Halfway to Hosepower: Phase 1 of the engine swap is complete

The first half of the swap is officially behind us, and for once, everything has gone suspiciously according to plan. That alone makes us nervous.

What started as a straightforward engine replacement quickly turned into the kind of project where every decision matters—not just for performance, but for survival over long stints. The new heart of the car, the K24 RBB3 engine, is now sitting comfortably in the garage, looking far more at home than we expected. But getting it there wasn’t just a matter of getting it on the stand and calling it a day. This phase was all about smart compromises, strategic reuse, and setting the foundation for reliability (and future builds).

One of the biggest decisions we made early on was to retain several components from the original K24A8. Specifically, we kept the sensors and throttle body from the Accord setup. This wasn’t laziness—it was intentional. Keeping the factory sensors and throttle simplifies integration with the existing wiring and reduces the number of variables we have to troubleshoot later.

While we were in there, we also took the opportunity to replace a few critical components that are known to cause headaches if ignored. The VTEC control valve and solenoid were swapped out for fresh units, eliminating a common failure point before it has the chance to ruin a race weekend. The water pump was also replaced, because nothing says “DNF” quite like overheating halfway through a stint.

We made some deliberate choices when it came to accessory components as well. The original power steering system from the Accord was retained, keeping things familiar and functional. On the flip side, we kept the alternator from the TSX donor engine, ensuring compatibility with the RBB setup without introducing unnecessary complications. It’s a mix-and-match approach, but one rooted in practicality.

Of course, no swap is complete without a little bit of improvisation. The RBB intake manifold breathes better than the stock Accord intake manifold, but needed a vacuum source to properly support the automatic transmission… so we decided to tap it and add a dedicated vacuum line. It’s a small modification, but a critical one.

One of the more satisfying moments of this phase came when we confirmed that the flywheel from the TSX matched up perfectly with the Accord setup. In a project full of “we think this should work,” it was nice to get a definitive win without needing to fabricate, modify, or spend three hours gently negotiating with a stripped bolt while questioning our own life choices.

In an effort to avoid reliving the past, some much needed support systems are also on deck: a baffled oil pan to keep the pickup covered under hard cornering, an Accusump for added oil pressure insurance, and both oil and transmission coolers to keep temperatures in check during long sessions. Combined with the aluminum radiator, beefed up electric fans, and our heater core relocate, we think we should be running cool.

With the engine now physically in place and the major mechanical pieces sorted, attention turns to what comes next, because this is where things start to get serious. The upcoming phase includes ECU replacement and tuning using KTuner V2, which will bring the RBB to life and hopefully allow us to extract the performance we’re chasing.

We’ll also be installing a wideband O2 sensor for accurate air-fuel monitoring to work with the KTuner, along with what can only be described as a concerning number of gauges, because if there’s one thing we’ve learned, it’s that ignorance is not bliss when it comes to engine data and going the distance.

There’s still plenty of work ahead, but the foundation is solid. The hard part—the part where everything could have gone sideways—didn’t. Yet.

South Carolina, we’re coming for you!