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GJF GJF is offline
Slantnose from HELL
 
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Join Date: Dec 2004
Posts: 801
I run gravity drains to the timing covers with -12 drain lines. It is the scavenge system that causes the coked oil deposits. When the engine is shut down even letting the turbos cool down before shut off. The oil still has residual pressure to the turbo and holds oil pressure at the sump on stock systems. By having a gravity drain the oil tends to drain back to the case rather than sitting in the sump which doesn't allow draining of the hot oil after the engine is shut off. It just sits there till cool causing the oil to coke. The gravity drain lends itself to a cleaner oil because the oil doesn't have sumps to back up the oil. Of course this method requires repositioning of the turbo and exhaust to get the height to allow for gravity draining. I think the filter in the drain line is a great addition as long as it is checked regularly so blockage does not happen. Another solution would be to add a -4 or a -6 overflow port to a sump tank and drain to the case so when the engine is shut off the oil doesn't pressurize the sump tank and the oil doesn't just sit in the sump, with the vent it can overflow to the case for the oil pump to scavenge on next fire up and limit the amount of coking.
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87 911 Carrera platform
Twin Garrett's, Big Valve, Xtreme Cylinder Heads, JB Racing cylinders and machine work, custom JE pistons, GT2 EVO cams, GT3 oil pump, modified 3.2L intake, 80mm TB, custom Intercooler, equal length headers, DFI, KEP Stage 2 custom twin disc, G50 custom gear set, LSD, Tilton trans pump, Fluidyne cooler
Old 07-06-2010, 06:54 PM
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