LS/VTEC Head Swap - Tech - Honda Tuning Magazine

Lately, it's been all about the head swap. In November '04 we constructed a 2.0-liter CR/VTEC motor that never had the chance to dyno. Then, in the 2005 March and April issues we let loose our single-cam Mini Me swap-a-roo, which showed 30 percent more horsepower on the dyno than the engine sans VTEC. Hasport even did a next-gen CR/VTEC swap in October '04 using a K24 bottom and RSX-S top end that gave us 20 more ponies.

This month we revisit the swap that started it all-the LS/VTEC.

For the late bloomers and uninitiated, these cylinder head swaps traditionally involve taking a VTEC cylinder head and transplanting it onto one of Honda's anemic non-VTEC blocks. Only a handful of head/block combinations actually work, but in some instances, like in the aforementioned LS and CR/VTEC methods, power gains can be substantial. Plus, adding VTEC functionality makes driving much more fun.

The LS/VTEC swap generally utilizes a second- ('90 - '93) or third-generation ('94 - '01) Integra LS or RS bottom end and mates it with a B16 or B18 VTEC head. In addition to adding variable valve timing and lift, the modification also increases displacement a small bit. The labor, however, involves rerouting oil pressure to the head and enlarging two dowel holes on the head.

We got the wild hair to build an LS/V when Pro Street Import chief Eugene Castro, who laughed at us for putting together a Mini Me (even though he was the one doing the work), said he could build something much more worthwhile. He just sold his EJ Civic hatch and was piecing the engine together for the new owner. His goal was to put down 210 horses on the Dynojet at PSI.

This one's for the Honda newbies who are just now joining the HT fold. Our how-to, in conjunction with any number of super resources available in print (or if you're feeling lucky, you could try to get help from the Web), and most noobs should have enough info to plan their own stout hybrid. Folks more familiar with the build, though, will hopefully pick up a thing or two from Castro's experience.

When Castro breaks open our ECU he's surprised to find the remnants of a Hondata system already installed, everything but the header, board, and correct EEPROM (there is an EEPROM in the computer, but its origins are unknown). Normally he'd have to solder in the socket on the 27256 slot, as well as the one in the 74HC373 slot, but those appear to be done already. He pops out the old EEPROM and gets cracking de-soldering the CN2 port for the header.

We should make a couple more points about choosing a proper ECU for an LS-VTEC motor. The P28 Civic EX/Si ECU is a single-cam computer, and as such needs to be reprogrammed for a DOHC motor. Additionally, some B-series VTEC ECUs require a knock sensor, and unless the computer has been reprogrammed not to look for one, one will have to be retrofitted into the LS block. Fortunately with aftermarket engine management, like the Hondata, we can take care of those things.

The header is soldered to pins one through four on the CN2 port (arrow). Our rock star tuner, Dr Barrios, reminds us to heat the part, not the solder. The solder will do its job on its own.

Finally the proprietary Hondata board is plugged in. Everything is buttoned up and we head to the dyno with the electronics.

First, some kinda bad news: we didn't get to use the Hondata. This project came together as the crew at Pro Street was hauling ass to make a NOPI race in the AZ, and we were behind schedule making a magazine deadline - it was essentially a case of bad timing. Had we just another day...

Still, what Castro was able to accomplish is pretty remarkable, given that these hybrid engines started off putting down 170, 180hp when they were first being done, and the LS motor untouched is rated at 140. Although we couldn't get a printout, the computer monitor for the Dynojet shows all we need to see: 211hp, 144 lb-ft of torque. More importantly, Castro hit the goal he set for himself at the outset and has shown why these combos remain so popular.