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Frequently Asked Questions-FAST EFI
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Is your injection streetable?

Very! Combined with EFI technology our fuel injectors offer superior drivability under all types of conditions associated with aftermarket street performance. Although they perform very well on the street, they are not "street legal" or suitable for emission controlled vehicles, so we recommend that you check your local laws first.

Can I convert my old mechanical unit?

Although it is possible to convert your old Hilborn Injector to EFI, we have found that after spending the time and money required to accomplish this, it makes better financial sense to buy a new injector already set up for EFI. We’ve redesigned our original castings at the foundry level to accept all the necessary EFI components, which in the long run, can save you money by eliminating costly re-machining for conversion. Because of this, we do not offer machining conversion services at Hilborn Fuel Injection. However, most blown mechanical fuel injectors, whether scoop or hat style, can be easily converted to EFI.

How does the FAST XFI work?

Simply put, it uses inputs from the O2, air, coolant and MAP sensors and then determines the correct injector duty cycle in conjunction with the user defined inputs from the VE (volumetric efficiency) table.

A brief overview of the XFI?

A brief overview of the XFI is available here.

What if I'm not very computer savvy?

The windows based software of the XFI is much easier to learn and use compared to systems of yesterday, and even some current systems. At Hilborn Injection we do not tune your system for you, instead, we teach you how to do it yourself so you can have the confidence to make the changes you want. To get you started, we supply a base start-up program and go over the details. Our tech support is just one phone call away and we can walk you through any issues you might have. Unlike our competitors, we do not charge for this service.

What is the difference between a wide band and narrow band O2 sensor?

A narrow band O2 sensor can only correctly measure stoichometric air fuel ratios. For gas this would be 14.7 to 1. Measuring a specific air fuel ratio other than 14.7 to 1 accurately with a narrow band O2 sensor is not possible. The wide band O2 supplied with your XFI is capable of accurately measuring air fuel ratios from 8 to 1 up to 16 to 1, and is preferred over the narrow band.

What cam profile works best with the XFI ECU?

When tuning in speed density, a camshaft that promotes the highest engine vacuum is typically employed but can be a compromise for some performance engine builds. The XFI has greater flexibility than most OEM style ECU’s due to the ability to “scale” the MAP sensor, therefore allowing the cam of choice to be used. If the cam is extremely aggressive, the Alpha N tuning strategy may have to be used.

What is the difference between speed density and Alpha N?

Alpha N uses input from TPS and RPM to set the fuel curve, while speed density uses a MAP sensor to identify engine "load". An engine's fuel requirements are directly related to load and corresponding RPM. The ability to tune to the constant change in engine load is desirable compared to Alpha N.

What is the difference between open and closed loop control?

In open loop, the ECU uses information from user defined inputs, such as the VE table, to set injector duty cycle, and will not automatically correct to match your target A/F ratio. In closed loop, the ECU will monitor the A/F and automatically adjust the injector duty cycle in order to meet the target A/F ratio. However, one must still tune the VE table to keep the correction percentage as low as possible due to correction limits set by the user.

Do I need two O2 sensors?

The XFI comes with only one O2 sensor and, typically, that is all that is required for correct operation. A second O2 can be added and data logged, but the ECU will only correct off of one when run in closed loop.

Can I run an O2 sensor with zoomies?

Yes, but it may require open loop operation of the ECU since the O2 no longer averages the output of the other cylinders.

What distributor do I need?

We feel the best input signal for the XFI is a crank trigger. This may not be an option for most, so the use of any magnetic pick-up or hall effect distributor can be used. If you plan on running your system in sequential control, or want the ability to control individual cylinder timing, then a FAST distributor, which not only supplies a crank but a cam signal also, is your best bet.

Which is the correct MAP sensor for my application?

All naturally aspirated appications will only need a 1 bar sensor. Boosted applications will need a 2 bar or higher, depending on the boost pressure. Since a bar is equal to 14.7psi, then a 2 bar will handle boost up to 14.7psi, a 3 bar 29.4psi and so on.

Can I run an IAC valve?

On 8 stack applications using a MAP sensor, a second vacuum kit is recommended for correct engine operation using an IAC. Installation of the second vacuum kit is not available from Hilborn Fuel Injection. An IAC valve is NOT required for proper operation of your EFI system but, on the other hand, it is highly recommended for blown systems, and is easily attached with a -6 hose.

How well does your injection system idle?

As a rule, EFI does smooth the idle and on some applications we have seen a smooth idle all the way down to 700 rpm.

Can I run my vacuum accessories?

Yes, we provide a vacuum junction block for all of your vacuum accessories, provided your engine makes enough vacuum to power them.

Will I see a mileage increase?

Yes! The XFI not only provides premier fuel control, it also allows complete spark control. Used in conjunction, one is able to maximize fuel economy without sacrificing performance.

Can I run alcohol or E85 with electronic fuel injection?

Alcohol is very corrosive and unless you are prepared to constantly maintain your fuel system we do not recommend it. Larger injectors and fuel pump are required due to the additional flow required. E85, on the other hand, has proven itself as versatile fuel for performance street cars, whether n/a or blown. The XFI can easily be switched to run E85 or gas with the flick of a switch!. As with alcohol, larger injectors or fuel pump may be required.

Is the installation difficult?

Although a bit more involved than our Carabine system, the XFI instructions (on the C-Com disc) provide the required information for installation. The use of solder and shrink wrap is recommended over butt connectors, wire nuts, etc. Installation help is always available from our technical support.

Do I need a return line?

Yes, our injection system requires a return line.

How much CFM does your injector flow?

The standard of using CFM for flow potential was originally designed to aid engine builders in determining correct carburetor size. This was required to make sure that an adequate signal was available at the booster for sufficient fuel flow. Since an injector supplies fuel under pressure for engine demand, and does not use a booster, we have never seen the need to identify CFM. We size our injectors by butterfly size because only so much air can flow through a particular size orifice. It is important to remember that any CFM rating includes a pressure drop to provide a consistent comparison, such as 28 inches of water for cylinder heads.

Can I get my injector polished or plated?

Our standard process is a clear anodize which produces a matte grey finish. If polishing or powder coating is required, we would prefer to send you an unassembled casting to be finished by your favorite polisher or coating company, and then returned to us for assembly. Or, we can arrange for this optional service for you as a convenience. Due to the machining tolerances, the casting cannot be chrome plated.

Can I get my ram tubes polished or plated?

Our standard process is cad-plating which produces a silver finish. The steel ram tubes cannot be polished, but may be painted, powder coated, or chromed.

Do I need to run a thermostat?

We recommend the use of a thermostat with all EFI applications.

How much more power will I make?

As a rule, EFI shouldn't make any more power over your current combination, but because of the design of an eight stack injector, you could see an increase of 30-40 hp and 25-30 ft/lbs of torque. You will definitely feel an improvement in throttle response and low end acceleration.

Do you have air filters for my application?

We do offer billet aluminum air filters for some popular Ford and Chevy applications. We also supply sprint car styled filters from K&N. For those wanting to keep the look, our ram tube booties keep large debris out. New to the market are ram tube seals, which are an economical way of attaching a filter base to the ram tubes, thus, allowing a custom filter box to be designed.

Should I dyno test my system?

We advise dyno testing to get the most out of your EFI unit. We prefer a chassis dyno, instead of an engine dyno, since all the subsystems (fuel system, ignition system, injector) are installed on the car. A chassis dyno also allows you to work out part throttle tuning, saving the additional expense of two dyno sessions.

What is EMI?

It is short for Electromagnetic Interference. Picture EMI as an invisible Slinky wrapped around a wire that grows as current is increased. Certain components are more prone to producing EMI, such as ignition wires, analog style ignition boxes, and electric motors. When power wires from these accessories are run too close, or tie wrapped to other lower voltage wires, a current could be produced in the lower voltage wire as the EMI Slinky starts to grow, causing an unwanted signal. This creates a problem with all types of electronic equipment such as ECU’s. The remedy is to keep high power wires separated from signal wires, and to attach the power wires directly to the battery. The battery offers a natural buffer to absorb those unwanted EMI pulses.

What if there isn’t a dyno shop in my area?

The XFI has the ability to data log and will allow you to identify the changes required after you are done driving. Data logging can also be used in the same method at the race track for WOT tuning.

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