Oldfeller--FSO
Serious Thumper ModSquad
Offline
Hobby is now "concentrated neuropany"
Posts: 12671
Fayetteville, NC
Gender:
|
Why only use relatively stiff copper or mild steel tubing for the first leg out from the oil tunnel gage tap port?
HEAT, pressure and vibration are the reasons. Our oil temps can get up to 250-350 degrees F under certain fairly bad summertime type idling conditions. Racing nasty Dragon run type running conditions can hit similar dirt nasty hot oil exit temps as well.
Plan for some excess, I always say. Heat alone by itself rules out the use of engineering plastic tubing here.
Pressure really isn't the main reason. Exit pressures have been seen upwards to 50 psi under cold start conditions, so pressures can get on up there as well, but not generally while the oil is smoky hot. Smoky hot oil temps are generally found under 20 psi at full running temperatures as the engine is fully hot and oil pressures are relatively low.
Sure, engineering plastic lubrication tubing can stand up to 250 degrees F at 75 psi, but who wants to bet their whole engine on such specialty plastic tubing never accidentally seeing something just a tiny bit worse than their temp/pressure rating levels in actual real world use?
Not me, I'm chicken when it comes to material selections.
Plus, the vibration levels around our engines are a real beetch sometimes -- you gotta plan for something that can really take a beating for that first leg out from the pressure port as our engine's motor mounts can get loose (rarely yes, but I have had it happen) and then what is going to happen to this particular piping juncture if the motor mounts are moving around some? Consider vibration's effects on that first leg of tubing -- how is it going to be constrained?
So, think metal and think about maybe putting some sort of vibrational stress handler into it as well.
Also consider the location of the nearby exhaust pipe as far as radiating some extra heat at your gage port's exit tubing structure. If the oil in that tubing isn't moving (because of a pressure setting on a check valve for example) then it is just gonna be sitting there a' COOKING in the radiated exhaust pipe's heat while you are sitting there idling after a hard summertime run .... heat on heat on heat building higher and higher.
So think heat, some isolation from vibration, and some insulation from any radiated exhaust heat and see if you can come up with some clever way to beat all these potential issues using commonly available quarter inch OD 1/8" ID copper tubing.
Oh yeah, protect that tubing from getting mashed flat the first time you bottom out the engine on the edge of a ditch or something similar ... it's not like that sort of stuff doesn't happen occasionally on them there mountain trips.
Remember, last summer Ed's forward controls got pushed back hard enough to actually crack his left side cover and Toymaker's forward controls got pushed hard enough to slightly bend his forward control plates ... Yeah, them ditches and such surely do happen in the real world. Hell on them foot pegs too ....
|