Upgrading your SR20DET with a Precision 5857 turbocharger is one of the most effective ways to unlock serious horsepower and transform the driving experience. This ball-bearing, dual-ball-bearing turbo delivers quick spool, high flow capability, and proven reliability for both street and track applications. However, a successful installation requires careful planning, proper tools, and attention to detail. This expanded guide provides a complete, step-by-step walkthrough from preparation through final tuning, ensuring you get the most from your new turbo while avoiding common mistakes.

Why Choose the Precision 5857 for Your SR20DET?

The Precision 5857 is engineered for 450–650 horsepower on the SR20DET with proper supporting modifications. Its 57mm compressor wheel and 58mm turbine wheel are optimized for fast response and strong top-end pull. The billet compressor wheel and extended-tip design improve airflow efficiency, while the dual ball-bearing center cartridge reduces friction and oiling demands compared to journal-bearing turbos. This turbo pairs well with a quality manifold, upgraded fuel system, and a standalone ECU tune. For more official specs and compatible kits, visit Precision Turbo & Engine’s product page.

Tools and Materials Required

Before starting, assemble the following tools and components. Missing one item can halt your installation, so check this list twice.

Turbo and Mounting Hardware

  • Precision 5857 turbocharger (T3 or T4 flange, depending on your manifold)
  • SR20DET turbo manifold (top-mount or bottom-mount preferred; confirm the flange matches the 5857)
  • Turbo-to-manifold gasket (high-quality multi-layer steel or copper)
  • Turbo outlet gasket (for downpipe connection)
  • Grade 8.8 or higher bolts and lock washers for manifold and turbo
  • Anti-seize compound for threads

Oil and Coolant Lines

  • Turbo oil feed line (stainless steel braided with AN fittings, 4 or 6AN)
  • Turbo oil drain line (with appropriate flange and -10AN or larger fitting)
  • Coolant feed and return lines (if water-cooling the 5857; many include provisions)
  • Thread sealant (Loctite 567 or PTFE-based for oil fittings)
  • Oil feed restrictor (depending on oil pressure; Precision supplies a restrictor for high-pressure situations)

Intake and Exhaust

  • Silicone couplers and T-bolt clamps (2.5” or 3” inlet/outlet)
  • Intake piping (cold side) and filter
  • Downpipe with appropriate flange and O2 sensor bung
  • Wastegate (external recommended for the 5857; Tial 38mm or similar, with dump tube or recirculation)
  • Boost controller (manual or electronic)

General Tools

  • Socket set (metric, including 10, 12, 14, 17mm)
  • Wrench set (combination and flare nut for lines)
  • Torque wrench (range 10–80 ft-lb)
  • Breaker bar and extension
  • Gasket scraper and brake cleaner
  • Jack and jack stands or lift
  • Safety glasses, gloves, and rags
  • Catch pan for oil and coolant

Preparation Steps

Proper preparation reduces the risk of damaging components and ensures a smooth installation. Allow at least half a day on a clean, well-lit workspace.

Disconnect Battery and Drain Fluids

Disconnect the negative battery terminal to prevent accidental shorts or starter engagement. Drain the engine oil and coolant into clean containers. The SR20DET holds approximately 3.5 quarts of oil (with filter) and about 6 liters of coolant. Removing these fluids minimizes mess when disconnecting lines.

Remove Obstructing Components

Remove the engine cover, intake pipe (from air filter to turbo), and heat shields covering the exhaust manifold and turbo. Unbolt the battery tray if necessary for clearance. Access to the turbo studs and wastegate area is critical. For top-mount manifolds, you may also need to temporarily remove the hood latch support for easier upper bolt access.

Loosen Exhaust System

Support the downpipe and unbolt it from the turbo. If the exhaust has been in place for years, soak the bolts with penetrating oil beforehand. Disconnect the O2 sensor harness. Remove the downpipe and any catalytic converter section that restricts clearance to the turbo.

Removing the Factory Turbo

With the area clear, remove the original T25 or T28 turbo. SR20DET factory turbos are secured with four nuts on the manifold studs and two nuts on the downpipe flange.

Disconnect Lines

Loosen and remove the oil feed line from the top of the turbo and the oil drain line from the bottom. The drain line often uses a flexible tube with a banjo fitting; take care not to bend or damage it. Similarly, disconnect the coolant lines if your SR20DET is water-cooled. Have a rag ready to catch residual fluid.

Unbolt Turbo from Manifold

Working from underneath the car and above the engine, remove the four manifold nuts. If they are stubborn, use a breaker bar while bracing the manifold. Once free, carefully lift the turbo out from the engine bay. Inspect the manifold face for warping or cracks; replace if necessary. Also check the manifold studs – if any are loose or damaged, replace them now.

Clean Mounting Surfaces

Use a gasket scraper and brake cleaner to remove all old gasket material from the manifold face and the downpipe flange. Any debris left behind will cause leaks. If the manifold has threaded holes, chase them with a tap to ensure smooth installation of new studs (if using studs) or bolts.

Installing the Precision 5857 Turbo

With a clean manifold and new gaskets, you’re ready to mount the 5857. Follow these steps meticulously to avoid leaks and ensure proper alignment.

Manifold Preparation

If you are using a new aftermarket manifold, install it first with a new manifold gasket. Torque the manifold nuts to the factory specification (typically 30–35 ft-lb on SR20DET). Be sure to tighten in a crisscross pattern from the center outward. Allow the manifold to cool before mounting the turbo if you’ve run the engine.

Turbo Clocking and Gasket Placement

Before bolting the turbo, decide the clocking position of the compressor housing. The Precision 5857 uses a V-band or traditional flange depending on the variant. Rotate the housing so the compressor outlet points toward your intercooler piping route, and the turbine outlet aligns with your downpipe. Most models allow orientation with 360-degree rotation due to a snap ring or bolted connection. Apply a thin coat of anti-seize to the turbo flange studs or bolts.

Place a new turbo-to-manifold gasket on the manifold flanges. Position the turbo onto the studs, making sure it seats flat. Do not force it; if it binds, check for gasket misalignment or burrs on the manifold.

Torque Turbo Bolts

Thread the nuts onto the studs and tighten in stages. Final torque should be per manufacturer recommendation – typically 20–25 ft-lb for M8 studs. Over-torquing can warp the flange. For T3 flanges, use a cross pattern to ensure even clamping.

Oil Feed Line Connection

Attach the oil feed line to the turbo’s oil inlet port (usually a banjo bolt or AN fitting). Use a new crush washer and apply thread sealant only to the male threads – not the washer faces. Precision recommends a 4AN feed line with an internal restrictor if your oil pressure exceeds 55 psi at idle. Many SR20DETs with a high-volume pump benefit from a restrictor. Consult this SR20 forum guide for oil pressure specifications.

Oil Drain Line

The oil drain line must be routed downward with a continuous slope to avoid oil pooling. Use a -10AN or larger line to prevent backpressure. Connect the drain flange to the turbo’s drain outlet with a new gasket. Run the line to the oil pan bung (or return location). If you do not have a bung, now is the time to weld one. Ensure no kinks in the line and secure it with brackets.

Coolant Connections (If Applicable)

If your 5857 includes water-cooling, connect the coolant feed and return lines to the turbo’s ports. Many aftermarket kits use 5/16" or 8mm hose with hose clamps. Route them to the engine’s coolant circuit, typically tapping into the heater hose line or using a water pipe adapter. Bleed the cooling system after refilling.

Wastegate Installation

External wastegates are strongly recommended for the 5857 to control boost precisely. Mount the wastegate on the manifold’s wastegate flange (if present) or on a dedicated wastegate runner. Use a high-temperature gasket and copper anti-seize on the bolts. Connect the wastegate vacuum line to a boost source; a dedicated port on the compressor housing or intercooler piping is ideal. The wastegate spring chosen should match your desired boost level (e.g., 10 psi spring for low boost, 14 psi for high boost).

Intake and Exhaust Piping

Attach the intake pipe from the air filter to the compressor inlet using silicone couplers and T-bolt clamps. On the compressor outlet, connect the cold side intercooler piping. Ensure no debris enters the turbo during assembly. For the exhaust side, install the downpipe with a new gasket. Some downpipes may require modification to clear the 5857’s larger turbine housing. Torque downpipe bolts to 30–40 ft-lb.

Boost Controller Integration

Controlling boost pressure is critical to maximize the 5857’s potential without exceeding safe limits. Two types are common: manual and electronic.

Manual Boost Controller

A simple ball-and-spring manual controller is inexpensive and reliable. Connect it between a boost source (intake manifold or compressor housing) and the wastegate actuator. Adjust by turning the knob – more turns increases boost. However, manual controllers can be inconsistent with temperature changes.

Electronic Boost Controller

An electronic unit (like a GReddy Profec or AEM Tru-Boost) allows in-cabin adjustment and duty-cycle control. Power the controller from a switched 12V source, ground it, then connect the solenoid’s inlet to a boost source and outlet to the wastegate. Follow the manufacturer’s wiring diagram. These controllers offer features like gain, scramble boost, and overboost protection.

For either type, ensure all vacuum lines are silicone or reinforced rubber, and use T-connectors without restriction. A boost leak in this system will cause erratic boost. After connecting, test by pressurizing the system to 5 psi with a hand pump.

Final Steps and Tuning

The installation is nearly complete, but the engine must be properly prepared and tuned before you drive hard.

Reassemble and Refill

Reconnect the battery. Refill the engine with high-quality synthetic oil (5W-40 or 10W-40 recommended for turbo SR20DET) and fresh coolant. Do not replace the oil filter yet if you want to do a priming step first.

Leak Check and Priming

Disable the ignition or fuel pump fuse and crank the engine for 10 seconds to circulate oil through the turbo. Check for oil leaks at the feed and drain connections. Then enable the fuel pump, start the engine, and let it idle. Look and listen for exhaust leaks, coolant drips, and odd noises. Allow the engine to reach operating temperature, then check for leaks again after cooling.

Breaking In the Turbo

New ball bearing turbos do not require an extensive break-in period, but avoid full boost for the first 100 miles. Let the turbo spool gradually; this ensures the bearings and seals seat properly. After that, you may gradually increase boost in increments.

ECU Tuning – Non‑Negotiable

Any time you install a larger turbocharger like the Precision 5857, the ECU must be retuned. The stock SR20DET ECU will run dangerously lean at higher boost levels, risking engine failure. Use a standalone ECU (e.g., Haltech, AEM, Link) or a piggyback like Nistune with a wideband O2 sensor. A professional tune is recommended to set ignition timing, fuel maps, and boost control. Expect to spend $500–$1000 for a proper dyno tune. Without tuning, the 5857 will not perform correctly and may cause severe engine damage. Consider upgrading the fuel pump (Walbro 255 or larger) and injectors (at least 550cc for 400+ hp).

For more tuning resources, refer to this comprehensive SR20DET tuning guide.

Test Drive and Monitoring

Take the car on a test drive in a safe area. Monitor boost pressure, air-fuel ratio (target 11.5–12.0:1 under full load), oil pressure, and coolant temperature. Listen for any whining from the turbo (normal operation is a slight whistle). If you experience surge (flutter under deceleration), you may need a recirculation blow-off valve or adjustment of the compressor bypass. Also verify that the wastegate opens correctly by checking boost build – it should hit your set target and hold steady.

Conclusion

Installing a Precision 5857 turbocharger on your SR20DET is a rewarding upgrade that transforms the engine’s character. By following this detailed guide – from proper tool selection and removal procedures to careful mounting, line routing, and tuning – you set the stage for a reliable, high-performance build. Remember that supporting modifications like an upgraded fuel system and a professional tune are not optional; they are essential to unlock the 5857’s full capability and protect your engine. With patience and attention to detail, your SR20DET will deliver the exhilarating power you’ve been aiming for.

For further reading on turbo selection and dyno results, check out Precision Turbo’s tech support page and the SR20 Forum community.