Porsche enthusiasts are often traditionalists. Typically, but I’m not here to discuss rare exceptions. Instead, I’m excited to share something that I find quite remarkable: An ingeniously designed hybrid system for air-cooled 911s that may actually satisfy the discerning crowd.
It has minimal trade-offs, unlike heavily modified flat-sixes, turbos, and similar options that often come with many downsides. This innovation comes from Chuck Moreland and his team at Vonnen, who created an electric motor that fits snugly between the engine and transaxle. They refer to it as the Shadow Drive, as the entire idea is to make the installation nearly invisible.
“Our aim with the system was essentially to make it go unnoticed,” Moreland shared with me. “We desire the driving experience to feel unchanged. That may sound silly since we naturally want it to be more powerful. However, what we’ve accomplished is a system that virtually disappears. You can’t see it. It doesn’t alter the driving experience; it simply adds power. It feels like a stronger and more torquey engine.”
How much extra power are we discussing? Well, an additional 75 horsepower and 75 lb-ft of torque with the stage one kit, or 150 hp and 150 lb-ft of torque with stage two. That’s quite impressive, considering these cars are relatively lightweight; a 964 Carrera, for instance, only produced about 250 hp from the factory initially.
However, the impressive power output isn’t the most remarkable aspect of the Vonnen Shadow Drive. It’s the careful consideration put into its design.
It begins with the compact design, as the majority of the motor fits within the vehicle’s bellhousing. All the added power goes straight to the crankshaft, with no noticeable lag or losses. Vonnen is aware that people typically worry about the weight of batteries, so it has implemented a smart solution that involves fitting a smaller fuel tank and making effective use of the extra space.
“It’s a 20-gallon fuel tank, and we’ve adjusted the fuel tank to create a hybrid energy unit, which serves as both battery and fuel,” Moreland elaborated. “It occupies the same space as the original fuel tank. We sacrificed a few gallons of fuel for this, but you still get a 15-gallon tank and improved fuel economy. Hence, we didn’t significantly impact the car’s range, and the battery’s weight is quite light.
“If you open the trunk, with the stock carpeting in place, it would be challenging to notice any change, as it’s all concealed. Pull back the carpeting, and you’ll see the fuel tank is a combined battery and fuel tank unit, but again, it’s within the original tank’s dimensions.”
Moreover, the battery is just one kilowatt-hour. This also allows for quick recharging using energy from both the engine and the brakes.
Vonnen constructed a 1988 Porsche 911 featuring its Shadow Drive. The overall weight increase was 44 pounds, about the weight of a fully packed suitcase. The workshop replaced the heavy 12-volt battery with a lighter version, removed the spare tire, jack, and compressor, and eliminated the starter motor, since its hybrid system now starts the engine. Power surged to 335 hp, all while leaving the driving experience untouched.
Additionally, Vonnen’s kit comes with a specialized controller, allowing drivers to choose different drive modes for various situations through a smartphone app. Whether on the road or the racetrack, you can tailor how the hybrid system operates. It can also distribute power differently depending on the gear, which is beneficial for those cautious about damaging their transaxle or CV joints. Vonnen achieves this by sending less torque in first gear to protect the components and gradually increasing it in higher gears.
All this means you don’t need a long list of modifications for the Shadow Drive to fit your vehicle. Perhaps the most impressive aspect is its compatibility with all 911s from 1974 onwards, as well as 912s and 914s. It doesn’t matter if the engine is carbureted or fuel-injected, naturally aspirated or turbocharged—it simply bolts on. Thus, you can make your car as gentle or as aggressive as you prefer, and Vonnen’s hybrid system will enhance the overall setup.
It also delivers that extra performance without affecting the vehicle’s emissions, which is critically important in states like California.
You will invest a considerable amount for that level of convenience and versatility. The Shadow Drive stage one retails for $54,000, while the stage two is priced at $69,000 prior to installation. Of course, modifying these cars is never inexpensive, and you’re investing in the seamless integration as well as the increased performance. Furthermore, it’s completely reversible, so you don’t have to alter your classic Porsche significantly to install it.
I’m not attempting to convince you to purchase this kit. I can personally attest that I would never have the means to afford one. However, if you’re exploring intelligent methods to gain more power from an air-cooled 911, there’s arguably no more comprehensive solution available. It provides all the perks of electrification with virtually none of the downsides—aside from cost—and if a purist were to drive one, I doubt they’d ever recognize its presence.
That’s more or less the objective.
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### A Summary of the Ideal Power Enhancer for Aircooled Porsche 911s: The Invisible Hybrid System
The Porsche 911, especially the air-cooled models manufactured from 1964 to 1998, has achieved iconic status among car lovers. Renowned for its unique styling, rear-engine configuration, and thrilling driving experiences, the 911 has seen considerable development over time. However, as performance aspirations have intensified, numerous owners look for ways to boost their cars’ power levels. One of the most groundbreaking options is the integration of an invisible hybrid system as an ideal power enhancer.
#### Comprehending the Invisible Hybrid System
An invisible hybrid system merges conventional internal combustion engine (ICE) technology with electric power support. This strategy enables a substantial performance increase while preserving the classic driving experience that Porsche aficionados value. The hybrid system usually includes an electric motor, a battery pack, and sophisticated control electronics that function in coordination with the existing air-cooled engine.
#### Main Elements of the Invisible Hybrid System
1. **Electric Motor**: The electric motor delivers additional torque and power, particularly during quick acceleration. Its placement is strategically chosen to keep weight low and maintain vehicle balance.
2. **Battery Pack**: A lightweight lithium-ion battery pack collects energy for the electric motor. The battery management system guarantees peak performance and longevity.
3. **Control Electronics**: Advanced software orchestrates the synergy between the ICE and the electric motor, allowing fluid transitions between power sources. This preserves a smooth and responsive driving experience.
#### Advantages of the Invisible Hybrid System
1. **Boosted Power Output**: By augmenting the air-cooled engine with electric assistance, the total horsepower and torque can be considerably raised, enhancing speed and performance.
2. **Enhanced Fuel Economy**: The hybrid system can lead to reduced fuel usage by allowing the electric motor to manage low-speed operations and contribute during acceleration, resulting in superior overall efficiency.
3. **Lower Emissions**: Utilizing electric power lessens the reliance on the ICE, leading to reduced emissions and a minimized environmental impact.
4. **Improved Driving Experience**: The smooth incorporation of electric power provides immediate torque delivery, enhancing responsiveness and driving characteristics without compromising the traditional essence of the Porsche 911.
5. **Regenerative Braking**: The hybrid system can capture energy while braking, converting it back into electrical energy to recharge the battery, further boosting efficiency.
#### Challenges and Factors to Consider
While the invisible hybrid system has many advantages, it also comes with challenges:
– **Weight Distribution**: Adding electric components can change the vehicle’s weight distribution, potentially affecting handling. Careful design is crucial to uphold the 911’s legendary driving dynamics.
– **Complexity**: The integration of a hybrid system introduces additional complexity regarding maintenance and repairs. Owners should consider the availability of specialized knowledge and parts.
– **Cost**: The initial expenditure for a hybrid conversion may be significant, and prospective buyers should evaluate the costs against the benefits.
#### Conclusion
The invisible hybrid system signifies a state-of-the-art solution for boosting the performance of air-cooled Porsche 911s. By fusing the timeless allure of the classic engine with modern electric technologies, this hybrid method presents an enticing way to enhance the driving experience while addressing contemporary efficiency and emissions concerns. As technological advancements continue, the invisible hybrid system may increasingly appeal to Porsche enthusiasts aiming to update their classic vehicles while retaining the essential charm of what makes the 911 so distinctive.