Connecting Rod Oil Squirter Mod
 

Hi everybody,

I was hoping to get some info on modifying connecting rods. In my case I’m rebuilding a 2.4 engine with new pistons from JE. Some connecting rods have grooves gut into them to allow oil to be flung in the direction of the piston. As an example I attached the image of a Subaru Tuning rod.

By coincidence I stumbled over a YouTube video of doing a similar mod to an air-cooled Porsche connecting rod: https://youtu.be/7wuNuuEoN7Y

Is this a sensible modification and can somebody tell me proven dimensions for the grooves?

https://fullcartuning.de/media/produ...-57127-7a3.jpg

Your engine case dosen't have piston squirters? I don't remember when that became standard.
Depends on your rebuild I guess.

It does - this would be an additional feature.

That notch looks a bit large.
Cutting a poor mans squirter is common for the type one and four VW and 914 engines and I've done this on 356 builds, but I don't do it on 911 builds, I use the 911 squirters.

One thing I would question is does it do anything to the oil pressure?
Type one and four most of the time I'm using a bigger oil pump or sometimes even a oil pressure booster.

I agree with Mark: anything that would tend to compromise the oil pressure or connecting rods would give me pause.
If you need more oil, add a second squirter.

BTW: I knew John from his early days at CM R&D. He was more of an academic with great tools than a hands on machinist. His experience with Porsche engines was minimal at best.

More oil sprayed on the piston underside is better for temperature control.

The only downside would be if the additional oil slung from the big end overwhelms the ability of the oil ring to scrape excess oil from the cylinder walls.

I don't see how that notch would affect oil pressure. It's exit oil that's typically thrown off the rod in all directions before ending up at the bottom of the crankcase.

Sherwood

I don't believe that slotting the rod for an oil channel will affect oil pressure unless you don't have side clearance. Typically with rod side clearance at .010" and B/E clearance at .002"vertically and maybe .003-0035" from lensing near the parting face, I don't see how side clearance has a lot of effect on oil pressure with the bearing clearance being the largest restriction
That said I wouldn't bother with that mod, as others said, you have squirter , and if you were concerned and required more oil to overcome another issue, you could run a larger squirter from a turbo etc.

I've seen this mod in aftermarket rods for the 924. The 924 has an oilsquirter in the big end of the rod.
The recommended size for a notch has been given as ".100"-.125" wide, and .030"-.040" deep" by a rod manufacturer.
But the standard 911 squirters are a better design taking the oil from the mains and only above a certain pressure so you get oil cooling when you need it.

Looks like another gimmick. Rods take a serious beating I wouldn’t put one in my milling machine and start milling channels. Looks like a solution for a non existing problem.

Thanks for your input guys! Very interesting read. I will not be experimenting with my rods - especially because my build is close to stock.