> what is the difference between dry sump and a plain old pressurized > system. Just the fact that there isn't an oil pan on a dry sump system, > right?
I assume by "plain old pressurized system" you mean the stock oiling system. Now, a true dry sump system consists of a large oil tank (usually about 14 quarts - 3.5 gallons for a 4 cylinder application) which is mounted in the rear of the car (hatch or trunk), feed and return lines to the engine compartment, a belt driven high pressure pump, a sort of convex plate that replaces the oil pan that has a fitting at it's lowest point for the oil return to the tank, and various high pressure feed lines from the pump to the engine. There may be a low pressure transfer pump in/near the tank, and there may or may not be an oil cooler somewhere along the line - probably not necessary with that large of volume of oil and length of supply/return lines. The advantages are multi fold. Putting the holding tank in the rear (usually) helps weight distribution, the fact that the tanks are usually fairly tall and narrow, and that the feed line is located at the bottom of the tank, means that no amount of cornering/acceleration/braking force can cause the oil to "slosh" away from the supply line, therefore allowing for constant positive oil pressure. The large volume of oil affords very stable oil temps, as well as a much higher dilution factor in regards to contaminants in the oil. The fact that there is virtually no oil sitting below that crankshaft means that there is less HP loss from the crank having to "slice" through the oil in the oil pan. The down side is cost (a whole dry sump system is MAJOR $$), and loss of trunk/hatch space, which isn't an issue in a race car. The more cost effective way to deal with this is to get/fabricate a well baffled oil pan, and, possibly, get a device called an "Accusump", which is a small (1 or 2 quart) cylinder, similar in appearance to a fire extinguisher, that mounts vertically in the engine compartment, and is plumbed into the oiling system so that the supply to the pump comes from the bottom of the cylinder, and the return is attached to the top. This setup retains the oil pan and stock pump, but works like a dry sump system in regards to having a constant oil supply which is not affected by cornering/acceleration/braking, without the large tank and belt driven pump. The Accusump system can also be used as a pre-oiler to provide positive oil pressure prior to starting the engine. I think that about covers it, but feel free to ask any questions... --Holland Forced Failure Racing Don't Ask MotorSports [email protected] a2_16V List Owner [email protected] San Jose, California _____________ List Sponsor: http://www.netsville.com To remove yourself from this list, send mail to [email protected] with 'unsubscribe a2_16v' in the body of your message See us on the web at http://www.a2-16v.com Visit the 16V Homepage at http://www.gti16v.org
