The job of an engine tuner is to continually discover new ways of gaining performance by making engines live longer and produce more useable horsepower. The tuners sometimes 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 the car go faster. These are simple in concept, but very effective in reality.

Oil Pump Horsepower Drain The oil pump in your engine requires a certain amount of horsepower to pump the oil through the engine, filters, and to and from the sump tank. The amount of horsepower it takes is directly dependent upon the amount of pressure the oil is under at any one point along the route, and the efficiency of the plumbing that the oil has to flow through.

One restriction lies in how the oil is routed through the oil pump on a dry sump system. A more efficient plumbing of the oil flow can result in an increase of 5 to 10 hp, depending on the type of engine. A study of fluid dynamics teaches that a liquid will flow with less pressure through a larger opening and through bends in the plumbing that are designed with a larger and smoother radius.

If we are scavenging from three locations in the engine into the oil pump, but exiting from only one outlet, the oil from at least two of the pump sections must pass through the chambers of other pump sections in order to flow out to the reservoir can. The proper way to exit the oil is out of each individual pump section into a collector manifold where all of the scavenged oil will flow to the reservoir.

Most top engine builders will tell you to run a manifold, but most aren't willing to tell you how much horsepower gain comes from using one. It is substantial. Because this added pressure (which is actually felt as resistance that requires more horsepower from the engine) is inside the pump itself, it will never register on the oil pressure gauge and be detectible. It will, however, register on an engine dyno. The bottom line is that you need a manifold attached to the oil sump pump so that no oil from one pump section flows into or through another section.

Carburetor Jetting and Power Valve Adjusting Most engine tuning related to air density and humidity is done with the fuel jets, but a more efficient way to adjust the air/fuel mixture to react to small changes in atmospheric conditions is by changing the air bleed jets instead of the fuel jets. These units are easier to get to and are more appropriate for matching the changes in air density to air/fuel ratio.

The air bleeds assist the fuel jets in supplying fuel to the air. Most classes of circle track racing allow carburetors with changeable air bleeds. In the past, changes to the fuel jetting have not adequately modified the air/fuel ratio to affect a gain in horsepower. It was discovered that, in many cases, it is more appropriate to make adjustments to the air bleed to see a noticeable change in horsepower.

We all need to monitor the weather at the track on the day of the race. I have worked with many teams who take weather measurements at the track on race day. These are serious teams who have won big championships and left nothing to chance. They recorded the air temperature, the barometric pressure, and the relative humidity. The engine builder or dyno operator can supply the weather data recorded on the day the engine was on the dyno. That information is entered as the baseline into a small computer and compared to existing conditions. Most popular weather stations built for racing engine applications have provisions for changes to the air bleeds as well as the fuel jets to adjust the air/fuel mixture to current weather conditions.