Mgb Dual Carbs: Fuel Injection Upgrade?

The MGB is a classic car with a dedicated following. Owners of these vehicles often debate the best approach to fuel delivery, with some advocating for the retention of the original dual carburettor setup, while others suggest upgrading to fuel injection for improved performance and reliability. The dual carburettor setup, typically consisting of SU HS4 or HIF4 carburettors, offers a more traditional approach and can provide sufficient fuel delivery for the engine when properly tuned. However, the fuel injection option promises better performance, drivability, and fuel economy. The challenge with fuel injection lies in the complexity of the installation and tuning process, especially when dealing with the unique characteristics of the MGB's 5-port head and Siamese intake ports.

Fuel injection retrofit kits

There are a few options available for those looking to retrofit fuel injection to their MGB. One popular option is to use a Megasquirt ECU, which has a large following of EFI hobbyists who have added features and software. While it can be tricky to get set up, it is a good option for those who want to tinker and are knowledgeable about electronics and software.

Another option is to reprogramme an OEM ECU, such as a GM ECU. These are readily available and have been successfully hacked by many hot rod enthusiasts. They also have the advantage of being robust, self-diagnosing, and widely available.

For those who want a more stock-looking option, it is possible to hide the injectors inside twin SU carbs. This requires some fabrication skills, but the result is a system that looks totally standard.

There are also complete bolt-in setups available, which include everything needed to retrofit fuel injection, such as the inlet, crank timing wheel, ECU, and harness. However, some essential parts may not be included, such as injectors, ignition pack, O2 sensors, and fuel pump.

For those who want a more DIY approach, there are options to purchase just the necessary parts and create their own installation instructions and drawings. This can be a more time-consuming process but may be more cost-effective.

When considering a fuel injection retrofit kit, it is important to keep in mind the potential challenges of tuning the system, especially with the siamesed inlet ports of the MGB engine. It may be necessary to monitor both branches of the exhaust with wideband O2 sensors and log the air-fuel mixture at all operating conditions to ensure optimal performance.

The benefits of fuel injection

Fuel injection systems offer a host of benefits over carburetors, especially when it comes to performance, fuel efficiency, and reliability.

Performance

The primary benefit of fuel injection systems is that they deliver the ideal air-fuel mixture, or stoichiometric mixture, which is the ratio of air to fuel that achieves maximum engine efficiency. Fuel injection systems use an electronically controlled system to regulate the fuel-air mixture, ensuring it is always precise. This precision results in more power and torque, and better fuel efficiency.

Fuel Efficiency

Fuel injection systems save a lot of fuel over time. Carburetors dump an approximate amount of fuel into the engine, often overestimating to ensure it is enough. Fuel injection systems, on the other hand, deliver exactly the right amount of fuel to the engine, saving a tremendous amount of gas.

Reliability

Fuel injection systems maintain optimum air-fuel ratios, eliminating random engine stoppages, oiled spark plugs, and other problems associated with sub-optimal ratios. Carburetors tend to need frequent adjustments, whereas fuel injection systems eliminate the need for repeated modifications, increasing reliability and reducing the time and expense of maintenance.

Other Benefits

Fuel injection systems also offer improved cold and hot starting performance, as they can calculate the optimum air-fuel mixture for starting in any condition. They are also sealed, meaning the gasoline never comes into contact with oxygen, reducing the chance of contaminated gas and the need for servicing.

DIY Fuel Injection Kits

There are DIY fuel injection kits available for purchase, and some enthusiasts have even created their own. However, it is important to note that fuel injection systems can be complex, and the process of retrofitting one may require expertise in electronics and engine modifications.

Fuel injection vs carburettors

The internal combustion engine has long been powered by two fuel delivery systems: carburettors and fuel injection. Both systems are essential for controlling the fuel-air mixture that drives internal combustion engines, but their effectiveness, performance, and environmental effects are quite different.

Carburettors

A carburettor is a mechanical component that mixes the right amount of fuel and air before sending it to the engine's cylinders. It uses concepts from the late 19th century to operate and regulate fuel flow using vacuum and air pressure differentials. Carburettors are generally simple, cost-effective, customisable, and reliable. However, they can be sluggish, require frequent tuning, and are vulnerable to blockages and part wear.

Fuel Injection

On the other hand, fuel injection is a more accurate and complex way to distribute fuel to the engine. This technology provides better control over the air-fuel mixture by directly injecting fuel into the combustion chamber or the intake manifold. It has replaced conventional carburettor systems, delivering fuel to the engine cylinders with more control and precision. Fuel injection is also essential for achieving strict emissions rules and can adapt to changing environmental circumstances, resulting in smoother engine running, lower emissions, increased performance, and improved fuel efficiency. However, fuel injection systems are substantially more expensive and require advanced tools for repairs and tuning.

The argument over fuel injection vs carburettors emphasises how relentlessly the automobile industry pursues economy, performance, and environmental responsibility. While carburettors were important in the development of engines, fuel injection has become the best option for contemporary cars due to its accuracy, adaptability, and performance benefits.

Installation and tuning

The installation of a fuel injection kit on an MGB requires careful consideration of various factors, including the type of manifold, injectors, sensors, and engine modifications. Here is a step-by-step guide on how to install and tune fuel injection on an MGB:

Step 1: Choose the Right Kit

Before starting the installation process, it is crucial to select a suitable fuel injection kit that is compatible with your MGB's engine and specifications. There are different options available, such as the Megasquirt kit or the Throttle Body Injection (TBI) kit offered by Patton Machine. Consider factors like ease of installation, reliability, and customizability when choosing a kit.

Step 2: Prepare the Engine

Before beginning the installation, ensure your MGB's engine is in good condition and properly tuned. This includes checking items like ignition timing, compression, and valve clearance. It is also recommended to have a professional mechanic inspect the engine to ensure there are no underlying issues that may affect the performance of the fuel injection system.

Step 3: Install the Fuel Injection Kit

The installation process will vary depending on the kit you have chosen. Carefully follow the instructions provided by the manufacturer. This typically involves mounting the fuel injectors, connecting the necessary sensors, and wiring the system. If you are using a TBI kit, you may need to modify the carburettor throttle bodies or fabricate a new intake manifold for optimal performance.

Step 4: Tuning the Fuel Injection System

Tuning the fuel injection system is a critical step to ensure optimal performance and fuel efficiency. This process involves adjusting the air-fuel ratio, ignition timing, and other parameters to match the specific requirements of your engine. It may require the use of wideband O2 sensors and data logging equipment to monitor and adjust the system's performance.

Step 5: Test and Refine

Once the initial tuning is complete, take your MGB for a test drive to assess the performance of the fuel injection system. Pay attention to factors like throttle response, idle quality, and fuel economy. Make adjustments as necessary until you achieve the desired performance. Remember that tuning may require multiple iterations to get it just right.

Step 6: Ongoing Maintenance

Fuel injection systems require regular maintenance to ensure their long-term reliability and performance. This includes tasks such as cleaning or replacing fuel injectors, checking fuel pressure, and ensuring that all sensors are functioning correctly. Regular maintenance will help extend the lifespan of your fuel injection system and maximize its benefits.

Installing and tuning fuel injection on an MGB can be a complex process, but it offers significant benefits in terms of performance, fuel efficiency, and reliability. By carefully following the installation and tuning guidelines, you can enjoy a smoother-running MGB with improved drivability and potentially enhanced horsepower. Remember to consult with experts or seek professional assistance if you have any doubts or challenges during the installation and tuning process.

Fuel injection for performance

Fuel injection is a modern alternative to carburetors, offering several benefits for performance cars. Fuel injection systems deliver fuel directly into the engine cylinders, providing more precise control over the air-fuel mixture and improving fuel efficiency.

Benefits of Fuel Injection

• Improved Performance: Fuel injection systems can provide a more precise air-fuel mixture, resulting in improved engine performance and increased horsepower.
• Fuel Efficiency: By delivering fuel directly into the cylinders, fuel injection systems can improve fuel efficiency, leading to potential cost savings for drivers.
• Ease of Use: Fuel injection systems eliminate the need for manual choke adjustments, making the vehicle easier to start and reducing the time required for maintenance and tuning.
• Reliability: Fuel injection systems are generally more reliable than carburetors, providing consistent performance and reducing the risk of engine problems.
• Customisability: Fuel injection allows for custom tuning and mapping, enabling enthusiasts to fine-tune their vehicles for optimal performance.

Fuel Injection Kits

Several companies offer fuel injection kits for performance cars, including:

• Performance Fuel Injection Systems: They offer cost-effective fuel injection conversion systems and reliable service.
• CB Performance: They provide bolt-on electronic fuel injection kits.
• FiTech Fuel Injection: They offer free shipping on orders over $150 and have various EFI systems, such as the Go EFI 4 600HP System and the Ultimate Rebel LS 500 HP EFI System.
• DIY Kits: Some enthusiasts have created their own fuel injection kits for MGBs, utilising twin carb manifolds, modified carb bodies, and reprogrammed ECUs.

Considerations for Fuel Injection

When considering fuel injection for performance, it's important to keep the following in mind:

• Cost: While fuel injection can provide long-term savings, the initial cost of the system and installation can be significant.
• Tuning: Fuel injection systems require careful tuning to ensure optimal performance, especially for modified engines.
• Compatibility: Not all fuel injection systems are created equal; it's essential to choose a system compatible with your vehicle's specific requirements.
• Maintenance: While fuel injection systems generally require less maintenance than carburetors, regular servicing is still necessary to ensure optimal performance.

Frequently asked questions