Just recently, Vivid Racing gained the ability to flash BMW F-series vehicles through the ODBII port. We have developed tunes for the M2, M3, M4, and other M vehicles, but there has been one question in the back of our minds: what can we do with the BMW i8. The i8’s 1.5-liter turbocharged 3-cylinder engine powers the rear wheel whilst the electric motor powers the front wheels. Combined they output an impressive 357 hp and 420 lb-ft. Recently we had the opportunity to develop our VR Tuned ECU flash for the i8 and the gains were rather impressive.
Baseline Power
Developing any new tune requires baseline numbers to figure out what the vehicle actually puts down to the ground. With our all-wheel-drive Mustang Dyno, we typically see a 20% drivetrain loss. In theory, this would put the i8 around 285 wheel-horsepower (357 – (357*20)). To our surprise, the BMW i8 put down 333 wheel-horsepower and 388 ft-lbs of torque. This means that either the i8’s drivetrain is extremely efficient and only loses 8% of the power or BMW heavily underrated the i8. The latter is far more likely.
- 333whp
- 388 ft-lb
- 12.68 second 1/4 mile time
- 115mph 1/4 mile speed
One of the cool features of our Mustang dyno is the ability to do 0-60 and 1/4 mile testing. Although this isn’t completely accurate to real-world numbers due to lack of wind resistance and different grip levels, it’s still a good way of measuring how the tune affects the vehicle. As we tested, the BMW i8 ran a theoretical 12.68 second 1/4 mile at 115mph. Now that we have our baseline numbers, it’s time to move on to the tuning phase.
Tuning Phase
In order to increase power with a tune, you must optimize fuel mixtures, ignition timing, variable valve timing/phasing, limiters, and other various parameters. Luckily, the end user doesn’t have to mess with any of this stuff as we already found the optimal parameters. In the past, it wasn’t possible to flash a BMW F-Series vehicle without opening up the ECU. Thanks to Vivid Racing’s recent developments, however, the tuning is now done entirely through the OBDII port.
The tune will require a PC or a Macintosh running Windows (can be done easily with a Virtual Machine) to connect with the car’s ECU. The process is pretty simple and only takes around 5 – 15 minutes. Follow the steps listed in the instructions and you’ll be good to go!
Tuned Power
After flashing the ECU with our tune file it was time to hit the dyno again. It’s important to remember that peak numbers aren’t everything. Gaining power throughout the entire power band is much more desirable as it will make the vehicle way more fun to drive on the road. Now that the car is tuned it output 352 wheel-horsepower and 411 lb-ft of torque. This represents peak gains 19 wheel-horsepower and 23 ft-lbs. As we mentioned, however, peak gains aren’t nearly as important as the total gains throughout the entire rev range. Throughout the rev range, the tune consistently added anywhere from 20whp and 20ft-lbs to 30whp and 30ft-lbs. This will greatly improve 0-60 times and 1/4 mile times. Speaking of drag times, it was at this point we tested the 1/4 mile.
- 352whp
- 411 ft-lbs
- 12.47 second 1/4 mile time
- 116 mph 1/4 mile speed
Again, the 0-60 and 1/4 mile times we test on our Mustang dyno are not completely accurate representations of what that vehicle will do in the real world due to lack of wind resistance and different grip levels. With the tuned i8 we measured a 12.47 second 1/4 mile at 116mph; The stock car ran a 12.68 second 1/4 mile at 115mph. For just a tune this is quite an impressive gain in power and drag times. We didn’t get the chance to test how fuel mileage was affected by the tune, but we predict a slight improvement in day to day mpg averages.
Summary
There is a lot of information to digest here, but there are a few key points you should remember. Our VR Tuned ECU flash gained around 30 wheel-horsepower and 30 ft-lbs of torque through the powerband. Theoretical 1/4 mile times were also improved by 0.2 seconds and 1mph. The increased low-end torque makes the BMW i8 an absolute blast to drive around town and on canyon roads. You can purchase this tune for your i8 here. Be sure to check out the YouTube video below! There are also dyno graphs listed further below so you can see the exact before and after numbers.
