Porsche people are purists. Well, usually, but I’m not here to talk about crazy cases. Instead, I’m here to share with you all something I believe is pretty impressive: a brilliantly engineered hybrid system for the air-cooled 911 that might really please the fickle crowd.
There are very few trade-offs, whereas there are many trade-offs with hot-rodded flat-sixes, turbos, and the like. It’s the brainchild of Chuck Moreland and his crew at Vaughan, who designed an electric motor that’s sandwiched between the engine and transaxle. They call it a shadow drive because the whole concept is to make it look like the system isn’t even there.
“Our goal with the system was basically to make it disappear,” Moreland told me. “We want the driving experience to be as if it hasn’t changed. And that sounds silly because, sure, we want it to be more powerful. But what we’ve achieved is a system that basically isn’t there. You don’t see it. It doesn’t change the driving experience. It makes it more powerful. And it’s as if it was just a more powerful and torquey engine.”
How much power are we talking about? Well, an additional 75 horsepower and 75 lb-ft of torque on the stage one kit, or 150 hp and 150 lb-ft of torque with stage two. This is more than respectable, considering that these cars are quite light; Furthermore, the 964 Carrera initially produced only 250 hp from the factory.
But the most extraordinary thing about the Vonen Shadow Drive is not just its power. This is thoughtfulness.
It starts with the packaging, as the bulk of the motor fits inside the car’s bellhousing. As a result all the extra power is sent directly to the crankshaft, with no lag or parasitic losses. And Vonn knows people mainly worry about the bulkiness of the battery, so he addressed it with a clever solution that involves installing a smaller fuel tank and making good use of the newfound extra space.
“It’s a 20-gallon fuel tank, and we’ve modified the fuel tank to create a combination energy unit, which is both battery and fuel,” Moreland explained. “It sits in the same envelope as the original fuel tank. We sacrificed a few gallons of fuel to do this, but you still got a 15-gallon tank and better economy. So we didn’t hurt the vehicle’s range much, and the battery weight is significantly lighter.”
“You open the trunk, if you’ve got stock carpeting in it, you’ll be hard-pressed to know there’s been any changes because it’s all covered up. You peel back the carpeting, and you can see that the fuel tank is a combined battery and fuel tank unit, but again, it’s inside the original tank envelope.”
Plus, the battery is only one kilowatt-hour. This means it recharges quickly using energy from the engine as well as the brakes.
Vaughan built a 1988 Porsche 911 by installing Shadow Drive. The net weight change was 44 pounds, or about the equivalent of an overstuffed suitcase. The shop replaced the heavy 12-volt battery with a lighter-weight one; Removed the spare tire, jack and compressor; and removed the car’s starter motor, as its hybrid system now cranks the engine. Power reached 335 hp, without impairing the handling capability of the car.
And because Vonnnen’s kit includes a special controller, drivers can select different drive modes for different scenarios with a smartphone app. Whether you’re on the road or the track, you can customize the behavior of the hybrid system. It can also deploy power differently by gear, which is great news for those who don’t want to explode their transaxle or CV joints. Vonon does this by sending less torque in first gear and then increasing it in higher gears to preserve the hardware.
That said, you don’t need to make a long list of modifications to your car to get Shadow Drive running. Perhaps the best thing about it is that it is compatible with all 911s from 1974 and up, as well as the 912 and 914. It doesn’t matter whether the engine is carbureted or fuel-injected, naturally aspirated or turbocharged – it just bolts on. So you can make your car as mild or as wild as you want, and Vannon’s hybrid system will only complement the rest of your setup.
It also gives you extra performance without affecting the vehicle’s emissions, which is extremely important in states like California.
You’ll spend a lot more for that level of convenience and versatility. Shadow Drive phase one costs $54,000, while phase two costs $69,000 before installation. Of course, modifying these cars isn’t cheap, and you’re paying for seamless integration as well as added performance. Plus, it’s all reversible, so you don’t have to cut up your classic P-car to make it fit.
I’m not here to sell you this kit. I’ll tell you straight up that I could never buy it. But if you’re looking for smart ways to get more power from an air-cooled 911, there’s arguably no more complete solution than this. It has all the advantages of electrification and practically zero drawbacks – except the price – and if a purist ever got behind the wheel of it, I doubt they’d ever know it was there.
It’s something like this.
Have a suggestion or question for the author? Contact him directly: caleb@thedrive.com
