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Oil vapors and oil lower octane obviously vapors less than oil.
Isn`t that on the suction side where it will be in vacuum? A catch can takes all the oil and vapors to a remote location and keeps them at bay instead of making a mess. Mercury has been running a hose from the carb flange or flame arrestor to the valve cover for decades Hell, even Whipple doesn't include or prescribe a catch can. "While not strictly "required," installing a catch can on a Whipple supercharger engine is highly recommended as it helps to prevent excess oil from entering the intake manifold, which can be especially problematic with high-performance engines like those using a Whipple blower; this is due to the increased crankcase pressure generated by the supercharger. Key points about catch cans and Whipple superchargers:
https://cimg7.ibsrv.net/gimg/www.off...f11f89ff6e.jpg https://cimg8.ibsrv.net/gimg/www.off...d021483d80.jpg https://cimg1.ibsrv.net/gimg/www.off...9fb34345b1.jpg https://cimg6.ibsrv.net/gimg/www.off...11354dab47.jpg |
Originally Posted by ICDEDPPL
(Post 4918405)
Oil vapors and oil lower octane obviously vapors less than oil.
Isn`t that on the suction side where it will be in vacuum? A catch can takes all the oil and vapors to a remote location and keeps them at bay instead of making a mess. On a supercharged engine? Looks like you got it figured out then. "While not strictly "required," installing a catch can on a Whipple supercharger engine is highly recommended as it helps to prevent excess oil from entering the intake manifold, which can be especially problematic with high-performance engines like those using a Whipple blower; this is due to the increased crankcase pressure generated by the supercharger. Key points about catch cans and Whipple superchargers:
Yes. The hose will be connected to the intake side of the ProCharger. That's the whole point. The OEM intake included a vacuum tap on the bottom to do just that. All we've done is remove the potential for positive crankcase pressure due to intake manifold pressure. In other words, we've moved the vacuum tap to where it should be: Where there is always a vacuum. Is the catch can not drawn to by intake vacuum? If it is, I get how oil would be filtered, but how are the vapors "filtered"? If not, where do you get your crankcase vacuum from? I'm not running a vacuum pump. I'm not sure why a supercharger would make a difference, octane reduction aside (I didn't know this little factoid, BTW :ernaehrung004:). If oil in the intake is an issue, I'd think it would be an issue for a NA engine, as well. I would think fuel wash would do a sufficient job of keeping oil from building up on the valves. I could be wrong on that, though. Where is the additional crankcase pressure coming from with a supercharger? Genuine question.... Again, I'm not anticipating literally ANY actual oil in this circuit. Vapors? Yes. Oil? No. I'm fairly certain, if we had any oil making its way to the breather via this hose before, it was only due to the positive crankcase pressure condition present while in boost. That potential is gone. I appreciate the input. And I'm listening. I just want to try and understand, instead of just taking things at face value. It gets complicated when I get conflicting "absolutes" from voices I've learned to trust. Thanks. Brad. |
https://natrad.com.au/info-advice/wh...rged%20engines.
In other words, we've moved the vacuum tap to where it should be: Where there is always a vacuum. Two types of catch cans, remote like I have or inline like the above link. The oil or vapors aren` "filtered" your other questions don`t make sense , google catch can or youtube it to understand how it works. A supercharger creates more positive pressure leading to higher cylinder pressure leading to more blow by . Marine engines should be set up loose clearances especially on the ring package so to say I`ll have no positive crankcrase pressure is just not possible. You`re going to have positive pressure at the engine and negative pressure at the blower opening (unless Im not understanding your set up) so ofcourse it`s going to suck all the oil and vapors in the intake . If you think you`re not going to have positive pressure in the engine you`re dead wrong. n/A engines do not have the octane requirement a blower does, they also do not have positive pressure in the intake so why we talking about N/A engines , has nothing to do with this conversation. That being said here`s my N/A LS3 catch can I added because I don`t want all this **** in my throttle body/intake. I empty that can on the vette every 2 months and it`s full. https://cimg9.ibsrv.net/gimg/www.off...af75b05695.jpg |
Yes, oil or oil mist in the intake of an engine can effectively reduce the octane rating of the air/fuel mixture, as oil has a significantly lower auto-ignition point than gasoline, which can lead to premature combustion and detonation, especially in high-performance engines; therefore, introducing oil into the intake can negatively impact engine performance by essentially lowering the effective octane level. Key points to remember:
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Engines in an enclosed space will draw the local air and consume it, as the engine bay draws from the outside air.
Anything the crank case pushes out through a catch can...minor vapours etc will be diluted and also drawn in. No need to hook up the crank case to the intake vacuum. My BMW 540 V8 PCv system used to fail and suck the oil into the intake like a straw. Failed process and system. |
How an Oil Catch Can Works, And Why You Might Want One
You want one. The blower will push air past your rings and pressurize your crank case with gas/air. That helps to break down the oil along with heat. The oil then vaporizes and leaves as a gas through your valve covers. Factory reburns this to be green. Performance people do not want to burn this crap. You can do a couple of things to keep from re burning it. Vent to atmosphere, vent to a catch can then atmosphere (cleaner engine bay), Send it to your exhaust using to principal you are and using the exhaust to draw a vacuum, Send it to catch can using a vacuum pump (some people even use old smog pumps), or add a catch can in line with what you are doing. It will still re burn the crap (Go Green) but will be filtered and cut down on a lot of the crap. A boat exhaust would be hard to use as extraction point for the most part. Pulling a vacuum in the crank case will give you power but not sure if the negative of re burn is worth the minimal vacuum. If you try yours with a can and do not like the re burn/ or lack of vacuum it provides you can simply pull the line from the can to the intake and put a filter and plug in place. |
Originally Posted by ICDEDPPL
(Post 4918418)
https://natrad.com.au/info-advice/wh...rged%20engines.
So where does the other end of the hose go , one side is intake of blower.. the other side goes ??? Two types of catch cans, remote like I have or inline like the above link. The oil or vapors aren` "filtered" your other questions don`t make sense , google catch can or youtube it to understand how it works. A supercharger creates more positive pressure leading to higher cylinder pressure leading to more blow by . Marine engines should be set up loose clearances especially on the ring package so to say I`ll have no positive crankcrase pressure is just not possible. You`re going to have positive pressure at the engine and negative pressure at the blower opening (unless Im not understanding your set up) so ofcourse it`s going to suck all the oil and vapors in the intake . If you think you`re not going to have positive pressure in the engine you`re dead wrong. n/A engines do not have the octane requirement a blower does, they also do not have positive pressure in the intake so why we talking about N/A engines , has nothing to do with this conversation. That being said here`s my N/A LS3 catch can I added because I don`t want all this **** in my throttle body/intake. I empty that can on the vette every 2 months and it`s full. https://cimg9.ibsrv.net/gimg/www.off...af75b05695.jpg The other end is attached to a fitting in the oil fill cap, which is in the top of a 6-7” tall oil fill tube, which is located in the mounting flange of the intake manifold. If you’re pulling intake vacuum from your crank case, and you have positive crankcase pressure, you have something wrong. Like a broken ring. Hell, with the setup we had before, the only reason I think we had positive crankcase pressure is because we had oil bubbling out the top of the dipstick tube, but only after I’d run under boost. My “other question” is, with a catch can, is there vacuum drawing on it? I mentioned NA because you asked, “On a supercharged engine?” I can’t, for the life of me, understand why boosted or NA would be any different, other than the octane requirement and the potential for octane reduction from oil in the intake (as you’ve indicated). And, for the record, all the old school blower motors I grew up boating with had a vacuum port in the carb flange, with a hose leading to a PCV in the valve cover. Every single one of them. This is essentially what I’ve got, only my engine end connection for the hose is a country mile from any real exposure to incidental oil spatter, like what is present under a valve cover. I can say I’m not going to have any crankcase pressure because I’m drawing a vacuum on it. At the end of the day, if we see any indicators of a significant amount of oil getting into the intake tract, I can add a catch can. In the mean time… Thanks. Brad. |
Originally Posted by Tartilla
(Post 4918421)
Engines in an enclosed space will draw the local air and consume it, as the engine bay draws from the outside air.
Anything the crank case pushes out through a catch can...minor vapours etc will be diluted and also drawn in. No need to hook up the crank case to the intake vacuum. My BMW 540 V8 PCv system used to fail and suck the oil into the intake like a straw. Failed process and system. Yup. I remember watching my dad change the PCV valve on the blower motor I grew up skiing behind. It had a vacuum line between the carb flange and the valve cover, where the PCV valve was. He would notice a loss of oil, and that was his sign it needed changed. I think he replaced it every year, regardless, but, once or twice over the years, they would go bad mid summer and he’d have to spend the 24 seconds it took to change it. Otherwise, we ran that engine for years and did nothing but change the oil and plugs every year. The first year we actually had to pull the engine (an unfortunate incident involving a log and a cracked hull at the prop strut), I can remember looking down inside the blower, and there was no sign of oil or any kind. Thanks. Brad. |
Originally Posted by zfrilly
(Post 4918423)
How an Oil Catch Can Works, And Why You Might Want One
You want one. The blower will push air past your rings and pressurize your crank case with gas/air. That helps to break down the oil along with heat. The oil then vaporizes and leaves as a gas through your valve covers. Factory reburns this to be green. Performance people do not want to burn this crap. You can do a couple of things to keep from re burning it. Vent to atmosphere, vent to a catch can then atmosphere (cleaner engine bay), Send it to your exhaust using to principal you are and using the exhaust to draw a vacuum, Send it to catch can using a vacuum pump (some people even use old smog pumps), or add a catch can in line with what you are doing. It will still re burn the crap (Go Green) but will be filtered and cut down on a lot of the crap. A boat exhaust would be hard to use as extraction point for the most part. Pulling a vacuum in the crank case will give you power but not sure if the negative of re burn is worth the minimal vacuum. If you try yours with a can and do not like the re burn/ or lack of vacuum it provides you can simply pull the line from the can to the intake and put a filter and plug in place. How does drawing crankcase vacuum increase power? I’ve always understood it that a crankcase vacuum is to prevent excessive oil consumption. Thanks. Brad. |
If you’re pulling intake vacuum from your crank case, and you have positive crankcase pressure, you have something wrong No need to answer,I`m done arguing with you , I got better **** to do. 3 people tried to explain this to you , I gave you all the info , pictures and links you needed and then some but I wasted my time because after all the proof you still are like you`re all dummies I know better because my dad changed a PCV valve on a ski boat .:rolleyes: I can’t, for the life of me, understand why boosted or NA would be any different How do you not get that you will have positive pressure in the crankcase and negative pressure in the intake and that means that all the oil and vapors will be getting sucked into the emngine , I mean this is 5th grade physics. Blow into a hose and it comes out the other end , it`s not rocket science. Everything I referenced says put a fuking catch can on it but you know best so good luck. |
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