What the heck is going on in the oil pan?

[jayb]

I've been doing a little more testing on the dyno mule with my cylinder heads on it this week (up to 894 HP now).  After the last go around a few weeks ago I had some conversations with a couple of my head customers, and John S (oldiron.fe on the forum) mentioned putting a window in the oil pan to see what was happening.  Ever since I started with this engine on the dyno last September, I've noticed that at the higher RPM pulls I have a significant decrease in oil pressure, typically starting around 65 psi at 5000 RPM and dropping to about 50 psi at 7000 RPM, with the oil temperature around 180 degrees, using 10W-30 VR1 Valvoline oil.  Higher oil temps of around 200 degrees make it a few psi lower, and I really wasn't too comfortable with those levels.  I've seen this oil pressure issue before with vacuum pumps, so I figured that was a contributing factor, but I thought it would be interesting to see exactly what the oil in the pan was doing.

Since I was planning on pulling the pan to check the bearings, I decided to go ahead with the window, potentially wrecking the oil pan but hopefully learning a few things in the process.  After checking all the bearings (which looked almost new), I cut a big rectangular window out of the Milodon 7 quart oil pan and bolted a piece of 3/8" thick clear polycarbonate to the side, using a bunch of The Right Stuff to seal it.  The engine is using a Moroso windage tray between the block and the pan, and a Precision Oil Pumps high volume pump using the small spacer between the spring and the cup plug.  I've also installed a new vacuum pump from Star Machine to replace the GZ Motorsports pump that I had been running previously.  This pump gave me a few more inches of vacuum, and probably contributed to the latest HP numbers.

I set up a camera to take videos of the window in the oil pan while the engine was running, and during a dyno pull.  I also rigged up a tach so that you could see the engine speed in the video, but unfortunately the tach I used didn't work, or else it didn't like the tach signal from the MS3-Pro.  Regardless, I started testing the engine and then watching the videos.  I was really surprised at what I saw.  The first video link is below; this is with a total of 8 quarts of oil in the engine.  It takes a while in the video to get to the actual dyno pull, which happens starting around 1 minute and 45 seconds in.  The oil levels are marked on the pan in the video:

https://youtu.be/ZPL_05cKRKY


Wow, the amount of air entrained in the oil during the actual dyno pull is shocking!  Lots of big bubbles circulating in the oil, certainly contributing to aeration of the oil coming out of the pump.  As my dyno junkie friend Royce said, it looks like you are spraying a garden hose into a bucket of water.  There appears to be about 6 quarts of oil in the pan during idle, and it drops to about 4 quarts during the pull.  A while back on the Engine Masters show on Motor Trend on Demand, they did an experiment where they saw oil pressure drop as engine speed increased, attributed it to foaming of the oil, and solved the problem by taking some oil out of the pan.  I thought I would try the same thing, so we pulled 2 quarts out of the pan, and ran the test again.  Here is the video:

https://youtu.be/cQRGg-nI8m0


Well, that didn't work, we still had the same drop in oil pressure as before up at 7000 RPM, we seemed to have the same amount, or even a bit more, of foaming and bubbles in the oil, and we didn't make any extra power.  The oil level in the pan looked like 4-1/2 quarts during idle, and about 3 quarts at peak RPM. 

The obvious next test was to remove the vacuum pump and see how it looked without the pump on the engine.  We went back to 8 quarts of oil in the engine, and ran without the vacuum pump.  Here is the video:

https://youtu.be/sd29Ye2E0Q4


Unfortunately for this video I had decided to remove the tach (which wasn't working), and apparently after repositioning, the camera position was off a little compared to the last two videos, and we got some glare from the window that kind of obscured the oil.  However, if you look closely you can see that the oil level in the pan drops quite a bit farther in this video than in the first one, and there still seems to be a whole bunch of foaming and air bubbles in the oil.  BUT, the oil pressure stayed stable throughout the dyno pull.  Unfortunately the oil pressure win was offset by a large HP loss.

Based on the fact that the engine has been behaving like this (oil pressure wise) for several dyno sessions, and that the bearings looked very good when I inspected them, I'm not overly concerned about the oil pressure issue when the vacuum pump is running.  However, it seems like there ought to be some oiling system modifications that could mitigate this problem.  One thing I tried with this new vacuum pump setup was a second vacuum port lower in the engine; this was recommended by Star Machine, and also Andy Miller at Olds Performance.  I actually put a hole through the side of the block right across from the #3 main cap, and then milled a slot in the main cap to allow air from the crankcase into the slot, through the hole, and out to the vacuum pump.  The hope was that since the hole in the block was shielded by the cap, it wouldn't draw in too much oil, but that didn't work, so I went back to a single line from the valve cover to the vacuum pump.  I might try that again next time around with a baffle over the slot in the cap; Lykins also suggested going through the fuel pump opening in the timing cover, so I could try that too.

Another thing is the windage tray.  The Moroso tray has louvers that strip oil off the crank, and several of those louvers point straight down at the oil level in the pan.  You can see this in the videos when the engine is idling, one of those louvers is right above the window and oil is coming straight down.  It seems like using the Ford windage tray, which has louvers only on the right side of the engine and shoots the oil horizontally through the louvers, rather than vertically, would be a better design.  Also it seems like a kickout on the right side of the oil pan, designed to catch that oil and give it a chance to slow down before it hits the rest of the oil in the pan, would be good.  It's also possible that a screen on the windage tray, like the Canton pan has, would lead to less foaming in the oil.  Maybe no windage tray at all would work best? 

Maybe the standard volume pump would yield an improvement.  And of course if you ran a really, really deep pan, that also might help.  The list goes on...

I'm sure there will be a million theories on the best approach to this issue, but the problem is there is very little data to back up the theories, and getting data requires changing up oil pans, windage trays, oil pumps, etc., which of course is a huge pain.    But if I go forward with any modifications I will certainly post them here for general interest.  I'm not sure if there is really HP to be had with a better oil pan setup, but an improvement in the stability of the oil pressure would be a worthwhile goal.

[Hemi Joel]

Professor of FEology, have you tried a crank scraper?
What effect would that have?  How would a 2 layer windage tray work, with offset louvers?  It seems a very deep pan would be beneficial. 

[cammerfe]

During a walkthrough with Jack Roush, of his Prototype Engine Facility, some years ago, he pointed to a set-off area and, speaking of the activity there, he said, "There's a lot of power to be found in a properly constructed oil pan."

It is my present intent to use a dry sump system on every hot rod engine I make use of from now on. I'm sure you're familiar with Dailey Engineering in Temecula, CA

KS

[Stangman]

I don’t know if I’m the only one thinking that that pan with the engine off needs at least 1 qt if not a quart and a half. It just seems low for a deep pan. Are there certain oils that have a better anti foaming agent in them.It seems like with the vacuum pump the last couple of inches in the pan aren’t as foamy if you were to put an extra qt maybe the bottom will be less foamy. Just thinking out loud.

[cjshaker]

I think it's the crank beating the oil droplets into smaller, aerated droplets, as it returns. A knife edged crank and well done scraper would probably help in that area. It would be interesting to see what the screen tray does during a pull, but as long as the bearings come out looking good, I think it's pretty much a non-issue. A dry sump is obviously the best choice for an oiling system, but is it really worth the expense and logistics issues that go with it? On the vast majority of builds in 1/4 mile cars, I think it isn't, especially given the added weight. In a road race application or land speed run, or any very high HP build, then it's a different story. But having said that, learning is always a good thing, so any further testing done is always a plus (not saying you should take on that endeavor).

[My427stang]

Different oil formulations can do very different things.  On early Powerstrokes at up to 4 digit pressures in the high pressure oil pump used for injectors, foaming can be very bad with the wrong oil, or as good oil gets older.

I think I'd probably try a completely different oil first, could be a 50 dollar waste, but better than hundreds.  They make anti-foaming additives too, but hit or miss when you add one to an existing package

Barring an oil problem, I would likely look at restricting where I could and maybe trying a standard pump for a bit less bypass, but I'd also look close at your pump to see if there is any wear or damage or if vibration beat up the pickup

[John67427]

Not that I can add any solution to what is happening and why, one thing I’ve learned over the years is when dealing with fluid or air you have no clue what’s going on unless you can physically see it and usually it’s a jaw dropping experience

[jayb]

Not that I can add any solution to what is happening and why, one thing I’ve learned over the years is when dealing with fluid or air you have no clue what’s going on unless you can physically see it and usually it’s a jaw dropping experience

It certainly was for me LOL!

[jayb]

Different oil formulations can do very different things.  On early Powerstrokes at up to 4 digit pressures in the high pressure oil pump used for injectors, foaming can be very bad with the wrong oil, or as good oil gets older.

I think I'd probably try a completely different oil first, could be a 50 dollar waste, but better than hundreds.  They make anti-foaming additives too, but hit or miss when you add one to an existing package

Barring an oil problem, I would likely look at restricting where I could and maybe trying a standard pump for a bit less bypass, but I'd also look close at your pump to see if there is any wear or damage or if vibration beat up the pickup

I was thinking about that Ross, I do have a case of 10W-40 Amsoil here, just wondering if that would make a difference.  It would be easy to try, maybe I'll give it a shot...

[jayb]

Professor of FEology, have you tried a crank scraper?
What effect would that have?  How would a 2 layer windage tray work, with offset louvers?  It seems a very deep pan would be beneficial.

The Moroso windage tray has a kind of a crank scraper built in, but a better one might help.  I was actually thinking about a solid baffle welded to the bottom of the windage tray, so that any oil that came off the windage tray louvers dropped onto the baffle and was directed to the right side of the engine, before it returned to the pan.  This would at least prevent the straight down shot of oil that seems to be whipping up those big bubbles (again the garden hose into the water bucket comes to mind).

A dry sump tank is designed to run the returning oil around a circular path on the outside circumference of the tank several times, before it gets to the bottom of the tank; this is to remove air entrained in the oil.  It seems like if I could keep the oil up and out of the sump for some distance, yet continue to have it removed from the crank, it would mimic the effect of a dry sump tank. That would be a major modification to the oiling system, but maybe worth it...

[cjshaker]

I was actually thinking about a solid baffle welded to the bottom of the windage tray, so that any oil that came off the windage tray louvers dropped onto the baffle and was directed to the right side of the engine, before it returned to the pan.  This would at least prevent the straight down shot of oil that seems to be whipping up those big bubbles (again the garden hose into the water bucket comes to mind).

A dry sump tank is designed to run the returning oil around a circular path on the outside circumference of the tank several times, before it gets to the bottom of the tank; this is to remove air entrained in the oil.  It seems like if I could keep the oil up and out of the sump for some distance, yet continue to have it removed from the crank, it would mimic the effect of a dry sump tank. That would be a major modification to the oiling system, but maybe worth it...

Since gravity is the only factor in oil returning, I don't think the "straight down shot" is forming the bubbles. Gravity doesn't increase with RPM, and there is no pressure added at RPM in that down force, as the hose analogy implies. There is more volume, but a small hose feeding water into a bucket at low pressure is no different than a big hose feeding water under the same pressure. Unless the "hose" is raised to a point where speed of return increases (picture a hose feeding at 1" height, compared to 3'), thereby adding pressure when it hits the water column, there still won't be bubbles. Only when pressure is added at the hose will it force air down into the water column. The crank on the other hand, has a huge influence with RPM. It's a massive aerator in essence.

Directing oil away from the crank is a known power builder, but also has other known benefits, like less aeration. That's where cam tunnels, scrapers and other trick oil mods come into play. But it still can't be eliminated entirely. Rod journals will still sling oil at the pistons, and those pistons will still shoot it directly back to the crank on the downstroke.

[475fetoploader]

We used to buy an oil additive from International for the early ford Power strokes. It was created to help with foaming of the oil.  It came close to eliminating the effect created by 800 psi of oil pressure in the injectors.

[runthatjunk]

Well that's just fascinating.  It's a closed system (with leakage obviously) so it makes no sense to me how the vacumm can cause that kind a pressure difference.  The aeration just at idle was eye-opening, looks like one of Conleys pumps is needed here!  I'd be curious about a diesel oil for the anti-foaming but the shear volume of oil being thrown around I doubt there would be any signficant difference between oils of the same viscosity.

[jayb]

Since gravity is the only factor in oil returning, I don't think the "straight down shot" is forming the bubbles. Gravity doesn't increase with RPM, and there is no pressure added at RPM in that down force, as the hose analogy implies. There is more volume, but a small hose feeding water into a bucket at low pressure is no different than a big hose feeding water under the same pressure. Unless the "hose" is raised to a point where speed of return increases (picture a hose feeding at 1" height, compared to 3'), thereby adding pressure when it hits the water column, there still won't be bubbles. Only when pressure is added at the hose will it force air down into the water column. The crank on the other hand, has a huge influence with RPM. It's a massive aerator in essence.

Directing oil away from the crank is a known power builder, but also has other known benefits, like less aeration. That's where cam tunnels, scrapers and other trick oil mods come into play. But it still can't be eliminated entirely. Rod journals will still sling oil at the pistons, and those pistons will still shoot it directly back to the crank on the downstroke.

I don't agree Doug, gravity is not the only factor in oil returning.  The louvers on the pan that are directed straight down are allowing oil that is slung off the crank to be thrown at high speed into the rest of the oil in the pan.  As engine speed increases, the speed of the oil coming straight down is also increasing, and I think that is what is whipping up the oil so badly.  You might have to see the windage tray to understand what I'm saying...

[WConley]

From my experience, VERY few people truly understand what goes on in an oil pan.  In my early days at Ford, we were trying to get the 4.6L Modulars into production and there was a pesky issue of rods coming out of blocks. 

Finally they got smart and vacu-formed some clear oil pans.  It became clear that windage was keeping oil hung up and out of the sump.  It was also foaming badly.  All of the experts were shocked!  It took several weeks of adding guides and louvers to get the pan to an acceptable configuration.

Jay's videos show how hard it is to keep air out of the oil at any kind of rpm.  Yeah you could probably make the idle look better with a standard volume pump (or one of mine LOL), but at 7,000 rpm it won't change a thing.  What you need is enough of a sump to give the air time to get out before the pump pickup sucks it up.  Louvers and guides should be configured to hurry as much oil back to the sump as possible.

My big takeaway is this:  Did anybody else notice how quickly the oil clears up at shutoff with the vacuum pump on, or how it doesn't clear up with the vacuum pump off?  That's basic chemistry.  When there's low pressure, the air comes out of solution rapidly.  It's the same thing as opening a soda can.  The CO2 suddenly sees lower pressure, and out it goes.

The vacuum pump seems to really help the air separate from the oil in the sump.  That and a deep sump (giving more time before being picked up by the pump)  seem to be saving the day here.  I bet if you ran a clear line on the pressure side you could see the difference between vacuum pump and no vacuum pump.  At the very least you'd see what the bearings are getting...

Once again we are reminded how unlikely it is that these crazy contraptions even work!

Edit:  Jay - How much vacuum are you pulling in the pan?  Could it be that the oil level drops enough in the pan that the pump is seeing that reduced pressure on the pickup side?  At the beginning of the pull, you've got a big column of oil above the pickup.  At the end it's less than half that, likely with some air.  The pump is really putting out a delta pressure above what it sees on the pickup side.  When you're not pulling a vacuum, the pickup side is always atmospheric pressure.  Something to chew on...

[cjshaker]

Since gravity is the only factor in oil returning, I don't think the "straight down shot" is forming the bubbles. Gravity doesn't increase with RPM, and there is no pressure added at RPM in that down force, as the hose analogy implies. There is more volume, but a small hose feeding water into a bucket at low pressure is no different than a big hose feeding water under the same pressure. Unless the "hose" is raised to a point where speed of return increases (picture a hose feeding at 1" height, compared to 3'), thereby adding pressure when it hits the water column, there still won't be bubbles. Only when pressure is added at the hose will it force air down into the water column. The crank on the other hand, has a huge influence with RPM. It's a massive aerator in essence.

Directing oil away from the crank is a known power builder, but also has other known benefits, like less aeration. That's where cam tunnels, scrapers and other trick oil mods come into play. But it still can't be eliminated entirely. Rod journals will still sling oil at the pistons, and those pistons will still shoot it directly back to the crank on the downstroke.

I don't agree Doug, gravity is not the only factor in oil returning.  The louvers on the pan that are directed straight down are allowing oil that is slung off the crank to be thrown at high speed into the rest of the oil in the pan.  As engine speed increases, the speed of the oil coming straight down is also increasing, and I think that is what is whipping up the oil so badly.  You might have to see the windage tray to understand what I'm saying...

Now I understand what you're saying about the tray louvers. The factory tray has angled louvers, as you mentioned, so that would seem to be a step in the right direction. But at the same time, what you say seems to validate my point, at least partially; that the crank speed, and its interaction with the oil, is the major cause of the issue. Keep the oil off of the crank, and the issue will correct itself, at least to some degree. I would also not be surprised to learn that the windage alone, from the rotating crank at high RPM's, acts like a giant tornado against the oil below.

IF I recall correctly, I believe that Blair mentioned once that the screen was the better option for trays. Unlike a solid tray, it allows little resistance to return, yet slows down the 'slamming' effect of return oil into the pan. This is just a guess on my part, so take it for what it's worth, but I would think the screen tray gets so 'saturated' with returning oil during a run that it almost acts like a solid tray, as it stops the oil from passing through unimpeded. In other words, it is in essence a liquid 'curtain' at high RPM. I think a screen tray and/or factory tray would be a worthwhile test...should anyone feel giddy enough to try it. 

[frnkeore]

This is something that comes to mind, for me.

1. Use a truck pan.

2. Install a flat plate, angled from the top of the right side, to just above the oil level on the left.

3. Seal that plate around the oil pump, as well as possible.

4. Install waffled or corrigated, small mesh screening, on the plate, inline with the engine, to direct the oil, to the back of the crankcase. Leave about a 2-3 sq in area at the lower rear corner, for the return.

That way the oil will have a long path, flowing away from the pump, with the screen to separate the air from it and the longest path back to the pump pick up.

[jayb]

Bill, vacuum in the pan was right around 10 inches.  I was wondering about the very same thing, if lower pressure in the crankcase was directly subtracting from the pressure that the pump was putting out.  But 10" of vacuum is only about 5 psi, and I'm seeing much more of a drop than that. 

I think I can fab up a clear line coming out of oil filter adapter and dumping into another oil port, that would be very interesting too...

[jayb]

This is something that comes to mind, for me.

1. Use a truck pan.

2. Install a flat plate, angled from the top of the right side, to just above the oil level on the left.

3. Seal that plate around the oil pump, as well as possible.

4. Install waffled or corrigated, small mesh screening, on the plate, inline with the engine, to direct the oil, to the back of the crankcase. Leave about a 2-3 sq in area at the lower rear corner, for the return.

That way the oil will have a long path, flowing away from the pump, with the screen to separate the air from it and the longest path back to the pump pick up.

That's kind of what I was thinking about, Frank...

[machoneman]

Would be interesting to see a much deeper pan and the effect increased distance has.

[blykins]

I think a *deep* pan is an all-around win. 

I was discussing this with Jay last night and made the comment that I've never seen this kind of pressure drops in the past, even with the exact same oil pan, pickup, oil, at 7000-7500 rpm.  However, I can't make a direct apples/apples comparison because the engines that were in that situation did not have vacuum pumps.  However, the engines that did have vacuum pumps also did not see an oil pressure drop at high rpm.

The only differences I can think of are these:

1.  I do not use windage trays.
2.  I restrict oil to the lifters.

To echo one of Doug's points, I think there's an advantage to keeping oil off the crank, and this may reflect my #2 point.  The less oil that's rolling off of the cam/lifters, the less that falls onto the crankshaft. 

It would be nice to see a test without the windage tray to see what the difference would be.

As mentioned, a different oil type/viscosity may add a difference as well.

[jayb]

Maybe the Great FE Oil Pan and Windage Tray Comparo is in order...

[Barry_R]

I have tested numerous oil pan and tray combinations.  From what I can tell the best FE oil pan would be a 55 gallon oil drum and a 4 foot long drive shaft with the pump & screen upside down in the bottom.  Every single time we made the pan volume larger it picked up power.

As far as oil pressure readings with vacuum pumps - I have seen a drop in viewed pressure.  But if the pump is the same size, turning the same RPM, with the same inlet and outlet orifice (combined engine clearances) it is pumping the same amount of oil.

[RJP]

Jay, What oil pump pick up are you using? And do you think that might play a role in the aeration due in part to the resistance to flow [suction] to the pump?

[jayb]

The pump inlet is a Canton (or maybe Milodon, can't remember which for sure) 5/8" pipe with a square pickup on the bottom, screen on the bottom of the pickup.  Currently it sits about 3/8" over the bottom of the pan.  It has been heated up and bent slightly to get closer to the bottom of the pan than it was originally, but there is no noticeable necking down or kink in the tube.

I think the vacuum in the crankcase will contribute to a lower observed pressure, but not as much as I'm seeing...

[cjshaker]

Jay said his bearings looked fine after the dyno runs.
Brent says that his bearings always come out looking great, and JJ seemed to show that.
Blair's winning EMC engine's bearings looked like new after many thrashings, and the tear down showed that.

None of these engines had super trick oil pan or tray mods of any kind, that I'm aware of.

So I still have to ask...if nobody is seeing bearing problems related to oil, what is the issue? It seems like making a mountain out of a mole hill. Personally, it seems that in the real world, with G forces thrown in the mix, baffling is way more important to bearing life than aeration, especially on a front sump pan like the typical FE.

[wayne]

Years ago i helped on a stock car with a 427 chevy after each race it had foam all over out of the breathers He  ran Kendell gt 1 he changed  to Shell. no problem  he was told gt1 had to many cleaners.

[Joey120373]

I had some thoughts on this but most of what I was thinking has already been said!

Jay, something to try to get the tach to read;

If your using a general purpose output off the MS3 as a tach signal, try wiring it up as a ground switch for a general purpose relay, like the fuel pump relay is wired. The load terminals of the relay don’t need to be connected to anything, it’s the fly back voltage off the relay coil we are after, that should provide enough of a voltage spike to trigger the tach. But make sure that the relay output can be used to control a relay, I’m 95% sure that it can, but I would hate to damage your controller.
So 12v to one side of the coil, MS tach signal and tachometer input signal to the other coil terminal.

And, Congradulations on the 894 HP mark! So close….

Edit , just checked the MS3 manual:

3.3.6 Tach output
This output can be used to produce a 12 volt square wave signal. It can also trigger certain ignition modules such as an MSD 6AL or a Ford TFI, or be used as a general purpose on/off output. When used as an on/off output, it can sink up to 1 amp.

So triggering a standard automotive relay shouldn’t be a problem at all.

[blykins]

Jay said his bearings looked fine after the dyno runs.
Brent says that his bearings always come out looking great, and JJ seemed to show that.
Blair's winning EMC engine's bearings looked like new after many thrashings, and the tear down showed that.

None of these engines had super trick oil pan or tray mods of any kind, that I'm aware of.

So I still have to ask...if nobody is seeing bearing problems related to oil, what is the issue? It seems like making a mountain out of a mole hill. Personally, it seems that in the real world, with G forces thrown in the mix, baffling is way more important to bearing life than aeration, especially on a front sump pan like the typical FE.

Doug, I agree, if it's not broke, don't fix it.  If the bearings look fine, I don't know if I'd be that concerned with it, other than the curiosity of trying to figure out why there was so much foaming.

I think Jay was mostly concerned about the pressure drop, and I would be too, because I normally don't see drops like that during a pull.  But after I did a bearing check, I think I'd just shrug my shoulders and go on.  LOL

[jayb]

Yes, the pressure drop is what really has me concerned.  It can't be good, no matter how the bearings look.  Just for my own peace of mind, I'd like to get a handle on that...

[Barry_R]

The reason for investigation lies in the confluence of Jay's and Mr Conley's observations.  Right now the bearings look fine.  What we don't know is whether they are perfectly OK or whether the system is right on the ragged edge of failure.  We don't know if we are at 99% of capability or 65% and we have no practical way to find out.  Since Doug is a bit of an audio guy, look at it as the mechanical version of dynamic headroom in a sound system.  A safety factor.  As Conley noted - Ford themselves had a system that crossed that line and it caused a lot of problems even in a comparatively mild application.  The system "as-is" is visibly compromised (or at least non-optimal) - so if it can be improved at a modest cost it makes plenty of sense to address the observed issue now and increase the safety factor - - and maybe even find a couple horsepower while doing it.

[Cyclone03]

Maybe the Great FE Oil Pan and Windage Tray Comparo is in order...

This is a great idea , go ahead and task the Great FE Comparo R&D team this project.

We’re waiting…LOL

[WConley]

The reason for investigation lies in the confluence of Jay's and Mr Conley's observations.  ...

Barry - Did you have a root canal today?  You're starting to sound like me or Scott (pbf777) 

[frnkeore]

Regarding pressure drop, it could well be the aerated oil causing the pressure drop, fluid can't be compressed but, air can so, you could loose oil pressure with aerated oil and air doesn't lubricate very well, either.

My own little story on my pictured car. I had to pull the engine to replace a clutch and when I put it back in, there must have been a piece of something in the AN flare, on the intake side of the pump. I noticed a small drop in oil pressure, maybe 5lb (80 psi was normal). After 2 practice sessions, it had dropped more, maybe 12-15 total. I went all through the fittings and when I tighten one of them (a union) the pressure went up a little but, not to the full 80. With the external pressure adjustment I raised it to about 70+. I thought to myself, that will be ok. About 10 minutes in the race the engine, a rod bearing seized and put a hole in the block, about 10" behind me. Lesson learned!

Air and oil don't mix, so to speak! One compresses and one don't.

[machoneman]

Well, for an oil pan comparo, here's Moroso's all-clear oil pan they use for testing. Given the FE's similar crankcase design, making one like this may not be that hard.

https://www.chevyhardcore.com/news/moroso-oil-pan-testing/

[Tommy-T]

Just curious.
Would plumbing a large stacked plate oil cooler into the system "de-aerate" or at least reduce the amount of air-infused oil that's cycled back into the engine?

Amazing how the oil "de-airs" itself with or without the vacuum pump.

One of things I never think about. I usually put a "blue" spring in a high volume pump, put the largest sump in the particular chassis I'm building for, 'n go. But I ain't making 800...or even 700 horses.

Thanks for the school'n.

[Barry_R]

One other thing to consider is that most aftermarket oil pickups tend to be rectangular with perforated metal or a screen welded in.  Most every OEM pickup I can recall is more of a bell or funnel shaped with a much, much larger inlet area and screen surface.  Wonder if there is something there...

[MeanGene]

One other thing to consider is that most aftermarket oil pickups tend to be rectangular with perforated metal or a screen welded in.  Most every OEM pickup I can recall is more of a bell or funnel shaped with a much, much larger inlet area and screen surface.  Wonder if there is something there...

The large bell shape has much more surface area, many times larger than the pickup tube itself, so the screen would have to be very clogged to inhibit flow. Might be something of a whirlpool or vortex effect? The aftermarket pickups seem like they would be cheaper to make.
There used to be a guy here in the 70's that ran a Super Stock roundy-rounder at Petaluma in the mid-late 70-'s, had a 67 Mustang running 427 LRs and did pretty well. He ran a very simple homebuilt dry sump setup, pan widened on the right, and used a HV pump to scavenge to the "tank", and a simple single stage Weaver pump for pressure. The HV pump was able to easily keep up with scavenging. A large remote truck "oil filter" held 8 quarts, because of course dry sumps were not allowed

[6569fe]

Pump is getting aerated oil. Screen or Perforated metal pickup it is only going to supplying what it can get.

[Joe-JDC]

When the oil pressure stalls, or drops, the pump has reached its limit to draw in more oil.  It would be interesting to know what your rod side clearances are.  I agree with some of the other comments that the square/rectangular oil screen is not sufficient surface area to supply non aerated oil, and your pick-up tube might be too small in diameter or have weld slag causing some turbulence.  Did you smooth the entry into the oil pump, block entry point, oil filter adapter, oil pump housing under the gears?  Also, you may be bypassing too much oil causing the aeration.  Just random thoughts.  Joe-JDC

[jayb]

Joe, if I recall correctly rod side clearances were around .008" to .010".  All the oil modifications you mentioned have been done to the block.  Also, no welding on the pickup tube, it was just heated up and bent down somewhat.  I'm pretty convinced at this point that aeration of the oil is what is causing the oil pressure to drop, although I'm not sure why with the vacuum pump disconnected the aeration of the oil looks about the same, yet the oil pressure stays stable throughout the pull.  I may run that video test again, to try to get a better video without all the glare...

[427John]

Are the rpm levels at the onset of the aeration and drop in oil pressure comparable with Bills observations on his test rig?Does this appear to be due to the same causes as what Bill saw with the HV pump in bypass or does it seem to be more related to windage from the rotating assembly?A close comparison of Bill's data with your own observations may make your decision on whether or not to try a std.volume pump a little easier.

[Cyclone03]

The oil pressure by pass talk reminded me of an oil system discussion I had with a BOSS 302  road racer I know. In the days before drysump systems were allowed in trans am racing Ford tried many ideas and pump/pick up ideas to make the engines live. Many early ideas of course came from the Gt40 program and NASCAR as well. One idea that my friends group tried with the BOSS engines was to separate the bypass from the pump,like was done with the side oiler moving the bypass to the back of the block.
One solution I found interesting was to plumb a regulator at the rear  main oil gallery above #5 main bearing with the bypass oil line entering the pan on the rear left. Did it work? For a wet sump they felt the pressure was a bit more constant and the bearings looked better but it wasn’t so much better that it changed their inspection routine. The oil temp was down a bit though so they kept the set up with a change. They moved the regulator to the external line coming after the oil cooler,again with the return entering the oil pan on the left side.

[Gregwill16]

It would be interesting to see what difference it would make using a factory windage tray combined with a std volume pump with a C8AX style pickup.

[KMcCullah]

Fascinating tests, Jay! If your bearings aren't showing any signs of distress after being fed with aired up oil, then I'd thing your clearances and oil supply are sufficient. For what it's worth, I think my 504 has the same crank as this dyno mule and has been spun past 7k hundreds of times. The oil filters were showing metal when I pulled it down last year for inspection. The rod bearings had some ugliness. The crank looked great. When I built it, I used the old rule of .001 per inch of journal diameter to established clearance. So .0022-.0025 was the range of clearance on my rod journal bearings. About the same side clearances as this mule, .007-.010. I added .0005 clearance to the rod bearings when I put it back together. This dropped the oil pressure to 60psi (was 70psi) at 7k rpms (now I'm breaking the old rule of 10psi/1k rpm and almost zero psi at idle with a M57HV pump. But no metal in the filter. I wonder if aired up oil was my problem? Was running 15-40 Rotella. And I'm certain the oil was not getting up to it's designed operating temp. Have since switched to 10-30 Royal Purple.

My David Brown tractor has a oil bath style air cleaner. It has a series of screens stacked in the can body that the air is drawn through. I wonder if a stack of these type of screens at the top of the pans sump would help separate the air from the oil? 

[Katz427]

I know a couple of responders (Ross being one), already mentioned oil. I can only recall an owner of a dirt oval track modified, that was having a concern, over what they considered excessive foaming of the oil. At the time they did say they were using Valvoline, VR1. Not sure if it was a full or blended synthetic. They finally switched brands to a full synthetic, which I believe ( but not sure ) to have been a Mobile 1 racing oil, and found significantly less foaming.

[blykins]

Fascinating tests, Jay! If your bearings aren't showing any signs of distress after being fed with aired up oil, then I'd thing your clearances and oil supply are sufficient. For what it's worth, I think my 504 has the same crank as this dyno mule and has been spun past 7k hundreds of times. The oil filters were showing metal when I pulled it down last year for inspection. The rod bearings had some ugliness. The crank looked great. When I built it, I used the old rule of .001 per inch of journal diameter to established clearance. So .0022-.0025 was the range of clearance on my rod journal bearings. About the same side clearances as this mule, .007-.010. I added .0005 clearance to the rod bearings when I put it back together. This dropped the oil pressure to 60psi (was 70psi) at 7k rpms (now I'm breaking the old rule of 10psi/1k rpm and almost zero psi at idle with a M57HV pump. But no metal in the filter. I wonder if aired up oil was my problem? Was running 15-40 Rotella. And I'm certain the oil was not getting up to it's designed operating temp. Have since switched to 10-30 Royal Purple.

My David Brown tractor has a oil bath style air cleaner. It has a series of screens stacked in the can body that the air is drawn through. I wonder if a stack of these type of screens at the top of the pans sump would help separate the air from the oil?

You may wanna look at something else here….

I routinely run .003-.0035 on rod bearing clearances on factory FE rod journal sizes  and have never seen anywhere near zero oil pressure, with a B pump or a HV pump. 

I also don’t notice that big of a change in oil pressure between running the FE and BBC journal diameters.  As a matter of fact, the only time I see a big pressure difference is a huge change in viscosity, such as going from 20W-50 to 5W-20.

I’ll also say that I have mistakenly ran .012” main bearing clearances before and even then saw 10-15 psi of idle oil pressure with a B pump.

I think you have an internal leak somewhere.

Also to note, I’ve ran anything from .012” to .030” rod side clearances and don’t notice any big changes there.  I pretty much let it end up where it ends up and not worry about it.  I don’t like anything under .012” though as things just look tight to me.

[cjshaker]

A couple of last thoughts on the aeration. First, you can notice aeration as soon as the engine is started. I wonder if it has anything to do with the cleaning agents in modern oils, unlike the older non-detergent oils? I wonder this because I don't believe I've ever seen any type of cleaning agent that didn't foam at least somewhat when agitated. That may be the reason for the need for anti-foaming agents that are also found in modern oils. It would be interesting to see what a non-detergent oil did for one pull.

As far as the pressure drop, it stabilized when the vacuum pump was disconnected. Doesn't that indicate a direct cause from the vacuum pump? Of course it's basic science that it's harder to pull on something when there is a vacuum operating on the other side. Jay, you even mention that you see this on engines with vacuum pumps. That would seem to indicate a normal operating practice. Even if the bypass closed as the pressure dropped, you are still pulling against a vacuum at its highest point. Do you see this pressure drop in your Shelby's engine, with the dry sump?

I do think Barry has a valid point about the pickup. The square or rectangular ones certainly can't be friendly to a steady flow path.

[blykins]

A somewhat relative topic over on YB:

https://www.yellowbullet.com/threads/oil-pans.2664650/

It may be worth it to try it without the windage tray.....

[Stangman]

I don’t know I’m still sticking to the idea of adding a quart which will give you an extra half inch or so at high RPM and trying another oil that may have a better anti foaming agent in it. When you look at the pan with it not running it just seems like your not even using the deep part of the pan. When the motor is at full song it looks like the oil at the bottom of the pan is starting to DEarate which is what makes me think an extra qt of oil. I also like Barry’s idea with the bell pickup it might stabilize the aeration under it before it goes into the tube.

[Barry_R]

When I was at Holley we were developing a gerotor fuel pump that ended up being marketed as the Volumax.  They had IIRC a 170 GPH iteration and a 250 GPH version.  The 250 had a bigger pump section and a stronger motor.  At first they both shared a common external body with a single 1/2" inlet and outlet.  The 170 performed perfectly well in the lab, but the 250 had a significant cavitation problem.  The outlet would develop a bunch of entrained air and made a lot of noise with a big drop in flow.  Eventually the guy doing the design and testing decided to add an additional 1/2 inch inlet opening (now we had two inlets and a single outlet.).  The air disappeared, the noise went away, and the outlet volume cruised right past the 250 GPH target with no distress.  The inlet side of a pump is pretty damn important...

[427John]

When I was at Holley we were developing a gerotor fuel pump that ended up being marketed as the Volumax.  They had IIRC a 170 GPH iteration and a 250 GPH version.  The 250 had a bigger pump section and a stronger motor.  At first they both shared a common external body with a single 1/2" inlet and outlet.  The 170 performed perfectly well in the lab, but the 250 had a significant cavitation problem.  The outlet would develop a bunch of entrained air and made a lot of noise with a big drop in flow.  Eventually the guy doing the design and testing decided to add an additional 1/2 inch inlet opening (now we had two inlets and a single outlet.).  The air disappeared, the noise went away, and the outlet volume cruised right past the 250 GPH target with no distress.  The inlet side of a pump is pretty damn important...

I agree 100% on the effects of inlet restriction,this was also discussed over on Bill's test rig thread it is incredible how air can find a path given enough pressure differential,kind of like a mouse crawling under a door.Running the larger diameter tube 427 type pickup may not solve these issues but it surely can't hurt.Ford chose to use the larger tube pickups on their performance engines such as the 427,Boss 302,429 Boss and CJ/SCJ's,in the case of the 429's they even developed a dual entry pump though I think that had more to do with rotor pulsing causing spark scatter but it may be related.As far as the funnel or bell shaped pickup while I've seen no comparison to prove it,it sure looks like should work better.

[Nightmist66]

Good testing, Jay. I've often thought about a clear pan or at least a window to see what's going on. One can only speculate until you can physically see something.

While I'm down waiting on parts for months(because I can't leave well enough alone), I'm working on my own Frankenstein oil pickup. I have the Milodon 31130 pan and the matching pickup(#18370), but feel there is room for improvement. Hoping to have an update shortly.

[CV355]

Very cool!

I wonder what the aeration would look like in a dry sump application just for comparison...

There's something alluring about dry-sump...  Would that extra $2k-$2.5k be worth it though? 

[turbohunter]

There's something alluring about dry-sump...  Would that extra $2k-$2.5k be worth it though?

Agree, but I keep going back to the quotes from the builders with wet sumps, “the bearings look great”.

[CV355]

There's something alluring about dry-sump...  Would that extra $2k-$2.5k be worth it though?

Agree, but I keep going back to the quotes from the builders with wet sumps, “the bearings look great”.

Oh absolutely.  I think the hundreds of millions of engines that work fine on wet sump principle would agree too.  But to Jay's point, how would we know what's really going on in there without looking?

[wowens]

How about a full clear bottom in the pan. May show a issue at pickup.

[jayb]

The dry sump is better, period.  Twice I've run at Drag Week with the big SOHC and the dry sump.  Both times after the multiple passes and a thousand miles of street driving during the event, I pulled the pan and nearly all of the graphite coating was still on the rod bearings.  Prior to the dry sump, the same combination would come apart and the bearings would look fine, but the graphite coating was mostly gone.  With the normal pan and pump the engine ran fine and had lots of oil pressure, and I doubt if the bearing clearances had increased in any measurable way, but the dry sump results after the same treatment was eye opening.  You don't get the oil pressure drop with the dry sump, and the oil isn't aerated, and it really shows.

Is it worth the extra expense and hassle?  I don't know, but it is definitely an improvement over the wet sump systems I've used...

[blykins]

Agreed, dry sump is it.  Bearings always look brand new on tear down.  Another pro is that a good dry sump pump will pull a lot of vacuum on the crankcase.  If the engine is sealed up tight, a good Petersen/Aviaid pump will pull 15 inches of vacuum without an issue. 

The only cons are the cost and the real estate it takes up.  If you buy nice hose and fittings with wide radius turns, etc., I bet you can spend $400-500 just on plumbing the thing up.

[turbohunter]

Oh absolutely.  I think the hundreds of millions of engines that work fine on wet sump principle would agree too.  But to Jay's point, how would we know what's really going on in there without looking?

With you all the way. Would love to own a dry sump but my little middle ‘merica existence can’t quite convince my wallet that it’s worth it.
That’s part of the reason I love Jays’ experimenting. Makes me think about how to do things better.

BTW
I think Barry is on to something also with the shape of the pickup.
Maybe a modified OEM style.

[mbrunson427]

Jay, I'm not sure if it's the same episode of engine masters that you referenced, but on one of the episodes they do an oil pan test. They picked up 22 horse on an 818 horse engine by changing to the below pan. That pan is wide and has a screen for windage. Steve Brule actually made the comment that the pan is good enough that a dry sump doesn't really outperform it. When testing it they had the same pressure issue you're having and cited oil aeration as the culprit. They actually removed oil to solve it in their case (but of course not all situations are the same). With a 7 quart pan they got all the way down to 5 quarts before making the aeration go away. 

https://www.moroso.com/catalog/product/view/id/5804/s/chevrolet-big-block20376/

Not saying I know anything about stuff, but just regurgitating the information that they gave.

[Nightmist66]

I think Barry is on to something also with the shape of the pickup.
Maybe a modified OEM style.

Stay tuned.....


I feel a good alternative to the dry sump route is an accusump. I installed one on mine mostly for the ability to pre-oil the engine every time. But, the other thing it will do is keep the oil pressure fairly stable should you run the pickup dry for whatever reason and give you a small window of safety. I can't see any downside to an accusump.

[cammerfe]

I have used an Accusump for more than 20 years on my FE engines. I do it for the pre-oiling that's, therefore, simple---just use one of the available electric valves. Watch the oil pressure gauge while turning the engine with the starter. When the oil pressure just noses over, flip the ignition on.

KS

[babybolt]

Priceless - "my dyno junkie friend Royce"

[Royce]

That would be an accurate statement ... I just love that S--t. Nothing like seeing an engine straining and bellowing and watch the needles fly past 800 hp...I am sure I will be back for the next round...

[Royce]

As long as Jay does not hang the Dyno Monkey moniker on me...

[gregaba]

Ok guys
I am a little slow in the brain department but after looking at the link I have a question.
I am not that familar with the BBC but what difference is there in using the 168 tooth flywheel?
How would a flywheel interfer with a oil pan?
Thanks
Greg

[JERICOGTX]

As long as Jay does not hang the Dyno Monkey moniker on me...

He does now!!! LOL.

Jay, do you have a picture of the oil pump?

[Joey120373]

Ok guys
I am a little slow in the brain department but after looking at the link I have a question.
I am not that familar with the BBC but what difference is there in using the 168 tooth flywheel?
How would a flywheel interfer with a oil pan?
Thanks
Greg

I don't know for sure, but me thinks its the starter that might foul the pan ? Smaller flywheel diameter puts the starter closer to the pan?

[allrightmike]

   Is it possible the reason for more oil pressure without the vacuum pump is that the vacuum increases the size of the air bubbles that the oil pump must compress before it can actually pump oil?

[MRadke]

Assuming everything is working correctly, and there are no air bubbles, there should be less oil pressure when using the vacuum pump.  You need to think of the oil pump as a pressure adder, meaning that at a given flow and passage size and rpm, it will add x pressure to oil that is at atmospheric pressure.  If the oil is in vacuum, the pump is starting with a negative pressure value and adding to that.

[cammerfe]

Another benefit to a dry sump, not mentioned above is that the engine itself is more compact. I've owned several, but don't have one at hand right now. But memory serves that it's not unlikely that a dry sump pan only adds about six inches to the bottom of an engine assembly. That makes possible mounting the engine lower, or having more ground clearance or some combination of the two. If it's not convenient to place all the extras in the engine compartment, put the can in the trunk. You'll pay for the hose but the whole approach makes for neatness and may even contribute to fore-'n'-aft weight distribution. Use a smaller suitcase when you go on trips.

Another issue, albeit not a really big deal, is just what was mentioned above---there's no need for a vacuum pump. It certainly cleans up the front of the engine.

KS

[oldiron.fe]

                                                                                                                                                               i think most readers know oil pans/pickups  can cause problems if not correct-correct pans help good oil psi.--- i have built or added to pans from early 60s to now--NEVER lost a bearing --ran a built 427 center 66/67 before the nam.-- what worked-- scraper length of pan 1inch on pass side   about 2inch flat extended over back of sump-- -- BIGGEST NOTE 1g of force to sump with rounded bottom will let oil climb 3/4 inches to side or rear -- FIX sawsall off bottom rounded part of pan NEW all bottom with sides no rounds  -- about 88 degree angle will keep much oil from climbing--most race pans are built about this way--GOOD scraper will fit .010 or less to counterweight/rod bolts! use screen type tray-never smooth metal tray-use only with screen above ( directional type ) tray--tray should have scraper on driver side-- some hi/rev overseas tests show 8/10% hp+!! when you bounce 7000 rpm oil off hard non directed surface--look again at jays pictures  i believe BEST current wet sump has good scraper/proper screen/proper tray--2x accumulator look-Rays top t-bolt good scraper/screen/tray combination about 300$-- +accumulator set-up
                     

[galaxiex]

I think a *deep* pan is an all-around win. 

I was discussing this with Jay last night and made the comment that I've never seen this kind of pressure drops in the past, even with the exact same oil pan, pickup, oil, at 7000-7500 rpm.  However, I can't make a direct apples/apples comparison because the engines that were in that situation did not have vacuum pumps.  However, the engines that did have vacuum pumps also did not see an oil pressure drop at high rpm.

The only differences I can think of are these:

1.  I do not use windage trays.
2. I restrict oil to the lifters.

To echo one of Doug's points, I think there's an advantage to keeping oil off the crank, and this may reflect my #2 point.  The less oil that's rolling off of the cam/lifters, the less that falls onto the crankshaft. 

It would be nice to see a test without the windage tray to see what the difference would be.

As mentioned, a different oil type/viscosity may add a difference as well.

Hi Brent,


How much restriction do you use, (orifice size) and do you put the restriction in the 2 rear off-shoot passages from the main galley?


I was thinking .090 orifice.

Are the restrictions for solids only, or hyd lifters as well?

Thanks!