The Sixty Foot Myth
How often have you been in a bench racing session and heard the discussion turn to whose car has the best sixty-foot times? The guy with the littlest number is often credited with having the best overall chassis set up- yet many don't understand what goes into a quick short time. The sixty-foot time is probably the most hyped incremental measurement on the ET slip. It should be noted that the guy with the little number down low often doesn't have the biggest number up top, speed. (The best indicator of power.) It is the number most associated with chassis efficiency, or "hook'. If the sixty-foot time is in line with other racers in the car owner's class, the chassis builder/designer is given a pass and high fives are dispensed all around. Obviously, the race is not won or lost at the sixty-foot clocks. It's the quarter mile ET that matters, and if the driver has done his or her job at the line, it's the last increment that will indicate the win.
So, as the owner of ProCar, (a chassis shop) how is it I'm slagging the sixty-foot as the increment of choice? It's simple, really. The lightest car in any class (with equitable rules) should sixty-foot the fastest. In a class that adds weight for clutches, power adders, or model year, the lightest car should make its way off the starting line and to the sixty-foot clocks the quickest in virtually every case. While quarter mile speed is an excellent indicator of power to weight, the sixty-foot time is not. If it sounds nuts that a well-tuned light chassis can out run even the best tuned "heavy' car in a short sprint, let me break it down for you.
Initial acceleration, the charge a racecar makes off the starting line and through those sixty-foot timers doesn't require a ton of power to be quick. Contemporary 500” Pro Stocks will consistently go between .997 and 1.00 or so, and they have nowhere near the power of a Pro Mod blower car that will short .02-.03 slower. The blown Pro Mod has to do two things the Pro Stocker does not: move an additional 350 lbs. and deal with a power band that builds steam as the car moves out. The Pro Stocker uses mechanical leverage (gear ratio) and a manageable and relatively flat power curve to move its lighter mass forward very quickly. This allows the crew chief to manage that "thrust' in a way that will repeat and stay hooked, run after run.
Case in point: in 2002, our car wound up in a final round against Marc Dantoni in Stanton, Michigan. No one, including me, gave our driver (Randy Jewell) a chance against Marc. Pre-race preparations completed, I sought out a spot at the 330' mark to see how humiliating this was going to be. As the cars left, I noticed that our Corvette drilled Marc a half car length through the first 200 feet. For a split second, I let myself dream "what if?' - . Within the next 250 feet the 57 Chevy of Dantoni reeled Randy in and whacked our team by a solid 2-3 tenths - It was bloody. I couldn't wait to see what the ticket said. I knew our boy was ahead when they flew by me, but I didn't know how much. As it turned out, Randy had a mild advantage on reaction time and a whopping advantage in sixty-foot- a 1.04 to a 1.09- but Marc drilled his eyes out to the 330', the point at which his horsepower advantage came to light. It was then and there that I came to realize that the lighter car could be tossed about by the weaker motor much more easily that the heavier car could get motivated by the stronger engine. We had a 325 lb. advantage over Marc thanks to the rule book- 225 to the trans and 100 to the sheer cubic inch he held on us, our (at the time) low 7 second car easily made it's move off the starting line before his heavier car could get on the tire and do the same. Watching his car rip past us at the 300 foot mark taught me what those little numbers meant on the ET slip- almost nothing- until you read the last number row, MOV, or margin of victory.
Does this mean that we should crumple the slips at the end of the run and chuck "em? No. What it means is these increments don't mean much unless compared against cars of the same weight and same combination. It's a lot like comparing heads by only referencing flow numbers against each other, it only tells part of the story. The ET slip's greatest value is when it used as a gauge against the same car's performance, a way to measure progress. If we raced our dyno sheets against our competitors, all we'd have to do is compare the printouts and declare a winner. Yet we all accept that the dyno is a very relative number, and need to view the sixty-foot measurement the same way. It is a great measure against the cars past performance, but not necessarily a great yardstick against a car with a different combination.
So what are the common elements that link cars with good sixty foots together? First, they all make the tires "round' as quickly as possible. You really can hook a tire too hard. Consider the pulling tractor that slows its acceleration as the load slides up the sled and stalls forward progress- four link and shock tune ups that crush the tire and keep it wadded as the car drives out do much the same. The old adage is true; loose is often fast. "Stiff is better' is a truism many builders have recognized. While some still prefer a more flexible car, the latest trend in both Pro Mod and Pro Stock favor cars that are very rigid "between the tubs', and are loaded with X's that span everywhere from the upper four link area to the shock cross member. Builders are recognizing that even minute flex in this area wastes forward energy and slows the cars initial move from the starting line. A quick look into the rear window of a current Haas or RJ car will show this is true. Stiff shock settings that hold the housing in check as the power comes down the drive shaft aid in smooth power application- as long as the shocks aren't too stiff to upset chassis attitude over down-track bumps.
In closing, respect the data the slip shows you, and be proud of a personal
best sixty footer. Don't tune the car simply to achieve a max short time
however, as the 330' times may suffer, and it's hard to re-gain that margin
down track. It's all relative.