• January 21, 2009
• Category: DIY
• Written By: MonopolyMan
• 4 Comments

This explanation is basic, and describes basic engine swaps if you have never done them before. It will guide you through what you need to do in order to swap out your old weaker Accord engine for a more powerful Prelude engine.The stock 4th generation Accord engines vary from 125-horse power to 140, still not comparable to the Prelude’s 200-210-horse power. The Prelude also has more torque over the Accord’s engines; the Accords come with 140lbs, and the Preludes 160lbs. This is why you want the Prelude engine in your Accord, if you want more performance of course.

What You Need (4th Gen. Accord):
1. Stock Mounts
2. 93-95 Prelude Header (If using stock exhaust)
3. Stock Harness (Modified)
4. Accord Axles (5-speed or auto axles, whatever transmission you’re using)
5. Oil Pressure Sensor from F22 (Plug is different on H22 version)

Wiring (4th Gen. Accord):
1. VTEC Solenoid: Pin A4
2. VTEC Pressure Switch: Pin D6
3. Knock Sensor: Pin D3
4. Secondary Intake Solenoid: Pin A17

What You Need (5th Gen. Accord):
Same as above plus:
1. 92-95 Prelude Driver Side Mount. (Ground down to fit)

Wiring (5th Gen. Accord):
Same as above plus:
1. Swap Pin A6 with Pin A11.

If you’re using a 97+ H22 and are putting it into an OBD1 Accord (90-95), you are going to need:
1. OBD1 Injectors
2. OBD1 ECU
3. OBD1 Distributor

Instructions:
First, evacuate the AC system prior to starting this swap. Have an experienced shop do this to prevent any freon from escaping into the environment. Freon is used in your air conditioning system and is very bad for the atmosphere being that every one cvc (Freon) destroys 100 million O3 (atmosphere). Now that your environmentally safe, remove the battery, disconnect the power steering lines, radiator hoses, and front AC line. Remove the radiator, the power steering pump, alternator, and the AC compressor. Disconnect all the wiring plugs and label them if necessary. Remove the front wheels and disconnect the axles. Disconnect all the mounts; make sure you have the engine crane on the motor before removing the motor mounts. Now, remove the engine from the engine bay.

Next, prepare the Prelude engine by replacing any worn parts such as the timing belt and water pump. This is easier now that the engine is out of the car. Transfer the Accord wiring harness to the Prelude engine. Make sure you plug the same plugs into the same sensors on both engines. You will probably need to extend some wires like those for the alternator part of the harness. If the Prelude engine came with a harness, snip the plugs off of it for the VTEC solenoid, VTEC pressure switch and knock sensor. These are the wires you will be adding. Attach the Accord half shaft at this point. If the engine has a Prelude half shaft remove it and use the Accord one. The Prelude one will not work. Remove the front, rear, and driver side mounts from the Prelude engine. Place the front, rear, and drivers mount from the Accord engine onto the Prelude engine. For the transmission, use the mount that corresponds to the transmission you are using.

Now you are almost ready to drop the engine in, but first you must prepare the engine bay. Begin by swapping out the power steering line from the Prelude one, then run three wires through the firewall to correspond to the wires that you are adding for the VTEC system. Run four wires through the firewall if your car is an LX or DX because you will be missing one in the distributor. I am not sure which wire it is exactly, but I know the LX and DX are missing the one wire. Add two more wires if you are converting from Automatic to Manual for the reverse sensor in the transmission.

If you are doing an automatic to manual swap, this will be the point where you will do this. Unplug and remove the shifter and all of its components from the inside of the car. Replace it with the Manual shifter assembly. It should bolt right in using the same bolt holes. Now remove the brake pedal assembly and replace it with the manual brake pedal. Next remove the two bolts holding the cover plate that covers the holes for the clutch master cylinder and pedal assembly. Put the clutch master cylinder and pedal assembly together through the holes in the firewall. Next run the clutch hydraulic line from the clutch master cylinder along the firewall and the passenger side frame rail to the clutch dampener assembly. You will have to drill and tap holes to mount the dampener assembly.

At this point, you can drop the motor right into the car using the four mounts. Install the appropriate axles to the transmission and hub. Connect the wires that you added as well as the other harness plugs. Attach the new AC line, power steering lines, clutch line from the dampener to the transmission, and radiator lines. Attach the shifter cables at this point, but run them over the power steering rack or else they will be too short and won’t reach the shifter inside the car. Plug the ECU into the factory harness and wire up the VTEC wire to the appropriate pin outs. This is where the Chilton’s or Hayes manual comes in handy.

Finally, if you have converted from automatic to manual, you will have to wire up a starter relay, jump the shifter lock wire, and jump the key lock wire. You will also need to attach the reverse sensor leads to the reverse lights in the shifter wiring harness. These are all in the plugs that you removed from the Automatic shifter assembly. You will also need to switch a few wires around if you plan to use your cruise control. It’s all in the wiring diagrams in the repair manuals. Don’t worry about the automatic control unit that is next to the ECU. You can just unplug it and remove it. You don’t need it for the manual transmission.

Now that you’ve finished, you’ll be able to tell the differences in power from old to new. The Prelude’s engine will suit you a lot better with its higher performance, and its very good economy. Depending on how many miles were on your stock Accord’s engine, you might see an increase in fuel economy with the new more powerful engine. This is due to most of the engine swaps that come from Japan only having 40,000 miles or less on them, which means your engine should be in good working order and good condition.