Any seen this rod mod or tried it?

TdiRacing · 10-20-2010, 08:07 PM

Putting a cut in the connecting rod for more oil cooling? Has anyone actually done this?

YouTube - Porsche 911 Connecting Rod Oil Squirter Mod

Would this not create lower oil pressure on the rod bearings by allowing the oil to flow out that groove, rather than stay? Or am I reading to much into this?

Flieger · Flieger's Garage

Are the piston squirters used from 1971 onwards not enough?

TdiRacing · 10-20-2010, 08:23 PM

I am not sure why this would be necessary, but I am more concerned about if you would get LESS oil pressure on the rod bearings because of it?

tadd · 10-21-2010, 05:38 AM

It does the same as the squirters but with one BIG exception... there is no ball and spring in the orifice to turn the oil off when not needed at lower revs.

t

ratpiper71T · 10-21-2010, 05:40 AM

I've heard this fellow is a very well respected machinist. And maybe this has some value as a mod but all things aside doesn't that compromise the strength of the rod itself? The line passes through the ridge of the casting. I would think the piston squirters are already enough..

Grady Clay · 10-21-2010, 06:00 AM

The broken Porsche rods I have seen break way too close to this machining for my comfort.

Most common is at the red arrow. A close second is in the area of the yellow arrows.

I didn’t see any discussion about polishing the machined grove.

What is wrong with a pressure operated piston squirter? If you need more oil, install the Turbo version.

Best,
Grady

HawgRyder · HawgRyder's Garage

For those people without squirters in their case, this might be a cheaper solution.
Connecting rods have been modified in many ways over the years, such as gun drilling to lube the piston pin (small hole from big end to small end), radial grooves to "float" the connecting rod on the throw (many small grooves like in the video, on both sides to oil pressure the rod sides to prevent rod from touching cheek of throw), and I'm sure...several others.
I used to have an old Coventry Climax engine, and the rods and crank were all needle and roller bearings, oil everywhere!
Coventry simply put in several return or suction pumps to keep the crankcase from filling up.
Bob

Walt Fricke · 10-21-2010, 10:06 PM

Tdi

Your 2.4 (if a 7R case) has piston squirters to do better what this old hot rodder's trick might do. So why even consider it? There are various things on my list of what I'd like to do as refinements inside an engine. This sure isn't one of them. And no way is this "necessary" for any reason.

Walt

stevepaa · 10-22-2010, 06:39 AM

I would think a small hole away from the edge would be better than that grove casuing a stress riser right there.

Walt Fricke · 10-22-2010, 07:34 AM

Steve
It might, but isn't it is easier to grind a groove? Especially if you don't have a machine shop in your attached garage? Remember, this is, I believe, a shade tree hot rod trick for motors which weren't designed for high performance, and not something we need on our motors. Especially motors we are subjecting to the additional stresses of racing/track use. Grady's note on where he has seen rods fail ought to give one pause about trying this on 911 rods, no matter how well the work is done.

If it is wrist pin oiling one wants, I think gun drilling the rod would be better. But I don't think 911s have a pin oiling problem.

If it is piston crown cooling that is desired, the squirters should do a better job. You can get them in three orfice sizes - standard, 964, and turbo. I just put the turbo ones in a race motor slowly building. Before someone said that the intermediate 964 size should be fine (assuming the regular wasn't, which is open to question as that's all I have been running) and not waste the oil pressure/add to oil running around causing drag, etc. But I've got a GT3 pump, so I am not worried I will run out of volume/pressure.

cgarr · cgarr's Garage

Maybe something like this?

ratpiper71T · 10-22-2010, 02:41 PM

Stress considerations aside, I don't see how this is supposed to gett a lot of oil to the pistons any way. The crank isn't exactly sitting in a sump full of oil like wet sump engines-v8, i4, i6 etc.

Walt Fricke · 10-22-2010, 07:17 PM

This groove does not rely on splashing oil. It directs the oil under pressure between the side of the rod and the throws, and squirts it up. Same as the hole Craig showed in his picture, basically.

tadd · 10-23-2010, 04:49 AM

Walt:
Just FYI, the three sizes are 1 mm (standard), 1.5 mm (turbo), and 2 mm (993tt). The tt are a bit longer, but fit the early stuff. I had them added to a 67 case to go with a GT3 pump.

Given how mods are needed to get more oil to the rod journals, I should think this mod is not a good idea, even for a stock motor.

tadd