The C1J does NOT have under piston oil spray jets. The newer Renault (and most other manufacturers) engines do have these and they appear to help in several different ways. As the title suggests a Jet of pressurised oil is directed to the underside of each piston with the primary aim being cooling the piston the gets very hot during the combustion process.
The Oil Spray also assists with providing additional oil film to the cylinder bores.
The question though, is would it be worth it on the C1J?
Earlier Cosworth YB didn't have them, but they fitted them to all their rally engines, so there must be something in it? Burton Power (to name one supplier) sell a kit to retro fit to the YB Blocks that don't have them fitted.
Now there are several ways to achieve the effect. The most common is to drill into a block oil way and tap the oil off with metered tube. This is what Burton Power sell. Pic below:
Burton Power Kit
Another method is to put small holes into the Con Rod that direct oil from the Big End Bearings to then fire up towards the Pistons. I'd say this is the least common route.
The next method is the one that intrigues me. A hole is drilled from the Main Journal at an angle to then come out of the Block Casting in such a way to then spray directly to the underside of the Piston. Here's a video that shows what I mean.
https://www.youtube.com/watch?v=cqfijPy2Gn0
This final method is probably the way I'd go for the C1J if I was going to do it. What are peoples thoughts on the subject?