Re: CB PERFORMANCE DRY SUMP PUMP.
Posted: Mon Feb 19, 2018 10:47 am
This might be a little controversial. In addition to enlarging the internal passages of the CB dry sump pump, dong the usual blue-printing and o-ringing (on my build thread: http://www.shoptalkforums.com/viewtopic ... 5&t=150113), I added a second port to the pressure side of the pump. To get from the pressure stack to the main oil gallery, the oil has to make a bunch of 90 degree turns. What I did was simply add an alternative path, a parallel circuit IN ADDITION to the existing one. It taps directly off the area where the pressure gears fling their oil, through a 3/8 external line, and into the main gallery through the hole where a full-flow system is normally plumbed. I expect having a second path will reduce pumping losses; I don't expect it to have any effect on the volume of oil flowed. It might help pressure a bit. The size and RPM of the gears determines flow, I am merely reducing the amount of power it takes to generate that flow. The ratio of scavenge flow to pressure flow is also preserved, since that is simply a function of the relative sizes of the two gear sets.
The real trick was figuring out what kind of fittings and oil line would minimize the packaging problem. There is no elegant way to plumb it, because the inlet and outlet are so close to one another. Fittings take up a lot of space! And hose can't turn a sharp radius without collapsing. So I used a hard line of 3/8 copper-nickel alloy; it is sold as transmission cooler line in auto parts stores. Here it is in its rough configuration. It stays well away from the exhaust. I flared it with a cheap HFT flare tool. It turns out the AN standard (37 degree single- flare) is identical to the JIS standard that plumbers use for gas lines, so I went to the hardware store and was able to handle a bunch of different fittings to see what would work. I'll be keeping a close eye on it to look for leaks; the main worry is metal fatigue at the fitting. There shouldn't be any relative motion, and copper is fairly malleable, so I'm hopeful.
The real trick was figuring out what kind of fittings and oil line would minimize the packaging problem. There is no elegant way to plumb it, because the inlet and outlet are so close to one another. Fittings take up a lot of space! And hose can't turn a sharp radius without collapsing. So I used a hard line of 3/8 copper-nickel alloy; it is sold as transmission cooler line in auto parts stores. Here it is in its rough configuration. It stays well away from the exhaust. I flared it with a cheap HFT flare tool. It turns out the AN standard (37 degree single- flare) is identical to the JIS standard that plumbers use for gas lines, so I went to the hardware store and was able to handle a bunch of different fittings to see what would work. I'll be keeping a close eye on it to look for leaks; the main worry is metal fatigue at the fitting. There shouldn't be any relative motion, and copper is fairly malleable, so I'm hopeful.