Part of the reason that the BMW i8 was not a hugely popular car is that it featured a B38 three-cylinder engine. Another element is that it was a plug-in hybrid supercar, and many were not ready to adopt the technology a decade ago, but Trevor Elan from Bimmer Network is fixing both those problems. He’s ripping out the entire powertrain, including the electrified bits, and replacing them with a tuned B58 straight-six. It’s not really sacrilege, since BMW considered bigger engines for the i8, too, but this is not going to be easy, and it may have some unwanted consequences in the handling department. Nevertheless, work has already begun, and the battery pack has been stripped, among other things.
700-HP Engine for One-Off BMW i8
BMW
It remains to be seen how Trevor will fit an engine twice as long as the original in the i8 — especially since he’s not putting it behind the cabin but up front where the front electric motor once lived — but if he gets it to work, it will be a rowdy drive, with the inline-six coming from a crashed 2017 M340i xDrive that was capable of around 700 wheel horsepower. For the record, the original powertrain was only rated for a combined total of 369 hp, so Trevor will need to use the transmission and possibly even the drive shafts and hubs of his donor car to put that power down. He’s already conceded that custom subframes will be necessary, with these designed to allow the transmission and transfer case of the swapped power unit to fit where the high-voltage battery did.
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There’s also the issue of tuning, and we presume the 3 Series will have to donate its ECU to the build. Additional effort may also be required in the bodywork department, since the i8’s famously skinny original wheels may need upgrading, and that could cause clearance issues with the carbon fiber monocoque. At this point, it seems simpler to body-swap the i8 onto a 2 Series, but perhaps Trevor thinks that’s too easy.
Straight-Six BMW i8 Will Be Tricky to Drive
Weight distribution is going to be significantly altered, and to try to address this (and because the front bay was never designed to accommodate an engine, let alone its ancillaries), Trevor is putting the radiators and other cooling elements in the back of the car, where the three-pot engine previously lived. Whether this will be enough to neutralize understeer, and whether these cooling systems will be able to cope with the heat generated by a 700-hp turbocharged straight-six while being mounted in the back, remains to be seen, but if it all works out, this will be one undeniably unique build.