Why Use a Mazda MX‑5 Turbo on an Acura Integra?

At first glance, bolting a turbocharger originally designed for a Mazda MX‑5 (Miata) on a Honda B‑series or even a non‑VTEC Integra motor may seem unconventional. However, this hybrid approach is gaining traction among budget‑oriented enthusiasts for a few key reasons. MX‑5 turbo kits often use a compact IHI or Garrett unit that is well‑sized for small displacement engines. The MX‑5’s low‑mount turbo layout also leaves plenty of room in the Integra engine bay, simplifying manifold fabrication. Additionally, surplus turbo parts from MX‑5 builds can be found for a fraction of the cost of a purpose‑built Integra kit. When executed correctly, this swap reliably produces over 100 wheel horsepower beyond stock, turning a daily driver into a lively street machine.

Core Components and Cost Breakdown

Every turbo system is composed of several interdependent parts. The following sections break down each major component, with realistic price ranges for new or high‑quality used parts. Prices reflect the 2023‑2024 market; labor is covered separately.

Turbocharger

The turbo itself must be matched to your power goal. For 100+ wheel horsepower on a 1.8L or 1.6L Integra, a small frame turbo like a Garrett GT2554R, BorgWarner EFR 6258, or an IHI RHF5 from an MX‑5 works well. A used MX‑5 takeoff can cost as little as $200 but requires inspection for shaft play and shaft seal condition. New options offer warranty and greater efficiency.

  • Budget (used MX‑5 takeoff or eBay special): $200 – $500
  • Mid‑range (new Garrett GT25 or BorgWarner S200SX): $700 – $1,200
  • Premium (new EFR 6258 with dual ceramic ball bearings): $1,500 – $2,200

Most builders targeting 100+ HP find the mid‑range sweet spot, especially when buying from reputable suppliers like Garrett Motion or Full‑Race.

Turbo Manifold

The Integra B‑series engine block does not accept an MX‑5 manifold without modification. You will need a custom or universal manifold. Options include a cheap log‑style manifold ($150‑$350) or a higher‑flow tubular stainless unit ($400‑$800). If you can weld, a DIY tubular manifold kit with a T3/T4 flange can cost as little as $100 in materials.

  • DIY or budget log manifold: $100 – $350
  • Quality tubular manifold (e.g., from SpeedFactory or full‑race): $400 – $800

Intercooler and Piping

A front‑mount intercooler (FMIC) is strongly recommended for sustained boost. The MX‑5 turbo spools quickly, but without an intercooler, intake air temperatures climb, reducing power and increasing the risk of detonation. A universal 24”x12”x3” core and 2.5” aluminum piping kit is sufficient for 100+ HP.

  • Basic bar‑and‑plate intercooler with basic silicone couplers: $150 – $300
  • Higher efficiency core (Garrett or Treadstone) with T‑bolt clamps: $350 – $600

Account for extra couplers, reducers, and a blow‑off valve adapter (add $50‑$100). A BOV is recommended to prevent compressor surge; a basic 50mm unit can be had for $30‑$80.

Exhaust System

To reduce backpressure after the turbo, you need at least a 2.5” diameter downpipe and exhaust. The MX‑5 turbo’s outlet flange will need an adapter. A full custom exhaust from a local shop is often cheaper than a pre‑bent kit. If you already have a cat‑back system, you may only need a downpipe.

  • Custom downpipe and test pipe: $150 – $350
  • Full 2.5” cat‑back exhaust (if needed): $300 – $700
  • Complete header‑back turbo exhaust kit (rare for this hybrid): $700 – $1,200

Fuel System Upgrades

Adding a turbo increases fuel demand. A stock Integra fuel pump and injectors will run lean at 100+ HP. Upgrade to a Walbro 255 lph fuel pump and 440‑550cc injectors for reliable fueling. A fuel pressure regulator (FPR) may also be necessary for precise tuning.

  • Fuel injectors (used Flow matched set, 440‑550cc): $200 – $400
  • Fuel pump (e.g., Walbro GSL392): $100 – $200
  • Adjustable FPR (AEM or Aeromotive): $100 – $200
  • Fuel rail (optional, but common for cleaner spray pattern): $75 – $200

Engine Management System (EMS)

A stock ECU cannot properly control boost or fuel delivery. For a simple 100‑100+ HP setup, a piggyback or reflash may suffice, but a standalone ECU gives full control and is highly recommended. Popular options include Hondata S300 (v2), Megasquirt PNP, or a Haltech Elite 750.

  • Piggyback/refine (e.g., AEM FIC, simple reflash): $300 – $600
  • Standalone ECU with base tune (Hondata S300 PNP or Megasquirt Pro): $700 – $1,500
  • Professional tuning session (dyno tune): $400 – $800

Do not skip the tuning. An untuned turbo Integra is a ticking time bomb. Even a simple base map from a trusted tuner is safer than a “guess and hope” approach.

Additional Supporting Mods

Installing a turbo without addressing the rest of the drivetrain will lead to disappointment or mechanical failure. Budget for the following:

Clutch

The stock Integra clutch slips under double stock horsepower. A stage 1 organic clutch (e.g., Exedy Stage 1 or Competition Clutch) holds 100‑150 HP over stock and costs $300 – $500. A lightweight flywheel ($150‑$350) helps throttle response.

Cooling

Higher intake temps raise coolant temps. Upgrade to a Koyo or Mishimoto all‑aluminum radiator and a 160‑degree thermostat (total $250‑$500). A transmission cooler is optional but wise for automatic cars.

Boost Control

A manual boost controller (MBC) costs $20 – $50 and allows you to dial boost up safely. An electronic boost controller (e‑boost, Profec) runs $250‑$500 but offers in‑cabin adjustability.

Gauges

You must monitor boost pressure, air‑fuel ratio (wideband), and oil pressure. A set of three quality gauges (Autometer, AEM) with a pod mount costs $200 – $400. Installing a wideband O2 sensor is mandatory for safe tuning; include a wideband controller ($150‑$250).

Labor Costs

If you cannot install the turbo yourself, shop labor costs vary widely. A typical hourly rate in the US is $100 – $200 per hour. This installation is not a one‑day job. A competent shop will charge:

  • Basic install (welding downpipe, mounting turbo, wiring oil and coolant lines, installing injectors/pump): $600 – $1,200
  • Full install including custom manifold and intercooler piping: $1,200 – $2,500
  • Plus tuning labor: $400 – $800

If you DIY, expect a two‑weekend project for a first‑timer. Many junior enthusiasts underestimate the time and specialty tools (flare nut wrenches, tap and die kit, welder) required.

Total Estimated Cost Summary

The total investment varies dramatically based on part quality and DIY vs. shop labor. The table below summarizes a realistic range for a 100+ HP build using a salvage MX‑5 turbo or a new integrated kit.

Component Low‑End (Used/DIY) Mid‑Range (New/Quality) High‑End (Premium/Shop)
Turbocharger$200$700$2,200
Turbo Manifold$100$400$800
Intercooler Kit (including BOV)$200$400$700
Exhaust (downpipe + cat‑back)$150$500$1,200
Fuel System (pump + injectors + FPR)$350$600$800
Engine Management (ECU + tune)$550$1,200$2,300
Clutch + Flywheel$300$500$850
Cooling (radiator + thermostat)$200$350$500
Gauges + Wideband$250$400$600
Boost Controller (manual)$20$40$500 (electronic)
Labor (if not DIY)$600$1,200$2,500
Total (Estimate)$2,920$6,290$12,750

A well‑executed build using a second‑hand MX‑5 turbo and DIY labor can land near $3,000. A turnkey setup with all new parts and professional labor may exceed $12,000. Most enthusiast builds hit the $5,000 – $7,000 range for a reliable 150‑160 wheel horsepower setup (more than the 100 HP goal).

Installation Considerations and Tips

Oil System Modifications

The MX‑5 turbo traditionally uses a journal bearing oil feed and drain. On the Integra, you must tap the oil pan for the return line (use an –10AN welded bung) and connect a feed line from the oil pressure sender port or a sandwich plate. A restricted feed (single orifice) is critical to avoid blowing the turbo seals. Expect to spend $50‑$100 on oil line fittings and a drill kit.

Coolant Lines (If Water‑Cooled)

Some MX‑5 turbos are water‑cooled. If your chosen turbo has water ports, connect them to the heater core hoses or the throttle body coolant line. This adds complexity but reduces bearing temperature. A turbo timer ($40) is also wise to cool the turbo after full‑boost runs.

Boost Levels and Safety

For 100+ HP over stock, set wastegate boost around 5‑7 psi. Do not exceed 8‑9 psi without forged internals on a high‑mileage B‑series. A compression and leak‑down test before installation is cheap insurance. Use a wideband gauge to keep air‑fuel ratios between 11.5 and 12.5:1 under boost. Consult an experienced tuner for a safe VE table.

ECU Tuning: Don’t Skip It

Even if you use a plug‑and‑play ECV such as Hondata, you must have a base tune calibrated for your specific turbo and injectors. A one‑hour dyno session (Hondata has a network of dealers) is the safest route. Without proper tuning, detonation can destroy pistons within minutes.

Where to Find Parts and Information

Forums like Honda‑Tech.com and Team Integra are treasure troves of swap guides. Many members have documented custom turbo kits on a budget. Look for threads starting with “Budget B18 turbo build” or “MX‑5 turbo on a B20.” Buying used parts from the for‑sale sections of these forums can cut costs by 40%.

Conclusion

Installing a boosted Mazda MX‑5 turbocharger on your Acura Integra is a viable path to gaining 100+ horsepower while staying within a moderate budget. The key is careful planning: source a sound turbo, fabricate a manifold (or buy a quality custom one), upgrade the fuel and management systems, and don’t cut corners on tuning. Whether you do the work yourself or hire a shop, the final result can be a vastly more enjoyable, responsive, and head‑turning Integra. Expect total out‑of‑pocket costs between $2,900 and $12,700 depending on your goals and DIY capability. For most drivers, the sweet spot is a mid‑range build using a new Garrett turbo, Hondata ECU, and a quality exhaust – landing around $6,000 for a rock‑solid 150‑160 wheel horsepower.