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Why have conrod slits for oiling the piston instead of block squirters?

Why have conrod slits for oiling the piston instead of block squirters?

Why have conrod slits for oiling the piston instead of block squirters?

(OP)
I was reading how Honda developed the piston cooling setup for the B16 engine, having 4 slits in each rod and an additional block mounted oil squirter.
But why have the rod slits? If it's because it sweeps a larger area of the piston, why not make the block squirter do that like in F1 engines? Is it a very slight cost saving measure? are the long block squirter tubes unreliable?

Also, it the bore oiled from the oil return holes in the piston being forced with oil, or from windage splashing oil around? if windage is greatly reduced, would additional oil squirters aimed at the actual bore be necessary or would the oil squirters aimed at the piston for cooling suffice?

RE: Why have conrod slits for oiling the piston instead of block squirters?

I'm not sure of the exact mechanism as to how but it helps with improving oil flow in the area.

I don't much care for the rest of the vehicle, but Honda's engines are notoriously bomb proof so this is one of the few instances where I would be willing to go along with whatever the manufacturer says.

RE: Why have conrod slits for oiling the piston instead of block squirters?

Typically oil jets inject into a cooling gallery within the piston. I'm not familiar with the particular engine mentioned but typically when piston cooling is via the con rod its a simple splash on the underside of a piston without a cooling gallery. Ultimately its a tradeoff - lighter piston without a cooling gallery or more stable temps.

Cylinders are lubed by windage. Its not my area of expertise but I'd imagine its pretty difficult to have too little for the cylinders while keeping bearings alive.

RE: Why have conrod slits for oiling the piston instead of block squirters?

In the older engines there were no piston oil squirters, or jets, it was all extra costs, it was easier to use a small slit or cut in the big end of the con rod.
Maybe Honda has a skirt scuffing problem?

RE: Why have conrod slits for oiling the piston instead of block squirters?

(OP)
Well apparently there was tons of R&D done for that design, and it clearly worked since the B16 engine is legendary.
"After honda was done researching oil squirter designs they had a rail car full of scrapped parts and designs", So the rod squirters must've done something for them to use them.

RE: Why have conrod slits for oiling the piston instead of block squirters?

Quote (enginesrus)

In the older engines there were no piston oil squirters, or jets

Older engines were developing a lot less specific power - meaning the amount of heat that individual fire-facing components (pistons, valves, cylinder heads, blocks/sleeves) need to be able to handle was much lower.

Honda's B-series platform was introduced in the late 80s, right when small displacement/high specific output engines were first coming to market in large quantities. Honda was on the forefront of this area of engine development at the time - in other words, they were the ones solving the newly discovered problems associated with rapidly increasing specific output from a small displacement engine design.

New problems required new solutions. Honda was very good at small engine design in the late 80s and early 90s, and stayed among the best for a long time. I would not expect that anything they added didn't need to be there.

RE: Why have conrod slits for oiling the piston instead of block squirters?

Piston oil squirters were hardly new tech in 1980. The very first engine I worked on after graduation in '78 had piston oil squirters but I'm absolutely sure the manufacturer had used them long before that. If someone did the research I'd be willing to bet they were used in WWII piston aircraft engines. Now developing the most effective and efficient squinter for your particular engine, that can take some time and effort. But don't expect it to apply straight across to a different configuration.

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