Borg Warner EFR Turbochargers

About a month ago, we learned about an enticing new turbocharger product line from Borg Warner that was due to be released later this year. While we have been developing our Lotus forced induction kits around Garrett turbochargers, the rumors were enough for us to wait and see what Borg Warner was up to.
The rumors turned out to be true and now Borg Warner recently gave the green light for their distributors to go public with information about the revolutionary new turbochargers they are releasing.  The Borg Warner EFR turbochargers are a very exciting new addition to the afermarket turbocharger industry. These turbochargers are the result of a ground-up redesign with automotive aftermarket in mind.


Photo courtesy of: cosworthusa.com

Here are some of the features:

Low Inertia Turbine Wheel
Gamma-Ti turbine wheel cuts turbine inertia by roughly 50% dramatically improving turbo response.  Turbine sizes range from 55 to 80mm in exducer diameter

Heat Resistant Turbine Housings
Investment cast stainless steel turbine housings improve durability and offer an offer extremely smooth internal flow channel.  Turbine housings have thin walls to reduce weight and thermal inertia.

High Turbine Efficiency
Superback” and “Fullback” back-disk shapes offer very high efficiencies. The Superback shape adds a curved profile to the backdisk and has the effect of lowering centrifugal stress and permitting higher rotational speeds.

Enhanced Turbo Response
EFR turbochargers use a dual-row ball bearing cartridge with ceramic balls and metal cage.  This bearing system provides substantial friction reduction at low turbo speeds and in the process helps improve turbo response.  Metal cage improved the durability of the ball bearing assembly

Flexible Compressor Cover
The EFR turbo “large” cover has a dual-machined outlet, both for a hose connection and a v-band connection.

Simplified Installation
Integrated compressor recirculation valve (CRV) to help avoid compressor surge and backflow during a throttle lift event.  This feature helps to simplify the installation task and lowers overall system install cost

Forged Milled Compressor Wheels (FMW)
EFR turbos contain wheels that are fully milled from forged aluminum, commonly known as “billet”.  Cut from custom forgings, their strength exceeds that which is available from typical bar-stock and also exceeds the material properties of an aluminum casting

Sensor mounting convenience
Speed sensor mounting provisions are also supplied on every compressor cover.  Speed sensors are sold separately.

Boost Control Solenoid Valve (BCSV)
A boost control solenoid valve (BCSV) is included with every EFR turbo.

High Flow Wastegates
Purpose designed large wastegate ports give the wastegated EFR turbos the capability of handling the flow requirements of high performance applications

Ease of Orientation
Turbo orientation flexibility is facilitated by the wastegate bracket to bearing housing mounting arrangement.

Adjustable Wastegate
The fabrication and installation task is simplified with wastegated EFR models that feature adjustable wastegates available in three different canister sizes.

More information: http://www.cosworthusa.com/news/article.asp?idpage=57

Here at Radium Engineering, we are very excited about this new approach to the turbocharger and look forward to using them in future applications. Due to the increased size of EFR turbo's we will not be using them on our Lotus Elise/Exige turbo kits.

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Zero to 60 Testing

A vehicles zero to 60 time is considered a very basic and necessary performance statistic. It allows a direct comparison of the acceleration to any other vehicle.  We recently took some time to find out what our prototype turbocharged Elise could do. The car is making approximately 305Hp at the wheels using the stock 2ZZ-GE engine and our Stage II Sport turbocharger kit. We are also running the stock tansmission and clutch. Tires were Kumho V710's. Measurement was done with a Vbox PerformanceBox.  After many attempts, we were able to pull off a run of 3.8 seconds. Click the video below to see the action.

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Track day with the Golden Gate Lotus Club at Thunderhill Raceway

We had the great pleasure to spend a day at Thunderhill Raceway Park with the Golden Gate Lotus Club.  We drove 9 hours from Portland, OR to Willows, CA with our prototype turbocharged Lotus Elise in tow.  The goal of the trip was to test our products at elevated temperatures and at racing driving conditions.

We participated in six 20 minute sessions throughout the day, for a total of 2 hours of high-speed driving.  We were running our Stage 2 GT2860RS turbocharger kit that was making 300Hp at the wheels. We are also using the stock engine, transmission, and clutch. Ambient temperatures for the day topped 100 degrees F and this definitely had an effect on the vehicle. The car was not babied either.  Shifting was always done at or near 8,500 RPM, and the engine spent most of the track above 5,000 RPM.  The added low-end torque of the turbocharger did help to pull the car out of the occasional botched turn without the need to downshift.  The stock radiator was working hard, but successfully held the coolant temp at no hotter than 205F. Intake air temperatures did climb, but ignition timing was automatically reduced to account for the hotter air. This reduces power, but also keeps the engine safe by preventing knock. Even in these extreme conditions, driveability of the car remained perfect.  The power delivery was instantaneous, but  always smooth and very controllable. The GT2860 is definitely a very good match for the Toyota 1.8L.


At the mid day lunch break, we removed the rear clamshell for a full inspection.  Heat is a constant menace to the engine bay and we have been experimenting with different solutions. First off, we added a duct that directs fresh air from the driver-side intake vent directly to the underside of the intercooler, where an electric fan then forces it through the intercooler and out the rear deck lid. We also created an air dam to prevent hot air from the turbocharger from entering the suction zone of the electric intercooler fan. These solutions seemed to work very well, as the intercooler was not becoming heat soaked and consistently cooled the charge air by about 30 to 40 degrees. We were also experimenting with ceramic coatings. Out exhaust manifold, turbocharger, and downpipe were all treated with a thermal barrier coating designed to reduce the radiated heat. We made improvements to our stainless steel exhaust manifold heat shields and were testing those as well.


During the mid-day inspection, we were pleased to see no physical damage from the heat.  All components were intact and functioning just fine. But just because nothing broke, doesnt mean that we aren't going to make any improvements. We are currently exploring other heat management devices that can control the heat even more than what we have already. Keeping the heat trapped in the exhaust system not only lowers under-hood temps, but also improves spool-up of the turbocharger.

At the end of the day, I did get the pleasure to ride shotgun with a much more experienced driver in his '05 Elise.  Robert S. had no mercy on his vehicle and was able to push it around the track at an unbelievable rate.  We look forward to the day when we let an experienced driver like Robert track our turbocharged Elise and push it to its full potential.

Thank you to the Golden Gate Lotus Club for holding the event and running it in a relaxed and open format. It was a fun day, and we look forward to doing it again.

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P.I.R. Track day video

After almost a month, we finally got around to sifting through our footage and piecing together a video from our track day at PIR in early September.
You can read the full write up on the event on our blog.

*There was no useable engine audio for this video. We will be sure to get some next time. Sorry about that*

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