13B-REW in a FC3S

The idea of swapping to a newer, more powerful engine is always tempting, especially with the mechanics of the 13B-REW of a FD3S, which uses sequential twin-turbos, producing a stock horsepower of 255hp (nearly 55hp more than the FC3S Kouki). In reality, swapping a 13B-REW of the FD3S into an FC3S is NO easy task.

There are two methods to solve the engine support issue, which we’ll cover in this article.

The most popular methods is to adapt the 13B-REW engine mounts to the chassis of the FC3S, which is not a simple job, and is not recommended. The 2 factory mounts found on the 13B-REW are located on the rear side housing, while on the 13BT of the FC3S they are on the center side housing. This gives a sharp angle to connect the two points. When considering engine mounts in general. Weight distribution on the vertical plane is universal, the weight of the motor (top) puts downward pressure on the supports to stay straight and low. We need to keep this concept in mind. The easiest way to acheive this is by keeping the stock 13B-REW mounts and weld a new crossmember to the cradle, which is situated behind the motor of the FC3S. There is just enough space to weld a 3” crossmember, then the 13B-REW supports will be set in place easily, which allows you to keep nearly all of the 13B-REW components.

The other method is by drilling and tapping 3 holes with M14 x 1.50 threads on the bottom of the 13B-REW’s center housing to accept the 13BT’s OEM passenger-side engine mount. This requires a custom oil pan, or a modified 13BT oil pan. The driver side support on the 13BT  can be secured by two (2) nuts on studs that are already present on the 13B-REW. Once you have solved this support problem, the rest gets easier. The FC3S clutch can be bolted to the factory 13B-REW flywheel. The 13BT transmission will fit on the 13B-REW without any issues. If the 13B-REW was equipped with an automatic transmission, there will be a hole for an extra bolt on the bell-housing, and the 5-speed of the FC3S will not fit at all on the 13B-REW. The starter of the FC3S should fit with very little adjustment.

If you’re running the stock ECU of the 13B-REW, you’ll need the engine harness, ignition system harness, ignitor and coils from the FD3S 13B-REW. We strongly recommend going an aftermarket EMS to simplefy the setup and give you more flexibility  fuel over and ignition control an much more. Chosing an afermarket EMS as your controller will allow you to use the factory ignition input system (trigger wheel and magnetic pickups) of the 13B-REW or any other trigger pattern with the 13BT ignition coils although the trailing coil will need to be modified by adding a second trailing igniter.

Since the 13B-REW already uses a front mount intercooler, you’ll need to do the same with this setup. A popular option is to install a Greddy elbow at the throttle body, since it is aluminum and shorter than the original plastic one.

A higher flowing fuel pump is a necessity, since the 13B-REW uses 2x550cc + 2x850cc injectors while the 13BT uses 4x550cc. Denso MK4 Supra or Aeromotive/AEM 340LPH  are all perfect for the job

The radiator hoses for the 13B-REW are also different, so to connect it all up with the factory 13BT radiator will require some custom work. It is highly recommended to upgrade the radiator if you are still using the original one. An idler pulley is required to have a good contact surface on the water pump’s pulley, Greddy pulleys are a suitable option for that same reason but also to slow down the water pump and alternator rotating speeds. Both options comes with its own custom belt to fit.

The stock twin turbos will fit easily into the FC3S engine compartment, but you’ll need a custom downpipe in order for it to fit with the chassis exhaust of the FC3S. You can keep the air intakes for the twin turbos, but consider upgrading to new aftermarket filters.

You will need custom oil lines so the 13B-REW fittings can connect to the stock FC3S oil cooler. The front oil line on the 13B-REW is similar to the onse on the 13BT, but the rear oil line is fixed a little higher on the 13B-REW, on the oil filter pedestal.

Parts and comments:


-Clutch kit matching the transmission used.

-Downpipe (Wether you are twin or single turbo, this has to be changed)

-Front-mount intercooler (The GReddy V-spec front-mount intercooler kit is the standard for nearly all front mounts for the FC3S)

-Oil cooler lines

-Denso supra or 340 LPH upgrade fuel pump

-Aftermarket EMS(Strongly recommended – can replace the ECU, engine harness,  stock ignition system of the 13B-REW)

-Upgraded radiator

-GReddy elbow (Optional)

-Idler pulley kit Pineapple Racing/Full Functon Engeneering or GReddy pulley kit 13B-REW (Optional)