93 928 gts oil consumption
03-21-2014, 01:12 AM
#286
Archive Gatekeeper
Rennlist Member
Rennlist Member
How are these EDN holes fed? By grooving one of the rod bearings?
03-21-2014, 01:25 AM
#287
Nordschleife Master
This is not a necessity, and greatly depends on many factors as it if they even consider it as the cost is expensive.
I could not find one person who would consider doing this at lower vacuum levels, or at the low power levels we see in our cars.
03-21-2014, 01:27 AM
#288
Nordschleife Master
03-21-2014, 10:14 AM
#289
Nordschleife Master
Agree most Nascar rods have the EDN hole, in fact for a while Cosworth F1 rods in the modern era didn't have that drilling. However when they turned up the vacuum to Nascar levels, the rods I have seen now all have it. Some Nascar don't have it, these engine are the plate motors or the Nationwide motors that don't have the same power levels. These are normally brass or copper bushed and use a DLC pin.
Those engines because they are air restricted try to cut as much friction as possible, Dr Andy Randolf who was interviewed a couple of years ago for Race Engine Technology said he doesn't use the EDM drilling for these lower power motors. They have carefully targeted oil squirters. In fact they do hardness tests on the pistons to determine if they are getting enough cooling to the pistons via the oil squirters. These squirters also target the pins despite next to no clearance between conrod and piston. He said the pins hardly ever show any wear.
Those engines because they are air restricted try to cut as much friction as possible, Dr Andy Randolf who was interviewed a couple of years ago for Race Engine Technology said he doesn't use the EDM drilling for these lower power motors. They have carefully targeted oil squirters. In fact they do hardness tests on the pistons to determine if they are getting enough cooling to the pistons via the oil squirters. These squirters also target the pins despite next to no clearance between conrod and piston. He said the pins hardly ever show any wear.
03-21-2014, 09:50 PM
#290
These are piston guided or dual guided rod engines, right? If so, there's really not much gap between the piston and the rod small end. At high vacuum, it's the lack of gap that causes the oiling issue, otherwise the splash oiling would be good. What makes splash oiling even more challenged is the box in box piston structure in those pistons. Does this square with your understanding?
Non EDM Pankl, 6.4" length
Recess for oiling. 18 mm pin diameter
03-21-2014, 10:00 PM
#291
Nordschleife Master
I took out a set of S4 rods I've had sitting on the shelf for years as a reference point today.
These came from a TBF motor. I bought the pistons, and rods from TerryGT.
Measuring the wrist pin opening in the connecting rods I find the same variance that Rob Edwards found too.
My ID was .9451" for left/right, and .9453"-.94535" for top/bottom.
I measured 5 of the 8 rods and found the same numbers consistently.
The numbers may have been of by .0001" as I didn't zero the gauge 100%.
These came from a TBF motor. I bought the pistons, and rods from TerryGT.
Measuring the wrist pin opening in the connecting rods I find the same variance that Rob Edwards found too.
My ID was .9451" for left/right, and .9453"-.94535" for top/bottom.
I measured 5 of the 8 rods and found the same numbers consistently.
The numbers may have been of by .0001" as I didn't zero the gauge 100%.
03-29-2014, 07:38 PM
#292
Rennlist Member
Checked the pistons this evening, while busy doing new motor mounts and OPG and a few other "WYAIT" type of jobs (with much help from Erkka): no oil return holes present. This is a very late MY 1994 engine, which was exchanged under warranty.
Not really view-able from these pictures alone, however fact (take my word for it):
Hence as both Erkka (post #127) and Greg (post #131) predicted/stated earlier.
Not really view-able from these pictures alone, however fact (take my word for it):
Hence as both Erkka (post #127) and Greg (post #131) predicted/stated earlier.