The start of the 2008 Sprint Cup series saw the new "Car of Today" race in the Daytona 500 for the first time, the 24 hours of Fontana, and a 'Vegas track' which was significantly changed from winter testing. Roush-Fenway racing won back-to-back races at a 2-mile low-bank and a 1.5-mile high-bank track, and had the car to beat at Atlanta. Hendrick Motorsports (HMS) is no longer the dominate team with the COT. It took until the fifth race of the season at Bristol for a GM team to win a race. Toyota scored its first victory in Cup competition with a win at Atlanta. This is a season of change. While Cup racing may be the pinnacle of full-body, circle track racing, many lessons from the start of this season can be transferred directly to your Saturday night program.
The current Sprint Cup car has changed the face of Cup racing. It has eliminated much of the freedom that teams had in the past to alter the body shape for improved downforce. Overall, downforce has been reduced and mechanical grip (traction) has become much more important.
At the superspeedways of Daytona and Talladega, where rear shocks and springs are supplied by NASCAR, much of a team's ability to control vehicle performance has been removed. Teams are looking for small things to differentiate performance. Mechanical grip and engine performance have become more important. Driver ability is paramount. Does this situation sound familiar? Many of these same challenges are also faced by Saturday night circle track racers.
If we take a closer look, the face of racing around the world is changing. The world economy is no longer in a growth cycle and most forms of motorsports are facing consolidation. From Daytona to your local dirt track, money is getting harder to come by. This is likely to continue for the next several years.
As the racing world changes, the five most important things for a successful circle track racing program remain the same. This is as true for Cup and your Saturday night program:
2. Resource Management (managing time and money)
3. Handling (aero and mechanical grip)
4. Race Strategy/Pit Performance
5. Engine (unless it breaks)
Today's Cup car has reinforced the relative importance of these items. And if you are facing financial pressure in your racing, concentrate on these basics first. A successful race program always pays attention to the details! Make sure that your car is 100 percent prepared before going to the track so that you don't beat yourself.
As teams worked to find the last horsepower for this year's Daytona 500, both power and reliability were big stories. Engine power was more important during qualifying, but cars which were down 4 percent on power were competitive due to superior chassis setup and driving during the twin 150 qualifying races.
NASCAR typically runs selected cars from each manufacturer on a chassis dynamometer after the twin 150 qualifying races. This allows NASCAR to see what the power difference is from one competitor to another. This year, Toyota topped the power charts. Two Toyotas, four Dodges, and four Chevrolets were successfully tested by NASCAR. During the Daytona 500 telecast, it was reported that the Toyotas had a 30hp advantage over the Chevrolets. This was not the case! A GM car was tested on the chassis dynamometer with a valvetrain problem which generated the low numbers reported on the television coverage. The best to the worst was approximately 4 percent, with the Toyotas at the top. The average car tested was less than 2 percent down from the best.
The bigger engine-related story during Speedweeks was that many teams were reporting tappet-related failures prior to the race. More than 10 engines were changed because of this problem. Failures occurred in some, but not all, of the Toyota and GM engines.
The surface stresses on a flat tappet in a Cup engine are among the highest in motorsports today. Cup teams use a Diamond Like Coating (DLC) applied to a super-finished steel tappet which, in most cases, runs against a super-finished, though hardened, tool-steel cam. This solution has been widely used for the last five seasons. It has virtually eliminated cam/tappet failures which were common during the days of the welded inlay cam and the chilled-iron tappet.
An example of a traditional aluminum body roller- tipped rocker. Jim Mcfarland
DLC run against a lubricant and a properly prepared mating surface has an extremely low coefficient of friction. DLC-coated tappets run successfully because the low friction at the cam/tappet interface prevents wear.
Some teams run DLC on the cam as well. Running DLC against DLC may reduce friction, but this system is harder to run successfully. The DLC tappet running against the steel cam is very sensitive to the type and quantity of lubrication. Qualifying is a worst case scenario for engines as the oil is heated above 250 degrees and the water is chilled down near freezing. Qualifying oils approach a zero weight. This combination of hot, low viscosity oil with a cold engine is a recipe for failure if conditions are not perfect. The failures that occurred in some of the engines were directly related to the wear that occurred on the time trial laps, even though the engine failure occurred later during the 150 races. The lesson that may be taken from this is as follows: Always inspect critical components prior to the race, and if there is any doubt that damage has occurred, change the part or engine.
During Speedweeks, some teams did not provide a sufficient safety margin and problems occurred at the cam tappet interface. This caused good time trial efforts to be wasted. Many engines needed to be changed and thus cars had to go to the back of the grid for the 150s. The lesson to be learned here is that the last horsepower is not worth obtaining, if the risk of failure is significant. All the teams who had problems were able to recover for the 500, and only one unrelated engine failure occurred during the race.
Other engine news form Daytona: TRD engines were seen with a DLC-coated roller-less rocker. Why would a roller-less rocker be used? Roller-tipped rockers were first used to reduce friction as the rocker tip scrubbed across the top of the valve or lash cap. Removing the roller would seem to be a backward step. The low friction of the DLC coating has made it possible to run without the roller and have only a small friction penalty. The benefits of not having a roller on the tip are:
An example of a roller-less steel rocker. Jim Mcfarland
*A massive reduction in moment of inertia (less nose weight)
*An improvement in system stiffness
*Increase in accuracy
*Possible improvement in rocker-to-lash-cap contact
*A part with less complexity (no needle bearings to fail in the nose wheel)
In these examples shown, the roller-less rocker has a moment of inertia (MOI) reduction of 90 percent and stiffness increase of 60 percent. As mentioned in a previous segment of the CT Series on Cup engine technology, reducing the moment of inertia has a similar effect to reducing valve mass. This change may either allow a reduction in spring force or more aggressive valve motion. Without changing thevalvetrain to take advantage of the mass, no perform-ance gain would be obtained.
What may be learned from this example is that performance gains in either the vehicle or the engine rarely come from simply bolting on a part. A change to the system must be made to take advantage of the new component. All that is usually learned from bolting on a new part is determination of the system's sensitivity.
Here's an example. If the roller-less rocker (from the above case) was bolted on in place of the aluminum rocker with no other changes, a power decrease may occur. This result shows only that the engine was sensitive to the rocker change, not that the new part was inferior. To understand if the rocker itself was a positive change, other elements of the valvetrain may have to be made. The worst possible outcome of a bolt-on test is to observe no change. This means that the area you are working in has little sensitivity and may not be worth investigating.
Around the world, participants in motorsports are facing financial challenges that have not previously occurred. From the streets of Monte Carlo to your local dirt track, there are universal truths. If you work more efficiently than your competitors, you will have better results. You must spend your resources on those things which will improve lap times. You must continually ask yourself if the project you are working on is going to produce results. If the answer is you are not sure, then stop working on it! Only spend time and resources on projects which will make you faster.
Remember, no matter what type of racing you do, the driver is the key performance element. Mechanical changes which make the driver perform better are a plus!