96 Civic DX HB vs civic HX
 

I just picked up a 96 Civic to use as my commuter. Its in good shape, the outside just needs a little TLC. I've gotten 35 mpg out of the first few tanks without doing anything to it. I plan on giving it a tune-up, bumping up the air pressure, etc.

I was looking online at the ratings for 96 civics and see that the HX is rated for 10 more highway MPG. It looks like it has a Vtec engine in it. Anyone know what else is different? Anything that I can do to make my DX into an HX? Is it as simple as a head swap?

Thanks in advnace from the forum NewB

If you have an auto, forget about it.

Even if you've got a manual, the ratios may be different on the HX.

At the very least the heads are different (vtec-e), the O2 sensor and the ECU as well.

Mine is a manual. Can the heads, ECU be swapped? Looks like it has higher compression. Maybe I can just pull the stock head and shave it some?

not to mention HX prolly uses EGR and has a box mounted on the firewall by the vin, and 5wire wideband o2 sensor. that control box has a connector so you'd need a HX wire harness or manual to extend wires to the shock tower/ecu. also, as SVOboy pointed out to me - the fuel injectors are different they flow less fuel.

The engine in the HX is a D16y5. It uses vtec in a different way than other vtec engines. During low RPM and low throttle the engine only uses 1 of the intake valves while the other barely opens to create a swirl for combustion. It also uses an expensive wide band o2 sensor so the computer can engage in lean burn operation, and and EGR to reduce combustion chamber temperatures. This is what give the car engine such amazing gas mileage. The gear ratios in the HX are the same as the DX. In higher RPM around 2700 vtec is engaged and both intake valves work in unison making the engine just like your stock engine. To swap this engine in you will need the complete engine of course, the computer and engine harness. Unlike many previous hondas you can remove the engine harness from the car will relative ease, so no splicing or cutting of the wiring is necessary. If you are lucky you will be able to find the motor complete with all sensors intake saving you money. Everything else will be reused from your vehicle (radiator, hoses, motor mounts ect...). If gas mileage is your goal use a transmission out of a 92-95 civic vx/cx it has longer gears and a better overdrive. From my experience on the highway at 60mph 49mpg is possible and with the vx transmission 55+ is possible. Hope this helps.