Improving the Elapsed Time, or ET, is the primary reason for the changes that most of us make to our vehicles. The quicker (lower) the ET, the stronger our vehicles feel. An improvement of one second in ET to a relatively slow car capable of running 16.5 seconds is just as important and just as noticeable as a one second gain on a 14 second car. Although a very low ET is not necessarily a determining factor in winning bracket races, it certainly is important when bench racing with our friends! A very consistent ET most definitely is an important factor in bracket racing. We have discussed starting line techniques to make the ET more consistent. Such things as correct or higher front tire pressure, proper wheel alignment and minimizing weight by unloading the spare tire, jack, tool boxes, etc. and kicking the passenger out, will help lower the ET. In general terms, a weight reduction of 100# will lower the ET by .1 second. Correct engine condition and proper calibration of the carburetor and distributor are vital for good performance. Simply replacing parts, be it cams, carbs, manifolds, ignition add-ons, etc. usually does not make significant improvements, unless the replaced items were not operating correctly, or were terribly mismatched for the application.

It requires intelligent planning to change from good Factory matched systems to after market material. You should also optimize all Factory parts before switching to after market pieces. You may find more performance by carefully experimenting with and fine tuning your existing combination.

In all cases, be very wary of the slick advertising for greater horsepower producing parts for your driveable Pontiac. Don’t add high RPM horsepower if it causes a loss of low RPM torque. To do so will reduce drivability, and in most cases, will actually hurt ET. Improving the performance of a streetable vehicle that requires some idling at traffic stops, a full RPM range for each transmission gear, and the ability to operate normally in summer heat, is totally different from building and installing a race engine.

So how do we improve ET? It simply takes a lot of diligence and patience. Each vehicle/engine combination is different from others, and step by step testing of fuel mixtures, timing combinations, shift points, and even brands of tires, are necessary to obtain the best ET. After the engine is optimized, we must use that power to move the vehicle. This brings us to the common problem of traction.

Good traction is obtained when there is little or no spinning of the drive tires when the engine is accelerated. The size of the tires, the type of rubber (hard, soft and/or sticky) in the tires, the type of tread pattern on the tires, and the depth of the tread affect traction. The amount of vehicle load that shifts to the rear wheels (or shifts away from front wheel drive tires) when the vehicle begins to accelerate is extremely important. The driving technique used will always affect traction.

Tires. Standard tires, bias or radial belted, are compounded to provide the best overall combination of tread mileage, traction in both wet and dry conditions, durability in hot and cold driving, stability in turns, resistance to road hazards, etc. Specialty tires will trade one or more of these attributes for improvements in specific areas. Drag slicks with no tread pattern obviously would have no traction in wet conditions, and terrible handling in any kind of driving other than a straight line, but do provide optimum traction on a clean dry surface. DOT approved drag race tires provide some limited driving capability, (albeit very marginal) while maintaining good traction on clean roads. BF Goodrich has introduced a radial tire with improved straight line traction, and the normal good handling of the radial design. In general, long mileage tires are generally weak in straight line traction. If you plan to use conventional tires for drag racing, look for a relatively soft tread compound, a minimum of tread openings, a wide and flat tread, and a larger diameter. Increasing tire diameter by one inch will always increase traction more than increasing the tread width by one inch.

Weight Shift or Transfer. Normal acceleration tends to raise the front of the vehicle, and that slight raising of the front when combined with forward acceleration, shifts more of the vehicle weight (load) to the rear More weight on the driving tires improves the tire adhesion to the road surface, and that improves traction. The style of rear suspension – leaf spring, four link coil suspension, independent rear suspension, etc., all have some effect on the weight transfer to the rear tires. The most practical things we can do to help traction include maintaining the springs in good condition (and not using spring boosters or air shocks with conventional suspension), good shocks, and correct ride height. I will briefly discuss traction aids later. Driving style was mentioned as a factor in traction With a normal driveable street vehicle, it is very important to apply engine power in a manner that will allow the vehicle to begin to lift the front and transfer weight to the rear before the full engine power hits the rear tires. For example: If the engine is torqued up against the converter the front tends to lift (although the same amount of weight is still on the front), and when the brakes are released, the full engine torque shocks the tires loose before the car can transfer any weight to the rear. Once the tires break loose, they can not obtain enough traction to cause the front to lift more, which would add more weight to the tires. If the driver will apply power in a more constant and gradual manner, the car will begin to transfer weight to the rear before the tires break loose, and this process can be extended until the throttle is completely open. Of course, other factors, such as reaction time, must be considered, and the complete driving style selected to complement you and your vehicle. The point is that simply flooring the throttle and letting the tires spin is not the best method to obtain good traction and the optimum ET.

Most “A” body cars with automatic transmissions will leave the line hard with good traction (depending on tire adhesion) and no wheel hop. Manual transmission cars are more susceptible to wheel hop due to the harsher and erratic application of power to the rear axle. Faulty alignment of the rear axle, badly worn shocks and/or springs, and loose or faulty bushings in the rear control arms will contribute to the tendency to wheel hop, regardless of the transmission type. Changing the suspension design/operation by using air shocks or coil over shocks will almost always cause wheel hop, because both inhibit the normal rotation of the rear axle assembly. If you have a wheel hop problem and your rear suspension is in normal condition, you may want to try a set of the special lower control arms such as the Indian Adventures “Ground Grabbers”. They might help traction as well as preventing or improving wheel hop conditions. The rear of these arms mount lower than stock on the rear axle assembly, thus changing the angle at which they push forward and up on the chassis. The net result is that as the rear axle assembly tries to twist (wind up) in the opposite direction from the forward turning axles, it transfers the twisting torque up and into the chassis. By pushing up against the chassis, the rear axle is forced down and onto the tires harder, and that normally improves traction. This action also inhibits wheel hop.

To help those of you who run the 1/8 mile, or 1000′ tracks, to estimate your 1/4 mile performance, here are some randomly selected performance numbers from our local track. They do not represent any ideal performance, but do illustrate the general relationship of performance to 1/8 mile, 1000 feet, and the quarter mile.