GT4 Racing Guide

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Parnelli's GT4 Gold Links


Ever since I was a kid, I have been obsessed with cars to some degree. As a teen, I read Road & Track, Popular Mechanics, and other magazines and learned plenty of technical data. By the time I was 13, I knew of something called a weight to power ratio, (W2P) which is derived by taking a car's weight and dividing it by its power.

What results is a number that means alot so far as how that car will be able to compete against other cars. In Gran Turismo, it is effectively the first step to making sure lighter cars aren't over-classed with power, and heavier cars get a fair race as they have more of a burden in corners.

One day I was running some races in GT1. I was about to compete at Autumn Ring and noticed all the Ai cars are listed in the pre-race lineup. Taking a further glance, I also noticed each car's weight and power is also listed! Hmmm. I wondered if it was possible to take my car, figure its weight and power, and then take the weight / power ratio from the fastest AI car--and finally power my car so that it had a similar ratio. Would it make for a predictable race in which neither he nor I would have too much of an advantage?

And thus, the system was born. Unfortunately, in GT2, 3, and 4, each Ai car's power & weight are no longer listed. Despite this, I've still been able to create a system for each game which is not only predictable, but also can make for a closer, more intense racing experience. In GT3 and 4, I even figured out ways to introduce logarithms to create weight classes and further counteract the possibility of your car having too much or too little an advantage. In most cases, you can further fine-tune your gaming by limiting the tires, suspension, and other parts your car is equipped with and I've included rules for this as well.

Does the system work? Most of the time it does, but you should keep in mind that it is only a guideline--a place to begin more or less. Such variables as drivetrain layout, engine torque, gearing, and aerodynamics also come into play.

Since using weight-to-power ratios, I've found I can't live without them. In real-life, if your car had too much of a track advantage, you would be told to remove certain parts, and then disqualified or even banned if your team ignored these restrictions. Though this never happens in our games, there's nothing to say we can't simulate our own rules. 

You should ignore my guide if you're one of those folks who doesn't feel the passion of racing, and thinks nothing of pushing other cars off track or into walls, or if you're in the habit of buying as much power as possible by default racing guide is not for you. You will get the best results if you're driving with minimal contact amongst the other cars. This is basically for those who know how to drive.

How Weight to Power Works

Take your car's weight, and divide it by the number found in the race you're about to qualify for. Each race will have a 3 or 4 digit number (6.36 for instance) listed. Since all weight in Gran Turismo 4 is shown in kilograms, we must convert to pounds to use the system effectively first. Here's the formula.

kg x 2.204 = pounds 

So a 1,000 kg car will weigh 2,204 pounds.

So if you have a 3,000 pound car, take 3000 6.36 = 471. That last number (471) is the horspower your car should be near or equal to. Your final horsepower can be slightly below or slightly above the number on your calculator. Now tune your car with whatever parts necessary to get as close to this number as possible.

How Logarithms Work

Say you've got a Chrysler PT Cruiser with Stage 1 weight reduction and are entering it into a race. It weighs 2,598 pounds. The race has a weigh class which runs from 2,000 to 2,800 pounds. I've incuded a power to weigh ratio from 11.43 to 18.46 to correspond to the lower and upper portions of the weight class. Follow the method below:

2,000 Pounds= 11.43 P2P

2,800 Pounds= 18.46 P2P

2,800-2,000 = 800 pounds

18.46-11.43 = a difference of 7.03 pound to power points.

7.03 800 = .00878 pounds per hp

The Chrysler is 598 pounds over the 2,000 minimum so...

598 x .00878 = 5.25 pounds per horsepower over the minimum of 11.43

5.25 + 11.43 = final P2P of 16.68
so...2,598 pounds 16.68 = @156 final horsepower... should have about 156 horsepower to competitvely compete in the race.