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90RS13 · 03-22-2005, 12:22 AM

Actually underdriving the water pump can help on high rpm engines. It can help reduce cavitation. Also, lightened pulleys will let the engine rev more freely, but you aren't going to get a good hp gain without underdriving.

EDIT: Just incase people don't know what cavitation is. Cavitation occurs when the impeller in a pump, (or propellers on a ship) goes to fast. When the blades move too fast, low pressure areas form around the blades as the water passes through. If pressure becomes to negative the water will reach it's "vapor pressure". When that happens the water vaporizes and bubbles of gas are formed. Now the bubbles are the problem. When a bubble is formed in the cooling system, water can't carry heat away from the area the bubble is occupying. So you get severe hot spots in the engine. Also when the bubbles
collapse, they make little shock waves, damaging the impeller.

-matt

03-22-2005, 12:22 AM	#26
90RS13 Zilvia Junkie Join Date: May 2004 Location: Newark, Arkansas Age: 41 Posts: 348 Trader Rating: (0)	Actually underdriving the water pump can help on high rpm engines. It can help reduce cavitation. Also, lightened pulleys will let the engine rev more freely, but you aren't going to get a good hp gain without underdriving. EDIT: Just incase people don't know what cavitation is. Cavitation occurs when the impeller in a pump, (or propellers on a ship) goes to fast. When the blades move too fast, low pressure areas form around the blades as the water passes through. If pressure becomes to negative the water will reach it's "vapor pressure". When that happens the water vaporizes and bubbles of gas are formed. Now the bubbles are the problem. When a bubble is formed in the cooling system, water can't carry heat away from the area the bubble is occupying. So you get severe hot spots in the engine. Also when the bubbles collapse, they make little shock waves, damaging the impeller. -matt __________________ Last edited by 90RS13; 03-22-2005 at 12:43 AM..