The dry-sump pump is a verycompact unit. Notice the pump drive has a simple V-belt design.
The quest for horsepower, as it seems, is never-ending. We will try many unproven, unseen, unusual and unscientific products or processes in the search for that holiest of grails-horsepower. Sometimes the answer is right there in front of you, and all you have to do is reach out and grab it. If you are racing in a class that allows dry-sump oil systems, and you are still running a wet-sump oil system, you are giving away horsepower. But, you say, "If I have to buy some other stuff, it's not free." You are right, it is not free; but that is only the short-term view, and it just shows how many of us are trapped by conventional thinking. In the longer term, we may be saving money and gaining power. One of the many advantages to using a dry-sump oil system is not just the power to be gained, but also the ability to develop a level of control over various engine subsystems in addition to your oil system. These subsystems will be significant toward filling the grail with previously untapped power gains. There are gains from using a dry-sump system that transcend other measurable gains. They go well beyond being able to control the level of oil in the engine. Once you remove all of the traditional problems associated with a wet-sump application in racing engines, you have the ability to rethink many of the other systems on the engine in order to release even more horsepower. We need to start thinking about the big picture.
The engine in your race car goes through some dynamic conditions over the course of a race: acceleration and cornering loads, which force the oil back and to either side, and deceleration loads driving the oil to the forward portions of the engine. These conditions can cause oil starvation at a time when the engine needs the protection of the oil system the most. This starvation is caused by the pump pickup becoming uncovered for brief periods of time as the car goes through these transitions. For example, as you reach the end of the straightaway (when the engine is at max rpm and max load), this is the time you really need your oil system to work at its peak. Unfortunately, just the opposite is a real possibility.
Let's step back for a second and look at the advantages that are not horsepower related, from both a qualitative and quantitative perspective. First and foremost, the dry-sump system allows you to run the engine lower in the car due to the fact that the oil pan is 4 to 5 inches shorter than a stock OE pan or even a well-designed racing wet-sump pan. The ability to move the engine lower in the chassis gives you more freedom in the placement of the engine. If you could lower your engine and subsequently lower the center of gravity in the car, would you do it? Of course you would. Even if lowering the engine is not an option, it gives you added track-to-pan clearance and/or clearance for other suspension components. Placing the engine lower in the chassis also allows for a lower hood line, which may allow a lower coefficient of drag. If the drag is lowered, then more of the horsepower you develop can be used to accelerate the car, as opposed to being consumed by overcoming aerodynamic drag. Would you like a car that is a bit more slippery from an aerodynamic perspective? From a purely physical perspective, it is clear that the advantages are additive.
If you feel that you need to adjust the amount of oil in the oiling system, you are very limited in a wet-sump application. The addition of more oil capacity in a wet-sump system can cause some other serious issues. Elevated oil levels will cause some serious windage issues. Oil that comes into contact with the crankshaft and rods at speed can cause the oil to become overly agitated and introduce high levels of air into the oil. This foaming of the oil can cause problems, such as loss of oil flow and pressure. Oil that has a high air content or becomes foamed will not cool as well. In fact, it will tend to get even hotter, which causes a variety of other issues (e.g., cooking of the oil, reduced ability of the oil to lubricate, bearing failure). Ultimately, the engine blows up in your wallet. That makes the extra costs associated with using a dry-sump almost free. Are you seeing a pattern yet?
The back of the pump shows the externally adjustable pressure relief valve. This is just o
By utilizing a dry-sump oil system, you have an infinite level of control over the whole oil system that you couldn't have with a wet-sump system, where you are stuck with the pump running at half the engine speed. In the dry-sump system, you can adjust the pump's speed. If you want to run the pump slower or faster, you have that option (which you do not with a wet-sump system)-all it takes is a simple drive pulley change. This may not sound like a big deal, but if your racing rpm does not vary much, or you run for a very short duration at elevated rpm levels, it may make sense to slow the pump and use the extra power that would be required to drive the pump to drive the car. Variations in mounting options may place the pump on the cam cover with no external drives to fail. You have a choice here, unlike the situation with a wet-sump system.