For All the Engineers Out There in FJ Land …

[fj1289]

I was referring to the XJ oil cooler setup on that one. 

It's the FJ oil cooler lobe I plan to use to scavenge the turbo.  Block off the normal feed to that half of the pump and tap into it from the side of the oil pump case for the scavenge line.   Leave the primary part of the oil pump untouched for engine oiling. 

[fj1289]

I found this write up about an XJR turbo a couple weeks ago while stuck in quarantine in Goose Bay...

http://turbo-bike.com/XJR%201200%20Turbo.html





Only one I have found info on so far using the stock oil pump for scavenge.  I was not able to find any more info on this build, nor how well this modification worked.  I have my doubts about this setup though....

First, don't like the idea of the reed valve setup - seems (in my mind anyway) it would work opposite of intended.  I can see how it would serve to ensure to positively scavenge the turbo, BUT I simply can't get past two things:
1. ANY obstruction/restriction to the main engine side of the oil pump intake.  
2. It would seem to me the reed valves won't open unless you have a good "pull" on the turbo scavenge line.  If for some reason the scavenge flow "hiccups" (please excuse my highly technical jargon!) it seems the reed valves would close off flow to the main engine oil pump!  (since it would just be sucking air from the scavenge line?)  I might be totally off base how this works in reality and it might never "see" air in that line since the turbo IS being fed a pressurized supply of oil.  
3. Just thought of this - this oil on its immediate return from the turbo is being fed into the main intake flow of oil that flows to both sections of the oil pump - this could go to the oil cooler, or it could go to the engine oil galleys - or likely split between the two.   Hmmm...


This setup might work just fine and I might be trying to invent a more difficult solution that really isn't needed ... I just can't work it out in my mind.  Wish I could contact the owner and see how well it has worked in the real world (where results count and theory is just a discussion over a pint!)  

[RPM - Robert]

Wouldn't the easiest method be to take oil post cooler from a Y with the flow of the line to the cooler and then return it pre cooler with a Y there too? Once it's primed you shouldn't lose any pressure to the cooler or turbo.

[fj1289]

Robert - not sure I'm following you.  With a low mounted turbo, it will need positive suction for the return line to get the oil uphill back to the sump.  Without the positive suction, it will blow oil past the seals and smoke and get oil in the intake charge.   

If I'm following what you are saying, that would work well for a high mounted turbo (with an inline oil filter added to the turbo). 

I haven't decide how I'm going to try yet - high or low mount - need to put an engine in a frame and just start playing with it!

My placement of choice would be up under the swingarm pivot (like the old XJ650L Turbo) - but don't think there will be enough room ...

[RPM - Robert]

I guess I spaced cadeted on the low mount part, I will have to re-read I thought I was reading something with an airbox etc out the tail section. And now back to your normal scheduled programming.

[fj1289]

No - I've put a bunch of ideas out there - confused the whole question!   

I've got about three different thoughts on turbo placement - low in front of the engine, low below the swing arm pivot, height behind the engine .... Either of the low ones will require a scavenge pump of some sort.

[RPM - Robert]

Put an oil less turbo on it and call it a day.

[fj1289]

Unfortunately I've only been able to find them in big and expensive versions!