How Much Power Does the BorgWarner EFR 7670 B-Series Turbo Kit Add? Real-World Results

The BorgWarner EFR 7670 B-Series turbo kit is a cornerstone upgrade for Honda enthusiasts seeking serious power from their B16, B18, or B20 engines. Renowned for its quick spool, high efficiency, and robust construction, this kit consistently delivers gains that transform a daily driver into a track-ready machine. But the question on every builder’s mind is: how much power can you realistically expect? This article breaks down verified real-world results, explains the critical variables that influence output, and offers guidance on getting the most from your EFR 7670 setup.

Understanding the BorgWarner EFR 7670 Turbocharger

Before diving into numbers, it’s important to understand what makes the EFR 7670 unique in the aftermarket turbo landscape. The EFR (Engineered For Reliability) series is BorgWarner’s premium line, designed for high-boost applications with exceptional thermal and mechanical limits.

Key Design Features

  • Forged MFS (Machined from Solid) compressor wheel: 67mm inducer reduces inertia and improves transient response.
  • Gamma-Ti turbine wheel: 70mm titanium-aluminide alloy halves rotational mass compared to inconel, drastically reducing spool time.
  • Dual ball bearing center housing: Low friction allows the shaft to spin freely, enhancing boost threshold and response.
  • Integrated recirculation valve and wastegate mounting: Simplifies plumbing and eliminates boost spikes.

Specifications at a Glance

  • Compressor inducer: 67mm
  • Turbine exducer: 70mm
  • Maximum boost pressure: 30+ psi (limited by engine capability)
  • Flow capacity: Approximately 65 lb/min at 30 psi
  • Typical power range: 350–600+ wheel horsepower

The EFR 7670 sits squarely between the small-frame EFR 6258 and the larger 8374, making it an ideal match for 1.6–2.0L B-Series engines that aim for a broad powerband rather than a peaky top-end.

Real-World Power Gains on B-Series Engines

Power gains are highly dependent on the engine’s condition, supporting modifications, and tuning quality. We’ve gathered data from multiple well-documented builds to provide a realistic spectrum.

Setup 1: Stock Internal B18C1 (GS-R) with Minimal Bolt-Ons

A common starting point is a healthy, low-mileage B18C1 with only a 3-inch turbo-back exhaust, an upgraded fuel pump (Walbro 255 lph), and a Hondata S300 standalone ECU. The EFR 7670 kit was run at 12 psi on 93-octane pump gas.

  • Baseline (naturally aspirated): 170 hp, 128 lb-ft
  • After EFR 7670 installation: 385 hp, 310 lb-ft at 12 psi
  • Power gain: +215 hp (+126% increase)
  • Boost threshold: Full spool by 3,800 rpm

This result demonstrates the EFR’s efficiency even on a near-stock motor. Power delivery is linear, with strong mid-range torque—uncommon for a turbo of this size. To push higher, fuel injectors (750cc+) and a better intercooler become mandatory.

Setup 2: Bolt-On B18C with Supporting Mods (Injectors, Intercooler, Cams)

A more optimized build includes upgraded 1,000cc injectors, a front-mount intercooler (core size 24x12x3), a 3.5-inch downpipe, mild camshafts (Skunk2 Stage 2), and higher static compression (10.5:1). Boost was raised to 20 psi on a mix of E85 and pump gas.

  • Baseline (bolt-on with cams, no turbo): 225 hp, 155 lb-ft
  • After EFR 7670 at 20 psi: 505 hp, 410 lb-ft
  • Power gain: +280 hp (+124% increase)
  • Boost threshold: Full spool by 4,200 rpm

At this level, the EFR 7670 is operating in its sweet spot. The titanium turbine helps the turbo spool quickly despite the larger cams and compression, while the dual ball bearings ensure consistent response. This setup is streetable and capable of high 10-second quarter-mile passes.

Setup 3: Fully Built B20/VTEC with Forged Internals

The ultimate B-Series application is a sleeved B20 block (84mm bore) with forged pistons and rods, a fully ported head, oversized valves, high-lift cams (Jun Stage 3), sheet-metal intake manifold, and 2,400cc injectors fed by a surge tank. The engine was tuned at 32 psi on race gas.

  • Baseline (built, naturally aspirated): 310 hp, 210 lb-ft
  • After EFR 7670 at 32 psi: 640 hp, 510 lb-ft
  • Power gain: +330 hp (+106% increase)
  • Boost threshold: Full spool by 4,500 rpm

Even at extreme boost levels, the EFR 7670 maintains excellent turbine efficiency. The torque curve peaks early (around 6,000 rpm) and holds strong to 9,000 rpm—a hallmark of a turbo that is not choked on a large displacement engine. At this power level, driveability is still respectable thanks to the EFR’s low backpressure characteristics.

Dyno Curve Observations

Across all setups, the EFR 7670 produces an exceptionally flat torque curve from 4,000 to 7,500 rpm. The lack of a pronounced “spike” makes the car easier to drive and less stressful on the drivetrain. Compared to older Garrett or Mitsubishi turbos of similar size, the EFR spools 500–800 rpm sooner and delivers 5–10% more peak torque at equivalent boost levels.

Critical Factors That Affect Your Final Power Output

While the turbo itself is a high-performing component, several external factors will determine whether you land on the lower or upper end of the power spectrum.

Engine Displacement and Head Flow

Larger displacement (2.0L vs. 1.6L) provides more exhaust energy to drive the turbine, which improves spool and increases mass flow. A well-ported cylinder head with aggressive cams moves the power peak higher. For example, a B16 with a stock head may see 350 whp at 15 psi, while the same boost on a built B20 can exceed 450 whp.

Fuel Type and Octane

Pump gas (91–93 octane) limits boost to roughly 12–15 psi on a stock block and 15–20 psi on a built one due to detonation risk. Ethanol blends (E85) allow 5–7 psi more boost at the same knock threshold because of their high octane rating and cooling effect. Race gas (110+ octane) can push the EFR 7670 to its compressor flow limit—over 600 whp.

Supporting Modifications

  • Intercooler: A insufficient core causes high intake temps, reducing air density and power. Minimum 24x12x3-inch bar-and-plate core recommended.
  • Exhaust system: 3-inch mandrel-bent from turbo to tail is essential. Restrictive piping raises backpressure and hurts spool.
  • Fuel system: Injectors must be sized to keep duty cycle below 80%. For 500+ whp, 1,000cc+ injectors with a surge tank and dedicated fuel pump are required.
  • Engine management: A standalone ECU (Hondata, MoTeC, Haltech, or AEM) allows full control of boost, fuel, and ignition timing. Proper knock control and cold start maps prevent damage.

ECU Tuning Quality

The most overlooked factor. A mediocre tune can leave 50–80 whp on the table and risk engine failure. A skilled tuner will optimize timing curves, fuel trims, and boost targets specifically for the EFR 7670’s compressor map. We recommend consulting with a shop experienced in BorgWarner turbos, such as Hondata or EFI Source.

Installation and Reliability Considerations

A turbo kit is only as good as its installation. The EFR 7670 B-Series kit typically comes with a cast or tubular manifold, downpipe, oil/water lines, and all necessary hardware. Pay close attention to the following:

Oil Feed and Drain

The EFR requires an oil restrictor (0.040″–0.060″) in the supply line to prevent bearing overload. Use a -4 AN feed line from the oil pressure port. The drain must be -10 AN minimum, with a gravity-flow path to the oil pan. A poor drain oiling causes smoke and premature turbo failure.

Wastegate and Blow-Off Valve

The kit often assumes an external wastegate (Tial 38mm or 44mm) and a blow-off valve (Tial Q or HKS). Match the spring pressure to your desired boost level. For low-boost street driving, a 7–10 psi spring works; for high-boost track use, a 15–20 psi spring is common. The EFR’s integrated recirculation port (if using BorgWarner’s BOV) simplifies re-circulation setups.

Cooling and Intercooling

Heat management is critical. Upgrading to a larger aluminum radiator (Mitsubishi-style or Koyo) and an oil cooler with thermostat is strongly recommended. The EFR 7670’s integrated heat shield helps, but additional turbo blanket can reduce underhood temperatures. For sustained high boost, water-methanol injection provides a safety margin against detonation.

Comparing the EFR 7670 to Other B-Series Turbo Kits

How does the BorgWarner stack against alternatives like the Garrett GTX3071R, Precision 5858, or the older-compressor 6262? The EFR 7670 offers a distinct advantage in spool speed and efficiency due to its titanium turbine and advanced aerodynamics. The GTX3071R may make similar peak power but typically reaches full boost 300–400 rpm later. Precision’s 5858 is slightly smaller on paper but heavier, with slower transient response. For a B-Series that must balance street manners with power, the EFR 7670 remains a top-tier choice.

Conclusion

Real-world results confirm that the BorgWarner EFR 7670 B-Series turbo kit reliably adds between 150 and 330 wheel horsepower, depending on engine strength and supporting modifications. With a balanced approach to fuel, tuning, and cooling, a 400–500 whp street setup is easily attainable, while fully built combinations can surpass 600 whp. The key takeaway is that the EFR 7670 delivers exceptional spool and torque—two attributes that make high power enjoyable rather than scary.

If you’re planning a B-Series turbo build, the EFR 7670 deserves strong consideration. Invest in professional tuning, quality fuel, and no-compromise supporting parts, and you’ll unlock the turbo’s full potential. For more technical specifications and resources, visit BorgWarner’s official page or browse build threads on Honda-Tech for community-tested results.