The Car
A second‑generation Mazda 929 — chassis code HB — wearing factory‑style two‑tone silver. The brief is simple: 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 stock, what's been replaced, and why. It updates as the car does.
- Make / Model
- Mazda 929 Coupe
- Chassis
- HB
- Body
- 2‑door hardtop coupe
- Drivetrain
- Front engine, rear drive
- Paint
- Silver / Dark Silver two‑tone
- Status
- In build
Engine
A belt‑driven DOHC twin‑cam, turbocharged and swapped into the HB engine bay.
In the photos: a front‑mount intercooler with mandrel intercooler piping, a cone intake on the cold side, and a FENIX alloy radiator down front. The block, internals, head work and power figures get locked in below as the tune firms up.
- Layout — DOHC twin‑cam, belt‑driven, turbo
- Induction — front‑mount intercooler + cone intake
- Engine / capacity — TBD — confirm
- Internals & head — TBD
- Target power — TBD
- Config
- DOHC turbo
- Engine
- TBD
- Capacity
- —
- Internals
- —
- Target power
- —
Exhaust
Manifold to tip. Custom stainless, mandrel‑bent, twin‑tip out the rear.
- System — custom stainless, mandrel‑bent
- Flex joint — braided stainless isolator
- Tips — polished twin tip
- Downpipe / mid — TBD
- Material
- Stainless
- Bends
- Mandrel
- Tips
- Twin, polished
- Pipe size
- —
Cooling
Keeping it alive when it's working hardest.
- Radiator — FENIX alloy
- Fans — TBD
- Oil cooler — TBD
- Coolant routing — TBD
- Radiator
- FENIX alloy
- Core
- —
- Fans
- —
- Oil cooler
- —
Fuel
Surge‑tank fed, twin‑Walbro. A low‑pressure lift stage feeds the surge tank; a high‑pressure stage runs braided AN‑6 the length of the chassis to the rail.
Filtered twice — 40 micron before the surge tank, 10 micron at the firewall — with the old quarter‑inch return hardline decommissioned and capped.
- Lift pump
- Walbro GSL395
- HP pump
- Walbro 460
- Surge tank
- AN‑6, installed
- Lines
- AN‑6 200‑series
- Filters
- 40µ + 10µ
- Rail
- SR20 + FPR
Low pressure — tank → surge
High pressure — surge → rail
Overflow — surge → main tank
Turbo
Forced induction. The reason for everything else on this page.
- Intercooler — front‑mount, mandrel piping
- Turbocharger — TBD
- Manifold — TBD
- Wastegate / BOV — TBD
- Target boost — TBD
- Intercooler
- Front‑mount
- Turbo
- —
- A/R
- —
- Wastegate
- —
- Boost
- —
ECU & Wiring
The brain and the nervous system. Engine management, harness, and sensors.
- ECU — TBD
- Harness — TBD
- Sensors — TBD
- Ignition — TBD
- ECU
- —
- Harness
- —
- Ignition
- —
- Wideband
- —
Gallery
Build Log
-
Jul 2025
Bay stripped
Engine bay back to bare silver — brake booster and firewall out, HB chassis stamp showing. Clean sheet to build from.
-
Oct 2025
Engine in, exhaust on
DOHC turbo dropped in with the FENIX radiator, intercooler piping and cone intake. Custom stainless twin‑tip exhaust fitted up at the rear.
-
Nov 2025
Exhaust & fuel plumbing
Full underbody stainless run with a braided flex isolator. Surge tank in — low‑pressure inlet, high‑pressure out with the Walbro 460, and overflow port all installed.
-
Jan 2026
Running & refining
Out and about, dialling things in.
-
Next
Finish the fuel system
Order the AN‑6 200‑series chassis run, rail fittings and overflow hardline; confirm engine spec and target power.