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Mon Sep 15, 2008 5:36 am

any information and opinions on this mod? The purpose is to improve piston cooling. I cannot add oil squirters to my already prepped case (I don´t have the tools and know how) so I´m collecting info if notching my H-Beams will serve the same purpose.

Link: http://www.youtube.com/watch?v=7wuNuuEoN7Y

(notching 911 rods)

I´m afraid if it will not bleed to much oil from my system (26 mm schadeck pump, Berg´s mod on lifters)

Mon Sep 15, 2008 6:54 am

I did a similar modification back in the eighties to some rods on a 1776 motor I had built. I did not do this as a piston squirter though. What I did was to cut four or six (can't remember) notches with a chain saw file on each side of the rod in a star pattern. It was soley for rod main bearing oiling.... it did work well but you better run a deep sump so you do not run low.

Looks like an interesting mod.... just make sure to knock down any stress risers.... show us some picts when you are done.

Mon Sep 15, 2008 11:52 am

VW actually put out a service bulletin to do this on type 4 engines. I don't see why it wouldn't work on a type 1.

This thread has some good photos of the mod the way it's done on type 4 rods.http://www.shoptalkforums.com/viewtopic.php?t=95506&postdays=0&postorder=asc&start=30

I'm curious as to why they are doing this mod on 911 engines. I believe all 911 engines built after 1971 had a piston squirter system built into the engine. As I recall combustion chamber temps on the engines with the squirters are on average about 50* cooler than on an earlier engine, all other things being equal.

Tue Sep 16, 2008 1:29 am

thank you very much!

Tue Sep 16, 2008 4:02 pm

Great Post,

Looks like just the thing for a hard working T1 bus motor with a 30mm oil pump; any idea if and if so how much it would lower the oil pressure on the con rod bearings?

Tue Sep 16, 2008 10:34 pm

I was running a 26mm pump and I had two to three times the notching as the 911 mod and the only time I had oil pressure problems was from starvation in tight turns getting on the freeway..... a deep sump took care of that.

I do not believe that pressure drop is that bad.... the benefit is more flow through the conrod bearings and that would be good. That was what I was looking for when I did it.

Fri Dec 19, 2008 6:53 am

found a pic of this mod on Pauter website. If this is provided by The Man himself, it will be good enough for me on my H-beams.

this pic is a courtesy of Pauter Machine

Fri Dec 19, 2008 10:49 am

I had these mods done on my Carrillo rods.

Fri Dec 19, 2008 11:03 am

I Notched my 5.5 CB Rods for my 78.8x90.5 Bus engine, looking forwards to cooler running pistons, and longer P&C life :0)

Fri Dec 19, 2008 11:54 am

I did this to my Rimco super rods 26 years ago. If it was not for the NOS I would have the same pistons & cyl on there.

Mon May 11, 2020 5:18 pm

1961bluebug wrote: found a pic of this mod on Pauter website. If this is provided by The Man himself, it will be good enough for me on my H-beams.

this pic is a courtesy of Pauter Machine

Old thread (I searched, yay!)
Do the grooves go on both sides of the connecting rod?

Mon May 11, 2020 5:25 pm

Tue May 12, 2020 2:37 am

I notched mine.
Still got more oil pressure than I can shake a stick at with the hvx mods and a 26mm oil pump...

Tue May 12, 2020 4:00 am

Again educate me here, I fail to see how those little notches could have an effect on oil pressure. The clearance between the crank and the rod dictate the pressure, by the time the oil gets to the edge it has already had it's kick at the ball and is leaving the arena anyway. All you are doing is showing it which exit to take.

Tue May 12, 2020 6:50 am

Has exactly zero affect on oil pressure.
Rather it channels the oil seeping out all around the rod into one or two places to exit.
So, you are taking oil that was leaking all around and directing it to an exit.

Hopefully, it gets thrown onto the rods and pistons.

Tue May 12, 2020 7:35 am

Drilling a hole in the rod and brg that lines up with rod journal feed hole is more effective. The Porsche 911 system is even better as it sprays 100% of the time if the oil pressure is above the nozzle valve threshold (will still have good pressure at idle). I did the 911 system on a VW once, worked well. Dan

Tue May 12, 2020 7:46 am

Be careful here.....what you say ...because you do not know what condition teh parts are of the person you are speaking to:

Ohio Tom Said:
Quote: Has exactly zero affect on oil pressure.
Rather it channels the oil seeping out all around the rod into one or two places to exit.
So, you are taking oil that was leaking all around and directing it to an exit.

Hopefully, it gets thrown onto the rods and pistons.

and....

OPRN said:

Quote: Again educate me here, I fail to see how those little notches could have an effect on oil pressure. The clearance between the crank and the rod dictate the pressure, by the time the oil gets to the edge it has already had it's kick at the ball and is leaving the arena anyway. All you are doing is showing it which exit to take.

In a perfect world and engine you would both be dead on and I totally agree.

However bear in mind when you speak to a general audience in these forums....that far too many are not experts always employing every technique available to build their engine....and most importantly not everyone is using brand new, aftermarket rods or a new or welded crank...even when they should.

One of the biggest losses of oil pressure ....is at the rods....when bearing clearance is excessive....even .001" larger than ideal....especially when ADDED with excessive rod side clearance.

The vast majority of stock cranks laying around these days when coupled with a set of stock rods....will generally have rod side clearances that are up near the top of the...overly generous range listed in most books for VW. Too many people take what are really a wear limit ....as a usable spec....and figure if the rod side clearances are within that wide range....everything is peachy! And it will run just fine....but with a good bit of oil pressure loss.

However in an engine like I just described has oil notches added in....that can be quite bit of oil pressure loss. Then we see people getting into adding larger oil pumps....and then piddling with the oil pressure relief valve....etc...etc...etc.

Ray

Tue May 12, 2020 7:54 am

And then they have to use tar for oil to compensate...

Tue May 12, 2020 8:15 am

The notch has to be a semi circle. If its a V notch cracks can form.

Tue May 12, 2020 8:58 am

A chainsaw sharpening file works well. I have never seen it discussed but I assume both sides need to be done. That's what I do anyway.