Monty Mikho
04-18-2008, 03:12 AM
By George Klass
You are on the line in your new Mustang (or ‘Vette), staging. The pre-stage light is lit, now the stage light. The Tree comes down, you leave hard and you are on a good run. Your new supercharger is pumping and you are hauling ass through the traps. You know it was a good pass and then you take you foot off the gas and………nothing happens.
The engine is still pulling hard at full throttle. You do a quick tap dance with your right foot on the gas pedal to get the throttle “un stuck”, and still nothing happens. Now you are in trouble. You look up and you can see the sand trap coming up.
You could throw her in neutral. It won’t help the engine problem but at least it’s going to be out of gear. You could also turn the key off. This will fix the runaway engine situation but the moment you turn the steering wheel, the steering wheel lock comes in to play and it won’t turn.
Do you ever think about these things in advance, and what you might do if it happened?
If you have a new Mustang (2005 and later) or a late model ‘Vette or Camaro or a Firebird, or any number of other types of new cars, there is another little problem to think about. Your throttle is illegal for NHRA competition. These newer cars have a drive-by-wire throttle linkage. In essence, there is no linkage. The throttle is computer controlled, electronically. When you step on the gas, you really aren’t stepping on the gas, you are stepping on the computer. There is NO direct mechanical linkage between your right foot and the throttle body. Some of these drive-by-wire systems don’t even have a return spring.
According to the NHRA Rulebook, under THROTTLE in the General Regulations section, it states, “Each car in competition must have a foot throttle incorporating a positive acting return spring attached directly to the carburetor/injector throttle arm.” This is going to be a problem. On the Mustang, for instance, there is no throttle arm. The Rulebook further states, “In addition to the return spring, some means of manually returning the throttle to a closed position by use of the foot must be installed, except on cable operated systems, yadda, yadda, yadda.” Another little problem, since there is NO mechanical linkage to even consider. Which doesn’t matter too much anyway since the next sentence says, “Throttle control must be manually operated by the driver’s foot, no electronics, pneumatics, hydraulics, etc. permitted.”
This issue revolving around the drive-by-wire throttle systems has come up several times at FFW events. Every now and then some eagle eyed NHRA inspector tries to raise a red flag about the late model Mustangs. We get around it of course (money talks, inspectors walk) but it can be an issue. And because of that, I have pressed NHRA in Glendora to examine the rules in this area and come up with a solution. Being the politically correct guy that I am, I told them, “Time to think about getting into the 21st Century”. I have been assured that they will reword the THROTTLE description paragraph at some time in the future, and in the mean time, I was given a “letter” from their tech department, with the NHRA logo on it, basically giving the drive-by-wire systems a “waiver”, if and when any competitor gets hassled by an NHRA tech inspector. Anyone feeling that they may need a copy of this letter, give me a call at (909) 930-1751 and I can fax you a copy.
You are on the line in your new Mustang (or ‘Vette), staging. The pre-stage light is lit, now the stage light. The Tree comes down, you leave hard and you are on a good run. Your new supercharger is pumping and you are hauling ass through the traps. You know it was a good pass and then you take you foot off the gas and………nothing happens.
The engine is still pulling hard at full throttle. You do a quick tap dance with your right foot on the gas pedal to get the throttle “un stuck”, and still nothing happens. Now you are in trouble. You look up and you can see the sand trap coming up.
You could throw her in neutral. It won’t help the engine problem but at least it’s going to be out of gear. You could also turn the key off. This will fix the runaway engine situation but the moment you turn the steering wheel, the steering wheel lock comes in to play and it won’t turn.
Do you ever think about these things in advance, and what you might do if it happened?
If you have a new Mustang (2005 and later) or a late model ‘Vette or Camaro or a Firebird, or any number of other types of new cars, there is another little problem to think about. Your throttle is illegal for NHRA competition. These newer cars have a drive-by-wire throttle linkage. In essence, there is no linkage. The throttle is computer controlled, electronically. When you step on the gas, you really aren’t stepping on the gas, you are stepping on the computer. There is NO direct mechanical linkage between your right foot and the throttle body. Some of these drive-by-wire systems don’t even have a return spring.
According to the NHRA Rulebook, under THROTTLE in the General Regulations section, it states, “Each car in competition must have a foot throttle incorporating a positive acting return spring attached directly to the carburetor/injector throttle arm.” This is going to be a problem. On the Mustang, for instance, there is no throttle arm. The Rulebook further states, “In addition to the return spring, some means of manually returning the throttle to a closed position by use of the foot must be installed, except on cable operated systems, yadda, yadda, yadda.” Another little problem, since there is NO mechanical linkage to even consider. Which doesn’t matter too much anyway since the next sentence says, “Throttle control must be manually operated by the driver’s foot, no electronics, pneumatics, hydraulics, etc. permitted.”
This issue revolving around the drive-by-wire throttle systems has come up several times at FFW events. Every now and then some eagle eyed NHRA inspector tries to raise a red flag about the late model Mustangs. We get around it of course (money talks, inspectors walk) but it can be an issue. And because of that, I have pressed NHRA in Glendora to examine the rules in this area and come up with a solution. Being the politically correct guy that I am, I told them, “Time to think about getting into the 21st Century”. I have been assured that they will reword the THROTTLE description paragraph at some time in the future, and in the mean time, I was given a “letter” from their tech department, with the NHRA logo on it, basically giving the drive-by-wire systems a “waiver”, if and when any competitor gets hassled by an NHRA tech inspector. Anyone feeling that they may need a copy of this letter, give me a call at (909) 930-1751 and I can fax you a copy.