lobe at 295° duration and 12.7mm lift, exhaust at 288° duration and 12.0mm lift.

Dyno testing shows 10-plus hp across the entire powerband. That’s the right formula for a track build that needs durability alongside performance. Stage 1 means aggressive enough to show on a lap timer, conservative enough that you’re not rebuilding the top end prematurely after a hard season.

The pairing with a standalone ECU is what makes this worthwhile. The K24a2 uses Honda’s dual i-VTEC system — independent cam profile switching for intake and exhaust, plus variable cam timing (VTC) on the intake. A standalone ECU lets you dial in exactly when those switches happen. On a stock ECU, you’re leaving most of that potential untouched.

Fluidampr Crank Pulley: Why It Matters on a Modified Engine

Stock rubber-based harmonic dampers are tuned to a specific resonance frequency. When you change rotating assembly characteristics — different cam timing, revised tune, higher sustained RPM — the stock damper is no longer matched to the crankshaft’s new harmonic signature. For a street car that rarely sees high RPM for more than a few seconds, this is a minor issue. For a track car running sustained laps deep into the rev range, wear on main bearings and timing components accumulates.

The Fluidampr uses silicone fluid viscous coupling that continuously self-tunes across the RPM range. No recalibration needed when you change cams or adjust the tune. It’s a direct fit for K20/K24 engines. Small cost relative to an already significant build, and it earns its keep on a car that runs hard every session.

Moroso Baffled Oil Pan: Not Optional for Sustained Track Use

Oil starvation is a legitimate failure mode at the track. The stock K24 pan was not designed to handle sustained high-g cornering, and under hard lateral loads the oil pickup can uncover. That’s a fast path to a destroyed engine.

Moroso’s road race baffled pan for K-series swaps uses a trap-door baffle assembly and anti-slosh design to keep the pickup submerged under cornering loads. The sump is 5.5 inches deep, built from steel, and sized to handle the heat cycles a track car sees every session. One detail worth knowing: the pan is designed around the Acura RSX oil pump assembly. Confirm that’s in place before the engine goes in — the stock pump pickup geometry doesn’t work correctly with the deeper sump.

Haltech Elite 1500: What Going Standalone Actually Gives You

A standalone ECU is where a track-focused K-swap build separates from a street swap. The stock Honda ECU can’t be tuned for aftermarket cams, won’t datalog in any practically useful way, and doesn’t give you proper access to the K24’s dual i-VTEC system.

The Haltech Elite 1500 handles drive-by-wire throttle, dual cam control (both VTEC switching points plus intake VTC timing), short- and long-term fuel learning, and knock control. For S2000 K-swap applications, ASM offers a plug-and-play harness and ECU combo built around the Elite 1500 with a base map included. AC support is pre-wired in their F2K harness service, which removes one of the common objections to going standalone — sacrificing creature comforts to reach minimum competition weight.

For NASA TT5, the practical payoff is precise control over cam switching points at track temperatures, accurate fueling across the RPM range, and data acquisition that’s actually usable for lap analysis. The stock ECU leaves all of that off the table.

Pulling the F20 and Pre-Install Fitting

Removing the transmission first, then lifting the engine up through the top, is the cleanest approach. It avoids fighting the front crossmember. Hood struts that open to service height eliminate the need to remove or brace the hood. No special equipment beyond a standard engine hoist is required.

Test-fit everything before the engine goes into the car. Mock the adapter plate and intake manifold up to the engine and work out any interference on the bench. One detail that catches people: the brass fitting on the adapter plate has a specific angular orientation. Mark it before removal. Reassembling it at the wrong angle creates a leak path that’s genuinely annoying to diagnose once the engine is sitting in the bay.

If a pre-modified F20 intake manifold is available locally, it’s worth buying. Machining the flange and relocating ports yourself is doable, but it’s tedious work. Saving that step on a first-time swap is a real win.

Sources


Similar Posts