What Is Acceptable Crankcase Suction
12-01-2007, 04:23 PM
#2
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I use a vacuum pump. Doesn't make much HP at lower vacuum (3-5"), but it does a great job of eliminating the ER oil/blow-by and it really keeps the eng room clean. On the dyno in a wet sump/oil pump distributor gear driven application, the vacuum pump was fighting the oil pump at 15"+ with only + 5-7 HP at 6000+ RPM (oil pressure was fluctuating).
Today, I run one vac pump for both engines. It is my understanding that the bigger (+15-20) HP gains on a vac pump are mostly shown with real low tension oil rings...mostly used in a drag car set-up.
If your goal is more HP, you can invest in other options that will bring more value. To rig a single vac pump right, $1500-2000.
Today, I run one vac pump for both engines. It is my understanding that the bigger (+15-20) HP gains on a vac pump are mostly shown with real low tension oil rings...mostly used in a drag car set-up.
If your goal is more HP, you can invest in other options that will bring more value. To rig a single vac pump right, $1500-2000.
12-01-2007, 09:12 PM
#3
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Hi Ben, Do you believe idle quality and torque is improved because of the 3" to 5" at idle ? Would the Horsepower gain be the same for dry sump/wet sump ? Subject to crank to rod ratio, do you believe vacuum effects piston rock ? When using vacuum with dry sump,are piston sprayers more or less part of the equation ? What do you consider prudent for disposing of the fumes and vacuum sludge ? In the event one burns a hole in the piston, how can the pressure be best released ?
12-01-2007, 09:29 PM
#4
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- Subject to crank to rod ratio, do you believe vacuum effects piston rock ? No idea
- When using vacuum with dry sump, are piston sprayers more or less part of the equation ? Don't see a connection between piston sprayers and vacuum
- What do you consider prudent for disposing of the fumes and vacuum I use a custom catch can (oil/air separator)
- In the event one burns a hole in the piston, how can the pressure be best released ? A pop-off valve/vent from Peterson Fluid Systems. More likely needed if vac pump failed.
- When using vacuum with dry sump, are piston sprayers more or less part of the equation ? Don't see a connection between piston sprayers and vacuum
- What do you consider prudent for disposing of the fumes and vacuum I use a custom catch can (oil/air separator)
- In the event one burns a hole in the piston, how can the pressure be best released ? A pop-off valve/vent from Peterson Fluid Systems. More likely needed if vac pump failed.
12-03-2007, 06:50 PM
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Ben, Are you using a Peterson Valve ? Do you know approx. crankcase pressure required to open the valve ?
Subject to the amount of vacuum, would the dry sump system scavange the cylinder walls ? If so,the piston sprayers would lubricate the walls and pins while cooling the pistons.
Does your Catch Can vent into the bilge or over board ?
Subject to the amount of vacuum, would the dry sump system scavange the cylinder walls ? If so,the piston sprayers would lubricate the walls and pins while cooling the pistons.
Does your Catch Can vent into the bilge or over board ?
12-03-2007, 08:02 PM
#7
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I am not sure on the pressure setting on the Peterson pop-off valve. We don't use a dry sump, but do have the gun drilled pin oiler option in the rods. I also use a wet sump Peterson external oil pump. My catch can vent is rigged over-board.
12-05-2007, 08:07 AM
#9
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Rob,
These 2 pics show the vacuum pump system. The rigging is one-off that we have been polishing in for three seasons. The top view shows the hose connecting the engines at the rear of the valve covers. The front VC fitting on the outside allows you to adjust the max vacuum and the inside "breather" isn't really a breather but it is a pop-off valve to vent pressure in case of a system failure. The catch can separates the oil/air and the 3" black flex hose is connected to a side vent on the out side. The pump RPM ratio is at about 45%.
We have actually made a slight rigging change last winter where the adjustable vacuum level fitting is now mounted right at the pump inlet...new Moroso part...looks cleaner.
These 2 pics show the vacuum pump system. The rigging is one-off that we have been polishing in for three seasons. The top view shows the hose connecting the engines at the rear of the valve covers. The front VC fitting on the outside allows you to adjust the max vacuum and the inside "breather" isn't really a breather but it is a pop-off valve to vent pressure in case of a system failure. The catch can separates the oil/air and the 3" black flex hose is connected to a side vent on the out side. The pump RPM ratio is at about 45%.
We have actually made a slight rigging change last winter where the adjustable vacuum level fitting is now mounted right at the pump inlet...new Moroso part...looks cleaner.
