Improving your fuel efficiency involves various factors. Here are some straightforward suggestions to enhance the mileage you achieve per gallon of gasoline (petrol):
The most significant enhancement in gas mileage comes from your driving style – the pressure you apply on the accelerator pedal matters! 🙂 Opt for gentle acceleration. When you press the accelerator all the way down, the carburetor’s accelerator pump injects around 1.4-1.6 milliliters of fuel. However, by accelerating gently, you avoid triggering the accelerator pump, saving that 1.4-1.6 milliliters each time. This might not sound like a lot, but pay attention to how often you push the accelerator during your daily commute – you might be surprised!
Foresee upcoming red lights or traffic congestion and ease off the throttle early, so you don’t need to brake as forcefully. This approach consumes less fuel to reach your destination. Many people don’t realize that heavy braking actually uses more fuel – not due to the brakes themselves, but because they were burning more fuel while driving too fast just before applying the brakes. Consequently, the combination of rapid acceleration and hard braking consumes far more fuel than anticipating traffic and gradually releasing the throttle.
Ensure Proper Timing: Follow our timing procedure to ensure accurate timing for your engine.
Choose the Right Carburetor: Select the appropriate carburetor for your setup. For instance, if you’re using a 1600cc engine (or even up to a 1776cc engine), the stock 34PICT/3 carburetor will offer better fuel economy compared to a pair of Kadrons. While it might not provide as much power, it strikes a balance between efficiency and performance.
Carburetor Overhaul: Don’t overlook the importance of a well-functioning carburetor. A clogged carburetor not only results in poor performance but also wastes fuel since you need to apply more throttle to overcome the issue. Refer to our 34PICT Carburetor Overhaul procedure to address this issue effectively.
Consider Carburetor Switch: If you have the larger 34PICT/3 carburetor, you can enhance fuel economy by transitioning to the smaller H30/31 carburetor (or the older 30PICT/2). While this might slightly reduce horsepower by 2-3, it notably improves fuel efficiency. Installing this carburetor on a 1600cc manifold is simple, thanks to the available 30/34 adapter plate. Most users report around 25-26 mpg US with the stock 1600cc Bug using the 34PICT/3 carburetor.
Caution with Carburetor Versions: Avoid using the earlier version 30PICT/1 carburetor with a 1600cc engine. This version lacks a power (aux) jet, leading to lean running at higher speeds. Some later iterations of the 30PICT/1 do include a power jet, and all subsequent versions like the 30PICT/2 come equipped with this jet.
Adjusting Jetting: Adapting jetting in the smaller carburetor to suit the larger 1600cc engine is a necessary adjustment, but it’s manageable.
Enhance Mileage with Electronic Ignition: Installing electronic ignition can lead to a notable increase in mileage. This advanced ignition system provides a stronger spark and maintains consistent timing, resulting in more uniform and complete fuel combustion. Many drivers experience an improvement of 8 to 15 percent in their gas mileage. Beyond the mileage boost, the overall performance of your vehicle will also benefit. Electronic ignition eliminates issues like points-bounce and shaft-jitter, along with enhancing combustion at higher rpms. Additionally, it significantly improves starting reliability.
Realistic Power Gains: While there’s a common misconception about electronic ignition yielding significant power gains, the primary advantage lies in more consistent performance. Electronic ignition offers a lower-maintenance tuning experience, delivering consistent ignition timing across various conditions.
Addressing Compression Issues: If you’re facing poor compression, often due to worn piston rings or burnt valves, it’s crucial to take corrective measures. Refer to our Compression Check procedure to assess the compression levels of each cylinder. For a well-maintained 1600cc engine, a healthy compression reading should be around 130 psi or higher per cylinder. As the engine ages, compression naturally decreases. Once one or more cylinders drop below 100 psi, it’s a sign that the engine requires rebuilding. Poor compression can result in reduced power and rapidly escalating fuel consumption.
Cautions Regarding Fuel Choice: When possible, avoid using oxygenated fuels like “gasohol,” especially in the context of increasing ethanol content in modern fuels. While this might be challenging in the USA due to prevalent ethanol blending, other countries might have more options. Using oxygenated fuel can lead to increased fuel consumption since the additive dilutes the energy content of the fuel. Carburetors measure fuel volume without accounting for energy content, causing the engine to run lean. If you’re using ethanol-added gasoline, you’ll likely need a larger main jet to achieve an optimal fuel/air mixture. The right main jet size varies; for instance, a 10% ethanol blend might necessitate a 130 or even a 132.5 main jet, depending on your setup.
Altitude Impact: Keep in mind that altitude has an influence on fuel economy. Higher altitudes lead to increased fuel consumption due to decreased engine efficiency. Even when the carburetor is adjusted for altitude, the engine’s performance suffers. At every 5000 feet rise in altitude, the engine runs about 2 percent richer. This alteration requires a smaller main jet, such as shifting from 127.5 to 125. For those residing at 5000-foot altitudes and using alcohol blend fuel, adjustments are needed. Altitude requires one size smaller for the main jet (127.5 to 125), while a 10% alcohol blend demands two sizes larger. Consequently, the overall outcome is a size up (130 size) for the main jet.
Engine Capacity and Efficiency: Another avenue for improved gas mileage involves reducing engine capacity. Stock engines of 1200cc yield around 33 mpg US, 1300cc delivers about 31 mpg, and 1500cc offers 29-30 mpg. Although the increased weight of later model vehicles affects this, solutions like interior stripping have limitations. Swapping piston/cylinders from 1300cc or 1500cc into a 1600cc case is feasible, but retaining the same heads may cause a compression ratio decrease. This impacts performance and fuel efficiency. Using appropriate heads for the chosen capacity is vital for maintaining the stock compression ratio.
Optimal Cooling: Retain the larger 1600cc doghouse cooler/fan for the engine. Despite blowing approximately 10% more air than the 1300/1500cc cooling system, the doghouse cooler effectively prevents overheating issues, particularly for the #3 cylinder. This move ensures that improved fuel efficiency doesn’t compromise engine health.
Aerodynamic Enhancements: Improving aerodynamics can also contribute to better fuel efficiency. A front air dam, especially at higher speeds (above 50 mph), can make a difference. This addition not only boosts aerodynamics but also mitigates the “light” front-end effect at higher speeds, enhancing vehicle handling. Considering the Bug’s profile from the side, an air dam curtails airflow beneath the car, reducing aerodynamic lift as speed rises. This reduction in drag helps conserve fuel as increased lift is directly linked to heightened drag.
Geographical Considerations: It’s important to note that driving in mountainous terrain consumes more fuel compared to flatter landscapes.
Tire Impact: Opt for stock wheel sizes over fat tires to achieve better fuel efficiency.
Making informed choices based on these considerations can effectively enhance your vehicle’s fuel efficiency.