The orginal rods have a oil passage on top of one side on the big end. directed upward against the cylider wall. Is this for spraying the cylinder walls with oil? Or how is the cylinder walls and pistons lubricated?

I am asking because my Spool rods dont have this oil passage. And I dont want to ruin my engine bacause of no oil on the cyl wall.. Anyone have experience on using aftermarket rods on the FJ?

Thanks

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I have a collection of pictures of oem rods with oil squirters on the sides. The Honda B-series engines (B16, B18C) have 16 (20 total). Very easy to do but I would have a machine shop add them so that the amount of metal removed is very close for balance sake.

I have been thinking the same thing looking at my spool rods compaired with the factory ones. Let my know what you come up with.

Very simple modifications.

Honda B-series; four squirters per rod:



BMW S-50; two squirters per rod:



The above two modifications utilize oil that has already been ejected from the bearing margins.

I would not suggest adding squirters that draw from within the bearing surface area as seen in the pictures below. These types of squirters negatively affect the pressure differential on the interior bearing surface.


Here is an example from the Audi engine used in the Porsche 924:



Here is another example from the Nissan RB25DET:

In addition to the above: I have an assembled RB26DETT block here. The squirter part of the big end forging is not aimed at the thrust side of the cylinder wall but rather the underside of the piston for cooling. The oil squirters on this engine that sit at the bottom of the bores are aimed at a passage in the piston.

To the original question, the squirters in all the previous pictures are primarily for cooling the piston rather than lubricating the pin or the cylinder walls. Many builders justify leaving out squirters on aftermarket rods for say, the Honda B-series, by virtue of their use of forged pistons which have better heat transfer. To where? The rings?

Hard to get oil squirters on the rod/big end journal area to actually squirt oil onto the back of the piston - which is what is really needed if you are serious about removing heat from the piston (I would think this is only required for circuit work in moderate/high pressure turbocharge applications). The adaptations I have seen that work well for this take oil from a gallery in the block and aim the oil directly up at the back of the piston using special squirters designed specifically for the job. In reality the methods used by most OEMs for this are cheap, and the ones which drill the oil passages in the rods can be nasty.

Oilers that simply load the wall of the cylinder with oil probably cost horsepower as the rings have to work harder to get rid of the extra oil. And yes, the major heat path out of the top of the piston is the top piston ring.