Technical Figuring out oil capacity

Sorry if this has been asked before, I did a weak search and still don't know.

How to calculate the oil capacity of any engine, no matter what the manufacturer says or what the dipstick says, of any wet sump engine? Suppose the pan is taller/shorter than stock, maybe it's at a weird angle, whatever. Should it be X distance below the lowest high speed part? Below the seam where the pan and the block meet? Where should it be?

Thanks

 

I think you’re trying to make something simple more complicated than it has to be.

The engineers who designed the engine should know best what it needed.

 

Full sump plus a quart sitting not running...

 

If the engine loses oil pressure due to oil starvation, it needs more oil in the sump. Unfortunately, there are a whole lot of variables that make it difficult to make up one simple rule about what the level should be, for all engines.

 

Back when deep sump racing wet sump pans were used we still put the same amount in the pan but dropped the pickup the same amount to keep oil off the rotating crank. Go by manufacturers recommendations or pan manufacturers specs. All depends what your doing with the engine. Street, drag racing, road racing ect. Lippy

 

It would seem that if someone added a deep sump oil pan the purpose would be to increase the holding capacity of the pan.....not to just lower the existing capacity. That would allow more oil to disipate heat and by lowering the oil pickup too, there would be less chance of oil starvation. To my understanding you would then want to have an increased amount of oil in the pan. The logical(?) thing would be to put the original dipstick in place and fill the pan until the oil level is the same as it was without the deep sump pan. Thats the way I always looked at it.

 

A deeper sump with a corresponding lower level reduces the amount of oil "splashing back" at the crank after being thrown from it, especially at high rpm. This reduces the friction and frees up some horsepower, not a whole lot but apart from the pan/pickup modification work it's basically free horsepower. Various screens and scrapers can also be used to get the oil off the crank and keeping it away from it with the same kind of benefits.

 

Nope. And more oil won't run cooler. Just takes it longer to get to temperature. You can add more oil capacity but why? Lippy

 

Sorry this was for EK.. lol. Lippy

 

how about when running remote oil filter(s) - need to run more oil to keep oil in hoses?

 

with a remote filter, you fill up the system so the hoses and filter are full, then get the level in the sump where it would be, with a normal filter.

 

I guess just want to know how the engineers do it. There has to be a method to figuring it out.

 

I'd never heard of this oil level lower to reduce windage until a couple years ago , anyone else have a comment on this ?keep in mind that can lobe oiling in a SBC depends on crank / rod splash

 

It is discussed in "the Chevrolet racing engine" by Bill Jenkins, and if I remember correctly "Four stroke performance tuning" by A. Graham Bell. Probably many other books too.

 

That crank/rod splash is not the crank splashing sump oil though. It is spray oil 'leaking' from the rod/crank feed and the spray from the oiling holes in the rods, which is conveniently pointed at the cam/lifters.
Big block Mopars have used a windage tray dating back to the 60s to separate the oil from the crank.

 

For a stock engine, just use the MFGs recommended quality and quantity - assuming an OEM sized pan and the OEM dipstick. If your pan is a little deeper, then add oil until the dipstick reads normally. If the engine is tilted or raised for some reason at the front, you may need to remark (recalibrate) your dip stick at the new position with the stock OEM oil capacity in the car. Hopefully, the dipstick will be still be in a usable location.

If your pan is too shallow for some reason, like crossmember clearance, you will probably need to deepen the other end (if it hasn't been done already) where there is room and / or use a remote pickup that goes to the deep end of the pool. Again, hopefully the old dipstick is still usable.

As mentioned in posts above, if you have a deep pan and still use the stock level of oil, then you'll need to recalibrate the dipstick (or perhaps even fab up a longer one) so you still get the correct reading. If none of this works for you, consider a dry sump system.

 

Very good question Hex173t. I doubt if any of us non engineers know the real answer. I sectioned 2" from the sump of the Olds engine in my 30 roadster & raised the pump inlet so it just clears the bottom Then I keep the oil level just high enough so the pressure doesn't drop during hard braking, acceleration, or cornering. A windage tray & sump baffling would help. I have oversize tubing feeding the mechanical oil press gauge. I feel this gives a quicker reading of pressure drop. Greg

 

That's great , was there a conclusion reached ?

 

We'll have to disagree on this one Lippy. That's why increasing fluid capacity in an automatic transmission and using a larger pan helps keep temperatures down.

As for lowering the oil in the sump to prevent windage, the sump only exists in an area that is maybe 2/5 of the oil pan length, so the rest of the engine would get no benefit from the deeper sump. Oil scrapers and baffling help keep the oil off the crank. The deeper sump also helps insure the pickup remains immersed during hard braking or turning, and the additional oil works to insure there is plenty available. There have been situations where pumps have sucked a sump dry when all the oil ended up in the valve covers of an engine.

 

Have you actually tested the larger pan on a transmission thing? I don't see any reason it would keep temperatures down. But I haven't tested it, either.

fun tidbit: the two oldest engines I've played with recently, 41 Cad flathead V8 and Hudson 308 flathead six, both have dipsticks that show three quarts worth of "add". So the engineers back then didn't seem to be too worried about keeping the oil right where it belongs.

I've had a few engines that are rather picky about oil level....too low, it'll starve, too high, it'll starve. I expect there is some empirical stuff going on with oil level engineering.

 

Been a few years since I read them, but as I recall it it works well and they like it.

 

Squirrel - I like the 3 quarts of “add’. Let me explain: In my case, I bought a 348 Chevy without a dipstick. Got a dispstick and tube from Eckler’s for a factory 348. The book says 4 quarts plus 1 for the filter. With 5 quarts my dipstick says 1 quart low, so I added another quart. I was worried about being too full, crank sloshing oil all over, lowing power, etc. On the other hand, my thinking is that 1 quart one way or the other can’t truly make that much difference...... what is that, a half inch depth in the pan?

I set the oil pump pickup about 1/4 to 1/2 (can’t recall) inch off the pan bottom. It’s a street car.

 

Many years ago I was involved in a troubleshooting job for an old IH TD25 bulldozer that was suffering from an overheating transmission (powershift transmission, very similar to automatic, uses a torque converter, oil wetted clutch packs to engage different gears), everything checked out fine, except it was significantly over filled. We lowered the level down to the normal level as shown on the dipstick and put it back to work; no more overheating. The consensus at the time was that the additional oil in the system held on to too much heat for the stock cooling system to dissipate. Though that was an educated guess and we didn't run tests to confirm that, but the problem went away so we weren't going to spend more time on it. But I've remembered that all these years. My experience is increasing the oil level will not help reduce heat, but add too much and it may cause heating.

 

G'day, When drag racing our BBC engines we ran extended sumps but to the sides rather than deeper (side kick outs). We also ran a Milodon Diamond Stripper windage tray in each engine along with the appropriate scrapers. If I remember correctly we were running about 8 quarts. With times in the 9's and extreme low gear acceleration we never saw any type of low pressure problems. And there was a gauge and a big red warning light so we would have known. Three seasons on the motor and upon overhaul the bottom end was perfect.

One of the engines also ran a Canton oil pressure accumulator with another 3 quarts of oil. It took a lot of work to get that 20w50 up to operating temperature but it never went over even with delays in staging.

With engines used in the OT fiberglass cars, we ran the factory windage trays and the recommended oil fill even with the factory race pan (long sump). In the road racer we ran the big factory pan plus an accumulator. You can't have too much oil in a race car.

 

I have heard of this (oil windage on rotating assy)from a few Racing engine builders and figured it was one of the advantages of dry sump oiling systems.

 

If you add enough oil you'll have rotating axles etc. dipping into the oil all the time, even if they're not supposed to, or if they're supposed to they'll be in much deeper. Whipping around all that oil causes friction, friction causes heat. Possibly worse, the oil may be whipped to foam, and as foam doesn't lubricate very well. Paradoxically, this means too much oil can cause things to fail due to lack of lubrication.

Correct.

 

Here is an exerpt from an article that has an opinion from some experts.

Its common knowledge that the more area you have to exchange heat the quicker it will be exchanged. If you have a system thats overwhelmed with too much heat, a larger transmission pan will still exchange more heat than a smaller pan, but could still be insufficient to completely dissipate the heat. The larger pan will be more efficient if it actually contains more fluid to touch the taller sides of the pan. You can have too much of a good thing and overfill which can make things worse instead of better. Different situations produce different results. Drag racing will be different than the needs and results for a street driven vehicle. Remember too that in the street driven vehicle, The size increase of the surface area will be compounded by the speed of the air passing it when driving. As I said, it will always produce more cooling but can always be overwhelmed by vehicle conditions. Pulling a large trailer with a large boat behind a motorhome up some steep long grade (I-10 ?) comes to mind.

In Blues4U's example he mentioned an "overfilled" piece of machinery that had problems with overheating.

Yes, overfilling is a bad thing. Oil gets whipped about and becomes aerated and creates problems. There is a difference in increasing the capacity of any oil reservoir and taking the proper steps to control the oil......and just overfilling an existing reservoir. Look at Nascar. They use a dry sump oiling system. One of the main benefits of a dry sump is the ability to increase capacity while keeping the oil separated from the rotating assembly and preventing sloshing about. Since the system keeps virtually all the oil out of the pan and in the remote tank or in circulation, it would seem logical that only the bare minimum of oil would be required. In contradiction, they have oil tanks holding 5 gallons of oil.........20 quarts. Why would they need so much more oil than just a little more than the system requires?
There are various capacities for oil pumps, but the venerable Smokey Yunick said that an old smallblock Chevy Z28 was capable of 9 gallons of oil per minute at 7000 rpms. Lets say that you don't ever take your engine past 5000 rpms and your pump isn't blueprinted. So I will conservatively estimate that your engine only moves 5 gallons per minute. If you have a 5 quart oil pan and we assume that approximately 1 quart of that oil is always in circulation within the engine......that leaves 4 quarts (1 gallon) residing in the oil pan. That 1 gallon (4 quarts) will get taken out of the pan and put back in 5 times in 1 minute.............and you just drove it for 1/2 hour. So in your drive to work, the oil in the pan was taken out and put back maybe 100 times . Only 100 because you ain't driving at 5000 rpms and all this calculation is just a rough guesstimate. The oil in the pan is only exposed to air cooling when its in the pan. If you increase capacity, the oil can spend more time in the pan and fewer complete cycles made. It seems logical that increasing volume and area would be beneficial to any engine as long as baffles are employed to control the location of the oil. Scrapers would also benefit an engine whether a deeper sump is employed or not.

Thats my take on it, others are welcome to have a different viewpoint.

 

Yup....the surface area of the transmission will increase slightly with a deeper pan. But will you be able to measure a difference in transmission temperature? That's the question

Chevy used a deeper pan on some truck TH400s, which makes me think there might be a reason to use a deeper pan.

 

Again, it would vary with every set of circumstances. In some cases I think it would cure a problem or make an iffy situation tolerable. In a situation thats really in need of additional cooling, a heat exchanger/small radiator would provide much more cooling. Some of the pans I have seen had tubes running lengthwise thru the pan to provide more area and more airflow. They definitely won't hurt anything........except your wallet ? I did see something a while back where someone tested a deep sump pan and if memory serves me, I think they recorded maybe 4 or 5 degree temp drop. Don't know if that was idling or driving though.....and my memory sucks these days.
Found this video where a guy installed one of the pans with the tubes. He says during city driving not much help, but out on the road his temperatures dropped 20 degrees. (172/152) Skip to the 2:30 mark to avoid the babbling.

 

Air cooled VW had a finned oil sump. Got to help cooling a bit.