Running and tuning a new engine on the dyno is just the first step in the process of preparing a race engine for competition. When the powerplant is installed in our race car and run at the racetrack, we need to make sure that all of the components are working together. Let’s review a few tips that can help you get the most power.
The job of an engine tuner is to try to continually discover new ways to gain performance by making the engines live longer and produce more useable horsepower. They sometimes even run across undesirable engine mechanics that end up robbing some of the available horsepower. Here are some valuable tips that the average short track racer can use to help their car go faster. These are simple in concept, but very effective in reality.
Spark Plug Tech
The heat experienced by your plugs can dictate how efficiently your engine is burning the air/fuel mixture. One easy way to tell if your plugs are getting hot enough is to observe how far the heat has penetrated the threaded portion of the plug. We obviously need to make sure that we are using the correct length for the spark plug threaded portion. When the plugs are fully installed and tightened, the threads must not either extend into, nor end up short of, the combustion chamber.
Many top engine tuners have made a science out of inspecting the tip and insulator of the plug, but most short track racers don’t have the time or the patience to get that technical. If you just remove the plug and visually observe how many rings of the threaded portion of the plug are discolored, you can tell if the plug is hot enough for your application. Usually, if two to three threads from the end of the spark plug are discolored, it means that there is sufficient heat to provide complete combustion.
The level of voltage being supplied from the battery helps determine the degree of heat of the spark plug. Teams that run without alternators run the risk of having low voltage in the system which results in a cooler spark. A minimum of 11.5 volts should be maintained to the coil so that the spark will generate sufficient heat needed to completely ignite the air/fuel mixture. The engine will run at a lower voltage than that, but a number of negative issues may arise that decrease your engines horsepower.
Plug and Coil Wire Efficiency
There are a couple of tricks to know that involve the spark plug wires that supply the energy to the ignite the a/f mixture in the motor. The first important issue is the quality and size of the wire. It goes without saying that the better wire you run, the better ignition you will have.
It’s important to keep the length of the ignition wire from the coil to the distributor as short as possible—best at under 18 inches, preferably at or around 12 inches. It is the same with the plug wires, the shorter the better. Line loss, which is a loss of energy when electricity flows through a wire, decreases the heat generated by the spark and results in a less efficient burn of the air/fuel mixture.
The plug wires that are routed to cylinders that are beside each other in the firing order should be crossed to eliminate interference. High energy wires that run close together and parallel will pick up energy from each other unless the field is broken by crossing the wires to form an “X.” In a GM V-8, the fifth cylinder fires just before the seventh cylinder, and they are next to each other. Those two plug wires need to be crossed.
Oil Temperature Generates Horsepower
In any internal combustion engine, heat is horsepower. All of the elements of the engine must contribute to the overall operating temperature of the motor. The oil that flows through the motor is a source of retained heat and must be maintained at an optimum temperature.
As the oil becomes hotter, the engine will actually generate more horsepower. For circle track racing applications, the oil temperature should run around 220 to 230 degrees. Modern synthetic oils will withstand temps upwards of 300 degrees and most high-quality “standard” engine oils will live comfortably well in the 230 degree range. The hotter the oil, the better the engine will run, to a point. With modern components, and the way race engines are assembled, there should be no problems with the higher oil temperatures listed.
Setting Timing and Advance
How you set the timing in your race engine can affect how efficiently your ignition system will work. There is a better way to set the timing, than your team might be used to, and that will assure the proper timing advance at top engine rpm.
Many teams will set the low speed timing and then maybe check the high speed timing with any advance timing the distributor provides by revving up the motor to a high rpm. If at some point in the future the advance timing does change, and it can with mechanical systems, then we won’t necessarily have the proper high rpm timing we need.
With the higher rpm advanced timing activated, the No. 1 cylinder fires at exactly 36 degrees BTDC. We can then lower the engine rpm and check to make sure the timing is at the desired 30 degrees BTDC. If the advance in the timing is off from the expected 6 degrees, we will still have our needed 36 degrees of timing at high rpm. The low rpm range timing will be lower and should be 30 degrees. If the timing advance is off, only our low-speed timing will be different and not affect our timing at race speeds.
We need to run the engine up to an rpm that is just above the point where the maximum high speed advance is activated and set the total timing we will need before top dead center. Then at the lower rpm ranges, the timing advance will be deactivated and the engine timing will be retarded by some number of degrees. This low-speed timing is not as important as our high-speed timing. The only real reason we need less low-speed timing is so the engine will start easily.
Many distributors have a mechanical advance mechanism that may not be totally reliable for the advance curve. So, we can’t count on the distributor adding a constant number of degrees of advanced timing to the low rpm timing. When we set timing with full advance, whatever that may be at any given time, then we are assured of the correct high-speed timing when the engine is at race speed rpm.
Cooling Fan Techniques
Many racing engines do not need a cooling fan. Some need the fans only at lower rpm and need for them to be less efficient at higher rpm. Running a fan uses up some of the available engine horsepower. The idea is to run as little fan as you need to cool the motor.
Some of us think that having a high water temperature means we need a bigger and more efficient fan when the real culprit is the flow of water through the radiator is too fast to enable proper cooling. The radiator needs time to draw off the heat from the coolant. If we do not restrict the flow of coolant by the use of a restrictor inserted into the system, we may never be able to lower the water temperature to an acceptable level.
A stock water pump is designed to run at 3,000 to 4,000 rpm and not at or above 6,500 rpm as in racing applications. When we spin the water pump that high, we are forcing even more water through the system at a higher velocity, draining even more horsepower. There are several things we can do to help this situation.
We can alleviate the drain on horsepower caused by running a fan while at the same time slowing the flow of water through the motor by installing a larger pulley behind the fan. This slows down the rotation of the fan and the water pump which both drain horsepower. Less drag from the fan and a slower flow of water that helps the radiator do its job and can mean an additional 10-20 horsepower going to the rear wheels.
The average racer can benefit from the hard work and innovation produced by top engine tuners. You don’t need an education in electrical or mechanical engineering to understand and utilize the suggestions. If you are able to apply even a few of these simple, yet effective tips to your racing effort, you will enjoy a more powerful engine that just might live a bit longer.