Stock Car Science

I have never seen Robin Pemberton looking so disgusted as he did during an interview replayed on NASCAR Now Monday evening. (Well, maybe not since Daytona 2007.) NASCAR did a chassis dyno test after the Michigan race on a number of NASCAR Nationwide cars. They found 1/4-inch-thick magnets underneath the accelerator pedals of the 18 and the 20 Joe Gibbs Racing cars. To their credit, JGR took responsibility, apologized and started an internal investigation to figure out who was responsible.

You may have heard some strong reactions from some of the other owners. One of the reasons for the animosity is that Toyota runs the same engine in Cup and Nationwide, whereas the other manufacturers have to maintain separate engine programs for the two series. I know that some of the companies that run both series have 90% of their engine shop dedicated to Cup engines, so there’s some resentment that Toyota only has to run one program.

The facts: The purpose of the magnetic shims was to prevent the accelerator pedal from being pushed all the way down. In a carbureted engine, pushing the accelerator pedal opens valves in the carb. The more you push the pedal, the more the valves are opened. The valves regulate how much of the air/fuel mixture enters the engine. The wider the valves are opened, the more air/fuel mixture goes into the cylinders and the more energy is produced. If you prevent the pedal from going all the way to the floor, the throttle doesn’t open all the way and you produce less horsepower.

As you probably remember, NASCAR gave Toyota a more tapered tapered spacer than the other manufacturers after engine dyno numbers showed that the Toyota engines had a 15 hp peak horsepower advantage. The cheat was an attempt to have the Gibbs Toyota engines show lower horsepower than the engine actually was capable of and (I guess) either make NASCAR feel guilty that they penalized Toyota too much, or prevent further reductions of the tapered spacer. Some thought must have gone into how thick a magnet they needed: If they had knocked the horsepower down too much, it would have looked suspicious.

Why magnetic shims? You could have accomplished the same thing with a non-magnetic shim; however, you would have had to have come up with a way to hold the shim in place, like glue or tape. NASCAR mandates the use of magnetic stainless steel in the car. A rare-earth permanent magnet will stick really really well to magnetic stainless steel. I have a couple neodymium-iron-boride magnets that you literally have to keep a piece of cardboard between becuase if they get stuck together, you’re going to have a very difficult time getting them unstuck. So all the folks who are wondering if those magnets they claim you can put around your gas line to save money actually work, forget it. They don’t. The only reason a magnet was used was because it could be put there quickly, would stay put, and could be removed quickly. They could have used plastic or non-magnetic metal and had the same effect on the throttle action; however, the high heat in the car might have softened any adhesive or tape used to stick it in place or the driver might have knocked it loose.

Every report I’ve heard says that the magnets were in place during the race. (correction) As the story has evolved, it appears now that the crew members derived a ploy about needing to retrieve a forgotten notebook to get into the car after the race, so it now appears as though the magnets were NOT in the car during the race. (correction) Given how closely the cars are watched (especially the 20, which finished 3rd), there wouldn’t be many possibilities to slip something in place (although doing so would only have taken a very few moments). At Milwaukee, where NASCAR did engine dyno tests, the cars pulled off the track and headed toward their haulers, but the NASCAR officials stopped all the cars just inside the garage gates. None of the teams seemed to know what was happening until they got the word that there were going to be engines selected for dyno testing. The only other possibility I can think of would be the driver moving the magnet into place after the race and I just can’t see Tony Stewart going for that.

What makes the decision to try this even more questionable is that this was to be a chassis dyno test, not an engine dyno test. In a chassis dyno test, the cars are rolled up onto a mobile chassis dyno, which is a platform that has a large massive drum on which the rear wheels are placed. The car is strapped onto the platform and when the throttle is pushed, the rear wheels turn the drum instead of moving the car. If I remember right, NASCAR uses a DYNO-mite dynamometer.

A chassis dyno test doesn’t test only the engine: it also reflects all the frictional losses in the drivetrain. So, for example, if your oil were thick for some reason, you might have the best engine, but you would see lower numbers on the dyno because some of your engine power was being used to overcome friction and that power wasn’t available to the rear wheels. An engine dynamometer measures only the engine. I can’t see that NASCAR would make decisions on engine policy based on a chassis dyno measurement since a chassis dyno measurement measures much more than the engine. It is tough to imagine that, based on a chassis dyno test, NASCAR would decide to make the holes in the Toyota tapered spacer larger again. Just for the record, NASCAR used an engine dyno when they tested NNS cars in Milwaukee and Chicagoland and a chassis dyno in Atlanta earlier in the season.

So what was really the point of this? You make yourself less competitive (unless there was some way that the magnets got put into the cars after the race) and you chance a huge fine. I’m working on a novel and this seems like a perfect revenge scheme for a disgruntled employee, doesn’t it? You compromise the performance of the car AND you create a scandal that could result in long-term suspensions for crew chiefs and car chiefs. Or it could just be someone doing something amazingly ignorant.

The penalties are likely to be major. I’m sure NASCAR has the same feeling I get when I catch a student cheating in a really stupid way. You’re incensed because they’re cheating and then you’re more incensed because they think you’re so stupid that you wouldn’t catch it. When there was a major cheating scandal in F1, they made the guilty company ineligible for the equivalent of the manufacturer’s championship. That’s a punishment for the offenders, but it also puts an asterisk next to the manufacturer that does win the championship.

The arguments that it was justified for JGR to cheat because NASCAR unfairly took away 15 hp from Toyota when they were within the engine rules is just plain bogus and I bet that most of the folks at JGR would tell you the same thing. The people who work there that I’ve met are simply too good to resort to doing something like this.

UPDATE 8/20/08 Dave Moody has a really good summary of the penalties, announced Wednesday, so I won’t type in my own attempt to explain because I think he covered just about everything. I personally was expecting car and crew chief suspensions for the rest of the season, so the indefinite suspension came as quite a surprise.

UPDATE 8/20/08 Lee Spencer has a nice article with a rational description of the incident, the penalties and why this is all such a big deal.

UPDATE 8/23/2008: Mike Mulhern has a great column in which he sheds a little more light on the deception. Apparently the crew members involved had thought enough about this that they had a cover story. Great, except the cover story was that (as one of the comments below suggested) they were arguing that the magnets were stops to prevent the throttle cable from being overextended. They used a magnet in the car because then the driver could kick it out of the way if they wanted to. Sounds perfectly reasonable. Except they forgot to let the drivers in on the story, so it was obvious to the Nationwide officials when they asked the drivers that the driver had no clue what was going on.