thanks RB for making upgraded oil drains and giving the community an option up until now as the stock oil drains are terrible!
MMP maintains that stock oil drains are way too small to adequately drain a journal bearing turbo. A ball bearing turbos flows ALOT less oil through the bearing housing since it has a 1mm restrictor that the journal bearing dosnt and ball bearing turbos still use -10 drain lines (16mm ID). Standard design practice for turbos is a -10 return line as vertical as possible to let gravity effectively drain the oil with no line restrictions.
The stock oil drains being 9mm in the metal tubes and 13mm in the flexible sections are way too small compared to what is standard oil drain design practice and the flexible section tends to collapse and kink further upsetting things.. Remember that its flow area that matters so 9mm in area is more than 3x smaller compared to 16mm line!!! The stock oil drains can barely keep up and any little upset like a kink or partial blockage etc can casue the bearing housing to not drain and leak out the seals. I dont know why BMW did that but then again this was thier first turbo car in a long time and they got alot of things wrong such as injectors, HPFPs, plastic coolant fittings that break, plastic coolant tube over radiator that bursts, coolant pumps that fail, blower fans that catch on fire, wastegate rattle failure, oil filter housing gaskets that leak, valve cover gaskets that leak, oil pan gaskets that leak, rear main seals that leak, vanos solenoids that fail, boost solenoids that fail, coil packs that fail, chargepipes that burst, carbon build up on valves, vacuum lines that fail...etc etc.. just to name a few LOL!
So stock oil drains suck. What are we left with. Currently there is only one option on the market for upgraded lines but we think we can provide a better one and at half the cost. Out parts are already in process and will be for sale in a couple months tops.
there was some mention before that the largest the oil drain line can be is 14.5mm....this is too simplistic and not fully correct. What is more correct is the largest the oil drain fitting into the block can be is 14.5mm right at the point of connection, but as we will sho below it can then increase size in the fitting to 17mm and then the hose can be 19mm, as is the MMP design.
SO some might say..."well that wont flow anymore because your putting it through the 14.5mm bit". This is also wrong as it lacks understanding of fluid dynamics and line losses and the physics there. A 6mm section of 14.5mm diameter in the fitting + a 40mm section of 17mm diameter in the fitting + a 180mm or section of 19mm ID hose has
ALOT less pressure losses than a 226mm section of straight 14.5mm. Why is that? you can lookup line loses and how to calculate them but I wont go into the physics class here, rather I will just propose a simple experiment to prove it to yourself. Take a straw and blow through it and feel how hard it is to blow rapidly through the straw (the smaller the straw the better for this simple expiration to make the point). Then cut a 1/4" long piece of the straw and blow through that. You will see it get DRAMATICALLY easier to blow through the straw. And if you could attach the 1/4" section of straw to a large 1" tube the same length as the straw you cut off, you would still see it is DRAMATICALLY easier to blow through it. This is because the loses are MUCH less in the line with the short straw because loss calculations depend on not only diameter but the length of that diameter in the section of pipe.
Based on the explanation above I can tell you that the drain fitting below will flow WAY better than anything else on the market and will be attached to a 19mm ID drain hose and will be far less cost than anything else on the market. SO if your looking for the best drains, just hold tight, they are coming and you will save a ton of money too
View attachment 10343
Also here is a video that summarizes well some of the things I discussed in the first post.
