DIY Turbo Conversions on K Series

The Honda K-series engines are installed in a number of the company's sports-compacts. These cars are often candidates for performance upgrades such as exhausts and ECU remapping. One of the more drastic upgrades involves a installing a turbocharger that pressurizes the air entering the engine. This increases horsepower, which in turn increases acceleration and top speed. As there is already a production version of the K-series engine with a turbocharger as standard, it's not necessary to perform extensive modifications to the engine itself, but the manifold and downpipe will need to be replaced with turbo-compatible versions.

Things You'll Need

• Jack
• Axle stands
• Socket wrench set
• Crescent wrench set
• Oil tray
• Drill with 1/2-inch and 1/4-inch bit
• 1/2-inch threaded pipe connector
• Dedicated Turbo Kit for a K-Series engine with manifold and downpipe

Instructions

Access and Oil Pan

1. Disconnect the terminals from the battery and remove it from the car. Jack up the car at the front axle and place it on the axle stands. The configuration of the K-series engine means that the majority of the engine components need to be installed from underneath. Remove the wheel nuts and the pop-studs holding on the front bumper. Remove the wheels and the bumper, allowing unrestricted access to the underside of the engine bay.

2. Remove the screws holding on the undertray, also called the splash shield. Removing the headlights can give you more access to the engine bay, but it is not necessary. Likewise, removing the screws holding the washer reservoir to the underside of the chassis. Resting it on the floor will give you a little more access space into the engine bay. Place a tray under the oil pan and remove the plug with a crescent wrench, draining the oil.

3. Remove the corner bolts holding on the sub frame nearest the front bumper. This will allow it to hang down at the front, enabling you to remove the oil sump. Remove the bolts holding the sump to the chassis and slide it out from under the car. Take care not to scratch or dent the seal surfaces as you're pulling it out. Clean the sump thoroughly.

4. Use the half-inch drill bit to drill a hole in the side of the sump, around one inch above the standard port. Screw the pipe fitting into the wall of the sump from the outside, creating a second port. Reinstall the sump and replace the sub-frame bolts.

Intercooler Install

1. Remove the metal support located under the bumper by loosening the bolts holding it to the chassis. Position the intercooler against the back of the support, with the hoses pointing toward the driver's side of the car.

2. Make some marks through the intercooler brackets onto the bumper support. Remove the intercooler and drill holes on the marks for the mounting bolts.

3. Bolt the intercooler to the bumper support, and replace the support on the chassis of the car. You can lower the car now, taking it off the axle stands. Most of the remaining work will be done from above the engine.

Manifold and Wastegate Installation

1. Unbolt the standard manifold from the head and the exhaust using a crescent wrench, and lift it out of the engine bay. Remove the gasket from engine port. Take the modified manifold and the corresponding gasket from the turbo kit.

2. Lay the gasket over the manifold port on the engine, and feed the new manifold into the space left by the old one. Tighten the bolts holding the manifold to the engine block.

3. Attach the wastegate to the port on the new manifold. Hold it in position and slide the clamp around the join between the gate and the manifold. Tighten the bolt on the clamp, creating a tight seal.

Turbo Installation

1. Position the turbo unit so that the oil feed is pointing straight up and the drain is pointing straight down. Loosely bolt the turbo to the manifold and check there is adequate clearance all around.

2. Screw the downpipe studs into the turbo and slide the downpipe into the engine bay, so it protrudes into the space under the car. Check that nothing is snagged on the pipe or in contact with it.

3. Slip the gasket between the turbo and the downpipe. Connect the oil return line to the port on the turbo. Bolt the downpipe to the opposing side of the turbo. Tighten all the bolts securing the turbo assembly to the rest of the engine.

Connections

1. Drill a quarter-inch hole in the intake pipe. Insert the IAT sensor through the hole and wrap the sealing clamp around the pipe. Make sure that it completely covers the hole. Tighten it firmly. Connect the wire for the sensor.

2. Connect a pair of hoses to the oil feed and drain ports on the turbo. Run the feed to the oil supply port, and the drain to the new port you created on the oil sump. You may need to temporarily remove the VTEC solenoid to access the port.

3. Cut the brake booster hose above the check valve and install the T piece, creating a new vacuum attachment. Attach the single end of the Y-shaped hose to the T piece. Connect one branch to the wastegate, and the other to the Blow-off valve. Plug the Blow-off valve into the unoccupied port on the intake.

Final Assembly

1. Jack the car back up and place it on the axle stands again. Connect the downpipe to the exhaust and tighten the clamp.

2. Replace the front bumper and any other components you removed to aid with accessing the engine bay. Wipe down the intake to prevent any grease baking permanently onto the metalwork.

3. Refill the oil and turn the ignition to "On," without actually starting the engine. This will prime the fuel system. Check the whole turbo assembly from top to bottom for leaks. If everything is free from leaks, reconnect the injectors and start the car.

Tips & Warnings

• It can be a good idea to route fluid lines and wires away from the turbo unit. The fuel feed, heater, coolant, EVAP, power steering, wiring harness and brake booster lines may all benefit from being routed away from the high temperatures of the turbo. Wrapping them in heat shield can also help.

• Have your car checked for alignment and safety by a professional to ensure that it still meets all the necessary safety standards to keep it road-legal.

References

• Full-Race; Civic Si FG2/FA5 Turbo FAQ