FC3S Pro:  Cosmo 13B-RE engine swap

Stock power output:  ~200ps on Mazda Cosmo
Power potential:  500bhp+
Engine swap difficulty:  3 out of 5

In addition to the more popular 3-rotor 20B-REW, there is a smaller 2-rotor 13B-RE engine from the Japan-only Mazda Cosmo.  Dimensions are similar to the stock FC3S 13BT engine, so there is very little problems getting this engine to fit.  One of the big differences between the FC3S 13BT and the Cosmo 13B-RE is the sequential twin-turbos on the Cosmo 13B-RE.  Although it's almost impossible to retain the sequential operation of these twin-turbos (which requires the use of the stock Cosmo ECU), you can mod the sequential twin-turbos to run in non-sequential mode.
[Cosmo 13B-RE engine - ~$1,500]

Engine Mounts
The hardest part of the engine install is the engine mounts.  If you can fabricate some custom engine mounts, this'll make things a lot easier to bolt in.  Luckily, you can buy these pre-made by the following vendors:
K2RD.com > http://www.k2rd.com/
FC3S.org > http://www.fc3s.org/parts_services/13b_RE_20b_comso_mounts.html

The Cosmo 13B-RE bolts onto the stock FC transmission with no problem.  The Cosmo 13B-RE only comes with an automatic transmission option, so it will most likely have a counterweight and flexplate attached; if your engine did not come with a counterweight, you can use a Kouki FC3S/FD3S stock flywheel or automatic counterweight.  If you are going to use an aftermarket (lightened) flywheel, the automatic counterweight is required.  The automatic transmission counterweight makes it easy to install an aftermarket (lightened) flywheel in this case.  Be sure to install a new pilot bearing and pilot bearing seal before installing the clutch.
[Lightened flywheel - $400; ACT Heavy Duty clutch kit - $350]

The stock twin-turbo system does fit within the FC engine bay.  As mention above, it's almost impossible to control the sequential twin-turbos properly; modifying the twin-turbos to run in non-sequential mode is practical.  Else, you can always go with a large single turbo set-up.  All the aftermarket 2-rotor (13B) turbo manifolds should fit with very little work.
[HKS cast turbo manifold - $300; turbo - $1,500; oil/water SS AN lines and fittings - $200; intake piping - $100]

3-inch exhausts are the typical sizes for these engines.  A custom downpipe is in order whether you're going with the stock twin-turbo system or large single set-up.
[Custom downpipe - $100; aftermarket exhaust - $800]

You might run into minor fitment issues with the upper intake manifold and/or the stock intake piping on the Cosmo 13B-RE if you're keeping the stock twin turbos.  The stock Cosmo uses a front-mounted intercooler, so you'll need to have a front-mounted intercooler installed on the FC3S.
[GReddy V-Spec front-mount intercooler kit - $1,200]

Oil Cooler Lines
If you're still running stock oil cooler lines, it's a good idea to run some SS braided lines for this project.  If you alrady have a set of aftermarket oil cooler lines, they should fit the Cosmo 13B-RE with very little fuss.
[SS -10AN oil cooler lines with AN fittings - $200]

Cooling System
The stock FC3S radiator is borderline for this project.  You can also retrofit an FC3S 13BT water pump housing, water pump, and thermostat housing to replace the odd Cosmo 13B-RE units; it's easier to find replacement belts, since the Cosmo 13B-RE uses both serpentine and v-belts.  If you're keeping the stock Cosmo water pump (housing) both upper and lower radiator hoses might need to be addressed, as water pump housing outlets are slightly different.
[Upgrade radiator - $500; stock FC3S water pump housing, water pump, gaskets - $300]

Fuel System
The stock fuel injectors are 4x550; identical to the FC3S 13BT.  It's always a good idea to upgrade the fuel pump.  Keep in mind the stock fuel injectors are only good up to about 250bhp to the flywheel.
[Walbro upgrade fuel pump - $150]

EFI/Stand-alone ECUs
The stock FC3S 13BT ECU can push the Cosmo 13B-RE, with the exception of the sequential twin-turbo system.  This is the beauty of this conversion.  A stand-alone EMS would make for more efficient power.
[Haltech E6K with all options - $1,500]

Additional "Problems"
We've already mentioned the hood clearance problem if you're keeping the stock twin-turbos and intercooler piping.  The front of the upper intake manifold may contact the hood slightly as does part of the power steering pump.

Bottom line...
The conversion can be done cheaply.  The stock FC3S turbo ECU (and ignition system) can control the Cosmo 13B-RE fairly well.  To extract the full potential of this engine swap, a stand-alone EMS is highly recommended.  Power ceiling can top over 500hp, but the budget starts to edge toward the $10,000 mark.  This is not a very popular swap at the moment, but these engines are readily available from most Japan import engine dealers.

Cosmo 13B-RE components price breakdown
Component: Price: Comments:
Cosmo 13B-RE engine $1,500 Prices vary, but on average they range between $1,000 - $2,000.
Engine mounts $250 FC3S.Org offers their Cosmo engine mounts for $250.  K2RD offers their Cosmo engine mounts for $450.
Flywheel {$400} Typical price for lightened steel or aluminum flywheel.  Counterweight should come with engine.  A used Kouki FC3S or FD3S stock flywheel should be priced under $100.
Clutch kit $350 ACT Heavy Duty clutch is only good for ~450lb-ft of torque.
Downpipe $100 Whether you're going single turbo or stock twin turbos, this custom exhaust pipe is needed to mate with the rest of the exhaust system.
Front-mount intercooler $1,200 The GReddy V-spec front-mount intercooler kit is the standard for which all front-mount intercoolers are judges for the FC3S.
Walbro upgrade fuel pump $150 Recommended.
Oil cooler lines $200 Typical cost to custom fab a pair of oil cooler lines from any name brand SS AN manufacturer (i.e. Earls, Russells, XRP).
Exhaust system {$800} This might be optional.  If you already have a (larger) aftermarket exhaust system, this might not be necessary.  $500 average for a good "cat back" exhaust, and $300 added for a pre-silencer section to be made.
Upgrade radiator {$500} Optional, but recommended.
HKS turbo exhaust manifold {$300} Optional, but if you're going single turbo, this is your cheapest option.
Turbo {$1,500} Optional - see above.  Price is from Turbonetics.
Oil/water lines (for turbo) {$200} Optional - require for single turbo.  Includes prices for SS AN lines and fittings for both oil and water lines for turbo CHRA.
Intake pipe (for turbo) {$100} Optional - required for single turbo.  Piping and silicone hoses to adapt single turbo to intercooler and for intake going into the turbo itself.
FC3S water pump + housing {$300} Optional
Haltech E6X {$1,500} Optional - highly recommended for single turbo.
Minimally, you're looking at around $4,000 for this project.
With a single turbo upgrade, the project starts to edge towards $10,000.
Prices are typical retail, so it's possible to find lower prices.

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