FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Fordman on May 01, 2018, 07:43:26 PM
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For an FE application what would those in the know recommend for a oil tank size?. Can someone also explain the differences/advantages of 3/4/5 stages dry sump pumps?. I am only assuming it is nothing more than the amount of plumbed pickups in the oil pan?. Any other recommendations are appreciated...John
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The size of the tank depends on the application: drag race, road race, pulling truck, etc.
The number of stages is the number of scavenge points plus the "push" side. So for instance, if you have 3 pickups in the pan, 1 from the lifter valley or valve cover, and then a pressure side, then you have a 5 stage oil pump: 4 sucks and 1 blow.
Some pumps are strong enough that they will act as a vacuum pump as well, so you can have 3 pickups in the pan, 1 scavenge point in the lifter valley, and then a point that acts as a vacuum point. That would be a 6 stage pump.
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Are you building the first Comp Eliminator FE John :)
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There are SERIOUS packaging considerations involved.
Have you seen/measured a 5-6 stage pump.
Do you know where you're going to put the tank (in the passenger compartment)?
And then all the hoses/plumbing...
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I've been running a six stage on the SOHC in my Shelby clone for the last several years. Three pickups in the pan, one at the back of each head, plus the pressure stage. I was told by the dry sump folks (Peterson Fluid Systems) that this would give me plenty of crankcase vacuum. That turned out to be BS, it will deliver some vacuum at idle but not when the engine starts running at higher engine speeds. I was always able to get 15 inches of vacuum with my GZ Motorsports vacuum pump. For the cost, weight, and complexity of the dry sump system, and no crankcase vacuum to speak of, I'm very disappointed in it. I'm going back to a normal FE oil pump and pan, a vacuum pump, and an accumulator (Accusump) to ensure oiling under all conditions.
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I plumbed an Accusump into my street FE more than 15 years ago. As part of the starting procedure I'd trip the solenoid, watch the pressure come up, and hit the start button with max pressure showing. With the Holley EFI and a good hot Mallory ignition, it'd start instantaneously. When I'd pull the bearings, they almost looked like new.
KS
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There are SERIOUS packaging considerations involved.
Have you seen/measured a 5-6 stage pump.
Do you know where you're going to put the tank (in the passenger compartment)?
And then all the hoses/plumbing...
All of that is good truth. It's a very large package and the fittings/hoses are -12 and -16 usually.....and are not cheap. This engine has over $1000 in fittings/hoses alone.
(https://farm1.staticflickr.com/804/41405378832_51b2fc857c_c.jpg)
(https://farm1.staticflickr.com/789/40755668014_b8bc4604d6_c.jpg)
BTW Jay, I've seen dry sump pumps from Aviaid/Peterson pull up to 15-16 inches of vacuum with no external vacuum pump. Are you sure you don't have a way that air is getting in somewhere?
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If I had an air leak, why does my GZ vacuum pump pull 15" on the same engine?
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Good question. ;D
Where is the GZ pulling from? Same spot?
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No, it is pulling from the valve cover since it only has one vacuum inlet.
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Hmm. Trying to think of what the difference would be. On some of the pulling truck engines, the dry sump pumps can pull so much vacuum that the owners are advised to allow some air in when not running hard so that some oil can get to the wrist pins and other areas.
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Peterson has told me that there are some engines where they just don't get a lot of vacuum. That is why they are now offering a Star vacuum pump as an add-on to the dry sump systems. I just spoke with a Super Stock racer over the weekend and he's had the same experience as me. Maybe big block vs. small block or something? Regardless, no more dry sump for me...
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Hmm. Trying to think of what the difference would be. On some of the pulling truck engines, the dry sump pumps can pull so much vacuum that the owners are advised to allow some air in when not running hard so that some oil can get to the wrist pins and other areas.
If you're scavenging a lot of oil then the "vacuum" that a dry sump will produce will be minimal. Dry sump systems are not made to create crank case vacuum. If you get some as a byproduct, that's just a bonus. The more oil in the scavenge lines, the less vac it will pull. I pulled 14" on the 611 BBF I built with very leaky (Chinese) valve covers but we ran one scavenge to the valve cover strictly for vac. Had three in the pan, one in the lifter valley and one in the valve cover. Owner of the engine added a vac pump and went to 22", picked up 40hp on the dyno. Some pumps are also better than others and there are different rotor designs. "Starving the wrist pins" is an old wives tale. In a race deal you really can't pull "too much" vacuum. If you're getting 80% barometer you have a very well sealed up engine. If you're galling wrist pins, it's not from the vacuum, but that's another discussion all together.
I agree with Dumpling...plumbing and packaging is a big concern with dry sump systems. I would never depend on a dry sump for vacuum unless you're using one stage dedicated for that. Also, a dry sump has it's own challenges and is not a bolt on cure-all for oiling system issues. A good wet sump design is a lot simpler and can serve the oiling needs of any engine if set up right.
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Sometimes the wives' know what they're talking about though.....
Pulling a lot of vacuum on the crankcase can wick oil away from the wrist pins and other areas. Switching to a DLC coated tool steel wrist pin with .002-.0025" clearance will usually curb it, but high amounts of vacuum can cause wear there.
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Sometimes the wives' know what they're talking about though.....
Pulling a lot of vacuum on the crankcase can wick oil away from the wrist pins and other areas. Switching to a DLC coated tool steel wrist pin with .002-.0025" clearance will usually curb it, but high amounts of vacuum can cause wear there.
The only way vacuum will pull anything away form anywhere is if you have a big leak and you're creating an air stream through the engine. Evidence of that is a lot of oil in the breather/catch can. If the engine is sealed up and all you're doing is creating a depression, then there is no air movement...nothing is going anywhere, nothing is being sucked off of anything and the catch can will stay relatively dry. Usually what happens is; with more vacuum, we have more potential rpm and more power...light weight wrist pins, lack of clearance, poor piston design...all start showing their ugly little heads when they get pushed a little harder and things start flexing a little more. Heavier wall wrist pins, coatings, better piston design and/or a little more clearance usually solve the problem but it's not from oil being taken away. Fix those problems and run as much vacuum as you can. It frees up a LOT of power. I have a customer with a 1K HP BB Chev that he drives on the street regularly and pulls 22" hg, usually 15-18 cruising. Going on 5 yrs now. Engine turns 8K when he wants to. Plenty of other similar examples. If oil starvation was the problem, more clearance wouldn't help. I think .002" is a little excessive, but it might be what it takes if wrist pins are flexing or pin bores collapsing. If the parts are good, clearance is usually not an issue. I usually run .0010-.0012 on the rods and .0009 -.0010 in the piston (cold). Little more on big power stuff. Never ever had a wrist pin issue.
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Cool, man.
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High vacuum does contribute to wrist pin galling. Nascar engine builders found that out 15+ years ago. Many different combinations of pin oiling were tried and it was DLC coating that saved the day. They also found that vacuum in excess of 16"s didn't improve power in a "cup" engine. On a 351 style block an Autoverde ( for example) 5 or 6 stage pump can pull big vacuum numbers. Different dry sump gear styles have different efficiency levels too. Some do have a tough time pulling a vacuum. As the engine displacement and crank case volume increases a secondary vacuum pump is usually required.
I agree with Scott that a dry sump is not a "tremendous advantage" over a wet sump ( that keeps the pick up covered in oil) Some racing styles make a dry sump a necessity.
Randy
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If there are no leaks and you can't pull vacuum with a 5-stage pump, there are ring sealing issues. I have one running a 5-stage pump that I can get 16 inches if I want it. I prefer to regulate it to 12 inches because wrist pin galling is a real issue over the long haul. When the oil on the cylinder wall is minimized by the vacuum, the forced pin oilers in the oil ring groove just don't have as much oil to lube the pins, and the oil splash is less. Brent is correct that coated pins are a good practice for high vacuum. I dynoed a 4-stage dry sump in March that pulled 6 inches of vacuum. If the rings are sealed and it ain't sucking air........a good dry sump should pull vacuum. If the rings leak more than the pump can overcome, there will be no vacuum.
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If there are no leaks and you can't pull vacuum with a 5-stage pump, there are ring sealing issues. I have one running a 5-stage pump that I can get 16 inches if I want it. I prefer to regulate it to 12 inches because wrist pin galling is a real issue over the long haul. When the oil on the cylinder wall is minimized by the vacuum, the forced pin oilers in the oil ring groove just don't have as much oil to lube the pins, and the oil splash is less. Brent is correct that coated pins are a good practice for high vacuum. I dynoed a 4-stage dry sump in March that pulled 6 inches of vacuum. If the rings are sealed and it ain't sucking air........a good dry sump should pull vacuum. If the rings leak more than the pump can overcome, there will be no vacuum.
How is oil on the cylinders minimized by vacuum?
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Did you really just ask that question?……..........there is a tornado around the crankshaft. There are three (usually) or more scavenge lines plugged in the oil pan. They are pulling oil out of the tornado constantly. The splash that is normally created from the oil bleeding out of the bearings is bathing the cylinders with oil. Remove part of that mass of oil....remove some of the oil on the cylinder wall. Oil ring 101....the oil ring digests the oil from the cylinder bore and sends it to the underside of the piston via windows or holes in the groove. Good pistons also have forced pin oilers ducting from the oil ring groove. All of the oil picked up by the oil ring is sent to the wrist pin......either by forced oilers or by the "windows" behind the expander. If you reduce the splash, you reduce oil to the cylinders, and oil to the pins.
Really high vacuum apps have pressure fed pin oiling through the rod beam from the rod bearing source.
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Did you really just ask that question?……..........there is a tornado around the crankshaft. There are three (usually) or more scavenge lines plugged in the oil pan. They are pulling oil out of the tornado constantly. The splash that is normally created from the oil bleeding out of the bearings is bathing the cylinders with oil. Remove part of that mass of oil....remove some of the oil on the cylinder wall. Oil ring 101....the oil ring digests the oil from the cylinder bore and sends it to the underside of the piston via windows or holes in the groove. Good pistons also have forced pin oilers ducting from the oil ring groove. All of the oil picked up by the oil ring is sent to the wrist pin......either by forced oilers or by the "windows" behind the expander. If you reduce the splash, you reduce oil to the cylinders, and oil to the pins.
Really high vacuum apps have pressure fed pin oiling through the rod beam from the rod bearing source.
I thought the scavenge lines pulled oil from the pan, not off the crank. That doesn't make sense.
The "tornado" around the crank is an oil mist, not raw oil. The raw oil that gets thrown off the crank onto the cyl walls and back into the pan still does the exact same thing and in fact does it more effectively since there is less atmosphere in the crankcase. I think too many associate the word "vacuum" with the "vacuum" that you clean your house with. Unless you have a massive leak or tons of blow by, the word "vacuum" is really the wrong word. We should be saying depression. We are describing the atmospheric condition inside the crankcase, not the "action" of "sucking". There is "sucking" going on, but it's not "sucking" oil off the wrist pins and it's not "sucking" oil off the crank.
Very VERY few engines have rod beams with oil holes.
Some guys get this, some don't.
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The oil system is pressurized. So Scott, you're saying that vacuum has no effect on pressure? That the vacuum is not pulling oil out of the cranks pressurized oil paths? If it is being pulled out, where is it being pulled to? Even to a dummy like me, that would seem to be apparent.
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The oil system is pressurized. So Scott, you're saying that vacuum has no effect on pressure? That the vacuum is not pulling oil out of the cranks pressurized oil paths? If it is being pulled out, where is it being pulled to? Even to a dummy like me, that would seem to be apparent.
Doug
its more complex than you may think - but Scott has a legitimate point.
A vacuum is a measure of comparative pressure, and does not imply air (or fluid) movement. In a perfectly sealed container with a given volume of fluid, holding a vacuum on it will not cause any movement at all. The function of creating that vacuum will require mass movement and that is where the fun begins. If the creation of that negative pressure is a one time isolated event, the movement is going to be nominal over time. If creating and maintaining that depression requires a lot of work (leaks in the system) you will certainly have movement.
All engines are imperfect in terms of sealing, and will thus have some degree of leakage, meaning that some flow through the system is inevitable. Whether that is enough to have a significant impact on oiling and durability is where perceptions and opinions diverge. Its common to use NASCAR derived comparisons, but those folks actively manage oiling, trying to have the least possible amount of oil in some areas and to intentionally flood others - - not a valid comparison to anything normal in our world.
I do know that having a vacuum will improve ring sealing to the point that many racers will go down on ring tension and make even more power. I also know that if your clearances are a half a thou too loose nobody will ever know, half a thou too tight everybody will know....
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The oil system is pressurized. So Scott, you're saying that vacuum has no effect on pressure? That the vacuum is not pulling oil out of the cranks pressurized oil paths? If it is being pulled out, where is it being pulled to? Even to a dummy like me, that would seem to be apparent.
No, oil is not being "pulled out". Pressure differential, Doug. It's only being "pulled out" if there is less pressure in the crankcase than in the pump. 22"hg is not the low side of 50 psi. The oil is still being pushed although with less resistance. Think about where the oil pressure gauge is reading... it's not inside the crankcase. "Low oil pressure" is another misunderstood (non-issue) with vac pump. Oil is still flowing, still getting where it needs to get to, still doing it's job.
1 inch of mercury = 0.49109778 pounds per square inch so if we have 20"hg in the crank case and we started with 50psi oil pressure, we still have over 40psi measured oil pressure...but we've done nothing to the volume or flow of oil except maybe increase it. Remember that pressure is a measure of resistance and we've reduced the resistance by changing the pressure D.
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One thought, if you put a liquid under vaccum you lower its
boilingpoint could it bee that the oil at the pins that's not under pressure
are boiling at a certain vaccum and loose it lubrication ability?
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One thought, if you put a liquid under vaccum you lower its
boilingpoint could it bee that the oil at the pins that's not under pressure
are boiling at a certain vaccum and loose it lubrication ability?
From what I've seen and learned...and this is just me, now...I know I'm not the sharpest knife in the drawer here...but when rigidity was increased in the system of parts, it seemed to solve the problem believed to be associated with a lack of oil.
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Well i dont know just a thought i had , The aluminium in the
piston transfer heat to the pistonpin vaccum lower the boiling
point. I guess a nascar pin runs hotter than a Dragracing pin
atleast have longer time to heat up for sure
I dont know at what temp oil boils under say 20 or 30 inch/hg
or what temp a piston pin see so i can be at the wrong trail
Im just a selfthought backyard mecanic
Only drysump experiace i have is from brittish motorcycles
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A little off the main topic, but, a six stage pump PLUS a dedicated vacuum pump, what kind of load does that put on the crank snout?
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A little off the main topic, but, a six stage pump PLUS a dedicated vacuum pump, what kind of load does that put on the crank snout?
Not as much as you might think. Consider the size of an oil pump drive shaft
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I sit here and read this stuff---say 'yup' and 'nope' (and hope I'm right at least part of the time) and just grin and take it in and learn sumthin'. ;D
KS
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A little off the main topic, but, a six stage pump PLUS a dedicated vacuum pump, what kind of load does that put on the crank snout?
I do know that a vac pump takes less than 2hp to run. Don't know about the dry sump. Kinda depends on ratio/pump speed, oil pressure, etc. and some pumps are more efficient than others by design. I agree with Barry...it's not a lot.
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I've been running a six stage on the SOHC in my Shelby clone for the last several years. Three pickups in the pan, one at the back of each head, plus the pressure stage. I was told by the dry sump folks (Peterson Fluid Systems) that this would give me plenty of crankcase vacuum. That turned out to be BS, it will deliver some vacuum at idle but not when the engine starts running at higher engine speeds. I was always able to get 15 inches of vacuum with my GZ Motorsports vacuum pump. For the cost, weight, and complexity of the dry sump system, and no crankcase vacuum to speak of, I'm very disappointed in it. I'm going back to a normal FE oil pump and pan, a vacuum pump, and an accumulator (Accusump) to ensure oiling under all conditions.
Jay, are you using the new R4 pump design? I use a 5 stage R4 pump on my race engines and I can usually pull more than 10 inches. I'd think a 6 stage would pull a little more.
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I also built my own billet pan with extra thick rails to eliminate leaks and to reduce the thickness.
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Lots of folks here smarter than I am, but still seems that the biggest "leak" is going to be past the rings. I'd have to think that would affect the oiling available on cylinders, which is what feeds the pins, at least on some scale.
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Lots of folks here smarter than I am, but still seems that the biggest "leak" is going to be past the rings. I'd have to think that would affect the oiling available on cylinders, which is what feeds the pins, at least on some scale.
Part of what a vac pump is supposed to do is reduce that "leak" by increasing ring seal. If it doesn't, then something else is wrong and it's not doing what it's supposed to do. If you have a lot of blow-by, a vac pump isn't going to fix it.
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I didn't say "a lot" of blow-by. On a well sealed engine, it's still going to be the biggest source of incoming air. If there were no air movement, as you suggested by calling it a depression, then there would be no need for a catch can.
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I didn't say "a lot" of blow-by. On a well sealed engine, it's still going to be the biggest source of incoming air. If there were no air movement, as you suggested by calling it a depression, then there would be no need for a catch can.
Agree in principal. Now expand that thought to look at the differences between pulling the vacuum from a valve cover (vacuum pump) versus from the oil pan (dry sump). One would be pulling upward on vapor only, the other would be pulling downward on the oil return level in the pan. I would imagine that there would be a difference but have zero data to compare... Anyone?
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If the rings were the biggest source of incoming air, it wouldn't matter much where the vacuum is being pulled from, it still has to travel down the cylinder and into the crankcase before it can go into the upper part of the engine. I have zero experience with this stuff, just trying to reason it out.
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I didn't say "a lot" of blow-by. On a well sealed engine, it's still going to be the biggest source of incoming air. If there were no air movement, as you suggested by calling it a depression, then there would be no need for a catch can
OK, no argument there.
Not sure I get your point. I didn't suggest there would be no movement. A depression does not suggest "no movement". But, to follow your thinking, how much blow by would you expect on a well sealed n/a engine without a vac pump...say, in CFM? Lets say a 500hp 400ci engine at 6000rpm?
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I didn't say "a lot" of blow-by. On a well sealed engine, it's still going to be the biggest source of incoming air. If there were no air movement, as you suggested by calling it a depression, then there would be no need for a catch can.
Agree in principal. Now expand that thought to look at the differences between pulling the vacuum from a valve cover (vacuum pump) versus from the oil pan (dry sump). One would be pulling upward on vapor only, the other would be pulling downward on the oil return level in the pan. I would imagine that there would be a difference but have zero data to compare... Anyone?
There is no difference as far as vacuum is concerned. We've experimented with pulling from just about everywhere in the engine thinking that by pulling from somewhere in the crankcase, we had a more direct path to the back of the piston. Doesn't work that way. The only difference with the dry sump is, it can pull oil and not be a problem. If you try to pull vacuum from anywhere else in the engine except the valve cover, it's almost impossible to not pull oil, and a LOT of it. It's not raw oil that's the problem, either, it's the oil vapor. Talked to Stan at Stef's at length about this. They've tried about every oil baffle/screen/mesh/foam combination lower in the engine and it always ends up the same. Pulling too much oil and the vac pump doesn't work as well trying to move the oil. Kind of like a dry sump scavenge line full of oil doesn't pull much vacuum. Everyone I know who uses a vac pump and wet sump says the best place to pull vac is the valve cover. The crank case will "equalize".
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We may all be saying the same thing, and then again, we may all be saying something different. Either way, I don't feel the need to perpetuate an argument, because we are all basically just bench racing here, and some of us here would carry this argument into 2019. Here are some random thoughts, not in any order, and I'm not expecting (or really wanting at this point) a response.
1. A dry sump scavenge line isn't always sucking pure oil. There will be times where it will be picking up air, that's why your dry sump tanks are screened/baffled so that the air
and oil is separated. To compound that, in situations where you have a scavenge point in a lifter valley or similar, there will be times where it will be pulling a LOT of air.
Randy Gillis emailed me yesterday about this and I don't think he would mind if I shared an excerpt from his email:
"One of the cup teams I worked with at JE had a "pan camera" and logged data with varying vacuum numbers. The amount of oil "on the lens" changed dramatically with increased vacuum ( less with higher vacuum) , to the point where it wasn't too blurry at 16"s."
Cup engines have multiple scavenge points from both the crankcase, enclosed cam tunnel, lifter valley, valve covers, etc. If they have placed a lens on the oil pan where they are scavenging from, then Randy's quote backs up what some of us are saying about "pulling oil away" from critical engine parts and backs up Blair's tornado analogy. In a sense, the pump does act like a big vacuum cleaner in that respect.
2. Wearing wrist pins because of vacuum *is indeed* an issue, and is not only caused by poor parts selection or quality.
We all know who David Reher is, right? A quote from him regarding wrist pins, oiling, etc:
"Wrist pin problems were rampant in Pro Stock several years ago, and the cure was to apply some very expensive coatings. Spending $800 for coated pins is not a cost-effective solution for most sportsman racers, however; the object is to make as many runs as possible at a reasonable price. Assuming that the wrist pins have adequate strength, it’s possible to head off many problems simply by ensuring that the pins have adequate clearance and lubrication.
The crankcase in an engine with a conventional wet-sump oil pan is awash in oil. If there is a condition that’s heating up the wrist pins or stressing the piston and rod bores, the sheer volume of oil in the crankcase will carry off the excess heat. But a well-designed oil pan with a kick-out, crankshaft scraper and a vacuum pump (or a good dry-sump system) will dramatically reduce the amount of oil in the crankcase. While an efficient oil system reduces windage and increases horsepower, it can also put the wrist pins in jeopardy – another instance of unintended consequences. In fact, the wrist pins in the even-numbered cylinders are often the first to show signs of distress caused by insufficient lubrication because they are on the side of the engine that has much of its lubrication stripped away by the crankshaft scraper and oil pan kickout.
In this situation, my recommendation is to increase the wrist pin clearance. Most engine manuals recommend wrist pin clearances between .0008 and .0010-inch for conventional engines; my advice is to run .0020 to .0022-inch wrist pin clearance in a serious drag racing engine. My perspective on engine clearances is straightforward: When in doubt, a little loose will seldom result in catastrophic failure, but a little too tight will almost always cause problems."
3. Maybe I'll pull the oil pan off of the engine I posted and glue in a plexi window. Just kidding.
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Efficient scavenging, whether mechanical in a wet sump or by vacuum in a dry sump, and limiting the oil that may or may not be getting to the wrist pins, is not the same as saying "vacuum is sucking oil off the wrist pins". The scavenging effect on wrist pins makes sense.
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Never mind, have a good day.
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We all know who David Reher is, right? A quote from him regarding wrist pins, oiling, etc:
"Wrist pin problems were rampant in Pro Stock several years ago, and the cure was to apply some very expensive coatings. Spending $800 for coated pins is not a cost-effective solution for most sportsman racers, however; the object is to make as many runs as possible at a reasonable price. Assuming that the wrist pins have adequate strength, it’s possible to head off many problems simply by ensuring that the pins have adequate clearance and lubrication.
The crankcase in an engine with a conventional wet-sump oil pan is awash in oil. If there is a condition that’s heating up the wrist pins or stressing the piston and rod bores, the sheer volume of oil in the crankcase will carry off the excess heat. But a well-designed oil pan with a kick-out, crankshaft scraper and a vacuum pump (or a good dry-sump system) will dramatically reduce the amount of oil in the crankcase. While an efficient oil system reduces windage and increases horsepower, it can also put the wrist pins in jeopardy – another instance of unintended consequences. In fact, the wrist pins in the even-numbered cylinders are often the first to show signs of distress caused by insufficient lubrication because they are on the side of the engine that has much of its lubrication stripped away by the crankshaft scraper and oil pan kickout.
In this situation, my recommendation is to increase the wrist pin clearance. Most engine manuals recommend wrist pin clearances between .0008 and .0010-inch for conventional engines; my advice is to run .0020 to .0022-inch wrist pin clearance in a serious drag racing engine. My perspective on engine clearances is straightforward: When in doubt, a little loose will seldom result in catastrophic failure, but a little too tight will almost always cause problems."
He also went on to say;
"Remember that drag racing engines are usually stone cold when they go down the race track. We start the engine and get to the staging lights as quickly as possible because a cold engine makes more power than a hot one. Consequently drag racers don’t have the luxury of an extended warm up period to bring all of the parts up to operating temperature. In these circumstances, a little extra clearance is a good thing."
Keeping things in context is also important.
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Same principles apply, no matter whether it's a drag race engine, pulling truck, or Cup engine: pulling vacuum on an engine requires different allowances.
Listen, I know that you'll argue every syllable, semantic, and phrase until we're 100 pages in, so I'm just gonna hop on off this one. I don't have time to be dragged into a 2 month argument over individual words.
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I put a window in one of my big dry sump pans just to see what happens at various vacuum levels. I've tested really large dry sump pans and super small dry sump pans just to see what the difference is. I've run dry sump with a vacuum pump and without. Lots of various stuff to test with dry sump setups and I'm sure I haven't done 1% of the testing that the NASCAR boys have.
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Here is a 5 stage pump with a rear mounted vacuum pump.
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I like that rear-mounted suck pump.
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I think one of the best things I ever did with the dry sump setup was to install a sight gage on the tank. In the dyno cell we set up a video camera to watch the sight gage. That tells us if the dry sump system is pulling oil from the engine or if the oil is getting trapped. If you don't have a way to watch the oil level in the tank during a pull then you don't really know what is going on. I have a buddy who took his dry sump engines to the salt and burned them down. The oil was filling up the valve covers and after a couple of miles he lost pressure. Had he run the system on a dyno with a video camera he could've saved himself a lot of time and money.
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Where does the wrist pin get most of it's oiling from?
I like discussions like this because they get me thinking beyond what I think I already know...
It's not personal.
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Lots of semantics going on in this thread, but i love it!
I have often wondered exactly why people claim that running too much vac... negative pressure ( just gonna call it that cause it makes way more sense to me...) would harm wrist pins.
What Brent posted makes perfect sense to me. The fog of oil that is perpetually created around the crank has to provide both lubrication and cooling to the underside of the piston as it slams into it near BDC. A multi stage oil pump that is actively pulling away this fog will have an effect on both.
So to my feeble mind, there are a lot of things at play here. I can see how two completely different engines could have the same "negative pressure" in the crank case, and one could live forever while the other would eat wrist pins, simply based on mechanical variances like oil pump inlet location, crank scraper location, piston to crank clearance, piston design.... the list is almost endless.
Like most thing in life, everything is far more complicated than it would seem.
I am very keen to run a wet sump with a vacuum pump on my engine, but i would like to get more info on the issue. Not a ton of info out there on street engines running "vacuum" pumps, how do they hold up? how much maintenance do they require etc...
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I'm quoting a friend who probably knows more about this than anyone else I know;
"When our barometer gains or losses, we still have same air. Dust stays dusty, humidity stays humid. Inside the engine we merely change the barometer level to less than the out side of the engine."
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What Brent posted makes perfect sense to me. The fog of oil that is perpetually created around the crank has to provide both lubrication and cooling to the underside of the piston as it slams into it near BDC. A multi stage oil pump that is actively pulling away this fog will have an effect on both.
I disagree that the oil pump is pulling anything away form the crank. It keeps oil out of the pan which helps control windage, but a good wet sump pan will do the same (control windage).
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I cant tell you guys how many times in the last couple days Ive had a question or comment then erased it all because I was forced to think about it and figured it out myself. This is a great discussion, please don’t get exasperated or cynical.
Yes its minutia, yes it’s bench racing but its freaking interesting.
I’ve been thinking about when we see pictures of a bead of liquid in the space station just hanging there. Then when one is propelled mechanically and in the absence of atmosphere not losing any speed. Then relate that to having less atmosphere in a block, and if that liquid is a bead of oil traveling toward a wrist pin, or being scraped by a crank scraper, or, or.......
Also, I understand the concept of no suction in an area, but when is there suction? At the opening of the drain to the oil pump? In the pump?
To out there? ;D
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I'm quoting a friend who probably knows more about this than anyone else I know;
"When our barometer gains or losses, we still have same air. Dust stays dusty, humidity stays humid. Inside the engine we merely change the barometer level to less than the out side of the engine."
Very true.
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So I reached out to a friend of mine and asked him what his thoughts were on this. This comes from one of the leading Cup engine builders in the country. Not at liberty to share who...sorry, but good read.
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Looking back on it all, I think depression really didnt create the wrist pin issue, just exposed it with better scavenging. The depression, or lack of atmosphere, makes splash oiling slightly less effective, as it decreases it's resistance to movement. When we first started down the depression road, we pulled the wrist pins out of the piston, and blamed it on lack of oil to them. Such may have been the case slightly, as the crankcase was being better evacuated, so there was less left in the pan flying around. That, and the less resistance/effectiveness of the splash may have caused a little of the problem. But we opened up clearance, and then pressure fed them to try and help. Nothing eliminated the problem until we went to stiffer pins. Once we got that under control, it is surprising how little they need really. We spray the bottom of the piston, but there is only. 005 clearance between the pin towers and the rod (.0025 per side) and we run no oilers to the pin via the ring groove. We are higher in depression than we have ever been, and oil them less also. Which kinda points to the story of how we got here, and that it was really just weak pins all along, and we were just covering it up with lots of oil and big clearances.
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So that gives the pins was flexing more with "higher vaccum"
make sense in a way that there was bigger difference in pressure
over/under piston....
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Where does the wrist pin get most of it's oiling from?
I like discussions like this because they get me thinking beyond what I think I already know...
It's not personal.
Lower performance , production engines usually rely on splash oiling. Oil being "thrown around" in the crank case. For splash oiling to work , there has to be oil droplets of "fog" as you put it , present or and oil squirt hole drilled into the connecting rod ( older small block Fords for example).
Performance and race engines usually have "forced pin oiling" that comes from oil drains located in the oil ring groove which put oil directly on top of the wrist pin. Often there are two holes per side. Sometimes broaches are added to the sides of the pin bore as an additional source. Very high end race engines ( and high turbo boosted engines) have "oil squirters" off of the mains aimed at the underside of the pistons to cool them and that "splash oiling" also oils the wrist pins.
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Doesn't explain the issues that the Pro Stock guys were having, which arguably turn as many rpms (or more than) as the Cup engines do, while making almost twice as much horsepower.
When you're running a very small diameter wrist pin with a piston-centered rod, there is going to be room for improvement. Not so much with a conventional connecting rod setup and a large diameter, coated wrist pin.
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I am positive you Nascar friend is still using DLC coated wrist pins which can survive in a lesser oil environment. He wouldn't even consider a non coated pin , and not only for the fact his rods do not have bushings. Oh yes you failed to mention his pin diameters are under .800. Another need for a stiffer wrist pin. Wrist pin issues began first in the Truck and Busch series engines when they were still using .927 diameter pins. Much of it was due to camshaft timing with the 9.5 compression rule and then legal 18* heads. The exhaust pin bores were melting ( not the intake ) and causing piston failure. DLC coated pins solved that and were soon being used by cup engine builders too. Crank case vacuum came after that along with minimum weight rules.
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For an FE application what would those in the know recommend for a oil tank size?. Can someone also explain the differences/advantages of 3/4/5 stages dry sump pumps?. I am only assuming it is nothing more than the amount of plumbed pickups in the oil pan?. Any other recommendations are appreciated...John
I still don't think Fordman's original question has been answered yet. I've learned a lot by everybody going back and forth on this, but the original intent of the thread still hasn't gotten much attention. I guess it would probably help to know the application.....
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So that gives the pins was flexing more with "higher vaccum"
make sense in a way that there was bigger difference in pressure
over/under piston....
That's possible theoretically but we're only talking a few psi difference.
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Where does the wrist pin get most of it's oiling from?
I like discussions like this because they get me thinking beyond what I think I already know...
It's not personal.
Lower performance , production engines usually rely on splash oiling. Oil being "thrown around" in the crank case. For splash oiling to work , there has to be oil droplets of "fog" as you put it , present or and oil squirt hole drilled into the connecting rod ( older small block Fords for example).
Performance and race engines usually have "forced pin oiling" that comes from oil drains located in the oil ring groove which put oil directly on top of the wrist pin. Often there are two holes per side. Sometimes broaches are added to the sides of the pin bore as an additional source. Very high end race engines ( and high turbo boosted engines) have "oil squirters" off of the mains aimed at the underside of the pistons to cool them and that "splash oiling" also oils the wrist pins. Scrapers and windage screens are after the fact when it comes to rod throws.
I was leaning more toward what is the source of oil, not how it might be directed to the pin. I see it as two places; the rod throws and oil flying off the spinning crank.
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I am positive you Nascar friend is still using DLC coated wrist pins which can survive in a lesser oil environment. He wouldn't even consider a non coated pin , and not only for the fact his rods do not have bushings. Oh yes you failed to mention his pin diameters are under .800. Another need for a stiffer wrist pin. Wrist pin issues began first in the Truck and Busch series engines when they were still using .927 diameter pins. Much of it was due to camshaft timing with the 9.5 compression rule and then legal 18* heads. The exhaust pin bores were melting ( not the intake ) and causing piston failure. DLC coated pins solved that and were soon being used by cup engine builders too. Crank case vacuum came after that along with minimum weight rules.
I didn't fail to mention anything. I just passed along what he said.
"Nothing eliminated the problem until we went to stiffer pins."
The guy who wrote that is responsible for Cup, Truck, Bush, Infinity, and any other venue that HMS supplies engines for and has been there a LONG time.
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For an FE application what would those in the know recommend for a oil tank size?. Can someone also explain the differences/advantages of 3/4/5 stages dry sump pumps?. I am only assuming it is nothing more than the amount of plumbed pickups in the oil pan?. Any other recommendations are appreciated...John
I still don't think Fordman's original question has been answered yet. I've learned a lot by everybody going back and forth on this, but the original intent of the thread still hasn't gotten much attention. I guess it would probably help to know the application.....
Yes sir, it would. The size of the tank depends on the application.
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I am just more curious what John is building that warrants a dry sump?
Perhaps he dug up Bob MacLean's crashed GT40 and is restoring it? Or maybe like one guy I knew, put a Mustang II suspension without spacing it lower and using drop spindles and is using a dry sump to solve the oil pump hitting the rack issue?
Tank size depends on available space too.
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The guy that wrote this is responsible for conical and spherical dish piston tops that EVERYBODY in Nascar copied. I still don't walk on water and never will. You probably remember me from PRI.
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Cool to see how small this circle really is. Randy Gillis was at JE and made those early spherical dish pistons. He talked me into using those in one of my early EMC entries. They work well.
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Great discussion. Its always an interesting argument when everyone seems to have valid points!
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The guy that wrote this is responsible for conical and spherical dish piston tops that EVERYBODY in Nascar copied. I still don't walk on water and never will. You probably remember me from PRI.
If this is directed at me, I'm not sure what that has to do with anything, and I don't remember anyone named gt350hr from PRI.
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There was a time, some years ago, when I occupied part of most days at Jack Roush's 'Prototype Engine Shop'. With his permission, I was doing a multi-month series on building an engine---writing for Mustang Illustrated Magazine. The PES was the place, at the time, where all the NASCAR engines were built.
Depending on what I was observing and photographing, I pretty-much had the run of the place. But there were a few areas where they kept the doors closed. Talking to Jack one day, he pointed to one of those unmarked doors and said, "We're doing ongoing exploration regarding oil pans in there. There's a lot of power to be found in the sump of an engine."
This discussion points-out several aspects of the truth of that statement. It's still true today, even with all we've learned in the interim.
KS
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Tom.....My application is drag racing. Kids are moved out, sold a property so I finally have a budget for some fun. I actually learned a lot with this thread. My opinion now is that return VS expense and hassle I wont be going dry sump. I think for what I'm doing and good wet sump pan design with kickout and crank scraper, windage tray that will be fine.....John
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Tom.....My application is drag racing. Kids are moved out, sold a property so I finally have a budget for some fun. I actually learned a lot with this thread. My opinion now is that return VS expense and hassle I wont be going dry sump. I think for what I'm doing and good wet sump pan design with kickout and crank scraper, windage tray that will be fine.....John
Take a look at the cars going as fast as you want to go and see if they are dry sump or not. My guess is that they are not. Drag racers have figured out how to run 8 and 9 second cars with wet sump pans. Pro Stock uses dry sump as do some Comp guys but most drag racers have figured out how to make a wet sump work. There are some really nice advantages that come with a dry sump setup but it is a hassle in a door car and it is expensive.
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An accumulator will help you out tremendously. Get the big one for some extra reserve.
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gt350hr is the license plate number on my '66 GT 350 H and a screen name I commonly use. My PRI badge has always said Randy Gillis . I stop by Chris's booth every year. Last year he was out and about but I still said hi to you.
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gt350hr is the license plate number on my '66 GT 350 H and a screen name I commonly use. My PRI badge has always said Randy Gillis . I stop by Chris's booth every year. Last year he was out and about but I still said hi to you.
I couldn't help myself. I looked you up. Nice car, Randy!
https://www.youtube.com/watch?v=v9vYDK5-AyU
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gt350hr is the license plate number on my '66 GT 350 H and a screen name I commonly use. My PRI badge has always said Randy Gillis . I stop by Chris's booth every year. Last year he was out and about but I still said hi to you.
Sorry Randy, I meant no disrespect. Just didn't know who you were. Unfortunately PRI is mostly a blur for me with all the different people I talked to. I spent most of the time at the Rottler booth this year with our new 5 axis machine. Thanks for clearing that up for me. I'll know to be a little more attentive next year. ;)
Edit to add; just watched the vid that mbrunsen posted...beautiful car and now I do remember seeing you.
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Dang Randy, that is a fantastic story and a "bitchin ride".
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44 years of drag strip abuse by me and no end in sight. There is also a video of a run at Fontana Dragway as well.
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Surprised I don't remember that car, I was at all of the same tracks you mentioned with various mustangs I owned.
I sold a '67 GT500 in 1979, did you look at it in '79?
About '84 or so I was racing a red '67 coupe in super street at all the west coast tracks. Were you running mostly bracket races with it?
Very nice car!
(https://s31.postimg.cc/mq2oe74dn/67_mustang.jpg) (https://postimages.org/)
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Cool Shelby, Randy. I've seen H's at shows around here but never noticed if they have that master cylinder, that is very different.
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44 years of drag strip abuse by me and no end in sight. There is also a video of a run at Fontana Dragway as well.
[/quote
]Randy, you might appreciate this picture since I bought this GT-500 new, and still own it. I need to get it back on the road for some of these FE reunions. At least now I can show it and not worry about being judged for originality. I quit the car shows because of all the bickering about originality. It is hard to bite your tongue when you know your car from day 1. Joe-JDC
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Waaaay off topic but I have bracket raced this car since I bought it in '74 . Very little street driving has kept the actual mileage under 87,000. It was painted metallic blue for 27 of those years when I ran the Boss 302 in it.
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I've been running a six stage on the SOHC in my Shelby clone for the last several years. Three pickups in the pan, one at the back of each head, plus the pressure stage. I was told by the dry sump folks (Peterson Fluid Systems) that this would give me plenty of crankcase vacuum. That turned out to be BS, it will deliver some vacuum at idle but not when the engine starts running at higher engine speeds. I was always able to get 15 inches of vacuum with my GZ Motorsports vacuum pump. For the cost, weight, and complexity of the dry sump system, and no crankcase vacuum to speak of, I'm very disappointed in it. I'm going back to a normal FE oil pump and pan, a vacuum pump, and an accumulator (Accusump) to ensure oiling under all conditions.
I had a BBF on the dyno today, with a Peterson R4 dry sump pump. It made 5 inches of vacuum at idle and at full song, was pulling 12 inches by itself.
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Vacuum makes power, provides better ring seal and stops flutter. 14 and under is safe more needs DLC coated pins.
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Randy,
If you could, please do a once over lightly on why crankcase vacuum pulls oil out of the pin boss. I've read that many times but have never seen an explanation for this phenomenon. And does the vacuum pull oil out of other surfaces like cylinder walls or Second and Third rings? In my mind, if the pressure is equal throughout the crankcase then the only things affected would be things on the other side of that pressure differential. In that regard, I understand why crankcase vacuum is good for ring seal but can't reason out the other part unless the pin is somehow on the positive side of the pressure balance. Maybe that's it but I can't see how. Thanks.
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This engine was 556 cubes and made 1163 hp @ 8500. It indeed had DLC coated pins.
A dry sump pump that's good enough to pull crankcase vacuum creates a "depression" in terms of pressure. Instead of there being copious amounts of oil flung around in the crankcase, the oil wants to go to the low side of the pressure difference. Wrist pins are not pressure fed in most cases, so there is less oil going to them.
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So are you saying the free oil in the crankcase is migrating to one of the pickup points? If that's the case -and to be clear, I'm not disputing that- then is the same thing happening to oil on the walls and on the rings? And what are the longer-term implications of using crankcase vacuum if it's depleting oil from critical surfaces? After all, you can't use the same coating on the cylinder wall and rings as you can for the pin.
Again, not arguing the point just seeking clarity.
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So are you saying the free oil in the crankcase is migrating to one of the pickup points? If that's the case -and to be clear, I'm not disputing that- then is the same thing happening to oil on the walls and on the rings? And what are the longer-term implications of using crankcase vacuum if it's depleting oil from critical surfaces? After all, you can't use the same coating on the cylinder wall and rings as you can for the pin.
Again, not arguing the point just seeking clarity.
Yes sir. In my particular case, the pan has 3 scavenge points.
I would agree with you that the same thing could be happening to the cylinder walls. However, this engine was sent back to me last year for a freshen up and the cylinder walls looked fine. Now granted, this is a pulling engine that probably sees 25-30 pulls a season. All-in-all, it's not a heavily used engine, but it is a max-effort engine.
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Have to agree with Foxwell on some of this stuff. A vacuum implies a sealed (or nearly sealed) system. Unless its putting a bunch of oil and air out of the tank breather you should not have much "movement" of oil in the crankcase. The amount of oil thrown off of the rotating assembly and it's direction should not appreciably change. Now to keep things in context, the type of builds using a dry sump to generate vacuum are the same folks that will be pushing the envelope on other areas - RPM, weight reduction in pistons and pins, windage control and reduction, and cylinder pressure. This type of build will highlight anything marginal, and often the new and unusual modification takes the heat for an issue that actually originated someplace else - a part that was on the edge of "good enough" until the most recent modification pushed it over that edge.
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Regarding vacuum in the crank case, you are still going to have a flow of it's continence, unless your close the 29".
The inside of a engine is a fairly large area to seal!
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The new generation dry sump pumps are very capable of pulling over 18"s of vacuum. Oil is still "spraying" (pressurized) out of all of the normal areas and at speeds high enough to oil the cylinder walls , camshaft , etc. no problem. The vacuum actually "pulls" oil out of the crank and slightly lowers oil pressure. Oil is still flowing. I haven't ever seen a piston scuff caused by crankcase vacuum. In my experience , the pins ( unless pressure fed through the rod itself) receive splash oiling or non pressurized oil from the oil ring groove and high vacuum reduces the amount of oil they get. The DLC ( Diamond Like Carbon) coating provides a VERY hard surface that is also very slippery so it survives is a low oil , high load situation. At 3 to 5 times the cost of a non coated pin , they are pricey but since they don't wear on the surface , they can be used over and over and over. The cycle life ( amount of times it can flex before it yields) is far beyond the wear factor of the cylinder walls so "long term" use actually makes them cost effective.
Randy