What Is Acceptable Crankcase Suction
 

Does anyone use a vacuum pump or dry sump pump to produce crankcase vacuum ?

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.

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 ?

- 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.

Cat,
Missed one question...no measurable vac at idle...no impact. 3-5" is all I get at all RPM's with one pump on twins

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 ?

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.

do you have a pic of youre set up , i like to see it , where i you get youre set up from ? very intereste in the rigging !!

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.

Forgot one picture...

We were one of the first to run vacuum pumps in B class. I use them all the time when the customer can afford to run them. Horsepower gains on a N/A engine we have seen as much as 40 depending on how much Vac. is being pulled on the crankcase. With my drag race engines I pull as much as 40 inches. ( such as Pro Stock)

help me out here .... one belt driven pump ...the motors are tied together via rear valve covers ... I see the pop-off valve on the starboard side of the valve covers then on the port side looks like regular breather ? ... Are we talking mega HP motors here or is there an advantage for 550-600hp ? m

In these pictures the pop-off valves are on the SP and PS VC. The vacuum contol valves (holds vacuum @ max level by leaking air) are on the SP and PP VC. As rigged, you only really need one of each valve.
In my experience/testing, there is no significant HP gain with a vacuum pump up to 6800 RPM with standard tension oil rings.
Why do it?...you wouldn't if +HP is your primary goal.

What do you think of using a 5 stage dry sump pump that pulls 10 - 11"@ 6,000... Piston sprayers to lubricate the walls and cool the bottom of the pistons, DLC coated wrist pins, Valve spring sprayers and Lifter sprayers ? Oil pan w/ Nascar screens on each pickup line and a valve on top of each valve cover, capped and shrouded w/ a Moroso screened cap ? The valve is to close with vacuum and open w/ 2 - 3 oz. of positive pressure. At RPM the valve closes as vacuum is introduced and @ low idle may open, subject to ring clearance. While one valve would suffice, two valves are thought to flow volume that should accommodate a burned piston. Thus, safe guarding against a pressurized explosion in the pan. The MILITARY SPEC valve is designed to be trouble free for an extended period of hours.

The oiling /vacuum system may also stabilize piston rock, scavenge oil causing, parasitic drag ,oil aeration and add horsepower. Oil pressure stabilization may also be improved.

i thought the engine required to be air tight to function ? i see youre running a breather , d oes this still work ? im no pro , just researched a little , and talked with rm builer on this subject recently im confussed ? does this pull air from one side an then exits through the pump? i thought you sealed complete engine incluing the dipstick witch losses vacumm .

also ive read to only pull 15 inches or less or could have oiling issues ? Do you run a vacumm Gauge on the dash to see / make sure youre vacumm stays below this amount very interested rigging looks good !!

If you are using a standard tension ring pack, decide how much you are spending on a vacuum system for maybe +5 HP. A dry sump oil pump system also adds little to no additional HP with a lot of cost. I think good oil control can be obtained with a well designed wet sump system for a lot less $$ at a 6000-6500 RPM max operating range.
What you are proposing/doing is top shelf...just expensive :D

Rob,
Those are not breathers...just look like ones. They are one-way "pop-off" pressure valves...only open if the system pressurizes/fails.

These pics show some of what I am talking about.

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Ben, We have gone back and looked at your rigging several times....Very professional ! Now we appreciate more about what Benperfected represents.

Nice oil cooler brackets,Thats some trick water outlet/inlet fitting!!:D

Thanks Strip Poker, trying to move volume @ low pressure.

Incidently, is that a Wankle in Santa's Sliegh....looks like a rotory eccentric.....should pull a load.:D