Thank you Orma, well described, I had no problem fully understanding your arrangement and it certainly appears to be a good solution - it works.
I was not aware of the existence of a dual (piggy back) pump - sure is the ideal solution in this case. Is scavenging a turbo a new concept (first I heard of it) or are there many existing cases? My understanding has always been that having the oil under pressure (at the turbo bearings) is what created the "bearings" that the turbo shaft ran on. I would have thought that placing these chambers under vacuum (scavenging) would reduce the effective pressure at the bearing surface. That would reduce the pressure on the seals (maybe even produce negative pressure) and thus prevent any oil getting past the hot section seals into the exhaust, thus achieving what you set out to do. Question is, will the reduced pressure affect the turbo life? What is the consequence of a failed turbo in flight (in this type of installation). Could you lean out the mixture and still have say 70% Power? Do you know if a similar approach could be taken on the Corvair engine? Enjoy the Easter break Ron -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf Of Orma Sent: 25 March 2005 07:32 AM To: KRnet Subject: Re: KR> Tweety update Hello Ron First of all, type2 and type 4 parts are mostly interchangeable. The Vanagon automatic, utilizes a piggy back dual oil pump to provide pressure to the transmission. It is this pump that I am using for the turbo scavenge pump. The suction side of the pump is connected to the turbo oil return, and the pressure side of the pump is connected to the side of the engine case at the oil sump. Please see http://kr-2.aviation-mechanics.com/Turbo%20Oil%20Leak.htm The pump sucks hot frothy turbo return oil and passes it under pressure back into the engine case. The turbo oil supply is taken from the top of the original oil cooler boss and is routed directly to the top of the turbo. The Ford engine that this turbo is applicable for has a requirement for 50 psi. That being said, the turbo is getting what ford required. The pump is two pumps driven by a common shaft that is turned by a slot in the cam gear. Both pumps are completely separate, each with it's own inlet and outlets. Was it worth it? Even though the dust has not settled yet, I can tell that I have a lotttt more power. The difference is like night and day. My pervious top speed was 129 kts. I have exceeded that in the pattern at PTK, seeing 135 kts. My climb was always around 500 fpm ( my KR was over 615 lbs). On a calm day I can now do over 1000 fpm. Your short answer is YES. It brings back that YeeeeeeeeeHaaaaaaaa feeling. It takes the Hum out of Hum Drum and leaves the Drum with a quickened beat. Orma _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
