Thread: 1/4 mile times
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kellcats521 kellcats521 is offline
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Join Date: Feb 2005
Location: Atlanta Metro
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I won't beat this dead horse, but I guess the SAE is clueless too....

SAE Technical Papers
Title: Potential for a Ground-Effects Top Fuel Dragster
Document Number: 2002-01-3348

Author(s):
Murf McKinney - McKinney Corp.
L. Daniel Metz - Metz Engineering & Racing

Abstract:
The current performance of a top fuel (T/F) dragster racing car is very high. The cars can accelerate from a standing start to well over 330 mph (528 km/h) in \ml 4.6 seconds! The engine of a T/F dragster can make considerably more power than can be put down to the track surface. Intentional clutch slippage prevents wheelspin for most of the 1/4-mile (0.4 km) standard length racing run. Even though the drive tires used are highly specialized and specifically designed for this type of racing environment, more traction is needed. To create more traction, especially during the second 1/2 of the run, external wings have been employed by the designers of such cars. The size and configuration of the wings is limited according to sanctioning rules.

Titan - one of the biggest 1/4 mile clutch companies is prolly also clueless on what it takes to drag race.....

The automotive clutch was originally designed to disengage the driver (engine) from the driven (transmission). Drag racers learned that the clutch could be manually feathered i.e., slipped by a skilled driver's foot against the clutch pedal. This allowed the drive tires to spin less, yielding quicker elapsed times. By the mid-Sixties, Top Fuel teams were starting to experiment with clutches that had a certain amount of slip designed in, enabling a car to run quicker and repeat more consistently.

The long-style pedal clutch, which uses a combination of spring pressure plus centrifugal clamping to make the unit lock up, was used initially because it was a simple matter to make the springs adjustable and the counterweight adjustable. Eventually clutches appeared with their springs located behind the cover, instead of between the cover and the pressure plate (drive shoe). These became known as "'Glide" clutches, and allowed a driver to remove his/her foot from the clutch pedal before leaving the starting line. As engine rpm increases, the counterweighted levers overcome the static springs, and the clutch locks up. This system allows the tuner to put a fixed amount of load on the engine at idle (also referred to as "stall").

Both pedal- and 'Glide-type clutches can be operated in multiple stages. In these applications, pressure is applied to the drive shoe by a few of the many levers available. As the throwout bearing is allowed by the clutch controller to move back, more and more of the levers engage, adding squeeze to the clutch pack. Most Top Fuelers and AA/Funny Cars use multistage, 'Glide-type clutches. Most Top Alcohol Dragsters and Funny Cars, Pro Modifieds and Pro Stockers, plus many nostalgia cars, run single-stage, pedal-type clutches.

Here's a link to their site - maybe they can bring more credibility than I do.

Titan

And, to answer your question, I did previously own two 1/4 mile cars - one was a true 11 sec bracket mustang and the other was a 10.19 index 1970 Camaro. But, beyond that, I BUILT too many of these engine/clutch-trans (or automatic)/chassis setups to start to describe. The shop I spend my high school (and some college) summers at had 15 dedicated drag cars in the shop every day.

Pat Kelley
Old 04-17-2007, 02:58 PM
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