Turbocharger technology is ever advancing, and BorgWarner’s new Engineered For Racing (EFR) line of turbochargers represents some of the most advanced units we have seen. It’s not that BorgWarner had one good idea and incorporated it into an existing turbocharger—it had many good ideas and even came up with some brand-new materials to go along with them.
| forced Performance turbo Cut Away
Gamma-Ti Turbine
The EFR line was designed for use in all types of racing, but BorgWarner specifically targeted these turbos toward rally and road-racing applications. Normally, the turbine wheel is much heavier than the compressor wheel, but with the new Gamma-Ti material (which is known as an inter-metallic compound), the weight ratio from compressor to turbine is nearly 1:1. This means two things: first, a much quicker rate of spool-up, and secondly, a larger turbine wheel can be used—which is perfect for the massive exhaust flow rates of performance diesel engines. BorgWarner did let us know the EGT limit for the Gamma-Ti wheel is 1,760 degrees, so diesel race engines will need to use water or intercooling to keep the turbine from overheating.
| The forged and milled aluminum compressor wheels in the EFR series are designed to withstand pressure ratios in excess of 4:1, which makes them perfect for the rigors of diesel race engines.
More Exhaust Ideas
The EFR turbo line integrates more than just new materials into BorgWarner’s new turbochargers. The turbos can be ordered with an optional 36mm internal wastegate with a 42mm valve that is aerodynamically integrated into the exhaust housing and offers the performance and exhaust flow of an external wastegate. The exhaust housing is also cast from stainless steel to be able to withstand extreme EGT levels. In the if-it-isn’t-broke-don’t-fix-it category, the exhaust is a traditional T3 flange (a twin-scroll T4 flange is optional) with a 3-inch V-band-style outlet.
| For ease of use (and to make fabricating systems easier), the EFR comes with a compressor flange that can accept either a normal hose with a clamp or a V-band (red arrow).
Compressor Technology
The compressor-side technology of the EFR turbochargers got the best and brightest ideas BorgWarner could come up with. This included an integrated blow-off valve to relieve pressure during off-throttle time (such as during a shift, or at the end of a sled pull). This means no compressor-damaging turbo surge has to occur. The compressor wheels themselves are made from forged and milled aluminum and have strength properties that are said to exceed that of a traditional billet-aluminum wheel. The EFR turbos also have BorgWarner’s patented extended-tip technology, which means more airflow and turbos that act a lot larger than they really are. Think of a 68mm turbo that flows air like a 71mm ’charger and spools like a 64mm, and you’ve got the idea. Compressor efficiency is also very good, from about 70 to 77 percent on most parts of the compressor map. There’s even a provision to add a turbine-shaft speed sensor.
| From the front (compressor side) of the turbo, one can see the integrated blow- off and electronic wastegate controls.
The Center of Technology
The center cartridge of the turbo did not escape the technology cavalcade, either. The EFR series is equipped with ceramic ball bearings, which further enhance the spooling capabilities of the unit. Ceramic bearings also require less oil and have a much greater tolerance for thrust load. The EFR’s centersection can also be water-cooled for ultimate reliability.
| The big news surrounding the EFR series is the Gamma-Ti turbine wheel, which is half the weight of existing Inconel models.
Diesel Specific
So what does all this technology have to do with turbocharging diesels, specifically? Well, as it turns out, the largest of the EFR series, the EFR-9180, has a 91mm compressor with a 67.7mm inducer, and an 80mm turbine with a 73.4mm exducer and would be very well suited to the diesel crowd. The high-flowing exhaust side, ability to withstand 50 psi of boost, and high tolerance for thrust loads (as in compounding) make this turbo an enticing choice for the diesel market. At about $2,100 retail, it’s not cheap, but nothing this advanced ever is. In a single-turbo application, we’d say the biggest EFR would work well in the 500- to 700-rwhp range and offer unmatched spooling, reliability, and performance. For a truly insane idea, triple 68mm EFRs (two into one) would allow infinite exhaust pressure tuning, more than 100 psi of boost, and enough airflow for 1,000 to 1,400 hp.
| From the back (exhaust side) of the turbo, the huge internal wastegate is visible, which can relieve nearly 40 percent of the turbo’s overall exhaust flow, as compared to about 10 to 20 percent on other existing models.
