Piston squirters
 

In my lakester engine (blown alky hemi four) I'm considering adding nozzles aimed at cylinder walls below the pistons- which would also strike the undersides of pistons through part of their stroke.. The nozzles would receive full-time oil pressure, nominally 100 PSI. One reason is for piston cooling. The other reason is for better cylinder wall oiling. Prior to the just-finished rebuild, the pistons were badly scuffed (anti-friction coatings gone) and two were cracked. I'm not sure of the cause, but there are a couple of suspects. One is possible lack of cylinder oiling, due to extreme oil control measures (no cam in block to bleed oil, full-round crank counterweights to eliminate leading/trailing edges, crank scraper, efficient windage tray, and oilpan kickout)- and DOHC oiling is a separate drysump system. The other suspect is the finish of the bores in the steel sleeves (done per Smokey Yunick's "the smoother the better" edict), which might not retain oil well enough. So... in any case, I think dedicated cylinder wall oiling would be wise.
I don't know what volume of oil flow to shoot for- any suggestions? Or as a shortcut, any idea what orifice size for each of the four nozzles?

I have never done anything like that. But I have ran my oil pump with a drill with no lifter in one of the bores. Just to see how much oil came out of a .030 hole.
I was very surprised just how much oil came out of that tiny hole.

Are there any signs of pitting on the tops of the pistons that cracked?

How do those plugs insulators look out of those cylinders when viewed under magnification, any signs of shinny purple balls there?

Either of these two would be clear signs of detonation.

If the pistons where getting too hot due to the power level being made I would expect the exh valve notch to on its edges to show signs of overheating and or deforming first before the piston would crack.

How do the wrist pins feel, any tighter then you recall from when the motor was last put together?

Also what other things might be different about the motor that your having these issues now, I can see how too much oil control would eat up the skirts.

How would you implement the added oil feed holes?

Jack, we have some turbocharged imports down at my school. I can gauge several squirter holes and get back to you. It may take a week to pull a couple down to check.

Can you imagine having the oil mist system drilled into the rod throws? some expert drilling.

Maybe just drilling the Rod Caps Parting line is practical. Oh hey PMD did that.

The Boss Bird had scuffed and cracked piston skirts when we were using the recommended piston-to-wall clearance. We tried loosening the clearance (maybe .002" extra?....memory fading) and the problem disappeared.

The Pontiac piston is less massive than a hemi nitro piston so it was growing a lot quicker and binding in the bore.

I'll see if I can find a picture and post.

Edit: don't have pix anymore but the piston is at work in my show-and-tell stash so I can take a picture Monday.
The skirts would get 2 cracks on the side perpendicular to the pin bosses. The pin bosses are heavy and take awhile to heat up. 90 degrees from that, the piston and skirts are thin and heat quicker. So the piston goes oval while it is warming up.

I never could warm up to the idea of piston squirters being necessary since the crank is flinging oil up into the cylinders. But since the OEM's go to the expense on some engines, there must be a benefit. I'm willing to be educated.

Eric

Jack,might post over on Speedtalk.Tom

Good thought!
Those oil holes that use to be in the big end of the rods where for Cam oiling, but I bet they would help with lubing up the cylinder walls also.

We ran Piston Squirters on the 3.5L Le Mans race engines.
So for some applications it is an advantage. Same deal with extended high speed
like Jacks Bonneville Salt Flats eventual racer.

But drag race stuff and Bonneville racing is NOT the same requirements.

You have a 2 mile "run - up" before you actually start the first mile of the timed/speed
run. Jack will probably run on the short course until he can run 300 mph or higher.
The squirter parts are available and just need to be adapted to the 4 cylinder engine.

Tom V.

Tom: how do you aim the squirters? I'd think that all the air being pushed around by the pistons and rods would divert the oil from the direction that the squirter is pointed?? How much trial and error is involved ?

Eric

I have been doing over the road diesel engine work for over 30 years. Everything has bolt in piston cooling nozzles that spray onto the bottom of the piston crowns. Pretty much a direct shot throughout the stroke to control heat

Thanks Mike, I'll be interested in those factory squirter sizes;

Jack, PM me your address and I have a little assortment of the squirters and feed bolts to send you. The feed bolts have a little check ball and spring in them. BTW, the holes were from .027-.040" in the ones I checked.

Thanks Mike!

I saw on bookface this morning, Don @ DCI is modifying a block to put squirters in via the main tunnel. Interesting approach!

Great great idea doing it that way!
No extra piping to get vibrated apart of have to make retention brackets for.

I like that squirters-from-the-mains idea. However, I already had the engine ready to test-fire and install in the racer- hate to tear it back down. So I'm hoping to mount the nozzles in the block's pan rail- and attempt to come up with reliable plumbing.

Jack, the piston squirters I’m familiar with (6B and 6C Cummins) are plastic( yep, plastic) and fit in bosses in each main saddle. I’m pretty sure you could fabricate a common oil manifold that would fit in them in the side of the oil pan; the trick is going to be setting the angle on the squirters themselves. All the ones I’ve worked with are aimed at the underside of the piston to provide additional cooling to the piston head.

Thanks for the info. Yes, aiming them (to strike as much wall as possible) will be tricky.

Maybe just a typo mistake BUT you want the squirter oil to contact the underside of the piston and not the cylinder wall.

Tom V.