How a Borgwarner Efr 6758 Turbo Boosts Your Sr20det to 400+ Hp

How a BorgWarner EFR 6758 Turbo Unlocks 400+ HP on Your SR20DET

The Nissan SR20DET is one of the most respected four-cylinder engines in automotive history, especially among drifters, road racers, and street tuners. But to push this 2.0-liter powerplant past the 400-horsepower mark, you need a turbocharger that combines quick spool with high-flow capability. Enter the BorgWarner EFR 6758. In this guide, we break down exactly how this turbo transforms the SR20DET, the supporting mods you can’t skip, and what to expect when you turn up the boost.

The SR20DET – A Tuner’s Legend

Originally found in Nissan’s S13, S14, S15 Silvias and the 180SX, the SR20DET is a 2.0-liter inline-four with a cast-iron block and an aluminum DOHC 16-valve head. Its reputation for reliability under high boost comes from a robust bottom end and a well-designed oiling system. Stock turbo models (like the T25 or T28) produce between 200–250 hp, but the engine is capable of far more.

Stock Limitations

The factory turbo runs out of steam around 280–300 whp. The small turbine housing chokes top-end flow, and the wastegate cannot hold consistent boost at higher pressure. Upgrading the turbo is the single biggest bottleneck removal for serious power.

BorgWarner EFR 6758 Turbo – A Closer Look

The BorgWarner EFR (Engineered For Reliability) series is widely regarded as one of the most advanced turbo lines available. The 6758 model — where “67” refers to the 67mm compressor inducer and “58” to the 58mm turbine inducer — is perfectly sized for a 2.0L engine targeting 400–500 hp.

Key Technologies

• Dual ball bearing cartridge – Virtually eliminates friction for lightning-fast spool and reduced turbo lag.
• Forged-machined compressor wheel – High aero efficiency and durability against overspeed.
• Integrated boost control solenoid – Built into the compressor cover, simplifying plumbing and improving response.
• Housing options – Available in .64 A/R, .85 A/R, and 1.05 A/R twin-scroll T4 or T25/T3 flanges.

Turbo Specifications

• Compressor wheel: 67mm inducer / 91mm exducer
• Turbine wheel: 58mm inducer / 52.8mm exducer
• Maximum flow: ~65 lb/min (enough for roughly 650 crank hp)
• Maximum boost: 32+ psi
• Weight: ~18 lbs

The 67mm compressor flows more than enough air for 400 hp while still offering excellent response on a 2.0L. The EFR’s patented turbine housing design reduces backpressure and improves transient response.

Why the EFR 6758 Is Ideal for 400+ HP on SR20DET

Many turbo options can make 400 hp on an SR20, but the EFR 6758 stands out because it delivers that power with exceptional drivability. Its dual ball bearing core spools as quickly as a T28, yet it can hold boost to redline without falling off. On a built head and stock displacement, expect full boost by 3500–3800 RPM with the .64 A/R housing. That means you get the low-end torque of a smaller turbo and the top-end pull of a much larger unit.

The integrated recirculating valve and bypass valve also clean up idle and transient throttle response, which is critical for drifting or road course work.

Essential Supporting Modifications

Bolt the EFR 6758 to a stock SR20DET and you risk leaning out, knocking, or exceeding the stock fuel system’s capacity. You’ll need a minimum set of supporting upgrades to realize 400+ hp safely.

Fuel System

• Injectors: 750–1000 cc/min (high-impedance, top feed recommended)
• Fuel pump: Walbro 255 lph (or larger if E85)
• Fuel pressure regulator: Adjustable unit, preferably a quality unit like the Aeromotive 13109
• Fuel lines: -6 AN supply and return are adequate for 400–500 hp

This upgrade guide on FR Sport covers the fuel system in more depth.

Intake and Exhaust

• Intake: A 3-inch cold air intake with a quality cone filter (the EFR uses a 4-inch inlet, so you’ll need a silicone coupler and adapter)
• Exhaust: 3-inch full exhaust from turbo back, with a free-flowing catalytic converter (if emissions required) or no cat
• Downpipe: Must match the EFR’s V-band outlet (often 3-inch V-band)

Engine Internals

For 400 hp, the stock SR20DET block can handle it with careful tuning, but the pistons and rods are near their limit. For longevity, consider forged rods and pistons (e.g., CP-Carrillo, Wiseco, Eagle). If you keep stock internals, stay under 18 psi and keep detonation-free. Many tuners run 350–380 whp on stock blocks for years, but 400+ whp often reveals weak ring lands.

Intercooling

A front-mount intercooler with a core at least 600x300x76mm is recommended. The EFR 6758 pushes a lot of heat at boost pressures above 20 psi. Charge pipe diameter should be 2.5–3 inches. Avoid restrictive elbow joints.

Installation Tips and Common Challenges

Installing the EFR 6758 on an SR20DET requires careful planning because the turbo uses a different flange pattern and oil/coolant routing than stock.

• Manifold choice: Most SR20 tuners use a T3 or T4 divided manifold. A twin-scroll manifold paired with the .85 A/R T4 housing improves spool and reduces lag. The Greddy Log manifold is common but a quality tubular manifold (like Full-Race or CXRacing) yields better flow.
• Oil feed: Use a restrictor (e.g., -4AN with a 0.040–0.060 inch orifice) to prevent excessive oil flow to the turbo bearing. The EFR requires about 40 psi at idle.
• Oil drain: The drain line must be at least -10AN with a downhill slope. Many EFR kits include a specific drain tube; do not use the stock drain location without modification.
• Coolant lines: The EFR has coolant ports – connect them to the heater hose circuit or use an aftermarket coolant flow kit. Not strictly required but recommended for street use.
• Wastegate: The EFR 6758 includes an integrated boost control solenoid, but you still need to run a vacuum line from a manifold source to the actuator. For fine control, use a manual boost controller or electronic solenoid.

Patience with turbo placement and clearance to the firewall, downpipe, and radiator is key. The EFR is slightly larger than a Garrett GT2871R, so check clearances before finalizing mounts.

Tuning for Maximum Performance

With the EFR 6758 and supporting mods in place, tuning is the final — and most critical — step. A properly tuned SR20DET can safely make 400–450 whp on pump gas (93 octane) or up to 500 whp on E85.

• ECU options: Use a standalone ECU (Haltech, Link, AEM, PowerFC) or a piggyback like Nistune. The stock MAF will max out, so switch to a MAP-based system.
• Base timing: Typically around 15° BTDC at idle.
• Ignition timing under boost: Retard timing as boost rises; target 10–12° at peak torque, 14–16° near redline.
• Air/fuel ratio: Target 11.5:1 on gasoline, 11.0–11.5:1 on E85.
• Boost target: Start with 18 psi on stock internals, 22–25 psi with forged internals.
• Knock control: Use a knock sensor (KS4) and log knock count. If you see knock, pull timing or increase fuel.

Enjuku Racing’s SR20DET tuning guide offers additional insight into fuel and ignition mapping.

Consider a wideband O2 sensor and a boost gauge to monitor during the initial street tuning. A chassis dyno is the safest way to finalize the tune.

Performance Expectations and Real-World Results

On a well-built SR20DET with the EFR 6758 turbine (0.64 A/R T3 or T25), you can expect:

• Spool: 15 psi by 3500 RPM; full 25 psi by 3800 RPM
• Power: 400–420 whp on 93 octane at 18–20 psi
• E85 power: 460–490 whp at 25–28 psi
• Torque: 350–400 lb-ft peak, with a flat curve from 3800 to 6500 RPM
• Redline: Power holds to 7500 RPM before dropping off

Users on forums like Zilvia and SR20-Forum consistently report achieving 400 whp with this turbo and a basic fuel system. With a built bottom end and E85, the EFR 6758 can even touch 500 whp.

Comparing the EFR 6758 to Other Turbo Options

How does the EFR 6758 stack up against popular alternatives for the SR20DET?

Turbo	Max Flow (lb/min)	Typical WHP (SR20)	Spool (PSI @ RPM)
Garrett GT2871R	45	350–380	15 psi @ 3200
Garrett GT3076R	55	400–450	15 psi @ 3700
BorgWarner EFR 6758	65	400–500	15 psi @ 3500
Precision 5858	65	400–480	15 psi @ 3600

The EFR 6758 matches or exceeds the flow of a GT3076R while spooling 200–300 RPM sooner — a huge advantage for street and track driving. The integrated recirculation valve also makes it more responsive on throttle lift.

Conclusion

The BorgWarner EFR 6758 turbocharger is a match made in heaven for the SR20DET when the goal is 400+ horsepower without sacrificing daily drivability. Its dual ball bearing core, efficient compressor, and integrated boost controls deliver a powerband that feels both eager and capable. Combined with the right fuel system, exhaust, intercooler, and tune, you can easily hit 400–500 whp with confidence. If you’re building an SR20 for drifting, time attack, or just a joyride that never gets boring, the EFR 6758 is a proven path to serious output.

Learn more about the EFR series on BorgWarner’s official site — and start your build with a turbo that doesn’t compromise.