Oil Cooling Jets for Pistons Anyone?

[SleeperZ]

I would like to steer the discussion toward combustion temperature, which allows more timing, and not just piston temperature (durability). I agreed that a coated piston is more thermally efficent, but what is the cost of that efficency? I think the increased ignition timing that a lower combustion temperature (detonation margin) will provide will definately be quantifiable.

 

Lower combustion tempertures on a stock engine L-series (EGR recuirculation), allow more timing and power. I am postulating that oil spray will effect combustion temps and timing in the same way.

In that regard, coating can only help with detonation resistance, as it slows thermal transfer to the piston crown. Since there is less overall heat transfer and more work extracted, your overall combustion chamber temperature should not increase as a result of piston coating. It is also much easier to transfer heat out of the head than the piston.

Edited May 4, 2012 by SleeperZ

[johnc]

lso, with your comment on race oil systems, do you think, there is enough pressure/volume that tapping a squirter off the main bearing feed would starve the main bearing?

 

I don't know enough to answer that. My unintelligent guess is that, unless you're running some plumbing to direct the oil from the main squirter toward the piston, you'll most likely be spraying oil mostly on the connecting rod due t the angle involved:

 

[rsicard]

There have been Piston Oiling holes in the Generation 1 Small Block Chevrolet. They were drilled into the upper Main Bearing boss and bearing insert aimed upward at the piston. Likely the oil squirted landed on the connecting rod and cylinder wall. The only good way to get oil cooling to the bottom of the piston is to have pressurized oil up the center of the connecting rod with squirters spraying directly, and close to, the bottom of the piston. Likely there would NOT be enough pressure after the main bearings are oiled then to feed holes to the rod journals and then on up the connecting rod. This would be a LONG oiling path.

[Six_Shooter]

There have been Piston Oiling holes in the Generation 1 Small Block Chevrolet. They were drilled into the upper Main Bearing boss and bearing insert aimed upward at the piston. Likely the oil squirted landed on the connecting rod and cylinder wall. The only good way to get oil cooling to the bottom of the piston is to have pressurized oil up the center of the connecting rod with squirters spraying directly, and close to, the bottom of the piston. Likely there would NOT be enough pressure after the main bearings are oiled then to feed holes to the rod journals and then on up the connecting rod. This would be a LONG oiling path.

 

Most modern piston squiters are not laid out like that. The layout you are suggesting is used for additional lubrication of the wrist pin and cylinder walls.

Piston squirters are like nozzles, located at the bottom of the bores and aimed at the piston bottom when just before or at TDC.

[neotech84]

Still trying to wrap my head around this theory and application.

 

As I see it, there would be a huge benifit to going dry sump as well. You would gain the benifits of less heat, but this could give a better location for the squirters and could have full controll over WHEN they squirt.

[TimZ]

Most modern piston squiters are not laid out like that. The layout you are suggesting is used for additional lubrication of the wrist pin and cylinder walls.

Piston squirters are like nozzles, located at the bottom of the bores and aimed at the piston bottom when just before or at TDC.

 

Yep - for those of you that didn't check out the link the TheSwede provided, here's a pic, linked from that article:

 

I'm pretty sure that this was what the original post was asking about.

 

I looked into this briefly several years ago and was discouraged by the fact that it didn't appear that anybody else had done it on this engine, and I was worried about diverting oil from the mains, as others have mentioned. Now you've got me thinking about looking into it again . I already use ceramic coatings, but if this could be done successfully it could be a great help for overall durability.

[TheSwede]

While discussing oil flow and pressure.... I good buddy of mine has a Toyota Celica think its a 76....or some like that...and he´s a frequent drag/trackday driver.

 

The engine is from a Toyota Hiace, a 2.6liter straight four. Turbo converted with oil jets from BMW,the type you machine into your maincap bearings. Not much else done internally than forged pistons and rods. The last dyno sheet said 627bhp at the wheels. (2 bar/30psi of boost

Stock oilpump by the way.

 

 

So what im trying to say is that the jets must be a good way of extracting heat via the bottom of the crown without stressing the water based cooling system... which at thoose levels allready are taking care of alot. So with the oiljets and an oilcooler you have a second system to extract the cylinder heat.

 

Still not saying that coating is bad... but as I see it you need a good cylinderhead/gasket if you make the temperature stay in the top of the engine.

And another thing is..... when the coating has worn of you need to recoat them. The oil is easy to change... plus you can easily see if its time to change.... not as easy with the coating.

 

Then we have the topic of too much oil on the cylinder walls.... The jets, as they should work, will not put extra oil on the cylinder walls. Its a directed spray via a valve at higher oil pressuers...the picture is a bottom of a Saab 9000 engine.... damm best turbo engine ever build...

 

And as usual.... exuse my bad english.... hehe

[rsicard]

From what is being discussed here, it appears that ceramic and slippery coatings are not appreciated as to their value. NASCAR engine builders would NEVER build without these coatings. The ceramic coating on the top or crown of the piston DRASTICALLY slows down the migration of combustion heat though the piston. The same is true with valve faces and cylinder head combustion area if COATED with ceramic. Therefore the GREATEST amount of combustion heat is used to convert reciprocating piston motion to rotary motion of the crankshaft. More power is extracted from the combustion heat rather than being absorbed or LOST by pistons, valves and cylinder head combustion chamber. This is just GREATER EFFICIENCY of the combustion!

 

As far as underside piston squirters, the Oil Galleries must be tapped for this additional oil. Additionally, the oil pump must provide MORE VOLUME of oil. The oil squirters should have a relatively SMALL ORFICE in order to spray the hottest portion of the underside of the piston in order to remove heat from same.

[ckrell]

Squirter are not needed with forged pistons especially with coatings. Besides the parasitic drag of the extra oil cost HP. Alot of guys eliminate them on the 4G63T

[Leon]

Let's take a step back and realize that heat transfer has a very minor effect on combustion efficiency at high engine speeds. There simply is not very much time to transfer an appreciable amount heat to the cylinder walls during the time in which the piston is being actively pushed down by combustion. If you're looking to eek out every tiny bit of hp then so be it.

 

If you cool the piston, there will be more heat transfer.

 

The larger benefit in these "squirters" would lie in keeping the cylinders and piston cool, thus fighting off some detonation and keeping coolant temps at bay.

[roger280zx]

I am no expert and this would have no effect on the combustion temps or timing advance, but cooling the VAVLE SPRINGS with oil holds more performance value than piston spuirters do. This is well documented in both drag racing and Nascar, the technology and hardware are both cheaper and more simple. That being said I think you guys are barking up the wrong tree. I look at this in the same light as rod ratio, some people think it is everything and there is no amount of evidence to the contrary that will change their mind. Mean while others build engines to suit with out all their benchracing gizmos that hold up just fine. Naturally aspirated at xx,000 rpm piston squirters (as well as longer rods) will make some difference. I am not arguing against that. But on a turbo engine I think there are much better places to focus your efforts and resources that will be much more frutfull. If one of the race engine builders here thinks I am totally off base with this info, please by all means, prove me wrong. Until then my money will go to better quality pistons and other things to help my little Lgata hold up through the revs. And my power will be made with headflow and the snail hanging off the manifold.

[Six_Shooter]

I don't think anyone in this thread that are "pro squirters", are denying the fact that there are other items that can be a benefit, but why not use every advantage you have?

 

I think many people that are worried about the oil volume being an issue forget that the oil pump in stock form is bleeding off a lot of pressure AND with that volume of oil. There is more oil volume capability using the stock pump than most people realize.

 

The volume of oil directed at the pistons is not very much at all, but enough to give an ample amount of heat transfer capability, basically enough for a thin coating, not a drowning.

[ctc]

I don't think anyone in this thread that are "pro squirters", are denying the fact that there are other items that can be a benefit, but why not use every advantage you have?

 

Of course other things can benefit. And again can we talk about technical feasibility here, not cost or how easy it is.

 

To end the coating debate, I point to this link

 

http://www.techlinecoatings.com/articles/Coating_Pistons_Article.htm

 

I will agree that coatings help with detonation and keeping heat in the combustion chamber, and based on the last paragraph, oil cooling of the underside of the piston is possible as well.

 

So, to get this thread back on track, if the goal is to use oil to cool the underside of the piston, where do we tap the block for oil supply? Assume we have a race oil system with enough volume and pressure.

Edited May 6, 2012 by ctc

[TimZ]

I don't think anyone in this thread that are "pro squirters", are denying the fact that there are other items that can be a benefit, but why not use every advantage you have?

 

I think many people that are worried about the oil volume being an issue forget that the oil pump in stock form is bleeding off a lot of pressure AND with that volume of oil. There is more oil volume capability using the stock pump than most people realize.

 

The volume of oil directed at the pistons is not very much at all, but enough to give an ample amount of heat transfer capability, basically enough for a thin coating, not a drowning.

 

I'm not that worried about oil flow once the engine is above a few thousand revs - at that point there should be plenty of pump capacity.

 

I'm more worried about what happens when the engine is at low rpm and the pump output is low. At this point the oil required for the squirters would be a more significant portion of the total capacity. Does anybody know whether the squirters have some sort of check ball arrangement that restricts their flow below some preset pressure, or are they just literally a tube tapped into the oil gallery that flows all the time?

[Six_Shooter]

I'm not that worried about oil flow once the engine is above a few thousand revs - at that point there should be plenty of pump capacity.

 

I'm more worried about what happens when the engine is at low rpm and the pump output is low. At this point the oil required for the squirters would be a more significant portion of the total capacity. Does anybody know whether the squirters have some sort of check ball arrangement that restricts their flow below some preset pressure, or are they just literally a tube tapped into the oil gallery that flows all the time?

 

Proper squirters have a pressure valve in them that closes at low pressure. I would imagine that many are set at a point where they would close at idle.

[rsicard]

It is TRULY amazing how little people know about the science of ceramics. Does dumbth rule?

[TimZ]

It is TRULY amazing how little people know about the science of ceramics. Does dumbth rule?

 

Yes, apparently I'm dumb.

 

Nobody in this thread has said anything bad about ceramic coatings. I'm already using ceramic coatings on my forged pistons, combustion chambers, valves, exhaust ports, manifolds, turbine housing and downipe. I _think_ I understand how they work and why I wanted them (that was sarcasm).

 

All that said, I've been interested in the oil squirter idea for some time but had not pursued it, due the the concerns listed above. It's not about thermal efficiency or power gains, its about gaining durability by moving heat out of the piston and stabilizing its temperature, forged or not. Is it belts-and-suspenders? Yep. It's still an interesting concept and I'd appreciate it if you would stop trying to squelch any discussion on the topic.

The original question was about feasibility and that's why many of us are interested in this thread.

 

We are all aware of ceramics .

 

Really.

 

We are.

 

Seriously.

Edited May 6, 2012 by TimZ

[SleeperZ]

It is TRULY amazing how little people know about the science of ceramics. Does dumbth rule?

This is something a troll would say. If you want to educate us on "the science of ceramics", you need to be able to point out the fallacies in the discussion, and provide some facts to back up your position.

[ctc]

So digging around on the internet, I came up with a link to this BMW install. It's from Sweden, so local for some.

 

http://forum.e46fanatics.com/showthread.php?t=720393

 

Still haven't tapped into my block yet. I'm thinking I'll either have to bore diagonally back to the main oil galley on the side of the block, or tap the oil flow in each main bearing web and turn it to hit the piston with a custom nozzle. More research is required.

 

More links

 

http://www.e30m3project.com/e30m3performance/installs/installs-3/squirters/index.htm

Edited May 6, 2012 by ctc

[TimZ]

So digging around on the internet, I came up with a link to this BMW install. It's from Sweden, so local for some.

 

http://forum.e46fanatics.com/showthread.php?t=720393

 

Still haven't tapped into my block yet. I'm thinking I'll either have to bore diagonally back to the main oil galley on the side of the block, or tap the oil flow in each main bearing web and turn it to hit the piston with a custom nozzle. More research is required.

 

More links

 

http://www.e30m3project.com/e30m3performance/installs/installs-3/squirters/index.htm

 

I decided to go to the local BMW dealer and bought one of the part number 11 11 1 739 907 squirters to evaluate. It was $17 - a bit more than what was shown in the article, but still not that bad. There isn't much room in there if you want to find a spot that's near the main oil galley and out of the crank/rod throws, so I wanted the smallest one possible.

 

I rigged up a test jig out of some aluminum block that I had laying around - the banjo bolt's thread is 8mm s 1.0 thread pitch, so it's not hard to find a suitable tap.

 

The banjo bolt does have a check valve embedded in it, and I wanted to test it to find it's cracking pressure. After making sure I had the thread sealed properly, I found that the valve starts to open at around 25-30psi, and is full open at ~35psi. I think that this should be plenty to prevent starvation at low rpm.

 

Also, the main galley looks to run the length of the block and is just to the passenger side (in the US anyway) of the cylinder bores, so I don't think you'll have to angle drill to intercept it - I think you were looking at the galley that feeds the oil filter input.