Piston oil squirters in NASCAR engines

[pamotorman]

all the supercharged corvette engines use squirters to cool the pistons.

[Kevin Johnson]

I remember the main bulkhead squirter idea and thought it was ingenious!!

Thanks
Randy

Here is a Mike Laws post from 2006:

Hello Stevespeed:

I'm still here at BLP - Dad (Bo) keeps trying to run me off - but I'm like an old dog and keep finding my way back home!

Here is the quick version of our piston squirter story: We designed (and received a patent on) the method of drilling through the main journal bulkhead, into the base of each cylinder in order to send a stream of oil to the bottom of each piston. This was back in 1993/94 when I was approached by a Ford NASCAR Team to help with wrist-pin seizure/failure. (This is when the teams were first getting creative in utilizing crankcase vacuum to reduce oil wrap-up. "Vacuuming" the crankcase is/was definitely beneficial for HP - however it also removed the "oil-fog" that was keeping the wrist pins lubricated.) So we machined a block for the squirters and the problem was immediately solved. Another beneficial byproduct of oiling the underside of the piston dome is that heat is flowed out of the piston (dome). A portion of the intake charge in all IC engines is used to cool the piston - therefore when we cooled the pistons from underneath, we could then reduce the amount of fuel to the combustion chamber. This resulted in increased fuel mileage and also allowed for a more aggressive tune-up; so it was one of those rare "win-win" modifications.

For several years; NASCAR would not allow a separate oil squirter system (plate between the block/oil pan, squirters installed in the pan, etc.) - however they have since rescinded that rule. As another person stated, utilizing the squirters with external plumbing has the advantage of utilizing "cooled" oil to spray onto the pistons.

The piston-squirter kits remain a popular item for us, particularly with supercharged/turbocharged engines and those utilizing crankcase vacuum.

Thanks.

ML

Obviously, nothing as high tech as what Honda was doing in F1 in 2006-2008, and no doubt NASCAR builders have moved onto something a little more advanced.

https://patents.google.com/patent/US589 ... aws&page=1

Method of attaching an internal combustion engine piston oiler

Abstract
A method of attaching an internal combustion engine piston oiler includes the step of removing a crank shaft from an internal combustion engine to expose a plurality of block main bearing surfaces, selecting a drill guide shaped to fit one of the engine block main bearing surfaces, which drill guide has a predetermined drill guide bore therethrough, and positioning the selected drill guide on the engine block main bearing surface. The method includes positioning a drill bit through the bore in the selected drill guide and drilling a predetermined bore through the engine block webbing from one main bearing surface into the rear of the engine cylinder and then tapping the bore drilled into the engine block and installing an oil metering jet into the drilled and tap bore. The method also includes drilling an aperture into the oil groove in the crank shaft main bearing generally aligned with the engine main bearing surface drilled opening and then replacing the crank shaft in the engine block with the engine oil jet installed to enhance the lubrication of the engine piston dome and wrist pin. The process is repeated for each of the engine cylinders.

[dannobee]

Dunno how the patent office missed the "prior art" for that 1997 patent, but Porsche first used piston squirters off of the main bearings for 1971 model year 911's and much earlier than that in the race cars. I'm sure that the general idea predated those.

In the 962's, the piston was cooled with both a "normal" squirter that sprayed oil on the backside of the piston and pin, but also added a tube that was parallel to the cylinder and sprayed oil into holes drilled into the back side of the piston. The holes intersected with a circular hollow passage forged into the piston directly behind the ring package. The oil passage exit was just under the entrance, providing about 300 degrees of oil cooling (in addition to the oil spray from the normal squirter). The pistons were multiple piece forgings made by Mahle that were electron beam welded together. This was about 1984 or so. In these pics you can see the entrance and exit holes in the pistons, along with the two types of piston squirters on each main bearing webbing.

[Kevin Johnson]

https://scholar.google.com/scholar?hl=e ... ston&btnG=

[hoffman900]

Dunno how the patent office missed the "prior art" for that 1997 patent, but Porsche first used piston squirters off of the main bearings for 1971 model year 911's and much earlier than that in the race cars. I'm sure that the general idea predated those.

In the 962's, the piston was cooled with both a "normal" squirter that sprayed oil on the backside of the piston and pin, but also added a tube that was parallel to the cylinder and sprayed oil into holes drilled into the back side of the piston. The holes intersected with a circular hollow passage forged into the piston directly behind the ring package. The oil passage exit was just under the entrance, providing about 300 degrees of oil cooling (in addition to the oil spray from the normal squirter). The pistons were multiple piece forgings made by Mahle that were electron beam welded together. This was about 1984 or so. In these pics you can see the entrance and exit holes in the pistons, along with the two types of piston squirters on each main bearing webbing.

They briefly mention that design here as well. This would be circa 1985 or so (during the development phase).

[ptuomov]

Thanks, this is all very useful.

[Calypso]

IIRC, 351C stock rods also have a piston oil squirter channel in the big end cap parting line and a small notch in the rod bearing.

[Firechicken]

IIRC, 351C stock rods also have a piston oil squirter channel in the big end cap parting line and a small notch in the rod bearing.

Pontiac engines also had these back in the day and never really understood why.
Must have been a lot of oil slinging around inside the block.

[ptuomov]

IIRC, 351C stock rods also have a piston oil squirter channel in the big end cap parting line and a small notch in the rod bearing.

By my understanding, those are for wrist pin and bore wall oiling, not for piston cooling. Piston cooling requires a different nozzle and flow volume.

[Calypso]

IIRC, 351C stock rods also have a piston oil squirter channel in the big end cap parting line and a small notch in the rod bearing.

By my understanding, those are for wrist pin and bore wall oiling, not for piston cooling. Piston cooling requires a different nozzle and flow volume.

Not sure what the original intention was, but they surely do oil the pistons as well by the looks of the old piston bottoms.

[dwilliams]

Older small block Chevys that had the little slot across and around one rod bolt (commonly known as the "spit hole") for oil to pass through. Various service manuals said they were for providing additional oil to the camshaft.

[Kevin Johnson]

Older small block Chevys that had the little slot across and around one rod bolt (commonly known as the "spit hole") for oil to pass through. Various service manuals said they were for providing additional oil to the camshaft.

I looked in my 1971 Motors Manual and it shows them and how they should be oriented toward the valley. Looks like they were used on the high performance Chevy engines. AMC V8 section shows them as well. I did not look at every OEM.

[Fusion Works]

Many high performance Japanese engines also use multiple slots on both side of the rod cheek . I figured it was to "leak" the oil in a specific direction instead of just letting it sling off where ever it goes naturally.




These are on the bottom of Honda production engines.



https://www.ebay.com/itm/00-08-Honda-S2 ... 3274366270

A bunch of engine builders block them off to increase oil pressure. Doesn't seem like a good idea. Honda spent a bunch of production money to put them in the engine. Not sure how a race motor would survive without them.

[needforspeed66gt]

Many high performance Japanese engines also use multiple slots on both side of the rod cheek . I figured it was to "leak" the oil in a specific direction instead of just letting it sling off where ever it goes naturally.




These are on the bottom of Honda production engines.



https://www.ebay.com/itm/00-08-Honda-S2 ... 3274366270

A bunch of engine builders block them off to increase oil pressure. Doesn't seem like a good idea. Honda spent a bunch of production money to put them in the engine. Not sure how a race motor would survive without them.

All the Honda and import racers I've seen eliminate the oil squirters....and then wonder why they trash pistons so quickly and they're black on the underside, I don't even bring it up anymore, they obviously know better.

Unfortunately it's rubbing off onto the LS crowd and even though I go to great lengths to retrofit in pressure activated (OE BMW) in many endurance builds and have seen without a doubt that there are great benefits to doing so in piston life, power, etc....many come in wanting their OE squirter equipped blocks (LSA, LS9, LT4, etc) to be blocked off because that's what they see done on the internet.

Piston oil squirters are a very good thing as long as you do it properly and don't starve the system as a whole.

[hoffman900]

Many high performance Japanese engines also use multiple slots on both side of the rod cheek . I figured it was to "leak" the oil in a specific direction instead of just letting it sling off where ever it goes naturally.




These are on the bottom of Honda production engines.



https://www.ebay.com/itm/00-08-Honda-S2 ... 3274366270

A bunch of engine builders block them off to increase oil pressure. Doesn't seem like a good idea. Honda spent a bunch of production money to put them in the engine. Not sure how a race motor would survive without them.

All the Honda and import racers I've seen eliminate the oil squirters....and then wonder why they trash pistons so quickly and they're black on the underside, I don't even bring it up anymore, they obviously know better.

Unfortunately it's rubbing off onto the LS crowd and even though I go to great lengths to retrofit in pressure activated (OE BMW) in many endurance builds and have seen without a doubt that there are great benefits to doing so in piston life, power, etc....many come in wanting their OE squirter equipped blocks (LSA, LS9, LT4, etc) to be blocked off because that's what they see done on the internet.

Piston oil squirters are a very good thing as long as you do it properly and don't starve the system as a whole.

Classic case of not seeing the forest for the trees. Also, just because one can assemble an engine, doesn't mean one understands how they work or how to improve them.

My guess, if they took advantage of what the squirters allowed them to do, they would gain way more than any windage gains they would see, let alone the reliability.