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Inside NASCAR: Fuel injection a 'really big step'

January 11, 2012, Mark Aumann,

After several decades of use, sport says goodbye to carburetors, embraces EFI

"Gentlemen, start your semiconductors!"

That probably won't be the command given at the beginning of next February's Daytona 500. However, it might be appropriate, given NASCAR's decision to require fuel injection for Sprint Cup engines beginning with the 2012 season.

After ruling the roost since the Kennedy Administration, the iconic -- and museum-worthy -- Holley four-barrel carburetor is finally being put out to pasture as NASCAR's fuel system of choice. The Cup Series is joining the computer age, and that means engine builders and tuners are trading in their wrenches and wet flow benches for laptops and software mapping.

"The technology's moved on. It's time to move on."


"The technology's moved on. It's time to move on," said Howard Comstock of Dodge Motorsports engineering. "But NASCAR understood this is a big step. It's a really big step for racing, it's a big step for these teams.

"We've basically used the same carburetor for 40 years, and there's a lot of people who have made a life's work out of learning carburetors and making them work as efficiently as they are today. It's unbelievable how efficient they are. But they're purpose-built for racing and every car on the road uses fuel injection. NASCAR felt like it was time to update our technology and here we are."

One of those people who has spent a lifetime in that occupation is Doug Yates, chief executive officer of Roush Yates Engines. He remembers getting the opportunity to play with carburetors in father Robert's engine shop.

"I followed my dad his entire career, building engines, growing up around him," Yates said. "He first let me sweep the floors and then he let me help build engines. It was probably in my early teens when I started tinkering with carburetors."

Ever been sprayed by a zealous employee at the fragrance counter of a department store? That's the basic principle behind a modern carburetor: combining fuel and air in a way that allows it to act like an atomizer, spraying the mixture through the manifold and into the cylinders for combustion.

History of simplicity

Watch: Larry McReynolds and Chad Knaus break down air flow into the carburetor

It's all Bernoulli's fault, in principle. In 1738, Swiss mathematician Daniel Bernoulli proved that the speed of a fluid increases simultaneously with a corresponding decrease in pressure. A downdraft carburetor is like a pipe in the shape of an hourglass that allows air to be sucked in from above and to pick up speed as the pipe narrows. At its narrowest point, fuel is combined with the air and the mixture is sent on its way.

The throttle doesn't directly control the fuel flow. Instead, it activates mechanisms that meter the flow of air being pulled into the engine, and the speed determines the amount of fuel being drawn into the airstream.

The idea behind carburetion has been around since well before the invention of the internal combustion engine. Karl Benz acquired a patent for one in the 1880s. Gottlieb Daimler perfected a carburetor with an atomizer nozzle in 1885.

It's an elegant and simple solution, one reason why Comstock said it took so long to come up with an alternative.

"The beauty of why they've lasted 100 years is because they're a wonderful, mechanical device that works pretty efficiently in this kind of application."


"The beauty of why they've lasted 100 years is because they're a wonderful, mechanical device that works pretty efficiently in this kind of application," Comstock said. "The problem with production cars is that with the range of conditions we see, it's hard to keep up with a carburetor."

Herbert Ackroyd Stuart began working on mechanical fuel injection in the 1920s, but it wasn't until 1957 --when Bendix and American Motors combined forces -- that electronic fuel injection began to be commercially viable. The advancement of smaller and more powerful semiconductor computer chips eventually spelled the end of the carburetor.

By 1990, every passenger car sold in the United States had gone to electronic fuel injection. But NASCAR held steadfast to the tried and true carburetor.

"In the racing world, we've got a pretty narrow band of conditions that we see," Comstock said. "So it has worked a little bit better for a longer period of time. But electronic fuel injection is what every car on the street has, and we'll be able to say it's on our race cars, too."

But the switch also means the end of an era of "black magic," as Toyota Racing Development president and general manager Lee White put it.

"They may look like Holley parts, but there's been a tremendous amount of technology and engineering that's gone from what is a pretty archaic mid-'60s design into something that's pretty advanced," White said. "It's pretty amazing how well it really does work."

Comstock doesn't even want to begin to know all of the tricks of the engine tuning trade.

"They're pretty well-guarded secrets," Comstock said. "But they've done some amazing work on making them this efficient. The fact that engines make approaching 900 horsepower, and we can still see 4.5 to 5 miles per gallon on the race track, that's incredible.

"It's incredible how they've been able to squeeze the fuel and still make the power, even this year, when we've gone to a pretty high concentration of ethanol."

And even more impressive is how the lowly carburetor has stood up to the pressures of today's fuel economy racing.

"The carburetor system has a power valve circuit in it, and it's really about how you use part-throttle operation and that power valve to help assist with fuel mileage," Yates said. "As we all know, fuel mileage races have been very instrumental this year. And we work with the drivers on percentage of throttle and how much fuel the engine uses. In recent years, that has been the biggest innovation: How to meter fuel at part-throttle."

The flow of things

Garage Expert: Larry McReynolds explains the technology behind fuel injection

Engine tuning with a carburetor is an amazing combination of engineering know-how, years of expertise and a bit of a craftsman's touch. For Yates, getting a right flow of fuel to an engine is all about making minute adjustments.

"The carburetor has a reservoir in the fuel bowls, and a lot of tracks we go to, we adjust float levels determined by whether the engine is starving for fuel at the higher RPMs or if it's spilling over coming off the corners," Yates said. "It's somewhat of a guessing game.

"Now, with the reservoir actually being in the fuel cell, we won't have those types of adjustments any more. We'll be looking at the data to make sure we fine-tune the system to the best throttle response, the best power and the best fuel economy. It should allow us to do a better job, once we get acclimated to the new system."

"In many ways, the engine will be much more efficient because we can give exactly the right amount of fuel to each cylinder that it needs."


One of the major advantages electronic fuel injection has over a carburetor, according to Comstock, is the ability to adapt to a changing racing environment.

"Not all cylinders of a V-8 engine -- turning left all the time -- get the same amount of fuel," Comstock said. "The carburetor mixes the fuel with the air up on top of the engine and just dumps it into the intake manifold. And when you're turning left, centrifugal force tries to take more fuel to the right-hand bank of cylinders, less fuel to the left-hand bank of cylinders.

"So you physically have to add more fuel than you would want to add, in order to make sure those left-hand side cylinders get enough fuel. We won't have to do that any more. In many ways, the engine will be much more efficient because we can give exactly the right amount of fuel to each cylinder that it needs."

In addition, Comstock said EFI takes care of another problem that carburetors don't.

"Some people don't think about the fact that a V-8 engine is pretty long, with four cylinders on each side, and those two inside cylinders are hotter," Comstock said. "So with a hotter cylinder, you're going to need a bit more fuel. So once again, we can tailor the mix of the fuel to get to the cylinders that need it."

But here's the thing: NASCAR's common plenum manifold throws a curve to the engineers and tuners who might have EFI experience from other racing series.

"In that common plenum manifold, each cylinder is still talking to each other through the firing order sequence," Yates said. "And it does still pull fuel from one cylinder to the other, which is something that's unique to our sport and a challenge, but also an opportunity that other series don't see.

"They run what you call a stack injection, or single fuel and air for each cylinder. So NASCAR still has its uniqueness."

Input and output

So how do you gain an advantage with electronic fuel injection? Is it the guy with the best spreadsheet wins? White said it's a matter of several steps. One, getting the data. Two, interpreting it. Three, making the correct changes to the computer mapping program. And knowing exactly how much data teams can download is still up for determination, White said.

"We're still waiting for NASCAR to tell us how many channels of data we will have available to us when the cars come into the garage," White said. "We know we won't be able to plug in on pit lane. We know there's no telemetry, like we had in sports cars and IndyCar and Formula 1.

An overhead view shows the fuel-injected engine for 2012. (Getty)

'The power'

Kasey Kahne was one of 11 drivers permitted to participate in an electronic fuel-injection engine test on Monday at Charlotte Motor Speedway and disagreed with other drivers who said there is little or no difference to them in the way the car reacts with the new fuel-delivery system.

"Certainly, in IndyCar for example, we harvested about 100 channels of data via real-time telemetry, as well as downloads in the pit lane. So here, we're still waiting to find out from NASCAR exactly how many channels of data we'll be able to pull out of the ECU [engine control unit]. And that will have an effect on the engineering support required for the teams."

That may mean more job opportunities for people with engineering degrees.

"In IndyCar, we had two engineers per car," White said. "Here, certainly you're going to have to have someone with some engineering capability, more than the mechanical support that we've had with this type of engine over the past few decades.

"So there will have to be someone with the ability to go in and run a computer and plug into a box and make mapping adjustments and so forth. And also, someone who's going to be able to harvest the information to provide to the crew chief and the chassis engineers, because in my opinion, this step makes the engine and the whole car more of a package."

Yates can barely contain his excitement at the idea of moving to EFI. It's an opportunity to showcase NASCAR's technology, which he feels sometimes gets a bad rap in the engineering community.

"The exciting thing is we're having interest from an engineering standpoint that we've never had before," Yates said. "We have people who want to be part of our sport who in the past would say, 'Well, I'd rather go work on Formula 1 engines because they are injected and it's a higher tech engine.'

"In fact, NASCAR engines are very sophisticated technology. But sitting on top of all that science -- through coatings and materials and innovation through the years -- is a carburetor, which kind of turns people off. Now people are saying, 'Wow, NASCAR is fuel injected. I want to be a part of that.' "

According to White, "some very bright guys" have already joined forces. Cosworth engine designer Nick Hayes is working with Richard Childress Racing. Roger Penske has the backing of Ilmor. And Jeff Andrews at Hendrick definitely knows his way around the shop.

Nobody wants to be the ones left behind, especially since electronic fuel injection plays directly into the relationship between manufacturers and racing teams.

"I want to make sure people understand how important this is and what a platform it allows us to go and brag about," Yates said. "I had an opportunity to talk to [president and CEO] Alan Mulally from Ford at Michigan, and he is really excited about this coming to NASCAR.

"The manufacturers like the fact that we're advancing our technology and getting closer to stock car racing. We've gotten away from that a bit, especially as it relates to engines. So it's a step in the right direction."

"There's a reason we're doing all these tests, because until you get it on the track and in some sort of competitive type atmosphere, we won't uncover any problems."


Comstock said Dodge is definitely putting its brainpower behind its teams.

"To me, it's been great because this is one project where we from the factory have so much experience that we think we can really help the teams make this transition," Comstock said. "But there's a lot of smart guys in that garage. They'll figure it out pretty quick."

The key, Comstock said, is making sure the drivers buy in. And for the most part, that's been the case.

"Without giving away any secrets, a few impressions -- even in the early testing -- the drivers have said when they get it adjusted right, they can't tell that it's not a carburetor," Comstock said. "And it's going to be those tweaks that we do here in the early stages of development, that hopefully by the time fuel injection sees the first race, it'll be completely invisible to the driver. But everybody will know it's more efficient, more effective and eventually, it'll make for better fuel mileage.

"We've got engines running on the dynamometers that can simulate race conditions, and consequently we've been able to tune on it already. And I think you'll find some surprises at the race track in the early stages of racing. But hopefully, we'll have most of those issues worked out beforehand."

For Yates, reliability of the new system will be critical.

"To start strong and not have any hiccups is very important," Yates said. "There's a lot of new components bolted on this engine, and we want to make sure that when we start the season next year, we have confidence that we understand the life cycle of the parts."

NASCAR vice president for competition Robin Pemberton has been in charge of several test sessions involving EFI.

"There's a reason we're doing all these tests, because until you get it on the track and in some sort of competitive type atmosphere, we won't uncover any problems," Pemberton said. "But it's going well. Teams seem to be dealing with it. And everything's on course."

Carburetors had a nice six-decade run in NASCAR. Now it's time to see what comes next.

"It'll be very interesting to see how the evolution goes into the 21st century with fuel injection," White said.

And for Yates, a chance for some of the old dogs in the garage area to teach a few new tricks to the younger engineers in the sport.

"It's a huge change and it's a very exciting time as an engine builder and engineer in this sport," Yates said. "That's exciting for engine technology. A lot of people look at our sport and see carburetors, and think it's somewhat antiquated. So this is exciting and a big step for us.

"I think it's a big step forward for NASCAR. And it's really the beginning of a new technology, from an engine standpoint. It's very exciting."