FC3S Pro:  Kouki FC3S 13BT into a Zenki FC3S Turbo

Engine swap difficulty:  2 out of 5

The 1989 - 1991 Kouki FC3S 13BT engine can be easily swapped into a 1986 - 1988 Zenki FC3S Turbo chassis.  Both engines are of similar dimensions, and they both use the same mount brackets.  We need to address some of the differences in the two types of motors.


Oil metering pump:
The 1986 - 1988 Zenki FC3S uses a mechanical oil metering pump that is actuated by a mechanical linkage to the throttle body.  The 1989 - 1991 Kouki FC3S uses an electronic oil metering pump that is electrically controlled by the stock ECU.  The electronic oil metering pump cannot be controlled by the 1986 - 1988 Zenki FC3S Turbo stock ECU.  To control the electronic oil metering pump, you'd need a 1989 - 1991 Kouki FC3S Turbo stock ECU (and engine wiring harness, etc.), which makes things complicated.  You can convert over to the 1986 - 1988 Zenki FC3S Turbo mechanical oil metering pump by swapping over to the Zenki throttle body, linkage, mechanical oil metering pump, and front cover.  An even easier option is to remove the electronic oil meter pump and cover the hole with a block-off plate; go pre-mix to substituted for internal oil lubrication.
FC3S Pro:  FAQ - Pre-Mixing

Turbo:
The 1989-1991 Kouki FC3S Turbo turbocharger is more desirable over the earlier 1986 - 1988 Zenki FC3S Turbo turbocharger.  Since we are assuming we're using a Zenki stock ECU, we need to modify the Kouki turbo control system.  The Kouki stock ECU uses a boost control solenoid to control boost; the Zenki stock ECU cannot use this boost control solenoid.  The "T" off the wastegate vacuum pipe will need to be blocked or capped.

Fuel injectors:
The 1989 - 1991 Kouki FC3S Turbo 13BT uses high-impedence, top-feed Nippondenso fuel injectors that utilize oval electrical plugs.  The early Zenki FC3S Turbo models uses low-impedence, top-feed Nippondenso fuel injectors that use rectangular electrical plugs.  The later Zenki FC3S Turbo models uses high-impedence, top-feed Nippondenso fuel injectors that use rectanglar electrical plugs.  All Zenki FC3S Turbo's use fuel injectors with rectangular plugs that are not compatible with the Kouki FC3S Turbo 13BT engines.  It's easiest to just swap over your old fuel injectors onto the Kouki 13BT engine.  Although the intake manifolds and fuel injector rails are slightly different, the fuel injectors swap over no problem.

Water temp sensor:
The water temp sensor for the instrument cluster is located next to the oil pressure sensor under the oil filter.  The 1986 - 1988 Zenki engines use a bullet connector for the water temp sensor.  The 1989 - 1991 Kouki engine use a spade connector for the water temp sensor.  This plug needs to be modified to get the water temp gauge to work correctly after the engine swap.

Throttle body / TPS:
Due to the slight differences in the throttle body, there are two different TPS units available.  The 1986 - 1988 Zenki FC3S uses a single, narrow-range TPS.  The 1989 - 1991 Kouki FC3S uses a double TPS with both narrow-range and full-range TPS'.  You can modify the Kouki double TPS to work with the Zenki stock ECU, which only requires the narrow-range TPS.  The throttle bodies are directly swappable between Zenki and Kouki models.

Intercooler:
The Kouki intercooler has a 2.0" inlet, while the Zenki intercooler has a 1.75" inlet.  The outlets for both intercoolers are 2.0".  Due to differences in the intake manifolds (see below), the mounting tabs on the passenger side of the intercoolers are different.  The intercooler cores are identical, but due to the larger inlet on the Kouki versions, the Kouki intercooler flows slightly better.

Intake manifolds:
The Kouki FC3S Turbo upper intake manifold is slightly taller than the Zenki version, which implies the Kouki intake manifold was designed for better low-end torque.  Due to the taller intake manifolds, the fuel injectors rails are slightly different between the Zenki and Kouki models.
FC3S Pro:  FAQ - Zenki Versus Kouki Upper Intake Manifolds



Questions?  Comments?  Send email to:  reted@fc3spro.com

10/30/2004