Do you love the idea of a hybrid Porsche sports car, but don't have enough money to own a 918 Spyder? Well, this aftermarket system designed by Vonnen Performance (a spinoff of Porsche suspension specialists ) could be the upgrade you've been waiting for.
Designed to fit any 911, Boxster, or Cayman built from 2012 to 2016, the system turns your normal Porsche into a functioning hybrid by adding an electric motor in place of the stock flywheel, an inverter mounted on top of the engine, and a battery pack mounted in the front trunk. Here's how it all works.
I called Chuck Moreland of to learn more. Basically, Vonnen's system plugs in the car's ECU via a CAN bus connection and "observes" what's going on. Things like RPM, vehicle speed, and throttle input are monitored and relayed back to Vonnen's computer, which releases energy through the crankshaft-mounted motor accordingly. So when the driver steps on the gas, the hybrid motor sends power to the motor mounted on the crankshaft and gives it more rotating force. The engine's ECU and Vonnen's system don't interact otherwise—to the engine's computer, it's kind of like you're going down a steep hill. It results in an increase of 175 horsepower and 150 lb.-ft. of torque over stock, with just a 120-pound weight penalty. You're essentially adding an entire Ford Fiesta worth of power to your 911.
How does Vonnen get so much power with such a small weight penalty? The stock flywheel is no longer needed, replaced by Vonnen's 38-pound motor, which sits between the engine and transaxle. The starter motor is gone too—the car uses the hybrid's battery to get itself started. And since it no longer needs a big 12-volt battery to start the engine, that's replaced with a smaller, lighter unit to power the accessories. The 144-cell 400-amp hybrid battery pack only weighs 80 pounds.
No cutting to the chassis, engine, or transmission is needed since Vonnen's motor slots nicely in where the stock flywheel would be. It creates a 25-millimeter gap, which is fine for rear-wheel drive cars, but creates a problem for all-wheel drive 911s because there's a driveshaft involved. Moreland told me for those instances, Vonnen will cut the driveshaft down and rebalance it to make everything fit just right.
Cooling the battery and electric motor are two separate additional liquid systems. Moreland told me they run on separate cooling systems because the batteries have to run at a cooler temperature than the electric motor does. And yes, these two cooling systems are in addition to the gas engine's cooling system. I hope you're starting to see how impressive that 120-pound weight penalty is.
Vonnen has also incorporated regenerative braking to harvest back energy into the batteries while slowing down, if all that other stuff isn't cool enough for you.
Moreland told me Vonnen currently has one functioning development car, and the team is currently working on refining a finished product before it starts any customer builds. As for price, well, it's a lot. The upgrade, which includes all parts and installation, will cost $75,000. Enough to buy a brand-new 718 Boxster S. Some might argue that money is better-spent on a twin-turbo system (or a new car altogether), but if you want to stand out, this is a pretty cool way to do it.
As for future offerings, Vonnen is planning on releasing a "Stage II" upgrade, which will have twice the battery capacity and double the power output. Perhaps even more interesting is Vonnen's plans for a version of the system designed to work with air-cooled cars. It's currently in early development stages, but Moreland told me it'll only be compatible with cars with G50-style transmissions (since the electric motor has to be designed to fit on the housing) and offer similar performance to its water-cooled upgrade.
An air-cooled Porsche hybrid seems like it'll simultaneously interest and enrage Porsche fans. Count us in.