Turbo FA24, done right
The FA24 in the second-gen 86/BRZ is a real step up from the FA20. Bigger displacement, direct injection, a torque curve that actually pulls. Even so, 170-odd kilowatts in a chassis this good leaves money on the table. Balance and centre of gravity are there from factory. Power isn’t.
This ZD8 came in with a clear brief: bolt-on turbo, proper engine management, fuelling sorted, driveline that can take it. Street car that sees track days, so it had to be reliable and finished. Not a project on jack stands chasing boost leaks.
The HKS GTIII-RS turbo kit
We’ve fitted the HKS GTIII-RS bolt-on kit on this platform enough times to know it works. HKS have done the engineering so it goes on the FA24 without fabrication or cutting. Turbo, tubular manifold, dump pipe, front-mount intercooler, all the charge piping and hardware come in the box.
The GTIII-RS uses a billet compressor wheel in a compact housing. It spools early and pulls clean through the mid-range and top end. On a light car like the BRZ that matters more than peak numbers. You want the power there when you ask for it, not all arriving at five thousand RPM.
Front-mount intercooler and charge piping
The HKS intercooler takes the spot of the factory air conditioning condenser. We stripped the front end to get at the crash bar and radiator support, then ran the charge piping from the compressor outlet through the engine bay, down to the intercooler, and back up to the intake manifold.
On a boosted car doing laps, hot intake air pulls timing and you lose power. A properly sized front-mount keeps charge temps in check no matter how long you’ve been on circuit.
Exhaust side and heat management
The hot side runs the HKS tubular exhaust manifold. Tubular flows better than cast and helps the GTIII-RS spool quickly. On a flat-four the turbo sits close to the block, so heat soak is a real problem. We wrapped the dump pipe to keep radiant heat off the charge piping, fuel lines, and looms that run nearby.
Why MoTeC instead of the factory ECU
This is where the build steps up from a typical bolt-on turbo job. You can tune the factory ECU to run boost and plenty of people do. MoTeC gives us a level of control the factory ECU can’t.
With MoTeC we have full authority over fuel, ignition, cam timing, boost targets, safety strategies, and flex fuel logic. Tuning the factory ECU always means working around an architecture that was never designed for forced induction. MoTeC lets us calibrate from a clean slate for this engine, this turbo, this fuel system.
Flex fuel was a key part of the brief. A Zeitronix sensor reads ethanol content in real time and feeds it to the MoTeC, which adjusts fuel, timing, and boost targets on the fly. Fill up with 98, E85, or any blend and the ECU handles the rest. On E85 we can run more aggressive timing and boost for more power. On 98 it dials back to safe, optimised numbers.
Upgraded fuelling
E85 needs about thirty percent more fuel volume than petrol for the same power, so the factory pump and injectors aren’t going to keep up. Xspurt 1050cc injectors give enough headroom on E85 with margin, and they atomise well at low pulse widths so idle and light throttle stay clean. A DeatschWerks DW300C 340LPH replaced the factory in-tank pump to hold pressure and volume at full boost. Running a fuel system out of capacity is one of the fastest ways to lean a boosted engine and damage it, so we always spec with headroom above target.
Driveline and chassis
A turbo on the FA24 roughly doubles crank torque. The factory clutch will slip almost immediately under boost, so an Exedy Kevlar ballistic clutch went in during the same stripdown. The Kevlar gives a progressive engagement that’s still manageable in traffic, unlike a full ceramic puck that chatters and grabs.
MCA Reds coilovers went on at all four corners with an alignment set for the new ride height. They’re two-way adjustable with separate compression and rebound, so we can fine-tune the balance for how the owner actually drives the car. With this much extra power, the chassis has to put it down predictably.
How it drives now
The GTIII-RS comes on early and pulls clean through the mid-range. The MoTeC tune is sharp on both 98 and E85, and the flex fuel switches between them without any input from the driver. The Exedy handles the torque without fuss and the MCA Reds have sharpened up how the car turns and puts power down. Daily driveable, ready for a track day without thinking twice.