Nice animation of how oil flows in an engine
- Thread starter Ken4
- Start date
- Status
Too bad it doesn't show where my engine burns it. LOL.
Which engines have oil fed to the wrist pins via connecting rods?May-be I'm getting old but I thought the crank and it's counter-weights splashed the cylinder walls with oil to keep the piston and cylinder wall away from each other
Oooooo, you are getting old. At least to my understanding, splash lubrication engines went the way of the dinosaur back in the 1950s!quote:
Originally posted by Greaser:
Which engines have oil fed to the wrist pins via connecting rods?May-be I'm getting old but I thought the crank and it's counter-weights splashed the cylinder walls with oil to keep the piston and cylinder wall away from each other
My 2001 Jeep straight six just has a "spray" hole on the top of the connecting rod to "splash" the cylinder wall on the way around the crank...
I was thinking more of the way old, low rpm engines of the 50s and earlier were lubricated. Also, maybe I'm splitting the hair too thinly, but is "spray" considered to be the same as "splash"? Or do they partly overlap.quote:
Originally posted by Greaser:
My 2001 Jeep straight six just has a "spray" hole on the top of the connecting rod to "splash" the cylinder wall on the way around the crank...
My thanks to you too, Ken. The last animation got me thinking. Is it depicting a motorcycle-specific system? I know that the 3.0L six in my car has a baffle plate between the crankshaft and the oil in the pan below, so it's not doing any dip and splash lubrication. Although I haven't seen my V-6 apart, I've seen similar engines in various stages of teardown, and from those observations, assumed, mistakenly perhaps, that the piston and cylinder were supplied via pressure up the con rod to the wrist pin. Please don't tell me that my cylinders are being lubricated only by whatever vapor makes it up there -- I won't even be able to turn the key tomorrow morning . . .
MolaKule
Staff member
I know for sure my two Nissans have spray nozzles that spray the underside of the piston mainly for cooling purposes.
Most if not all diesels have the same system.
Most if not all diesels have the same system.
Don't forget that as the crankshaft turns, it will sling oil in every direction, including on the underside of the pistons and on the cylinder walls.
An engine turning at 3000 rpm will turn oil into a force that will tear the flesh from your hands if you could hold your hand under a running engine at that speed.Windage trays will yeild 10-20 HP in a HO engine just by letting the reciprocating assembly not get oil spray back on itself from the sump.Vapour coating your cylinder walls is almost amusing
Yeah, I thought it was almost amusing too . . . until I considered what it meant in terms of oil supply volume to critical parts.quote:
Originally posted by Greaser:
An engine turning at 3000 rpm will turn oil into a force that will tear the flesh from your hands if you could hold your hand under a running engine at that speed.Windage trays will yeild 10-20 HP in a HO engine just by letting the reciprocating assembly not get oil spray back on itself from the sump.Vapour coating your cylinder walls is almost amusing
Another "violence of oil" thought: in Naval Aviation training, we're taught to get the **** away from "pink clouds," which is what you see in the vicinity of small high pressure hydraulic leaks (atomizing fluid). Typical aircraft systems run at 3000 psi, and the flow from a small leak can slice your fingers off like a liquid laser beam. Trust me, I've got plenty of respect for moving oil.
BTW, I wasn't trying to offend anyone in my last post. The blanked out word was a reference to that timeless place where the unsaved go after their run through this existence to learn about their own personal flashpoint and Nowak percentages. . .
I am not a mechanic, but I have read some material over the years that I think is correct on the topic of a typical passenger car engine's bottom-end lubrication. Here goes:
1) Most production car engines do not have an oil passage drilled through the connecting rod to lube the wrist pin or cool the back of the piston.
2) The oil that is squeezed out of the main rod bearings at the crank is thrown all around, and is the main method to lube the cylinder walls and wrist pins.
3) The cylinder walls do not require very much oil to be lubricated properly. In fact, there is generally concern about too much oil overwhelming the oil-scraper ring. Even in racing engines, there is the desire not to force too much oil on the cylinder walls. Just a little dab will do it.
4) Most big truck engines do have pressure lubrication to the wrist pins though a drilled oil passage in the connecting rod. This oil is then forced through the ends of the wrist pins to wash the cylinder walls in oil on every stroke. Remember, these are rather low-speed, high-load diesel engines that have 20:1 compression, higher temps, and are designed to run >500K miles.
5) The rotation of the oil flying off of the crank can be extreme, causing a rotating "oil cloud" that does indeed needlessly reduce power. Also, the "oil cloud" can whip-up the oil with air to the extent that it foams, won't pump right, and damages the oil. Hence the wise use of windage trays in the best engines.
6) The "oil cloud" is not a simply described. On an old Chevy NASCAR engine bolted to a dyno in a shop, the oil cloud was observed to move around and back-and-forth like a tornado. What is it doing as we go around corners, hit bumps, etc?
7) The above applies to oil-pan sumps as well as dry-sump set-ups.
8) For a modern gas engine, with full-pressure lubrication to the main bearings, there is no case that you want the crank / rods / weights to dip into the oil in the oil pan. This will stress the oil a lot, add air bubbles, and reduce power significantly.
9) Most of us are concerned about oil-starvation, but it is also easy to over-lubricate an engine. Engine deigners have a big task to properly lube an engine!
10) My main concern is on start-up. I conclude that oil with good long-term coating properties & film strength is critcal for intial lubrication on start-up, until the oil pressure builds up.
Best wishes as you drive along!
SWS
1) Most production car engines do not have an oil passage drilled through the connecting rod to lube the wrist pin or cool the back of the piston.
2) The oil that is squeezed out of the main rod bearings at the crank is thrown all around, and is the main method to lube the cylinder walls and wrist pins.
3) The cylinder walls do not require very much oil to be lubricated properly. In fact, there is generally concern about too much oil overwhelming the oil-scraper ring. Even in racing engines, there is the desire not to force too much oil on the cylinder walls. Just a little dab will do it.
4) Most big truck engines do have pressure lubrication to the wrist pins though a drilled oil passage in the connecting rod. This oil is then forced through the ends of the wrist pins to wash the cylinder walls in oil on every stroke. Remember, these are rather low-speed, high-load diesel engines that have 20:1 compression, higher temps, and are designed to run >500K miles.
5) The rotation of the oil flying off of the crank can be extreme, causing a rotating "oil cloud" that does indeed needlessly reduce power. Also, the "oil cloud" can whip-up the oil with air to the extent that it foams, won't pump right, and damages the oil. Hence the wise use of windage trays in the best engines.
6) The "oil cloud" is not a simply described. On an old Chevy NASCAR engine bolted to a dyno in a shop, the oil cloud was observed to move around and back-and-forth like a tornado. What is it doing as we go around corners, hit bumps, etc?
7) The above applies to oil-pan sumps as well as dry-sump set-ups.
8) For a modern gas engine, with full-pressure lubrication to the main bearings, there is no case that you want the crank / rods / weights to dip into the oil in the oil pan. This will stress the oil a lot, add air bubbles, and reduce power significantly.
9) Most of us are concerned about oil-starvation, but it is also easy to over-lubricate an engine. Engine deigners have a big task to properly lube an engine!
10) My main concern is on start-up. I conclude that oil with good long-term coating properties & film strength is critcal for intial lubrication on start-up, until the oil pressure builds up.
Best wishes as you drive along!
SWS
VW watercooled engines have drilled rods that lubricate the wrist pin. The multivalve engines have oil squirters too along with rifle drilled rods
Would like to know why some engines need this type of oil feed and some don't.I have a piston and connecting rod from John Forces' Castrol funny car,signed by John to yours truly,and there's no hole in the rod...this is for a nitro burning 7000 HP funny car...wierd isn't it...by the way John Force is a heck of a nice guy,down to earth,and one of the fastest human beings on 4 wheels around.that I had the pleasure to meet
just to add to what sws posted,
i've never seen or heard of a rod that is drilled with an oil passage to the small end(that doesn't mean they don't exist, i just haven't come across any). the ones i've seen that do squirt oil into the back side of the piston (for cooling on diesels) do it from the big end which squirts oil when the hole in the rod and bearing line up with the hole in the crank, it has a simple timing system. the small end of the rod has a bronze bushing that fits on the hardened wrist pin, it needs almost no lubrication so just a splash or vapor is plenty, it also doesn't move much, just a few degrees each way.
i've never seen or heard of a rod that is drilled with an oil passage to the small end(that doesn't mean they don't exist, i just haven't come across any). the ones i've seen that do squirt oil into the back side of the piston (for cooling on diesels) do it from the big end which squirts oil when the hole in the rod and bearing line up with the hole in the crank, it has a simple timing system. the small end of the rod has a bronze bushing that fits on the hardened wrist pin, it needs almost no lubrication so just a splash or vapor is plenty, it also doesn't move much, just a few degrees each way.
I too, have never seen or heard of a piston pin being lubed via pressure through the rod.
I have a motorcycle that has its valve train lubed by the oil mist method. It's a Moto Morini, a 500cc, 72 degree V twin. It has a belt driven cam located at the base of the V. There are relatively large passages for the pushrods extending from the crankcase to the top of the head. The mist of oil created by the crank is drawn up the passages, aided by the design of the ventilation system. The oil collects on the rocker covers, that have nipples cast into them above the rocker shafts. The oil drips off of the nipples into corresponding holes in the rocker shaft supports. These engines are known to be able to easily make 100,000 miles.
Ed
[ April 25, 2004, 01:17 AM: Message edited by: edhackett ]
I have a motorcycle that has its valve train lubed by the oil mist method. It's a Moto Morini, a 500cc, 72 degree V twin. It has a belt driven cam located at the base of the V. There are relatively large passages for the pushrods extending from the crankcase to the top of the head. The mist of oil created by the crank is drawn up the passages, aided by the design of the ventilation system. The oil collects on the rocker covers, that have nipples cast into them above the rocker shafts. The oil drips off of the nipples into corresponding holes in the rocker shaft supports. These engines are known to be able to easily make 100,000 miles.
Ed
[ April 25, 2004, 01:17 AM: Message edited by: edhackett ]
I'm not an engineer but it has to do with heat,rpm or just a need for more lube at certain critical points that the force fed wrist pins are needed
- Status
Similar threads
- Locked
