How does the oil get there?

[Al]

Hello All,

I am curious about how oil moves in an engine. I am very familiar with the main bearings and the big end of the connecting rod along with the head on OHC engines.

What I am curious about is how oil gets to the wrist pin and cylinder walls. I saw diagrams where the connecting rod had a galley in it which fed the wrist pin, which in turn fed the piston rings and then the cylinder bore. I heard elsewhere that windage is what gets oil in the cylinder bores and wrist pin.

Is there anything I am missing here or additional details? I Googled this many times with different search terms, but have yet to find a complete answer.

Thanks.

[GTSLOW]

A few seconds on google turned this up:

http://forums.pelicanparts.com/uploads2/oil_sys_small1074124035.jpg

[HITMAN]

Hello All,

I am curious about how oil moves in an engine. I am very familiar with the main bearings and the big end of the connecting rod along with the head on OHC engines.

What I am curious about is how oil gets to the wrist pin and cylinder walls. I saw diagrams where the connecting rod had a galley in it which fed the wrist pin, which in turn fed the piston rings and then the cylinder bore. I heard elsewhere that windage is what gets oil in the cylinder bores and wrist pin.

Is there anything I am missing here or additional details? I Googled this many times with different search terms, but have yet to find a complete answer.

Thanks.

A lot of it is based on splash. If you look at a set of stock small block Chevy conventional connecting rod bearings , you with see the tang on one side of the bearing, and a small hole on the other side. This hole and the corresponding channel in the mating surfaces of the rod shoot a stream of pressurized oil on to the cylinder walls.

http://img805.imageshack.us/img805/8401/sbcbearing.jpg


Others just use the inertia from the oil as it leaves the connecting rod rotating at high speed to get it on to the cylinder walls. Once on the cylinder walls, it lubricates the piston and rings, the oil rings scrape enough off and channel it toward the inside of the piston where it lubes the wrist pin and on a full floating pin set-up the small end of the rod as well.

[Al]

A few seconds on google turned this up:

That shows nothing about how the oil gets to the wrist pin and cylinder bores.


A lot of it is based on splash. If you look at a set of stock small block Chevy conventional connecting rod bearings , you with see the tang on one side of the bearing, and a small hole on the other side. This hole and the corresponding channel in the mating surfaces of the rod shoot a stream of pressurized oil on to the cylinder walls.

Others just use the inertia from the oil as it leaves the connecting rod rotating at high speed to get it on to the cylinder walls. Once on the cylinder walls, it lubricates the piston and rings, the oil rings scrape enough off and channel it toward the inside of the piston where it lubes the wrist pin and on a full floating pin set-up the small end of the rod as well.

That photo is very informative.

I heard that some engines have nozzles that spray up towards the bottoms of the pistons too.

[spooln30]

On 7m and 2jz (Toyota Supra) the rods have oil passages that run from the big end to the little end that supplies oil to the wrist pin and bushings. Most import turbo engines have oil piston squirters in a attemp to cool the pistons.

[HITMAN]

That photo is very informative.

I heard that some engines have nozzles that spray up towards the bottoms of the pistons too.

Yeah, oil squirters. As spoolin said, a lot of forced induction engines have them. The higher stressed F/I domestics are starting to get them as well. LS9 in the Corvette ZR1 comes to mind...

[Al]

Is it safe to assume that vary little oil ends up on the cylinder bores of older domestic engines?

[HITMAN]

On 7m and 2jz (Toyota Supra) the rods have oil passages that run from the big end to the little end that supplies oil to the wrist pin and bushings.

I've seen that in some domestic race engines as well. I don't like it. I can see in light of how durable the 2jz GTE is, it might seem like paranoia on my part not to trust something like that, but (to me at least) it seems like place for trouble to start. No need for a hole straight up through the middle of one of the most highly stressed components of an internal combustion engine, especially when the squirters are already shooting oil right up there. A small hole at the top of the small end (which most engines have anyway and it's an area that only sees stress on deceleration) and a ton of oil will get to the wrist pin and bushing. After all, it's a wrist pin not a crank pin. That area doesn't have a lot of slop in it and it doesn't spin around at high speed so it doesn't need a shit load of pressurized oil. Damn Japs get carried away sometimes...

[HITMAN]

Is it safe to assume that vary little oil ends up on the cylinder bores of older domestic engines?

Nor in modern engines. They really don't need a lot especially with today's DFL skirt coatings and besides, too much oil on the walls can cause it's own share of problems. Lubricating oil doesn't resist detonation very well. Zero octane enhancement.

[spooln30]

There's always tricks of the trade that people over the years have tried and work to increase oiling to certain places in the block and or heads that otherwise had been troublesome. Just do enough research before you go by what one person says on the net. When muiltable builders use the same method then in most cases the mod will work. There's always something to be improved on in almost every engine.

[HITMAN]

There's always tricks of the trade that people over the years have tried and work to increase oiling to certain places in the block and or heads that otherwise had been troublesome. Just do enough research before you go by what one person says on the net. When muiltable builders use the same method then in most cases the mod will work. There's always something to be improved on in almost every engine.

No doubt about that. But I spent a LOT of time pulling engines apart and analyzing what made them fail. It was my job for over two years and I never saw one that failed due to a wrist pin. Most of them were destroyed because the engine detonated long enough for the piston to come apart. Once that happens the wrist pin become the enemy and no amount of lubrication will keep the wrist pin from wreaking havoc on the cylinder wall. And when a con-rod actually snaps, it gets REAL ugly in a hurry. A pin failure MIGHT seize an engine. A rod failure WILL destroy it. I'll take my rods as strong as they can make them, with NO holes down the beam. JMO.

[spooln30]

I see your point. IMO 2jz is one of the most robust engines ever engineered. In stock form they can handle 900+hp with ease. It's more about the material and the process of making the parts. Like cast vs forged. Dont get me wrong engineering also plays a huge roll as well. You rarely see 2jz rods break, bend yeah. Even seen ones so bent I was puzzled why it didn't break. I'm just very happy to see American car companies engineering engines these days that are able to handle hundreds if not almost double the amount of HP over the stock output and higher reving. It's almost like their finally taking some of the "Japs" engineering ways they've been doing since the 60's.

[HITMAN]

I see your point. IMO 2jz is one of the most robust engines ever engineered. In stock form they can handle 900+hp with ease. It's more about the material and the process of making the parts. Like cast vs forged. Dont get me wrong engineering also plays a huge roll as well. You rarely see 2jz rods break, bend yeah. Even seen ones so bent I was puzzled why it didn't break. I'm just very happy to see American car companies engineering engines these days that are able to handle hundreds if not almost double the amount of HP over the stock output and higher reving. It's almost like their finally taking some of the "Japs" engineering ways they've been doing since the 60's.


I agree. Domestic manufacturers are finally stepping up their game. It's not all that uncommon to see stock long block '03/'04 Cobra engines making in excess of 800+hp to the tire. The Germans, on the other hand, are still showing EVERYBODY WTF is up. The engine coming in the Porsche GT3 RS for 2012? 4.0 liters, 500hp @ 8250rpms, Naturally Aspirated. Thats 125hp per liter or 2.05 hp per cubic inch in a street going, emissions legal engine with NO power adder. Fucking sick...

[TheRX7Project]

That's downright disgusting. Wish I could afford one. ^