Assuming that you are not pumping the oil pan dry, is it beneficial to have the oil SLOWLY return to the oil pan? This question was raised by one of the engineers here at work (no, he's not an automotive engineer), his position being that the oil that coats the inside surfaces of the engine cools as it slowly flows back to the pan. If this is the case, then coating the internal engine surfaces; block, valve covers, oil galley, windage tray, etc..to improve the rate of oil flow back to the pan, would actually increase the temperature of the oil. I have always thought that oil in the pan was cooler than any other place in the engine, mainly because it was farthest away from the hottest areas, the combustion chambers. What do you all think?
I believe that getting the oil back to the pan as fast as possible is key to a high performance engine. If temperature is an issue then an oil cooler should be incorporated in the system. The pump should always have an adequate supply to draw from and any delay in oil return could starve the pump,even momentarily, with disasterous results. Frank
Yeah, you want the oil to return to the pan as fast as possible. Any starvation could lead to big time problems. That's why some peolpe use galley plugs on the bottom end to keep all the oil from going to the top end when you drop the hammer and drill additional oil return holes in the gallel to get it back down in a hurry.
I want to see the oil reach back to the pan as quickly as possible. What happens IMO is, just like a cooling system, after the oil has done it's job lubricating if it hangs around on a hot parts and slowly moves toward the pan all of the oil in the engine will soon become overheated. If you return the oil back to the pan quickly it dosen't soak up as much heat but it also dosen;t become overheated. If the oil is becomeing to hot it will never cool down while the engine is running. A system with a quick return and sufficient flow volume will keep all of the parts in the engine cooler because when it returns to those parts on the next trip it will not have as much heat in it from the previous cycle. Hope that makes sense. It is just like a cooling system, you should be moving the water quickly to keep the fluid from becoming overtaxed and then requiring the parts that cool the fluid to have more work to do. I assume you are thinking of some of the coatings that we were discussing earlier this week that help create a faster oil drainback. As a side note by returning the oil to the pan faster you can also reduce the windage in the crankcase and free up some power. Shawn
[ QUOTE ] This question was raised by one of the engineers here at work (no, he's not an automotive engineer) [/ QUOTE ]Todays score: HAMB 1 Engineer 0
I agree that it is better to have the oil in the pan waiting to be pumped back into the engine than it is to have the pan dry. That's why my intial assumption was that the engine was not starving for oil. I also believe that the oil pan should be cooler than most any other area of the engine that the oil comes in contact with. Does it sound reasonable that the valve covers would be cooler than the oil pan? That's the only way I could see that the oil would cool more by staying in the top end. Yeah Shawn this discussion came up as the result of another idscussion about dry-film lubricants and the benefits of creating internal engine surfaces that would shed oil quicker. Even if it were possible to gain some amount of oil cooling in the valve covers or other areas, there are other areas such as the rotating assembly that suffer from oil build-up. Oil clinging to crankshaft journals and connecting rods rob horsepower and create vibration. I just thought I'd throw this out to see if anyone who has more theoretical knowledge of internal combustion engines had ever dealt with the trade-offs. I'd set the score at HAMB:5 Engineer:-1
Every performance engine I build,gets a windage tray or a crank scraper. The cooling effect of oil is a very interesting subject.It does pull some heat away from the valve train assemblies and the top of the cylinder heads,but,I would think, the very fact that you are supplying oil under pressure,generates heat in the oil itself.I have always been curious how much oil cooling can/is achieved thru aluminum valve covers and oil pans. I just ran my 408 inch stroker small block(MOPAR) on the dyno a few weeks back.This engine has a custom fit windage tray and an aluminum oil pan(6 qt). After we stabilized the coolant temp at 160 degrees,we put it thru nine,back to back,full load pulls to 6 grand. The oil pressure ran as high as 80 psi at 6 grand.The oil temp never exceeded 78 degrees.The oil was Shell Rotella T,15-w-40.This engine produced 450 ft lbs of torque and 350 hp all done by 5800 rpm. I think it would be very interesting,to see what the oil temps are in different parts of the engine,at a given engine temp and load.
Isn't also possible that if the oil were to cling to the internal surfaces it would act as an insulating blanket thereby causing the block to shed less heat? I have known motors that actualy seem to return very little oil to the crankcase but appear to send most of it out the tail pipe or spewing out on the ground. and yes, as said above, they don't last very long. Paul
The pro racers have been trying to get the oil back to the sump as fast as possible for ever. Thats part of the reason that the lifter galley and bottom end get polished and painted with armature paint. The other part being to releave stress of course. The pan would be the coolest part of the engine because its made out of sheet metal instead of cast iron. Iron retains heat better than sheet metal. If your worried about your oil getting hot, put an oil cooler on it or one of those really trick finned aluminum pans, or increase the capacity of your pan, IE make the sump deeper (wider for you scraper guys). Avoid things like chrome pans if you want to keep your oil cool (did I mention that I hate chrome?) chrome holds the heat in. if it dont make ya dirty it aint yours.
Some good discussion going on here. I tend to agree that the oil should return to the pan quickly, and that the function of the opil is for lubrication, not cooling. The water passages and radiator have the function of cooling. One interesting note is that oil needs to be at a certain minimum temp to work best, so that it flows through the oil passages and back down to the pan. That is why many racers use a pan heater to get the oil up to operating temp. Here is a little food for thought. On some Suzuki motorcycle engines (GSXR for one), they use a combination of oil and air cooling, no water. The engine does have cooling fins, but not as large or sufficient capcity for the engine without the added cooling of the engine oil. The engine <font color="blue"> IS </font> designed for the oil to carry away heat from engine parts, especially internal areas that do not have the benfit of air cooling. The engine actually has oil sprays built in to cool the pistons and other key parts. But this engine also has a big oil cooler so that the oil does not get overheated. On this engine the oil is still intended to run back to the sump quickly though, as with any high performance engine. The oil needs to be pumped through the cooler and back to the engine for lubrication first, and then cooling second. I think this is a unique way of cooling the engine.
[ QUOTE ] The oil pressure ran as high as 80 psi at 6 grand.The oil temp never exceeded 78 degrees.The oil was Shell Rotella T,15-w-40.This engine produced 450 ft lbs of torque and 350 hp all done by 5800 rpm. I think it would be very interesting,to see what the oil temps are in different parts of the engine,at a given engine temp and load. [/ QUOTE ] The oil temp never passed 78 degrees? Wow, how does that happen, the engine has to be running at 200+ degrees, how can the oil temp stay so far below the engine temp? I have heard about the Suzuki engine spray set-up, that is an interesting way of pulling heat out of the pistons...
I wondered about the "78 deg", maybe he meant "178?" The "flip" side to this discussion is a few snow mobile owners around here have been using oil in place of water in their radiator equipped machines. They claim the oil "carries away" and "dissapates" heat better than water.
[ QUOTE ] motors that actualy seem to return very little oil to the crankcase [/ QUOTE ] [ QUOTE ] The oil temp never exceeded 78 degrees [/ QUOTE ] obviously you must supply a constant source of fresh oil.. it's common sense Paul
I feel the snowmobile owners are a little misled. Oil will not disapate heat faster. I think what is happening that is helping them is that they are having localized boiling of the water in the cooling system, when they are running water, next to the combustion chambers. This causes vapor pockets on the walls of the cooling jackets and prevents the cooling system from doing it's job..cooling.. Since the oil will not boil as soon as water this prevent the boiling and hence prevents the detonation that occurs when localized boiling happens next to a combustion chamber. There are a few products on the market that they may want to try. water boils at 212 degrees, a mixture of water coolant will boil higher dipending on the mixture up to around 242 dedgrees when under pressure from the radiator. There is a product called NPG by a company evans cooling. Their coolant system is a non-aqueous solution(no water) water is considered a contaminant. Their solution does not boil until 375 degrees this prevents the localized boiling and detonation entirely. On a side note it will not prevent preignition(ping) which is caused mainly by hot spots in the combustion chamber such as sharp edges from machining etc. this will need to be aproached with some polishing. Shawn
[ QUOTE ] I feel the snowmobile owners are a little misled. Oil will not disapate heat faster. I think what is happening that is helping them is that they are having localized boiling of the water in the cooling system, when they are running water, next to the combustion chambers. This causes vapor pockets on the walls of the cooling jackets and prevents the cooling system from doing it's job..cooling.. Since the oil will not boil as soon as water this prevent the boiling and hence prevents the detonation that occurs when localized boiling happens next to a combustion chamber. [/ QUOTE ] I wondered what the benefits were. (if any) Being up in the "land of ice and snow" the snowmobile racers are always looking for "the edge" but seldom could explain WHY they did use oil in their rads; only that "the other guys do it." [ QUOTE ] There are a few products on the market that they may want to try. water boils at 212 degrees, a mixture of water coolant will boil higher dipending on the mixture up to around 242 dedgrees when under pressure from the radiator. There is a product called NPG by a company evans cooling. Their coolant system is a non-aqueous solution(no water) water is considered a contaminant. Their solution does not boil until 375 degrees this prevents the localized boiling and detonation entirely. On a side note it will not prevent preignition(ping) which is caused mainly by hot spots in the combustion chamber such as sharp edges from machining etc. this will need to be aproached with some polishing. Shawn [/ QUOTE ] Now you have some "gears grinding." (thinking!) Could the NPG product you mention, work in say a flathead?
NPG will absolutely work in a flathead. it is not cheap(about $24 a gallon) but it is designed to last 1 million miles. Also this product does not freeze until -70 so it could prove useful in very cold enviroments on machines that are not used daily. you can check out their website at www.evanscooling.com . Shawn
I realize this is an old thread, but I'm wanting to know what if anyone out there has coated the internals of their engine. If so what brand and/or brands do you recommend? Eastwood sells a product by the name of Glyptal.
The bigger sump is to keep the sump from running dry. Oil is efficient enough in heat transfer that 8 Qts gets just as hot as 4 qts, & in not much longer time.
Glyptal has been used forever as a internal coating. Seals the block and promotes oil return. The original purpose of finned aluminum covers, pans and valley covers was to help cool the oil. Dates back to the turn of the last century.
There's been several threads on this over the years, so I'll give you the shorthand version based on experience. Note that others here disagree, so take it for what it's worth. If...and it's a big if...you decide to do this...make sure the area to be painted is absolutely oil-free (virtually impossible with a used block because oil gets into the pores, just like a cast-iron skillet , but try your very best); after the usual scrubbing, use denatured alcohol and scrub the area multiple times. Use Glyptal according to the directions; if none, then it's better to use two light coats than one heavy coat. After you are done, I suggest using a heat lamp to cure it for 48 hours. Rustoleum is another possibility, with the same procedure, though I trust it even less. Keep in mind that if the block prep is not adequate, the paint will flake off and end up in the pickup screen, bearings, lifter orifices, or wherever it will cause the most damage. I will say this: I used to go through all this, and I no longer do. I know a fair number of respected engine builders, and they don't do it either. As I say, some people still do. On my personal engines, I grind and polish ALL the drainback areas, not just the casting flash, but I wouldn't do it for other people...it's a LOT of work. In terms of Glyptal, etc. helping oil return...I'll just say that the time spent can be used more effectively doing other oil control mods, like grinding drainback channels where needed, etc. In terms of Glyptal,etc. sealing the block...if the block is ground and cleaned up properly...and it is a seasoned block...you shouldn't have to worry about chunks of anything working loose.
I fear loose paint too. There are other heat issues. Generally, engines only really heat the oil when running at high power levels...on the street, you can typically use most of the car's power only a few seconds at a time til you reach a point at which legal danger becomes excessive or you are slowed by traffic, redlights, corners, idiots texting, etc. Most of the time car is at low power levels and oil can actually be too cold...it needs to be up around water temp to discharge water (from combustion gases and condensation) and to cook off any gasoline that gets down there. It also needs to be pretty warm to be at the flow and viscosity it was designed for. I believe the little heat exchangers Ford and Chevy put between oil filter and block on Mustangs and Camaros a few years back were actually meant to bring oil temp up, both during warmup and in cruise mode with very low RPM in overdrive. At low chug, cold can be the problem. And of course street cars are out there in the snow and ice in February, too, unlike racecars. Hot becomes the problem under sustained load OR under slightly odd racing uses, such as the use of oil orifices pointed at undersides of pistons to cool them in some racing SBC's.
thats the stuff you want almost no one else sells it, thats what they refer to as armature paint, it's a red color, oil cooler helps a lot,but you need to run it with a high quality thermostat, this makes sure the oil gets hot enough to burn off condensation, use a thermostat that allows some oil through the cooler all the time,this prevents air pockets in the cooler. also a good pcv system helps cut down oil sludge and lets the oil flow better back to the pan,
Homespun91 and Bruce, The possibility of the paint flaking off is what kept me from coating the internals of my block when I rebuilt it years ago. I'm currently in the process of a rebuild and figured I'd research any possible ideas for building the best engine I can. It didn't really need rebuilding, but one of the cylinders never did seal right and it would smoke a little every once and a while. So I decided to freshen it up a little: new rings, bearings, seals, etc. As you suggested, I've already ground and polished all of the drainback areas on the block. Thanks for your input.
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