Wait, the 2006 Civic Si only just started appearing in dealerships and you're swapping engines already? You are if you're the self declared kings of Honda swaps-Hasport. Lucky for Hasport, Honda handed out some preproduction Si's to select aftermarket companies prior to the on-sale date. With that extra time (only about 3 weeks), Hasport was able to complete a swap for the SEMA show, and SCC is the first magazine to tell you about it.
Basically, there isn't a lot of aftermarket equipment for the new Si yet, but considering how similar the engine is to the RSX-Type S's, and the lead time Honda gave the aftermarket by handing out those pre-production cars, there will be a entire catalog of goodies by the time the car hits dealerships.
What And WhyIts hard to top 197 bhp, a limited-slip differential and a 6-speed transmission as a starting point. But the new Si is more of a running back than a horse jockey when it comes to weight, and any extra off-the-line torque will make a difference. There's not much head room if you're not going to add forced induction, unless you add some displacement by using the 2.4-liter engine from a TSX.
We have a bone-stock '06 preproduction Civic Si that will lose its K20Z3 in exchange for a TSX K24A2. Stock horsepower on these two engines is nearly identical but torque on the K24 is 166-lb-ft, versus the K20's 139 lb-ft. It also comes lower in the rpm range.
Picking The ChassisThe Civic's chassis comes in a four-door version, too, which Hasport thinks will work just as well for the swap. Honda says the two- and four-door cars share the same engine bay dimensions, but the Si is the only car of the line offered with the K-series engine. Other Civics (except the Hybrid) have the new R series 1.8-liter mill. As soon as Hasport can get their hands on a vehicle with an R series engine, they'll try the swap and let everyone know, but they expect it will be no different.
Picking The EngineHonda's K-series has become their engine of the future. It's in the Civic, CR-V, Accord, RSX, TSX and Element. Hundreds of thousands are made every year with not too much variety between them. The K20A was the first generation of the 2.0-liter, and today we are on the K20Z. The K24s come in quite a few versions, but like the old B series, it's the head that makes the difference.
The K20A (JDM), K20A2, K20Z1, K20Z3 and K24A2 are the engines with the real DOHC VTEC heads. All the other versions are just poseurs. If there aren't three lobes per cylinder on the intake and exhaust cams, it's not real VTEC, no matter what Honda marketing tells you. For this swap, it was easiest to take a K24A2 from a TSX rather putting a VTEC head onto a K24 from an Accord or CR-V block.
Engine RemovalAt Hasport, these always seem to come out easy. But with the '06 Civic, Honda has done a great deal of improvement. The best new features are the new torque mounts, up top and down below. These new mounts limit engine rocking from hard or drag-style launches. The upper-right side engine mount is in the usual place but is directly connected to a stout aluminum arm on the strut tower. The lower mount, which is normally at the back of the block near the middle of the car, is now attached at the oil pan.
The mount on the oil pan connects to the engine subframe with a second aluminum arm to control movement. If you haven't already guessed, the oil pan from the K20Z3 will need to go on the K24A2.