How Will They Restrict at Daytona & Talladega with No Carburetors?

With the advent of electronic fuel injection, I guess the dreaded carburetor restrictor plates are out at Daytona & Talladega. Having two left thumbs and being not at all mechanically inclined, my question is simple. How will the cars be restricted at those two tracks with electronic fuel injection? Is it simply a matter of injecting less fuel, and if so, how is that accomplished?


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"Any Day is Good for Stock Car Racing"
updated by @dave-fulton: 03/11/17 01:54:38PM

I'm thinking boat anchors and small chutes. But I'm also not the most technically knowledgeable person so I could be off the mark here.


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Schaefer: It's not just for racing anymore.

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"Any Day is Good for Stock Car Racing"

Dave, as you know, the basic argument for fuel injection is to "modernize" NASCAR racers. Supporters wail about the fact that Detroit ceased producing carbureted vehicls in the mid 1980's and today's fans will not continue to stand for such antiquated race cars....... and it somehow resembles 'green' technology. (.like it makes any difference to anybody as to the mod of fuel delivery) But,EFI is where it's gonna get real tricky. It's all electronic and monitored/controlled by an on-board-computer. One could change the injector-opening-time-duration, for example, but will everybody be on the same page (electronically)...during the race? Seems such parameters could be changed, remotely, and a car that was "illegal" in racing mode, could be "legal" in the inspection line.

Thank you folks.


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"Any Day is Good for Stock Car Racing"

I am not an engineer, so I can not give a detailed technical description of the system or it's components but I will repeat what I have heard. As Jim stated the injectors can be sized to deliver a maximum amount of fuel. Nascar looked at both throttle body and multiport injection but I think they settled on throttle body which means they will still use the same type of intake manifolds as they run now and the "carb" will just be an air meter and restrictor plates will still be used to limit air flow. The other main part of the system is the electronic control module or on board computer. I don't know if the first generation ECM will control fuel and ignition or just fuel with readings from the ignition system. If it doesn't now it will eventually, only makes sense that it would. This module has an enclosure or box that is tamper-proof. That is, when the box is opened a switch is tripped or released that can not be reset so it would be known if a module were to be opened. The program for the computer resides on a chip and it can not be over written without the proper license. There is no transmitter or receiver but you can plug in a laptop and see the units history.

I think all the reasons that have been given as to why this change is taking place is nothing more than spin. It is a revenue source for Nascar. The vendor "company" supplying the EFI system paid big bucks just for the privilege of doing business with Nascar. Once that money is in the bank then they talk about how much they have to contribute each year. The teams have to buy the EFI system from the vendor and Nascar controls their distribution.

A whole new bottle of wax will be opened when fuel injection is used

The injectors will be in the manifold and the throttle body will resemble the traditional carb. That said nobody has mentions the distributor going away and welcoming the crank trigger ignition. I have seen the set up and software and believe me its WAY more involved than the original plan. Also the pr geeks have failed to mention its a long way from ready. Still work to do .The only way it works now so i'm told is with the long time illegal electric fuel pump. The system requires about 70 psi to function so it appears the boys have some thinking to do.

Back when only mechanical fans were legal in NASCAR I had an electric fan manufacturer approach me and Robert Yates at the SEMA show in Vegas and offer to pay for assistance to have their fan o.k.'d for use in NASCAR. I said o.k. and approached NASCAR with a written proposal and got a quick no. Next thing I knew, that damned fan manufacturer was the official electric fan of NASCAR, but ole Dave never got paid a dime.


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"Any Day is Good for Stock Car Racing"

NASCAR chose Freescale Semiconductor, a Motorola Division, and McLaren Electronic Systems, which has deep roots in Formula One, to come up with the new fuel injection systems.

McLaren will be making the Engine Control Units (ECU's) which will drive the fuel injection, and Freescale will be providing the electronic brains to run them. McLaren engine control units have had Freescale technology at their hearts since 2000. Freescale is the largest U.S.-based producer of automotive electronics.

So what's to keep teams from changing the programming in their new ECU's? Just this the chips will know. Any alteration will leave an electronic "fingerprint": not something you can lift with flour and Scotch tape, but something NASCAR officials will be able to detect. Even supposing any team could get close enough to their cars with the device that changes the program, they won't be able to hide it. Supposedly, the fail-safes are built in. The ECUs will work only with NASCAR-specific code in sealed units. Without the code, the engine will not start.

The hard parts of a fuel injection system are, really, simpler than a carburetor. It consists of an electric fuel pump and a throttle body with a fuel injector controlled by the Electronic Control Units. The carburetor consists of collection of tiny holes, floats, plates, cams, levers and rods and is very complicated.

Lets look at what it takes to make combustion. What burns in the engine's combustion chambers is a mixture of air and fuel. Gasoline needs oxygen in order to burn. So in order to create an explosion in the cylinders, it's necessary to mix fuel and air. In the past the best available way to mix air and fuel was through a carburetor, which brought the air and fuel together in what amounted to a mixing valve, combining the two at a ratio of about 15:1.

The real magic of a carburetor was in the ways it managed separate circuits i.e. an idle circuit, a high-load circuit, a cold circuit, and so on. In a fuel-injection system, all these functions are simplified and controlled by the engine control unit (ECU), the so-called "computer" in the modern engine.

The throttle is a plate which opens and closes depending on how far you press the gas pedal. In a carburetor, the throttle is downwind from where the fuel is mixed, and thus admits the mixture to the intake manifold.

In fuel injection, the throttle (gas pedal) controls the amount of air admitted to the system; the mixing is done later, just as the air enters the cylinder at each cylinder's intake valve. The ECU, via sensors, measures air volume and velocity, and then it signals the injector to admit the precise amount of fuel needed for the correct burn ratio.

The intake manifold, therefore, conducts only air, not the final mixture. The problem with a carbureted system is that once the mixture is throttled into the manifold, it's pretty much on its own. It is conducted by the manifold runners, one per cylinder, to the intake side of the combustion chambers. Some cylinders get more, some get less hence all the thought and expense in manifold design.

With fuel injection, the mixing, controlled by the ECU, is all done at the intake valve, ensuring that each cylinder gets an identical charge at each firing of its spark plug.

McLaren will provide the hard parts for the NASCAR's proposed injection system.Texas-based Freescale, a division of Motorola, is the largest maker of ECU-type systems in the world. These two companies, in partnership with NASCAR and its teams, will develop and supply all fuel-injection components for the race teams. Holley will supply the actual Electronic Fuel injection units to .

Many had hoped that NASCAR, with injection, could do away with the much-despised restrictor plates. No, not so fast. Although McLaren and Freescale have more-than-adequate know-how to dump the plates for good, NASCAR apparently wants to keep some last-minute control in choking the engines. The plates are the easiest and most economical way because you govern the air flow.