Developing A High-End Racing Fuel Injector And Why It Matters

When people think about modern fuel injectors for all-out race vehicles, the consideration is whether the injector can flow enough fuel to support a given power level for the intended application. Injectors are not particularly intricate or complex to understand, with few components that comprise the entire unit. After hundreds of hours of manufacturing tweaks, testing, and performance adjustments, FuelTech recently released its FT Injector line of fuel injectors explicitly designed for these racing applications.

Fuel injectors are mechanical valves controlled by electronic means; in this case, it would likely be your favorite aftermarket fuel injection system such as the FuelTech FT600, FT550, FT450, or similar. The typical fuel injector performs two functions: metering fuel flow, and atomizing that fuel as it exits the injector into the engine.

The FuelTech Injector’s electrical connector uses the same EV1-style plug as most other injectors, but it has been flipped on the body of the injector to provide positive locking engagement. De Leon said they came up with this fix after realizing that racers had injector plugs zip-tied on to prevent them from vibrating loose. The FT Injector’s connector doesn’t have that issue.

The internals from top to bottom are simple: a filter basket, electrical connector, solenoid (electromagnetic coil), spring, magnet, and injector needle.

“Fuel injectors are not complicated, but they are really important. The way they behave is as important as how much they flow because, in the end, it’s not how much they flow, but how they flow the amount of fuel that you are asking them to,” says Luis De Leon, FuelTech’s Tech Director.

FT Injectors work in any application; the builder can specify the necessary inlet and outlet style for the fueling requirements and manifold type. FuelTech has had excellent success with these in Pro Nitrous and Pro Boost applications, which are drastically different from every perspective, from volume to delivery method at the tip of the injector.

“In different words, how precise is the injector? Not even the spray pattern matters that much, but when you ask it to flow 100 pounds, is that 100 pounds? Is that one 110? Or is that 90? That’s when it matters. That’s what we look at, an injector that will do what it’s told, just like we do on our ECU.”

As the FuelTech team became more involved in racing here in the United States with the top-flight teams using their products, one thing they kept hearing from the tuners working with their systems is that they could do more with an injector that could handle what they were asking it to do.

And thus, the FT Injector concept was born. FuelTech pursued a relationship with South American Pro Mod Racer Roderjan Busato of MRB Machining — and the partnership began searching for solutions to fulfill the requirements and characteristics they needed from this all-new line of fuel injectors.

De Leon stresses that FT/MRB holds manufacturing tolerances so tight that the FT Injectors don’t need to be flow matched — they come out of the final manufacturing step already optimized.

“MRB is a large engineering company. We were able to pick those guys that have the knowledge of materials and designing in shapes to pick and choose. ‘What is the best material for the needle? What is the best material for the sprayer? What is the best material for the O-ring? Because that makes a difference. If your O-ring is not right, you put that in your intake, and when you take it off the next time, you can’t put it back in because it’s swollen. All those small details make it different,” says De Leon.

A single FT320 injector is used per cylinder in a Pro Nitrous application. Although the injector is a bit larger than what the engine needs in terms of ultimate flow, De Leon says the injector is precise enough to be used here without any concerns.

What Did The Tuners Want?

De Leon credits the Pro Line Racing group for prodding FuelTech in the right direction. A few years back, the PLR tuning group adopted the FT engine management system as its weapon of choice, then started to provide in-field feedback about what the engine management system could and couldn’t do. Any limitations they found to make more horsepower and control it efficiently on the track were passed along to the engineering team.

“Pro Line was the very first group of people here in the United States that gave FuelTech the knowledge to build the FT500 that would have what they required to manipulate a domestic vehicle properly. We were used to the import scene, 4 cylinders, 6 cylinders, 1,000, maybe 2,000 horses. But we were not used to handling 4,000–5,000 plus in 3.5-seconds,” says De Leon.

Created from the jump to become the gold standard in racing fuel injector technology, it’s clear that FuelTech is onto something with these injectors. By addressing the needs of the tuners who use them most often, FuelTech created an injector line that will perform effectively for the vast majority of professional and top-level sportsman racing programs using electronic fuel injection.

The Pro Line team shared specific parameters they would like to control, and then it was up to FuelTech to develop the engine management system with those capabilities. It was a similar story for the FT Injector program; Pro Line’s tuners identified inefficiencies and other wish list items they desired in a fuel injector. The FuelTech manufacturing team worked to deliver on those requests.

“They felt like there was a big gap in the market for an injector that would do better. And as soon as we had a good working prototype that we tested, we brought it here, and we had those injectors working on their dyno to get the final injector out there to sell to the customer. Something that would be a winning product — not just a test product, but a winning product,” he says.

Here, we see the capabilities of each FT Injector: the 320, 520, 720, and the new FT820 at each of three fuel pressure settings. Base pressure with FT Injectors is considered 90 psi to promote atomization in the combustion chamber.

Put simply, what the tuners were after was an injector that offered characteristics optimized for racing applications. Specifically, the ability to deliver precise fuel amounts as commanded, every time, without fail. To do so, the engineers determined the optimal specifications for each internal component and then developed the manufacturing capability to build the injectors in-house. Everything down to the electrical connector came from a clean-sheet design. The change they made to the standard injector plug — flipping it backward to create positive engagement on the lock mechanism to keep it tightly secured even on alcohol-fueled combinations with massive vibration — came at the behest of the teams testing the product in the field.

Size Matters — Or Does It?

Well, it does, and it doesn’t. To flow large amounts of fuel like the FT320, FT520, FT720, and all-new FT820 can, the injector’s internal orifice must be large enough to support the claimed flow capability of the injector to ensure enough flow in significant demand situations.

He used an interesting analogy concerning injector design.

“The key word for the injector is ‘reliable,’ because it’s just like a tire. You don’t need the tire to do much, just what it’s told every lap. If that tire changed the grip from one run to another, you’re just chasing your tail. So, the injector is the same way. The injector won’t flow fuel on its own. It’s going to flow what you are asking for,” he says.

“And sometimes you do a lap, didn’t change a thing, and one hole is really hot. You go over there, add a little fuel, and now it’s really cold. You didn’t ask for it, you didn’t tell it to do that, but it was always in the back of people’s minds: ‘Man, how hard can I run? Because if it gives me that surprise temperature, it’s going to burn the ground strap, so I need to run a little bit colder.’ A more reliable injector allows you to run closer to the edge without burning up and hurting the motor. This injector will do exactly what you want every single time.”

The traditional atomization tip is resistant to corrosion and is compatible with any type of fuel: gasoline, ethanol, nitromethane, nitropropane, MTBE, and ETBE.

FT Injectors open more slowly than some other types of injectors — because robust internals are heavy and take a moment to get moving — but then once they are open, provide the linearity and accuracy sought after by the tuners trying to maximize vehicle performance.

“A high impedance small injector may take only 0.5-milliseconds to open and close, but it doesn’t even flow 100 lb/hr. Ours can flow above 800 lb/hr, but it will take over one millisecond to open and flow something. But, as soon as it’s open, you already have good management of the injector, and they idle really nice even on a small car. My daily driver has an LS stroker 408, and I run our injectors at 320, even if the motor only needs 100 lb/hr injectors, because the injector is pretty reliable to do what I’m asking for,” he explains.

Other Considerations

The FT Injector’s linearity provides the tuner with the confidence that the injector will supply the fuel as directed. Additionally, the sprayer design is not overly sensitive to fuel pressure, which means FuelTech can provide the tuner with expected fuel curves from 30 psi to 130 psi, and the tuner can create calibrations with confidence.

The tuning flexibility of the FT Injectors offers enough range for the 320 to be used in a Pro Nitrous Pro Mod (which would typically use a 220 lb/hr injector), and the 820 will go to 1,000 lb/hr at a higher base pressure without losing its resolution. Internally, the injector’s dimensions change as you move up the range, but the coil assembly is similar throughout the lineup.

The fuel flow graph/table is the data representing optimal fuel flow versus injector usage, compared to the measured numbers of fuel flow on the injectors in real-life situations. DeLeon says, “It’s essential to have the fuel injector characterization to be able to understand how the injector behaves, and if the engine is being fed the way you want it to be fed.”

The FT Injector works with any EFI system but will require driver boxes to handle the peak-and-hold injector style to work correctly if the system is not configured for these. FuelTech makes this item; each box will drive four injectors, so if you’re running the latest centrifugal-supercharged Hemi, you’ll need a pair.

Various fuel system coupling styles are available, from O-ring top and bottom, ORB6 on the bottom, AN4 on top, and so forth. Providing these options allows the FT Injector to be used in anything from a turbo 4-cylinder to a screw-blown Hemi Pro Mod.

Let us not forget that less than one year ago, Daniel Pharris became the first-ever radial tire racer to creep into the 3.40s with his 3.498/212.73 mph blast, which makes Pharris’ machine the quickest EFI vehicle ever — and the FT Injector — to reach the 660-foot mark in all of drag racing.

“We have so much good feedback from people who swap to our injectors. We collected several achievements over this past month. We have this injector out there for less than three years, and the injector holds the NHRA Pro Mod record. Manny Buginga just broke the 1/4-mile radial record with that injector. Even the Pro Boost champion (Kevin Rivenbark) is using the FuelTech injector,” says De Leon.

“It’s a bunch of people achieving results. And one of the parts of the puzzle for that car to win was the injector doing exactly what the tuner was asking for.”

Necessity is the mother of invention. In the case of the FT Injector, Steve Petty, Jamie Miller, and others came calling, and FuelTech answered the bell.

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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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