Can you port/ match the oil return holes in girdle to those in block?
03-07-2012, 03:01 AM
#16
RL Community Team
Rennlist Member
Rennlist Member
This is a cool thread, I'm eager to hear experiences, or your results if you end up doing it.
I have an engine in the garage that I want to put together soon and the simple basic things are always the things I'm interested in. Keep in mind, since most people haven't messed with this oil passage mismatch, and most people get 150k miles or more out of their engines, it's safe to say it's not a problem.
I have an engine in the garage that I want to put together soon and the simple basic things are always the things I'm interested in. Keep in mind, since most people haven't messed with this oil passage mismatch, and most people get 150k miles or more out of their engines, it's safe to say it's not a problem.
03-07-2012, 12:00 PM
#18
Burning Brakes
Thread Starter
Jugdging by the colour and the casting seams I would say they are of different materials. The block is darker and duller, probably because of the silica. I would think it would be cheaper to not us alusil where it is not needed, but I'm only guessing here.
What I end up doing with the ports depends on whether there really is a drainanage problem from the head or not.
@Greg. I have considered the possibility that the chutes do function as some form of Air Oil separators. My conclusion was that they are too narrow to allow time for a significant amount of bubbles to escape. In my case, the oil will flow onto the crank scraper, probably splatter onto the crank counterweights, get whipped around and areated again before reaching the sump, so the loss of the AOS happeneing in the chutes may be negated anyway. I will have to look into this a bit more before I make my decision. Perhaps this does not matter as the oil will be scraped after one revoluition anyway.....
What I end up doing with the ports depends on whether there really is a drainanage problem from the head or not.
@Greg. I have considered the possibility that the chutes do function as some form of Air Oil separators. My conclusion was that they are too narrow to allow time for a significant amount of bubbles to escape. In my case, the oil will flow onto the crank scraper, probably splatter onto the crank counterweights, get whipped around and areated again before reaching the sump, so the loss of the AOS happeneing in the chutes may be negated anyway. I will have to look into this a bit more before I make my decision. Perhaps this does not matter as the oil will be scraped after one revoluition anyway.....
Last edited by bebbetufs; 03-07-2012 at 12:16 PM.
03-07-2012, 12:49 PM
#19
Rennlist Member
If you cut it apart, there would be an air space where the saw blade or cutter was (called the kerf) ... and then, if you put it back together flat, the hole would not be perfectly round.
So, what they do is start with two different parts, machine them each flat, then assemble them and machine the bore for the crankshaft so it cuts both pieces at the same time. This guarantees that the bearing openings make a perfect circle. It also means each girdle is match to the block is was machined on.
The same method is used for connecting rod end-caps and the balance shaft housings (late style).
03-07-2012, 01:53 PM
#21
Burning Brakes
Thread Starter
If you cut it apart, there would be an air space where the saw blade or cutter was (called the kerf) ... and then, if you put it back together flat, the hole would not be perfectly round.
Last edited by bebbetufs; 03-07-2012 at 05:20 PM.
03-10-2012, 02:59 AM
#22
RL Community Team
Rennlist Member
Rennlist Member
Plus, why make the girdle and other parts out of special alusil rather than plain aluminum alloy?
I read somewhere that newer BMW connecting rods are made as a whole piece, then frozen in some special way, and the end caps are cracked off clean, so there's no machining, and each end cap is a perfect match for its rod. I doubt this process would work with aluminum.
But I still don't see the logic behind mismatched oil ports. Probably one of those "eh, it's just a half-engine" things where the factory just made something that would do the job, for an engine that was adapted from another engine, which was designed for a different platform, performance level, and engineering standard. Just my 2.
I read somewhere that newer BMW connecting rods are made as a whole piece, then frozen in some special way, and the end caps are cracked off clean, so there's no machining, and each end cap is a perfect match for its rod. I doubt this process would work with aluminum.
But I still don't see the logic behind mismatched oil ports. Probably one of those "eh, it's just a half-engine" things where the factory just made something that would do the job, for an engine that was adapted from another engine, which was designed for a different platform, performance level, and engineering standard. Just my 2.
03-10-2012, 04:52 AM
#23
Burning Brakes
Thread Starter
But I still don't see the logic behind mismatched oil ports. Probably one of those "eh, it's just a half-engine" things where the factory just made something that would do the job, for an engine that was adapted from another engine, which was designed for a different platform, performance level, and engineering standard. Just my 2.
