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Mobil 1 Auto Tech: When less horsepower is more

June 27, 2014, Ron Lemasters Jr., for,

Things to consider as NASCAR looks to reduce horsepower in its Cup cars

Now that the Gen-6 NASCAR Sprint Cup Series car has undergone some tweaks to make it handle better, NASCAR is thinking about taking away some of its horsepower.

Is that a good idea? The racing has been good, the cars are quick and they look great, they handle better and are providing the kind of excitement on the track that NASCAR and its fans want to see. Taking away some of the 900 horsepower the engines currently generate is bound to change that.

How it changes things depends on what is done.

The choices on how to go about this reduction in power are a tapered spacer, which is essentially a thicker restrictor plate; a new throttle body that would restrict fuel flow; and a reduction in cubic inches from the current 358.

Each solution would do what NASCAR intends and limit the horsepower the cars have available. As with any change like this, however, the costs must be considered.

Any kind of reduction in horsepower means that the engine suppliers -- TRD for Toyota, Roush-Yates for Ford and Hendrick and Earnhardt Childress for Chevrolet -- might look for more horsepower elsewhere. That's what racers do, after all. 

Second, a horsepower reduction means the cars will likely have more speed in the center of the corner.

During tire testing in April at Michigan, Trevor Bayne did laps with a tapered spacer in his Ford. His center-of-the-corner speeds picked up by 10 miles per hour.

That's good in a way and creates problems in a couple of others, according to six-time champion Jimmie Johnson.

"I am not sure those (added) miles an hour through the center of the corner is going to allow us to run comfortably through the corner side-by-side," Johnson said at Richmond. "Now we have picked up a lot of speed through the corners, and are the tires going to hold up? Is the suspension going to hold up? It costs a lot of money to even put a tapered spacer on the car. We are going to go and work to change all the internals to maximize the role that the engine performs. So I sympathize with NASCAR because there isn't an easy way to go about things."

Johnson brings up a good point. Goodyear has to design tires that will deal with the additional loads through the center of the corners. Typically, the cars are off the gas in the center until they can get back to the gas, and by getting on the gas earlier, they'll use up the tires more. There's a suspension component, too, with more time under acceleration while in a corner.

The idea behind reducing horsepower is to start cutting engine costs by making the engines able to complete more than one race. In the Nationwide and Camping World Truck Series, engines are run for two races, not one.

"It's as much getting more use out of engines as it is (reducing) horsepower," NASCAR Vice President of Competition and Racing Development Robin Pemberton told "They kind of feed off of each other. There's no guarantee horsepower may or may not do anything for the quality of racing, but it will allow us to do other things."

Team owner Jack Roush had definitive thoughts on the process and made it clear what he prefers.

"The race teams can only afford to change so many things at a time," he said in April. "With the expanding technology and the engineering costs that everybody has with the pressure for sponsorship and investment in the sport, a dramatic or unnecessary engine change would not be welcome in my world."

A reduction in RPM would be the way to go, Roush said. "(That) would be less hard on the engine, and a requirement that you use the engine for two races."

A reduction on the intake side through the throttle body opening would be easier and less painful for the teams to implement, Roush said.

The question is, how long will it be before those anticipated cost savings overcome the initial rush of R&D around the changes? If it's a throttle body change, it wouldn't take long. An engine is basically a very expensive air pump. Air goes in at the top of the engine, is mixed with aerated fuel droplets and is burned after being injected into the combustion chamber.

From there, unused fuel/air mixture goes out the exhaust valve and out through the headers. Air in, power out. Reducing the amount of air in reduces the amount of power, and it all depends then on how much air you let in to be mixed with the fuel. There is no other change to the process.

Reducing horsepower on its own is a good idea, both for cost and possible competition uses. How NASCAR does it will be interesting to see.


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