Honda Civic Si H-Series Engine Swap - Honda Tuning Magazine

In the last installment of this project (months ago, we know), we'd finished assembling the H22 VTEC Prelude engine and were ready to drop it in our EG Civic Si. So without further ado, let's get to it. Fitting the H22 in our Civic engine bay poses a challenge since it's larger than the B- or D-series engines. Installing the H is like getting a size-12 foot into a size-10 shoe. It'll fit, but it's cramped and you'll lose some functionality.

The first things you'll sacrifice to do this swap are your power steering and A/C. The Civic engine bay isn't wide enough for the necessary accessory belts. You can make it work with a lot of cutting, so if your fab skills are up to scratch, have at it. Our recommendation: If you want power steering and A/C, build up a B series instead.

The passenger-side engine mount needs slight trimming to clear the new mount when attached to the car. Also, a new and larger assembly is attached to the rear of the engine for the rear engine mount, again for clearance reasons. One of the studs on the transmission must be cut to clear the engine mount. There are also several minor mods you need to make, such as re-routing hoses.

That said, installing the engine isn't terribly difficult if you have the right tools. But there's more to the install than the engine itself. It shares the same general configuration as the B- or D-series engine, but the transmission is another matter. It requires its own amount of cutting and even welding.

The problem is the linkage. The B-series trannies use a rod linkage, while the H series uses cables. The two systems mount to their respective vehicles in totally different ways. The B-series linkage is directly under the shifter, while the H-series cables snake under the console to a hole in the firewall on the Prelude.

The only way to make it work is to weld the entire shifter mechanism onto the Civic center hump, in place of the old shifter. The firewall hole is enlarged with a Sawzall and four nuts are welded in place where the shifter's mounting bolts will go.

Finally, you need to cut a hole in the Civic floor to route the two shifter cables. This is a tricky proposition. Route them too far back and the cables will kink, making it difficult or impossible to shift; too far forward and you risk cutting through one of the main conduits of the Civic brain. Luckily, Holeshot Racing's Aaron Bonk knows where to cut and got it right, although even with his expertise, it was a tight cut.

From this point, it's a straightforward matter of re-attaching the various accessories, hoses, cables and wires. It's more time consuming than difficult, although if you didn't keep track of what goes where, you're screwed. Take notes! For the most part, the various coolant lines and accessories snap into place. The only belt that needs installation is for the alternator.

In the next installment, we'll add an intake and exhaust system from HyTech and then hit the dyno for a tuning session with Hondata's Doug MacMillan. For now, we just slapped on the stock Prelude intake pipe with K&N filter and 'Lude exhaust manifold. Not too glamorous, but it works and gets us on the road.

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