What started as a dream-team of engineering partners designing a turbocharger lineup from scratch - refusing to be limited by availability of what already exists - resulted with EFR turbochargers. Engineering decisions were made that embody the state-of-the-art in high performance turbocharging. Top shelf aerodynamics were developed. Features like ceramic ball bearings, FMW compressor wheels, and Gamma-Ti turbine wheels were combined with Twinscroll stainless steel housings as our intention to maximize the performance of these turbos in every possible way.
EFR Hot Side (Turbine)
The most exciting technology in the EFR package is the low inertia Gamma-Ti Turbine Wheel. All EFR turbine wheels are made from a high performance lightweight material known as "Gamma-Ti". This material innovation is not quite metal and not quite ceramic, it is considered an "inter-metallic compound". Comprised primarily of titanium and aluminum (titanium-aluminide) with other trace elements, the Gamma-Ti turbine wheel is so light it's nearly the same weight as the forged-machined aluminum compressor wheel. This approximate 1:1 turbine:compressor weight ratio dramatically improves turbo response. Further strength benefits are realized at high temperatures as Gamma-Ti gains ductility and exhibits very high stiffness-to-weight ratios with good vibration damping characteristics. The EFR debut marks the first time Gamma-Ti has been offered to the public across a range of turbine wheel sizes and at an enthusiast's price point. EFR Gamma-Ti Turbine wheels come in six sizes: 55mm, 58mm, 64mm, 70mm, 74mm, and 80mm OD (turbine inducer diameter) and utilize the latest generation Fullback/Superback turbine wheel blade aero designs specifically tailored for high turbine efficiency and high flow at elevated boost levels. The fullback wheel hubs employ a full aerodynamic back-disk, meaning that the hubline extends all the way to the inlet tip. This feature allows for incredibly smooth (low energy loss) guidance of exhaust flow out of the housing and into the blade channels. Going one step further, the Superback shape adds a curved profile to the backdisk and effectively lowers centrifugal stresses - improving stability at elevated rotational speeds. Impossible in the past due to material stress limitations, the combination of Gamma-Ti and the exciting new .fullback/superback. design works in concert to allow best possible efficiency, high speed capability and durability.
There are (4) investment cast stainless steel turbine housings that make up the initial release of the EFR series (with more to come). Sizes are available in .64 A/R T25, 0.83 A/R T3 and 0.92 A/R internal WG or 1.05 A/R external WG T4 twinscroll footprints, all use a 3" Vband outlet. Stainless steel is a superior material choice for manifolds and turbine housings in turbocharged engines which operate at extreme EGTs. From a performance standpoint, the combination of material properties and thinly cast wall thickness allow less heat energy to escape AND are lighter weight while also being more crack resistant. The investment casting process results in a perfectly smooth surface finish that resembles a ported/polished cyl head and serves to lower gas friction losses - all while looking beautiful in the engine bay (a perfect compliment to the Full-Race header it's attached to). Stainless Turbine housings offer exceptional corrosion resistance at elevated temperatures - far superior to rusty/corroded cast iron housings we are used to seeing in the past. These turbine housings are truly fit for street use, road racing, or even endurance racing and when polished they look like modern-artwork. NOTE: These are NOT designed to be direct bolt-in replacement turbine housings for other mfg turbos so do NOT expect them to bolt up to your car/manifold without changes unless stated.
The optional EFR internal wastegate is truly designed for high flow, even for big-power setups. EFR optional internal wastegates are aerodynamically-optimized to offer the same performance as an external wastegate recirculated back into the downpipe - no 90 degree corners here. This is a real "value" feature of the EFR program, particularly in the case of twinscroll applications which require (2) external wastegates, (2) manifold wastegate ports (2) dumptubes for maximum performance. Furthermore, the manifold fabrication and installation are both simplified with the wastegated EFR models. Boost levels can be easily adjusted by swapping adjustable wastegate canisters available in three different spring rates/boost levels. Lastly, different turbo clocking positions are easy to accomodate without changing the wastegate bracket. This is because the bracket is bolted to the bearing housing backing plate - not to the compressor housing as is the case with most internal WG turbos. For space constrained applications which can not fit the EFR internal WG or Hardcore racers that want to keep their dual external wastegates mounted to the exhaust manifold - you can do that too!
EFR Internal WG Fitment is application specific: most longitudinal engines such as 2JZ, SR20, RB26, will fit the Internal WG, whereas many transverse engines such as some FWD Hondas and some AWD applications will not fit the EFR internal WG. Applications prone to boost creep may prefer large external wastegates for boost levels under 7psi. exceptions to the rules confuse this. Keep an eye out for a Full-Race fitment compatibility chart coming soon!
Cold Side (Compressor)
All EFR turbochargers use Extended Tip Forged Milled Compressor Wheels ***AKA Billet Compressor Wheels*** The six EFR compressor wheels range from 62mm OD (~50mm inducer) to 91mm OD (~67mm inducer). These Extended Tip Technology designs are unique in that they are BorgWarner's highest-boost capable wheel designs yet still produce outstanding map width and flow capacity for efficiency at all boost levels and engine types. EFR compressor wheels are manufactured from forged aluminum for maximum strength and light weight, then CNC machined on a 6-axis CNC Mill. The blade geometry utilizes State-of-the-Art aerodynamics that delivers efficiency, boost capability and surge limits beyond any turbo we have ever seen. The forging strength exceeds that of typical aluminum billet bar-stock and also exceeds the material properties of an aluminum lost-wax compressor wheel casting. These compressors define "top shelf" in terms of strength, efficiency, range/width, and of course pressure ratio (boost) capability. EFR turbo compressor housings incorporate an integrated BOV. Yes, you read that right - the BOV is a recirculating style *built-in* to the Compressor Housing. The major performance advantage in this design is that it redirects the high-pressure compressed air from the outlet of the compressor wheel -> right at the low-pressure inlet of the turbo. This helps to keep the turbo spooled between shifts and offers cost savings/convenience while keeping MAF-based engine mgt happy. With this in place, there is no need for a BOV or flange on the charge piping. The only downside of this feature is the fact that it makes the compressor housing about 1" (~25mm) longer in axial length. For the hardcore racers who want to use an external traditional BOV, and for applications that can not fit or do not want to use the internal valve, we offer a disabling cover plate. This cover plate installs in place of the plastic cover and uses the original diaphragm to seal the port. There are three compressor housing sizes and types - All housings come with the same features BOV, BSCV, V-band connection, hose clamp surfaces, etc. The first is a small compressor housing for the T25 turbos. The medium is used with the mid-sized 70mm and 76mm OD compressor wheels available. The large compressor housing is used with the 83mm and 91mm wheels. Lastly, exclusive to the large cover is a dual-machined outlet, useful for both a hose connection and/or a v-band connection. If the v-band feature is needed, the hose connection portion can be cut off and discarded. Full-Race will offer vband 90 degree bends for applications which require a tight bend, close to the turbo (such as RB26 and many subaru rotated setups). The medium and large housings both use an inlet recirculation groove (AKA ported shroud) for maximum compressor map width and anti-surge characteristics.
A Boost Control Solenoid Valve (BCSV) is included with every EFR turbo -- For electonically controlled boost levels, an Electronic Boost Control Solenoid (EBCS) is integrated right into the compressor housing. This solenoid is truly OEM quality and uses an industry standard fuel injector plug, making it easy to connecting to multiple boost control systems. Of course if the hardcore racers want to use an external solenoid OR a manual boost controller (without the integrated EBCS), that is very easy to do. Speed sensor mounting provisions are also supplied on every compressor cover (speed sensors are sold separately). Turbo speed sensors are not new technology, but the installation procedure has always been difficult for even the most experienced tuners/installers. Traditionally the customer must remove their compressor cover and take it to a machinist. This machinist then has to set up the cover at a compound angle to precisely drill the speed sensor bore while carefully hitting the contour area of the wheel bore at the right angle. The BorgWarner EFR solution provides this precision machining already done to every compressor cover. The hole stops short of protruding into the compressor wheel bore. If a user decides to buy a speed sensor as an upgrade accessory, they simply remove the compressor cover and extend the hole the rest of the way through to the wheel bore using a hand drill. A ¼" drill bit is used and the length required to be drilled is quite short. This hole allows the tip of the sensor to come flush with the contour surface. The hole does not have to be precise, as no sealing takes place in the small hole that the user just created.
All EFR turbochargers use high-end Ceramic Ball Bearings for Enhanced Turbo Response -- Even though BorgWarner has been known as a long-time manufacturer of high end journal bearing turbos, the engineering team developed ceramic ball bearing cartridges for the uncompromising EFR series. EFR bearing cartridges house dual-row ceramic balls in special alloy bearing races to provide substantial friction reduction. The biggest benefits of ball bearings are most clearly realized at low turbo shaft speeds (spool-up region) and they also help improve turbocharger response/boost recovery as found between gear shifts. Once the engine is at full boost, ball bearings offer no advantage in performance - BUT - there are huge performance benefits for getting up to the desired boost level FAST and delivering quick throttle response for on-off-on-off aggressive driving. From a durability standpoint, the EFR cartridge bearing system provides a huge increase in thrust load capacity over conventional systems and requires much less oil supply. From a fuel efficiency standpoint, parasitic loss is reduced at low turbo speed so MPG increases can be realized. Lastly, the EFR bearing system includes the latest in turbo seal technology reducing oil seepage/burning problems often found in aftermarket installations (more on this later!!) EFR bearing housings have the option for water-cooling. Water cooling is recommended where possible to do so, but not mandatory. If watercooling is not connected, be sure to use clean, high viscosity synthetic oil (15W) and do not repeatedly perform "hot engine shutdowns". A properly sized "restrictor" aka oil metering orifice is integrated into the bearing housing so EXTERNAL OIL RESTRICTORS SHOULD NOT BE ADDED TO EFR TURBOS. A -4AN male fitting has been provided on the EFR turbo and a -4AN (¼") line is recommended. Oil return is tapped to 3/8NPT as well as 2 bolt flange comaptible.
The BorgWarner EFR turbo is set to become the new world standard for performance turbocharging due to the high-technology feature package, unbeatable performance, and installation convenience. The EFR turbocharger was designed and manufactured with only one purpose in mind: to dominate the street, track, and strip. Multiple different size turbos, optimally matched for the 250-1000hp per turbo segment - and in (4) different turbine housings are the result. The combination of this top-shelf geometry and the Gamma-Ti turbine wheel significantly raises the bar for performance aftermarket turbochargers. Combined with our ball bearing technology, it is the most responsive range or turbos that are available anywhere, at any price. The EFR series covers all applications except the hardcore drag racers. For those hardcore customers, we still offer the highly popular S400SX and S500SX product lines, and will continue to update those turbos during the next year.