929 HB COUPE — FE3 Turbo Build

The Build

From Marketplace,
sight unseen

Years ago I owned an S1 929 with a 13BT. Loved the 80s look — and regretted selling it ever since.

The old Series-1 HB 929 with a 13BT — The one before — a Series‑1 HB 929, 13BT‑powered. The one I regret selling.

I'd kept my eyes open for a Cosmo for a while: mostly average ones popping up, or just never the right time. Then one fine day a low‑kilometre 929 in genuinely good condition appeared on Marketplace. After some waiting around, mid‑COVID, I finally decided to snap it up — sight unseen, off the internet.

The 929 as bought, on original NAC 104 plates — As found — 58,000 km, interior immaculate, body largely amazing. Original NAC 104 plates.

I'd always modified my cars — Gemini, E30, Forester GT — but never done a conversion from scratch. I wanted this one to be by my own hands. Knowing every bolt, every bracket, every fitting was done by me (and mates!). That's the bond you get with a DIY build — the charm and the character.

A driver, not perfection.

The carby FE and the automatic were never going to stay. I'd first planned the obvious rotor route — but after a lot of Googling, and a lot of just enjoying driving the minter around, I crossed paths with a legend in South Australia and settled on a Mazda FE3: the 2.0 L DOHC variant of the FE. They handle power, the simple design meant I could do most of it myself, and I love the 80s/90s twin‑cam look. So I hired a ute and went and got it.

Engine loaded in the ute — Loaded up and headed home from South Australia.

This variant of the FE never hit Australian shores — only sold front‑wheel‑drive in the Probe GT and the JDM MX‑6 GT (and likely a few others). Converting to RWD mostly means deleting the dizzy for a CAS, some custom mounts, and a bit of engine‑accessory fun. This one was rebuilt not long ago, with a fair few good bits.

The rebuilt FE3 — The FE3 — rebuilt, and about to go to work.

It came set up with a modified SR20 intake, rail, injectors and throttle body, plus modified SR20 headers — which means a T25 flange and a big selection of bolt‑on turbos. I went with a good‑condition T28BB off Marketplace.

Carby FE removed, bay stripped — The original carby FE came out, and the swap prep began.

Then the test fit — followed by the usual: wiring, intercooler, dump and exhaust, fuelling, and a million other things.

FE3 lowered into the bay — FE3 dropped in for the test fit.

It's come a long way this year. The engine bay got painted. The Fenix radiator and mounts were... fun. The intercooler piping earned me some seat time on the MIG. And the fuel system was my first proper AN job — a big step up from a low‑pressure carby setup.

Next step: the full exhaust system.

The Car

The 929 HB Coupe in two-tone silver — Silver / Dark Silver two‑tone · NSW 929·MAZ

A second‑generation Mazda 929 — chassis code HB — wearing factory‑style two‑tone silver, now running a boosted FE3.

The brief: keep the long, low coupe lines honest, and make everything underneath sharper than it left the line. This page tracks the build system by system — what's done, what's next, and the parts behind it.

Make / Model: Mazda 929 Coupe
Chassis: HB
Body: 2‑door hardtop coupe
Drivetrain: Front engine, RWD
Paint: Silver / Dark Silver · code TBC
Status: In build

The 929 as found, front three-quarter — As found

Profile

Engine

FE3 Gold Top installed in the HB bay — FE3 Gold Top — in the bay

Genuine Mazda FE3 "Gold Top" — 2.0 L DOHC 16‑valve, fully rebuilt 20,000 km ago. The owner's own engine, built for boost.

Belt‑driven twin‑cam from the JDM MX‑6 GT lineage, freshened with the right hardware and dropped into the HB on a 929 turbo sump.

ARP head studs + genuine Mazda head gasket
Clevite race‑series bearings
Hastings chrome turbo‑rated rings
929 turbo sump & 929 flywheel
GMB Japan water pump · new oil pump
Fresh timing belt · compression & oil pressure checked

Engine: Mazda FE3 Gold Top
Capacity: 2.0 L DOHC 16v
Origin: JDM MX‑6 GT
Rebuild: ~20,000 km ago
Internals: ARP · Clevite · Hastings
Target: 180 rwkW

Gearbox: 929 Turbo, rebuilt
Internals: Bearings · synchros · seals
Clutch: Extreme
Limit: Gearbox & diff

Gold Top

The FE3 is the DOHC 16‑valve evolution of Mazda's F‑series — alloy head on an iron block, factory‑rated up to ~170 PS in the MX‑6 GT, 626 GT and Capella.

VICS intake

Factory FE3 ran VICS — a variable‑inertia intake that holds secondary runners shut until ~4,400 rpm, then opens them for top‑end breathing.

Twin valve springs

One of the few Mazda engines with two valve springs per valve — stiff enough to keep the valvetrain honest at high rpm. A stout base for boost.

FE3 twin-cam front in the bay — Twin cam

Turbo

Intercooler piping and front-mount in the HB bay — Front‑mount & intercooler piping

Garrett T28BB — ball‑bearing, ex‑S15 — hung off a custom stainless low‑mount manifold built to suit the FE3.

Internal gate, no blow‑off, front‑mount intercooler with mandrel piping and GRP high‑temp silicone joiners. Conservative, reliable 12 psi to match the driveline limit.

Garrett T28BB — ball bearing (Marketplace find)
Modified SR20 low‑mount manifold — T25 flange
T25 flange opens up a big bolt‑on turbo range
Internal wastegate · no BOV
Front‑mount intercooler, mandrel piping
GRP 2.5" (64 mm) high‑temp silicone joiners

Turbo: Garrett T28BB
Flange: T25 (SR20 headers)
Manifold: Modified SR20, low‑mount
Wastegate: Internal
BOV: None
Boost target: 12 psi

Intercooler piping routed both sides — IC routing

Engine bay, intercooler and plumbing — In the bay

Exhaust

Turbo manifold to tip in stainless — custom from the low‑mount, mandrel‑bent the length of the car, twin‑tip out the rear.

Custom S15‑pattern stainless turbo manifold
Mandrel‑bent stainless system
Vibrant twin rear muffler + resonator
Polished twin tips

Manifold: Custom stainless, low‑mount
System: Stainless, mandrel
Muffler: Vibrant twin + resonator
Tips: Twin, polished

Cooling

FENIX alloy radiator and FE3 timing belt — FENIX alloy radiator

Keeping a boosted FE3 alive when it's working hardest — alloy radiator, genuine Japanese pump, hard plumbing.

FENIX alloy radiator
GMB Japan water pump (not china)
GD metal water pipe — block to rad, heater & turbo supply
Syltech 1/8" NPT motorsport fluid‑temp sensor

Radiator: FENIX alloy
Water pump: GMB (Japan)
Coolant pipe: GD metal
Temp sensor: Syltech, Deutsch DTM

Radiator support and front-of-engine mounts — Rad mounts

FENIX radiator in the finished bay — Rad in bay

Fuel

Surge‑tank fed. A Walbro 255 lifts from the main tank to a Radium FST; the surge pump runs braided AN‑6 the length of the chassis to the S15 rail.

Filtered before the surge and again at the firewall, with the old quarter‑inch return hardline decommissioned and capped.

In‑tank pump: Walbro 255LPH
Surge tank: Radium FST
Rail / injectors: S15
Lines: AN‑6 200‑series braided
Filters: 40µ + 10µ
Regulator: FPR + return

Low pressure — tank → surge

1Main tank + Walbro 255LPH in‑tank lift pump

2Existing 5/16" low‑pressure hardline — unmodified

340µ AN‑6 inline filter TC5746

4AN‑6 bulkhead + 4‑way plate — boot wall TC4111 / TC6101

5Radium FST — low‑pressure inlet

High pressure — surge → S15 rail

6Radium FST HP out + surge pump

7AN‑6 bulkhead + 4‑way plate — boot wall TC4111 / TC6101

8AN‑6 hose end → 200‑series braided — full chassis run TC1089 / TC1787

9200‑series → AN‑6 hose end — engine bay TC1089

1010µ AN‑6 inline filter — firewall / guard TC5745

11AN‑6 hose end → leftover 200‑series → AN‑6 hose end

12AN‑6 swivel → 5/16" barb → S15 rail inlet TC1217

↕ S15 rail + FPR

13Rail → FPR → 200‑series → back to surge

Overflow — surge → main tank

14Radium FST overflow port (AN‑6)

15AN‑6 swivel → 5/16" barb TC1217

165/16" rubber → new 5/16" hardline → main tank TC3641

⚠ Old 1/4" return hardline — decommission, cap both ends.

Radium FST surge tank with braided AN-6 lines — Radium FST

AN-6 bulkhead through the firewall — AN bulkhead

ECU & Wiring

Link G4+ Xtreme — the flagship red‑case WireIn — already mapped to this exact FE3 running the S15 ball‑bearing turbo.

Total overkill‑headroom for a four‑cylinder: 8 peak‑and‑hold injector + 8 ignition drives, e‑throttle, anti‑lag and traction control all on tap. Comes with a 90%‑complete S15‑based loom — a handful of mods to sit happily in the HB. Trigger is a genuine FE3 distributor converted to a CAS (pending a firewall clearance check).