Hot rodders are a strange lot. They’ll spend thousands of dollars on performance parts to improve acceleration, handling or braking, but most won’t spend one dime on testing to discover if all those parts really made a difference! Thankfully, some hot rodders are interested, and they would love a tool that is simple, accurate and inexpensive. If you’re one of those more dialed-in hot rodders, take a look at the g-curve by Analytical Performance.
The g-curve is a simple, curved-glass tube mounted in an aluminum plate. The tube encloses a small steel indicator ball suspended in a calibrated viscous fluid. The mounting plate is graduated in fractions of a g, which are directly read out by comparing the position of the ball to the scale. The plate uses suction cups to mount on the passenger’s inside window for measuring positive (forward) or negative (braking) accelerations. If you want to measure lateral (side to side) acceleration to test handling, the meter can be affixed to the rearview mirror. Analytical Performance also includes an excellent 85-page User’s Guide that outlines information you can generate, including quarter-mile trap-speed estimations, launch g’s and how you can plot rear-wheel horsepower and torque curves that Analytical claims are within three percent.
What is a g? The force of the Earth’s gravity is 1g. Accelerations in any direction are measured as a force compared to the force of gravity, which is defined as 32.2 feet per second per second (ft/sec2). As an example, a very quick street car could pull as much as 1g instantaneous from a dead stop. A new Corvette can pull close to an average 1g lateral (higher instantaneous) on a skidpad. These figures represent accelerations that you can use to evaluate and compare performance.
As an example of how to use this tool, let’s say you plan on installing a new dual exhaust system. A baseline test followed by a retest once the exhaust is installed would reveal the increase in acceleration the exhaust was worth. Analytical Performance suggests that you use a passenger to record the data so that you can concentrate on driving. For example, you could do a Second gear acceleration test from 2000 to 5000 rpm, record g readings every 1000 rpm, and compare that data to the baseline to measure the performance improvement. You could also use this procedure to check the results of any change you make to the engine or drivetrain.
Analytical Performance’s manual includes a number of different test procedures that you can perform, such as lateral acceleration, coast-down, gearing for optimal fuel mileage and others. For its low price of $75, the unit is very accurate and requires no electronic or mechanical connections to the car other than sticking the unit on a window. If you’re looking for an inexpensive testing tool that is simple to use, Analytical Performance has the answer.
