piston oil-cooling idea

[mendelmax]

Hi guys. Lately I had some idea, but haven't found anybody who actually done that on 4.0, and I'm not 100% sure whether my thinking is right, so correct me if I'm wrong.

The whole concept is, that oil pump has its pressure relief valve, which reduces pressure at high revs. By using high-volume oil pump we are pumping more volume, therefore we are also more frequently using this valve to relief the excessive pressure. Therefore, we have pretty good amount of oil under pressure that is "wasted"- it goes back to the pan.

Now, if we take a pipe from the relief valve, divide it into 6 smaller pipes and bring each of them near the cylinder bore, facing up, we could spill the excessive oil on the piston bottom, just like it's done with high performance applications. The best thing is that this spill would occur only when excessive pressure is present, which simply means high revs, and high revs equal high load and high piston temperature.

This would help to cool the piston dishes, reducing (very minor reduction, but some nonetheless) pinging potential, and permitting to use the tighter piston to bore clearance. The cost is very minor- some extra pipes to route. It would also rise the oil pressure a little bit, by creating a little restriction behind the relief valve (not sure whether to count it as a profit or loss).

What do you guys think?

[lafrad]

Squirters are usually driven off the pressure side of the system... I would do that in this case too... just make sure you tap into it BEFORE the pressure regulator.

The reason for this is: if they provide ANY restriction... as soon as flow increases, the restriction will also increase and you will REALLY drive the pressure up.

Just pipe them appropriately so they use the high pressure side of the pump without taking any flow away from where it enters the block itself... use some dedicated oil squirter nozzles.... and your idea would work great.


I personally don't think it is worth the effort on these applications... the amount of extra oil the rings will have to fight may allow for more oil in the Cyls....

[Plechtan]

How brave are you? Try this, drill a small hole from the top of the small end of the connecting rod all the way down to the crank journal surface (of the rod) , drill a matching hole into your rod bearing. as the piston gets up to top dead center, the oil hole in the crank should be close to the hole in the rod and will squirt oil on the bottom of the piston. Oh i forgot, you have to put a groove into the piston pin to allow the oil to flow around it so it can get out the hole in the top of the rod. Now figue out how to drill an 1/8" hole 6" long and keep it striaght.

[Alex22]

Oil squirters are typically fed by the main oil bearing. The block is drilled, sometimes a plastic or metal tube is pressed in and directed at the under side of the piston and sometimes the holes are tapped for an insert. Depending on the size of the nozel a HV pump may be necessary. The 6 smaller tubes would work but you would begin to clutter the inside of the block, and would need to anchor them to keep them where they belong.
Squirters are found on just about any turbo vehicle out there and they do reduce the piston temp. This would also be nice if you are using a full floating pin.

I may have to look into this for my build.

[mendelmax]

I personally don't think it is worth the effort on these applications...

Yeah, I think you're right, but you know- when you get some idea it starts to drill your head, so I simply had to consult it here

How brave are you?

I guess not brave enough to try

I was just thinking about easy way to use wasted energy, you idea is way too "professional" approach for me

and would need to anchor them to keep them where they belong

That doesn't seem too difficult, I was watching my junk 4.2 block and I think it is doable. The only problematic thing is that some anchor points would have to be welded, and (the main problem)- the welds would have to be good enough to be 100% sure the pipes won't drop on the crank and damage whole engine. That's pretty risky.

Does anyone know, what kind of volume and pressure may we expect in this case? Because the whole concept is based on my assumption, that at top revs there is enough oil bypassed to create at least 2" high oil stream from the end of mentioned pipes, to reach the piston bottom. I have no idea how can I check the pump volume at these revs, does anyone know?

[lafrad]

If you are serious about it, I would look into some other factory implementations.

On the SRT Hemi's, they use a dedicated oil squirter driven off the pressurized side of the oiling system.
http://www.hotrod.com/techarticles/113_ ... to_12.html

this requires extra pump and filter capacity (remember, you don't want to be shooting unfiltered oil around your engine)

THe next steps on a jeep build, would be to open up and radius the oil passages between the pump, and Filter. then from the filter back into the block to where you can drill and tap a new oil feed hole into the stock oiling circuit.

From there I would drill and tap holes for bolts to mount the oil squirter piping, aiming them at the close side of the piston when its fully "down".

THis will give you oil circulation at all RPM, and would be taking advantage of any extra capacity a high flow pump can provide.

[cavaliers1323]

Remember HV pumps also have an increased by-pass pressure. There are also many other variables besides the pressure reading on your gauge. Please do not ask me to explain because I cannot, as I do not have a full understanding of it. If you search on BITOG a fellow by the name of Gary Allen has tried to explain it a number of times. I'll see what I can dig up. My point is I wouldn't rely on the bypass for the squirters oil source.

[mendelmax]

Well, we could always add extra by-pass valve in the squirters feed pipe, to reduce excessive pressure, but I agree with you, that it starts to be more complicated than simply doing it "the right way", from the oil gallery.

[Alex22]

I was working on a DT466 today and it used dual squirters that were fed from the main oil supply. The holes were about a .050 diameter, 1 that size or smaller would be fine for a smaller piston. I mentioned that I was thinking about putting some on my stroker and they said that a .035 to .045 should be plenty large for a jeep. He also said that a HV pump won't be nessescary unless I have loose bearing clearances, the HV would just put more stress on the distributor gear and increase parasitic power losses. A HV pump can also suck too much oil out of the pan and get you in trouble when cavitation starts.