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2015 Eight Stack Fuel Injection | 500 Borla Drive Johnson City, TN 37604 | MADE IN THE USA

Eight Stack Frequently Asked Questions


What is the Eight Stack Injection?

Eight Stack injection is an all new fuel injection platform harnessing retro looks with modern performance. Styled around the traditional carbureted systems of the 1960s; the Eight stack system will give you all that classic WOW! Factor without the headache!


Why is fuel injection better than carburetion?

Modern electronic fuel injection offers superior control over the fuel and timing curves to optimize power production, fuel economy, and even emissions. A conventional carburetor and vacuum or centrifugal advance distributor can only offer a compromise because the fuel metering and timing curves cannot be precisely controlled. The sophisticated engine management system deployed on the Eight Stack fuel injection provides maximum performance while optimizing drive ability.


Will the Eight Stack Fuel Injection improve fuel mileage?

Depending on how your current setup is tuned; the Eight Stack injection will change your current fuel economy either drastically or make nominal improvements. Allowing precise fuel delivery with a modern fuel injection system; your tuner will be able to tweak the ECU of their choice to accurately deliver how much fuel your engine will see at idle, WOT (wide open throttle) and cruise conditions. Furthermore systems that employ a closed loop operating system will be able to constantly correct for conditions.


Will the Eight Stack fuel injection improve performance?

The Eight Stack fuel injection has been thoroughly tested on both engine and chassis dynamometers against most four-barrel carburetor and intake configurations. Please see the dyno graphs supplied in the dealer package for description of power gains offered on various test motors. The power gains offered by Eight Stack fuel injection come from a combination of improved airflow offered by the high-flow throttle bodies, the optimized runner length provided by the throttle bodies and dedicated intake manifolds and the optimized air/fuel and timing curves provided by the sophisticated management systems. One of the largest gains with the Eight Stack fuel injection is the near instant throttle response that can only be delivered by something packing as much airflow and as precisely tuned with modern electronic fuel injection.


Do I need a different fuel pump when converting to an Eight Stack system?

When switching over from a carbureted motor, you will need to upgrade the fuel pump. As with most modern electronic fuel injection systems, the Eight Stack system requires a high-pressure fuel system. Carbureted motors generally require the use of fuel pump that will provide roughly 5-7 psi of fuel pressure to the float bowls. Electronic fuel injection requires much higher system pressures (over 40 psi in most cases). Please consult your installation technician to help you upgrade your vehicle to best suit your application. Some vehicles may require changes in line size or the addition of a fuel return to the tank. Fuel pumps will vary based on the needed volume of your high performance engine.


Do I need high-pressure fuel lines and fittings?

Like the fuel pump, the fuel lines employed on a carbureted motor are generally designed to withstand low pressures. It will be necessary to upgrade the fuel lines run to and from the fuel tank to high-pressure fuel line. Once again, please consult with your installation technician to best suit your needs


What distributor do I run with the Eight Stack fuel injection?

We recommend MSD billet distributors for use with the Classic Fuel Injection system, though other manufacturers will also work. Due to the proximity of the four throttle bodies, it is necessary to run small-cap distributors. MSD offers the necessary distributors for all CFI applications. Large-cap (late-model) Ford TFI and HEI Chevy distributors will not fit the CFI system. Your installer may recommend a different distributor or ignition system based on their software needs. This is okay so long as they clear the system physically and are compatible with the engine management system of choice.


Is the Eight Stack difficult to install and tune?

Installation of the Classic Fuel Injection hardware is no more difficult than a typical intake and carburetor. It is best to have the system installed by a professional with the necessary experience, but we have had first timers install the system with great success. Tuning is something best left to a professional, as a mistake can literally ruin a perfectly good motor. Levels of difficulty in the fuel system upgrades will vary from system to system. Once again we stress HIGHLY the system be setup and tuned by a qualified professional for optimal results. Eight Stack recommends Accell, F.A.S.T. and Edge products.


Do I need a custom throttle linkage for the Eight Stack system?

The Classic Fuel Injection system comes compete with a dedicated throttle linkage. In most cases, the throttle linkage will connect to the same systems used by either a conventional 4-barrel or Weber carburetors. However in some cases your stock linkage may not be located on the same side needed for proper operation or is of a different style than the receptacle found on the Eight Stack linkage. In these cases modifications may be needed to adapt to the Eight Stack system.


Will the Eight Stack injection adjust for changes in weather conditions?

The Eight Stack system is designed as a modern fuel injection system. Ask your installer/tuner about their choice in electronic tuning devices and what they may offer.


Why does the Eight Stack system offer better performance than Weber carburetors?

The additional performance offered by the Eight Stack fuel injection comes from the additional airflow supplied by the high-flow throttle bodies along with the precision tuning offered by the sophisticated engine management system. Additional power gains are offered by our dedicated intake manifolds, especially when custom ported to further improve the flow rate.


What is closed loop operation?

Closed loop operation means the management system is run using information provided by an oxygen sensor. Installed in the exhaust system, the oxygen sensor reads the actually air/fuel mixture. If the desired air/fuel mixture is different than the registered air/fuel mixture, a signal is sent to the ECU to alter the fuel supplied to the motor via the fuel injectors. These self-adjusting systems allow the motor to run at an optimized air/fuel mixture under all throttle and load conditions (except wide open throttle). This closed-loop operation provides optimized performance and fuel mileage under cruise conditions.


How much power can I make with the Eight Stack system?

Currently the Eight Stack system has been tested on motors exceeding 691 horsepower, but the flow potential of the high-flow throttle bodies can support in excess of 750 horsepower. Limitations will depend on maximizing the airflow of the throttle bodies, manifolds and the support of your electronics system.