Rod side clearance oil squirting?

[modok]

I see what you are getting at, as far as,
often when this topic comes up, guys want to get very specific about the exact size, shape, and location of the grooves. because, they assume it maters. I doubt it does tho. I think you add SOMe kind of relief in the side, of whatever shape, it would just improve the probability that the oil would be thrown off more that direction, and don't forget side clearance. is the rod centered all the time? Probably not.
If it IS thrust to one side or the other on occasion, then that would make the grooves MORE valuable. right?

Should be mentioned that some aftermarket or offset ground cranks, the cheeks don't cover the side of the rod, so, I don't think grooves would improve anything in that case. And that's why aftermarket rods usually come without any reliefs in the sides. You decide to add that or not. But more often that is overlooked.

[BigBlockMopar]

Like Roy's, it's my view on things too that those slots are there to provide 'fine droplet' oiling (more: cooling/lubrication), flung around to the camshaft/lobes, rods and cylinderwalls. Either to carry away excess heat or lubricate.

On '50/'60s big/smallblock Mopar engines, there are grooved channels/slots on the 'upper' side of the rods.

[ptuomov]

Like Roy's, it's my view on things too that those slots are there to provide 'fine droplet' oiling (more: cooling/lubrication), flung around to the camshaft/lobes, rods and cylinderwalls. Either to carry away excess heat or lubricate.

I think that the fraction of the bearing oil spray (slots or no slots) that hits the piston crown underside is relatively small and the flow rate from the bearings is also not that high compared to what the piston oil cooling jets output. So while some of it will undoubtedly make it to the piston crown underside, I think oil spray jets are far superior way to cool the piston. Given the degree of freedom in piston cooling oil jet sizing, the bearing oil spray slots are in my opinion mostly about directing bearing oil spray to vs. away from the bore walls.

If the engine in question has too much oil on the bore walls, one might want to underside the rod cap a little bit in terms of bore side clearance to direct the oil away from the bores?

[Kevin Johnson]

Oil jets and slots have been in use for many, many, many decades. Interested readers should look up so-called "cocktail shaker" pistons that have a duct and gallery/chamber to capture the oil jet for maximal cooling effect.

Someone at Honda likely suddenly realized that most of the world was (and now the USA as well) first to patent rather than first to invent. So they safe-guarded themselves. The slots still appear on some OEM rods: off-center on each face of the beam (Mazda, for example); using slots created around beam/cap fracture lines, in addition (Opel for example); machining slots in a linear path on both the beam and cap (VW Audi for example).

A point that is stressed in Honda's patent is that a simple change in the casting or forging allows an economical method to cool the piston. Notably. Honda used both the slots and squirters when necessary. OEMs love to reduce the number of parts to reduce costs.

Over the years that I have discussed this with customers the most common rejoinder is that they are using forged pistons versus the factory cast pistons (forged pistons being efficient at conducting heat and better able to resist higher temperatures/pressures). My thought has been that if the slots are put there by the OEM it is for a good reason, as often they are not. But then, they need to offer (typically) 3 year/36,000 mile warranties on the engine. I think the days are long gone from when engineers published extremely candid remarks about engine development problems (1950s Packard and Studebaker SAE papers come to mind).

[modok]

Like Roy's, it's my view on things too that those slots are there to provide 'fine droplet' oiling (more: cooling/lubrication), flung around to the camshaft/lobes, rods and cylinderwalls. Either to carry away excess heat or lubricate.

I think that the fraction of the bearing oil spray (slots or no slots) that hits the piston crown underside is relatively small and the flow rate from the bearings is also not that high compared to what the piston oil cooling jets output. So while some of it will undoubtedly make it to the piston crown underside, I think oil spray jets are far superior way to cool the piston. Given the degree of freedom in piston cooling oil jet sizing, the bearing oil spray slots are in my opinion mostly about directing bearing oil spray to vs. away from the bore walls.

If the engine in question has too much oil on the bore walls, one might want to underside the rod cap a little bit in terms of bore side clearance to direct the oil away from the bores?

Good question. one of my favorite designs the case/cummins B has always had piston cooling nozzles. the Connecting rod caps are narrow, only as wide as the bearing. The lower side of the rod is very much open. I doubt they would have built it that way if not for the oil nozzles.

As far as the effusiveness of the notches, well, it's no miracle cure.....but, it is one of many SMALL design details that could be added improve oiling and adds no additional parts at all. There are many little details like that which are NOT very exciting, but can add up to a significant improvement.

[miniv8]

Regardless of its effectiveness of cooling the piston or lubing the pin, I think we can come to the agreement that a slot, that opens a passageway for the oil from the rod bearing clearance, will direct most of that oil through it.

That conclusion can bring the discussion in the other direction, would having the slot directing the oil downward into the oil pan, reduce windage?

[Kevin Johnson]

Regardless of its effectiveness of cooling the piston or lubing the pin, I think we can come to the agreement that a slot, that opens a passageway for the oil from the rod bearing clearance, will direct most of that oil through it.

That conclusion can bring the discussion in the other direction, would having the slot directing the oil downward into the oil pan, reduce windage?

https://www.ebay.de/itm/Pleuel-Pleuelst ... SwDJNbxf9u

Q7.jpg

Q7 b.jpg

4.2L V8 079.D FSI DOHC V8

This design was based on an existing Audi 40 valve 8 cylinder engine. The new version was heavily revised to differ from the prior engine with a new crankshaft, cylinder heads, valve train, pistons, connecting rods, oil system, cooling system, intake, exhaust, and engine management systems This engine is available in two different forms, one being a comfort version initially used in the Audi Q7 — the other being a sports centric high-revving engine borrowed from motorsports for the B7 RD4 Quattro and Audi R8. This engine is the first eight-cylinder engine to use Fuel Stratified Injection — a technology developed by Audi for their LeMans champion R8 race car.

[ptuomov]

From Carrillo:

“Grooves in Thrust Face

For weight reduction and reduced friction, grooves are machined on the big end thrust faces”

00300FFE-E6D5-408B-AFA3-6F7CD82D01F1.jpeg

[modok]

That conclusion can bring the discussion in the other direction, would having the slot directing the oil downward into the oil pan, reduce windage?

You might be right, but depending how you consider windage, I might think the opposite.
the oil is going to get thrown SOMEWhERE anyway, and pan is in the LEAST need of it, well, unless it's empty
A smaller quantity of oil taking a LONGER path might be more overall efficient than having separate lubricating passage to each part.

May simple engines ONLy the crank receives pressure oiling, and the rest is splash,,,,,,and, you know, that CAN BE a good system.
Best way to reduce windage is to reduce the AIR movement IMO, the oil movement is usually a good thing for many reasons.
I'd say something like a lifter or roller bearing is just as happily lubricated with oil mist as any other strategy.
For instance the lifters on a cummins B are lubricated ONLy by the oil draining from the head, and whatever comes off the cam. No pressure feed to them at all, seems to work great.

With Air-cooled OR watercooled engines I have come think of the pistons and cylinders as being at least 50% OIL cooled. And that oil comes from the crank as a mist unless they have dedicated nozzles with work ALL the time, and few do. .

Or at least the movement of oil circulating everywhere in the engine helps to keep all parts temperatures of ALL parts steady FAR better than conduction through the metal. You can do little mods to make that work better. Many OLD designs have "dead end" areas.
A shaft seal or cam plug lives in a cavity and has a SINGLE oil drain passage, which makes sense....but, actually it is better to have several paths to all cavities, so air and oil circulate THROUGH is better, for lubrication, ventilation, and that also makes the interior of the engine more LIKE a mist filter and less like a mist generator.

[modok]

From Carrillo:

“Grooves in Thrust Face

For weight reduction and reduced friction, grooves are machined on the big end thrust faces”

00300FFE-E6D5-408B-AFA3-6F7CD82D01F1.jpeg

The amount of weight saved there is FAR FAR less than reducing the OD of the crank.
Why even have the far end of the crank cover the sides of the rod? I'd like to know!

[ptuomov]

Heat flow:

F8EDD95B-2F1E-47E4-9FC5-41DBCF0AD3DF.jpeg

[dannobee]

Expanding on what Kevin said regarding piston cooling, the Porsche 962's had pistons that were Mahle forged two piece welded affairs with a cooling channel just behind the ring package that was cooled with oil sprayed via a straight tube squirter into the hole drilled in the piston, along with the "regular" Porsche piston squirter that was aimed at the bottom of the piston and pin.

962 piston.jpg

[modok]

I'm not sure of what I was sayingmade any sense....but, maybe,
windage is bad, but oil circulation is good.
Circulation meaning traveling throughout, not the "windage" of it just flying round and round.

[ptuomov]

Interesting info on the 962.

Gallery cooling.

Oil tubes that feed cooling galleries need to be long narrow and straight with sharp opening, so they hit the gallery hole. Squirters often have wider spray cone.

Both are approximately unrelated to the rod big end slots that direct big end oil spray bearing. The length, diameter, and flow velocity in those slots are such that the oil goes wherever the crank g forces throw it.

3A2DF87A-DA68-4C68-88BF-838448331621.jpeg

[Kevin Johnson]

From Carrillo:

“Grooves in Thrust Face

For weight reduction and reduced friction, grooves are machined on the big end thrust faces”

T142802273.jpg

Yes, it looks like that page was created at the end of 2015:

https://web.archive.org/web/20151218205 ... -rods.html

I notice that many other rod manufacturers are parroting some version of this. Going back to the discussion on the need to warm up high-end competition engines that have clearances minimized: with crank-guided rods having minimal crank-cheek side clearance it would be necessary to provide vents for oil to bleed and lubricate the faces. The oil would rapidly carbonize if flow were not allowed for heat rejection. I think this comes from an engineer familiar with radial grooves on, say, thrust bearings for crankshafts. The slightest effort at research, however, would reveal that the vast majority of such grooves are present on rods with normal side clearances. For lightening? Well, why are they absent on piston-guided rods?

Kohler F1 alloy rod with lightening grooves.jpg