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Pan Evac question

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    Manage MacTilley Racing Dry docked's Avatar
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    Default Pan Evac question

    Thinking about changing the small puke tank on SE61 SBC to a pan evacuation system. Running the engine WOT with open headers; do I need to install the check valves?
    I brought the boat to Needles last weekend and a few guys recommend I do this. Welcome any input.
    Thank's Dave.

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    Quote Originally Posted by Dry docked View Post
    Thinking about changing the small puke tank on SE61 SBC to a pan evacuation system. Running the engine WOT with open headers; do I need to install the check valves?
    I brought the boat to Needles last weekend and a few guys recommend I do this. Welcome any input.
    Thank's Dave.

    Dave, all crank cases need to be vented. I've successfully run a collector based pan EVAC system on my boat for years now. I have no problems with oil leaks because of crank case pressures and the oil will stay clean for 2 summers of run time.
    Yes, you need to run flash valves at the collectors. They negate the possibility of flame traveling back down the EVAC hose and igniting the oil vapor in the crank case.
    Also, for what ever volume of air that you try to pull out of the crank case you must replace that volume with fresh (preferably clean filtered) air. I've always run a vent at the front of each valve cover and the EVAC hose at the rear of the cover. Not the most effective set up. I've considered running a 1" vent on the front of one valve cover and a 1" EVAC tube on the front of the other cover and a 1" by 1/2" by 1/2" tee that splits off into each collector (most EVAC systems run 1/2" pipe fitting in each collector with a flash valve on each). That way you are not collecting as much oil vapor as you would by having the EVAC discharge point at the back of the covers (oil has a tendency to move to the back of the covers under hard acceleration).
    Rob
    Last edited by White Lightning; 03-05-2016 at 11:02 AM.

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    Senior Member Bubbletop409's Avatar
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    Why would you want to add a vent to a system that is designed to create negative pressure?
    Larry

    62 Bel-Air 409

    260 Eagle XP HP500EFI

    2016 Corvette Z51

    79 Cole TR-2 Sunset Racecraft 565 (RIP Tracy)

    Remember in November

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    Quote Originally Posted by White Lightning View Post
    Dave, all crank cases need to be vented. I've successfully run a collector based pan EVAC system on my boat for years now. I have no problems with oil leaks because of crank case pressures and the oil will stay clean for 2 summers of run time.
    Yes, you need to run flash valves at the collectors. They negate the possibility of flame traveling back down the EVAC hose and igniting the oil vapor in the crank case.
    Also, for what ever volume of air that you try to pull out of the crank case you must replace that volume with fresh (preferably clean filtered) air. I've always run a vent at the front of each valve cover and the EVAC hose at the rear of the cover. Not the most effective set up. I've considered running a 1" vent on the front of one valve cover and a 1" EVAC tube on the front of the other cover and a 1" by 1/2" by 1/2" tee that splits off into each collector (most EVAC systems run 1/2" pipe fitting in each collector with a flash valve on each). That way you are not collecting as much oil vapor as you would by having the EVAC discharge point at the back of the covers (oil has a tendency to move to the back of the covers under hard acceleration).
    Rob
    Why would air need to be vented for a Pan Vac?
    I've run a Pan Vac for years without a vent without problems, that I'm aware.
    While I think Pan Vac's are beneficial, they aren't super powerful.

    I've also connected my Pan Vac into the forward part of both valve covers, because as you say, during acceleration the oil wants to go to the back of the cover, which is away from the Pan Vac mounting location.
    Last edited by jimsplace; 03-05-2016 at 01:05 PM.

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    Manage MacTilley Racing Dry docked's Avatar
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    Thanks Rob for the explanation, very we'll said. I didn't think I needed them until you mentioned the word fire.

    To to me this is about oil mess control. We have a classic Stevens v-drive with a 389 Pontiac, after a hard days run we spend hours cleaning up the oil. Just trying to avoid that with this boat.

    Dave

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    Quote Originally Posted by jimsplace View Post
    Why would air need to be vented for a Pan Vac?
    I've run a Pan Vac for years without a vent without problems, that I'm aware.
    While I think Pan Vac's are beneficial, they aren't super powerful.

    I've also connected my Pan Vac into the forward part of both valve covers, because as you say, during acceleration the oil wants to go to the back of the cover, which is away from the Pan Vac mounting location.

    2 words: Oil contamination.
    Unless you are running a competition only closed crankcase with a vacuum pump then the crankcase needs to be vented. Back in the day the crankcases were vented with a road draft tube. Extremely inefficient at getting rid of contaminating vapors from the combustion process that gets past the rings. Not having a slight negative pressure in the engine also allow the engine to tend to weep oil past gaskets.
    Vacuum pumps are for competition only. They are designed to help a set of low tension rings seat against the cylinder wall....cutting down frictional losses and helping to keep as much combustion pressure in the cylinder where it can do all the work possible. It's a sealed system with no way to effectively get rid of oil contaminating vapors. That type of system requires the oil to be changed quite often.....such as daily.....after the race day is done.
    As far as having enough flow goes......look at an automotive PCV system. Most only use a hose that is 3/8" or 7/16" ID and a PCV valve that flows very little at any given time. A system like that is good enough to keep the oil clean for several thousand miles of use. A header EVAC system uses 2 1/2" lines and far out flows one PCV valve.
    Rob
    Last edited by White Lightning; 03-06-2016 at 08:55 AM.

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    I have. Pan Evac set up no vent makes 11 pounds of vacuume and was worth about 20 hp on the dyno at wot and I change my oil once a season

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    Quote Originally Posted by tbscustoms View Post
    I have. Pan Evac set up no vent makes 11 pounds of vacuume and was worth about 20 hp on the dyno at wot and I change my oil once a season

    If you're making 11 inches of vacuum, how much oil pressure are you losing? More than what is good I'd venture to say. Are you running low tension rings? If you're not then there's no reason to put a crankcase under that much vacuum, unless you're trying to prevent leaks, even then there are special seals that are needed to go with the system.
    The recommended vacuum is right about ~6 inches.
    Sealed crankcase vacuum systems are designed to have a regulator valve in the system so that excessive vacuum is not reached.
    There is only one right way to do it.
    Rob
    Last edited by White Lightning; 03-06-2016 at 10:34 AM.

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    My 565 was built with standard tension rings, when it was dynoed at SunsetRacecraft it made it made 797.2 HP. When dynoed with a vacuum pump it made 824.5 HP, no other changes. So I would think with low tension rings my power level would have been even higher. My engine now has six seasons, tall valve cover breathers mounted on the intake side of the valve covers, and have yet to see a drop of blow by oil or mist. I don't believe a pan evac is going to help an engine that needs attention else where with oil control.

    And regarding your question on how much oil pressure is being lost while using a negative pressure oil system, my dyno sheet shows a .7 lbs. oil pressure difference, I'd gladly give up .7 PSI for the additional 27.3 HP.
    Last edited by Bubbletop409; 03-06-2016 at 12:22 PM.
    Larry

    62 Bel-Air 409

    260 Eagle XP HP500EFI

    2016 Corvette Z51

    79 Cole TR-2 Sunset Racecraft 565 (RIP Tracy)

    Remember in November

    Well done USN Seal Team 6

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    Distinguished Member David 519's Avatar
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    Quote Originally Posted by White Lightning View Post
    If you're making 11 inches of vacuum, how much oil pressure are you losing? More than what is good I'd venture to say. Are you running low tension rings? If you're not then there's no reason to put a crankcase under that much vacuum, unless you're trying to prevent leaks, even then there are special seals that are needed to go with the system.
    The recommended vacuum is right about ~6 inches.
    Sealed crankcase vacuum systems are designed to have a regulator valve in the system so that excessive vacuum is not reached.
    There is only one right way to do it.
    Rob
    Old school thinking here, at least for any performance engine. Bubbletop's 565 shows a very typical HP benefit to a vacuum pump and is definitely a worthwhile upgrade to the OP's engine. There is no downside to a vacuum pump and you don't need special seals. Back in the day, we ran pan evacs before vacuum pumps were common and they could generate decent vacuum.
    To the OP, on my circle boat, I run breather vents to a puke tank as you sit so close to the motor, the fumes bugged my wife(it's mostly a play boat now but is still a legal SS). On the drag boat, always a vacuum pump except on blown motors. Pics of my set ups

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    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

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    [QUOTE=David 519;4079225]Old school thinking here, at least for any performance engine. Bubbletop's 565 shows a very typical HP benefit to a vacuum pump and is definitely a worthwhile upgrade to the OP's engine. There is no downside to a vacuum pump and you don't need special seals. Back in the day, we ran pan evacs before vacuum pumps were common and they could generate decent vacuum.
    To the OP, on my circle boat, I run breather vents to a puke tank as you sit so close to the motor, the fumes bugged my wife(it's mostly a play boat now but is still a legal SS). On the drag boat, always a vacuum pump except on blown motors. Pics of my set ups
    QUOTE]

    While I don't disagree with a vacuum pump being beneficial, I think the OP was asking about using a Pan Vac.

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    Default Pan Vac

    This is the puke tank system I currently have. I am planning on removing the tank and turning the hoses into the headers to burn off the oil and allow better access to the distributor.
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    Senior Member Bubbletop409's Avatar
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    QUOTE]

    While I don't disagree with a vacuum pump being beneficial, I think the OP was asking about using a Pan Vac.[/QUOTE]


    Exactly, and while I was not attempting to advocate a vacuum pump, I was trying to show that vacuum in the crankcase does indeed provide free power. And to have vacuum with a Pan Vac system you need a sealed crankcase.
    Last edited by Bubbletop409; 03-06-2016 at 09:23 PM.
    Larry

    62 Bel-Air 409

    260 Eagle XP HP500EFI

    2016 Corvette Z51

    79 Cole TR-2 Sunset Racecraft 565 (RIP Tracy)

    Remember in November

    Well done USN Seal Team 6

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    Quote Originally Posted by White Lightning View Post
    Quote Originally Posted by tbscustoms View Post
    I have. Pan Evac set up no vent makes 11 pounds of vacuume and was worth about 20 hp on the dyno at wot and I change my oil once a season

    If you're making 11 inches of vacuum, how much oil pressure are you losing? More than what is good I'd venture to say. Are you running low tension rings? If you're not then there's no reason to put a crankcase under that much vacuum, unless you're trying to prevent leaks, even then there are special seals that are needed to go with the system.
    The recommended vacuum is right about ~6 inches.
    Sealed crankcase vacuum systems are designed to have a regulator valve in the system so that excessive vacuum is not reached.
    There is only one right way to do it.
    Rob

    I don't know when the last time you played with Vacuume on a dyno was or what crap oil pump you had but on my 540ci bbc we pull 30 inches of vacuume and my dry sump pump runs oil psi at 60 pound of oil
    And that's with piston Oilers and spray bars on the valve covers

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