Quote:
Originally Posted by Dsmguy1993
That was very well said I do agree with you as well there are many mistakes to make and insane amounts of room for error. With that being said in regards to the oil orifices being clean is that not what the machine shop takes care of? Perhaps im wrong but I thought thats what hot tanking and cleaning the block does? Now I got some experience working on engines I redid my own timing belt in my 4g63 turbo water pump etc but this would be my first actual rebuild if I did do it. I should clarify as well when I mean piece it together I dont neccesarily mean cheap out per say I would pay to get machine work done on the block and get it cleaned and make sure the crank gets looked at as well. Perhaps that is a lot of work altogether and I may even be better off just buying a swap from someone I dont know because I dont know about sr20det but I want to learn as much as I can before I put money in so I know I am making the most educated decisions.
|
This is what I am saying, if you choose an engine which is NOT currently clean and running well, there is a very high chance the machine shop will 'clean it' and it will NOT be cleaned properly. The rebuild will fail quickly. For example if you find a motor that lost a cam lobe and then a rod bearing. Let me tell you how that happens, first the oil orifice for the cam lobe fails because a tiny, less than 1mm of carbon crust is all it takes, lodged in the hole permanently and that melted the cam lobe quickly. The metal washed through the engine and took out the oil passage for a rod bearing and started taking out the next one and so forth.
You can take that motor apart and try to clean it. You can take it to three different machine shops and have each of them clean it. It will still spin bearings for the rest of its life because nobody will ever put the full time and attention required to remove every bit of debris, its "impossible".
If you let a block sit exposed to the atmosphere for very long, it becomes un-cleanable in a similar manner, because every tiny bit of organic carbon life form from the air (fungus, pollen, bacteria, tree materials, skin, the air contains everything and there are something like 200,000 particulate per square not-so-large volume) is just as deadly as metal particulate to engines with the only main difference that when metal finally sticks down its under a significant pressure or trapped in a space, whereas organic carbon is gooey and smaller particular may tend to stick wherever it feels like or to an already growing pile of itself somewhere (atherosclerosis, coalescent carbon chains of fat as in cell membranes), and the organic carbon can react vigorously in the high temperature and pressure of the engine's oil and internal combustion. In many ways air exposure is more deadly to an engine than metal particulate, when we consider all the potential reactions with engine oil and combustion byproducts (pollen for example contains myriad constituents as: potassium, iron, sulfur, calcium, molybdenum, sodium, the elements of life) that are available.
Oh sure, the machine shop will take it and 'clean' it for you, but that doesn't mean anything because it is typically a very basic approach and there is very little inspection or attention to detail spent. There are changes that the atmosphere makes to exposed metal surfaces which may be slight at first but ultimately reveal themselves as permanent damage.
If you want to see the actual surface of the engine insides it takes microscopy, severe attention to detail, surface samples, oil orifice camera elapse footage, fluid dynamics for entry/exit of flow over journals, etc... there are thousands of influences inside the engine oiling system which a machine shop will NOT care about, they will likely NOT take the necessary time, potentially hundreds of hours to fully inspect and clean a highly "filthy", externally exposed engine or for testing and modifying existing oil passages for high performance nature. They don't consider that part of 'cleaning' the engine yet under any real racing conditions where winning was an absolute must, of top importance, yes the entire engine internally is inspected and dynamically challenged to meet the strictest of specifications, and that means not one little tiny bit of goop is inside one of the oil passages. Its up to YOU to clean every channel/orifice/hole and make sure the oil moves smoothly and completely from one to the next as it should. This is the mistake many make: assuming the machine shop fully "did everything" to clean and inspect 100% of the engine. And there are many who have been building engines for twenty thirty years still not really sure about how to fully achieve this. You can buy an engine, or assembly an engine, with the assumption the oiling system is perfect. But it rarely is and very few are actually testing the flow rate throughput in volume/time and modifying their pump and system to achieve the right flow range for each operating conditional.