What would happen if each car was fitted with an overdrive automatic? For our example, we’ll use a common 700R4. The only mechanical difference between the two is the rear tire diameter (height). The results are interesting.Īs you can see, there’s a considerable difference in the speed of the two cars at a given RPM level. This occurs just before the fat part of the torque peak for the ZZ4 engine. For the sake of comparison, let's assume that we'll use a figure of 2,500 RPM for a cruise speed. The above figures don’t mean much until they are plugged into the next formula, which is Cruising Speed. The following formula is used when crunching the numbers: The next step is to calculate the tire revolutions per mile for each car. With this information, we compute the vehicle speeds at a specific RPM number. Here are the basics:įinal drive ratio - transmission 1.00:1 1.00:1
In this comparison, we’ll assume that cars run a ZZ4 crate motor and they both carry 3.08:1 gears out back. For the sake of comparison, let’s "test" both cars with conventional Turbo 350 transmissions (the high gear ratio is 1:1). Let's compare a pair of hypothetical hot rods - one is a traditionally styled car with Firestone 7.50X16s on the rear and the other a high tech with P335-30ZR18 BF Goodrich G-Force T/A tires. Get a wee bit more complex and it’s easy to go too far. What all that means is less can often prove better than more. In the last issue we examined several different engine power curves and shared info on over-gearing.
0 kommentar(er)
