So I have an oil cooler with -12 fittings on it, a standalone -12 oil thermostat, a sandwich plate with just two holes for sensors and a thermostated sandwich plate with -12 feed and returns as well as holes for sensors. So do I; - Run the oil feed/return lines off of the stock tree/sump, through the standalone thermostat then oil cooler - Fit up the thermostated sandwich plate and run lines off of that directly to the oil cooler? I know it's two ways of doing the same thing, but is there any reason one would choose one method over the other? I was planning on the former. I can't remember the size of the stock oil feed/return lines, but I'm guessing they're not as big as -12... -A
No real point running from the stock port through a thermostat since the the flow through there has to be minimal anyway or you'll be dropping pressure everywhere else. I would even consider running the thermoplate and the stand alone thermostat together since you have them both, using just a mocal thermostatic sandwich plate mine ran uncomfortably cold most of the time. With my setup I'm considering moving to a ball T-valve or similar and just switching over when I'm going to run it hard or the weather is actually hot.
I don't think running two thermostats is the answer to a thermostat that opens at the wrong time, haha. Explain that bid about pressure drop again?
I think with the sandwich type stats at least its more about the size of the bypass opening, doesn't seem to reduce flow through the cooler as much as it could. I think the stand alone units might be a bit more effective. I was feeding the engine ~60 degree oil most of the time so the sump may have been up to temp but I still think that's a bit cool. Thermostat is supposed to be the usual 80 degree setting I'm pretty sure. With the pressure drop, since the standard cooler feed comes off the filter tree if you run that with nice big -12 lines through a cooler and back to the sump with no restrictor the oil isn't going to be very motivated to run through all those little oil galleys in the engine.
Interesting! I don't know anything about how the oil is pumped. So the oil pressure takes the path of least resistance, and in my case that may be going through the cooler back to the sump instead of through the motor? I guess the sandwich plate is a much better option since it'll go back to the filter. Does the flow normally go pump -> filter -> motor?
Stock the oil flow goes pump, filter, engine, with any excess pressure over 50psi going to the oil cooler and straight back to the sump pre filter. When installing an oil filter relocation / oil cooler kit on cars that don't have a cooler, you would normally go pump / cooler / filter / engine. Personally I'm not convinced this is a good idea with our cars.
From the research and testing I've done so far, I'll be sticking with the stock TT oil filter tree and stock cooler lines, with just a larger cooler. If we install the modified sump we made I'll have to relocate the filter, but that's it, will essentially still be stock oil flow. Both my track days at WP my oil pressure stayed a near constant 50psi, that's on WOT, off throttle, through corners both on and off throttle, etc. No sign of the dreaded pressure drop / oil pickup issues our engines are supposedly famous for while going around corners. My sump, oil tree and oil cooler lines are all stock, just with a larger oil cooler installed.
Yeah that's basically it, the oil cooler valve comes out between the pump and the filter and just returns to the sump once it's cooled; there's a schematic and flow chart in the lubrication/cooling section of the FSM if you're interested. Just looking at it again now the opening pressure for the valve in the cooling line is ~50psi so it shouldn't affect idle pressure (except when cold) but it might cause problems at high load if you don't keep a restrictor in the line. Given your options I would go for a normal sandwich plate and use the stand alone thermostat if it is a similarly reputable brand, compare the size of the little bypass opening in the sandwich plate to a thermostat block which look like they keep the bypass at about the same size as the ports. Brands like Derale advertise 90% bypass when cold for the stand alone unit while I haven't seen numbers advertised on sandwich plate type thermostats. Also, since I haven't tested this I want you to be my guinea pig so I don't have to buy another thermostat I'm assuming you'll have a good oil temp gauge in your rig.
Couple of thoughts behind my reasoning, and these are just theories at this stage, I need to do more testing and research. The oil filters on our engines (like many engines) have a built in pressure bypass, to stop the filter failing if they see too high a pressure. Once pressure to the filter gets too high, it simply bypasses filtration. On our engine, assuming this bypass pressure level is above 50psi, this would rarely happen, as any pressure above 50psi goes out to the oil cooler and straight back to the sump. Whereas if you go 'full flow', if the pressure to the filter is too high, any bypassed oil will go straight into the engine unfiltered. Admittedly this is standard on most cars, but still not ideal having unfiltered oil going into the engine. I think I've read people reporting oil pressures of 80psi(?) on our engines with full flow systems. The other reason is oil pickup. Stock, any excess oil pressure goes to the cooler and back to the sump. 'Full flow', all oil regardless of pressure goes back to the engine. This results in higher pressures in the engine, but also lower oil levels in the sump. This could be part of the reason some people see oil pickup issues at high revs and around corners.
The filter bypass valves are more about pressure drop than absolute pressure from what I can tell, the little check valves in the filter tree have very little pressure in their springs (I've checked two trees, hopefully this doesn't mean mine are broken) so it's the pressure of the oil on the other side holding them closed, once there's a restriction in the filter you get a pressure drop from one side to the other and they open. Oil levels in the sump shouldn't change due to the cooler once you've filled it up properly, mine stays full with the engine off thanks to the drain back valves so it wont be taking any out of the sump when it's working.
At idle I agree, but at WOT and full revs, you're pumping lots of oil up into the engine, and if it doesn't drain back fast enough your sump levels get low. This is a problem in a lot of motorsport applications. From memory early Ford V8's were notorious for this. A lot of motorsport applications have oil restrictors to restrict the amount of flow that goes to the heads. This is part of the reason. Too much oil up in the top of the engine means not enough oil down at the pickup. With our engines, at WOT and full revs, any excess pressure, and therefore oil flow, above 50psi goes straight back into the sump.
I was talking about the bypass valve in the filter itself, but actually from memory our filters don't have one? from memory if going full flow it's recommended to go with a different filter that does have one. Though with the check valves in the filter tree or block it's probably not needed, which also moots my first point above lol. Regardless too much pressure in the filter and the filter itself fails.
Edit: I also run the sump over full by probably around half a litre. Pretty standard for racing unless running modified and dry sump oiling systems. This also helps to ensure there is oil at the pickup at high revs and high cornering speeds.
There is a pressure control valve in the pump too although it's set higher than the cooler relief it should do it's job. To be honest I'm surprised the stock cooler lines flow enough to stop you from seeing any higher than 50psi, the manual even specifies higher than that at 3000rpm. Either way, I haven't seen any oil starvation in my setup, maybe I just need to pull more lateral G's. Did a bit of googling and the K&N recommended filter for the Z doesn't have it's own bypass valve so it looks like they do rely on the ones in the tree. All that said since your setup is easier to install the discussion should be why go full flow rather than why not, do you have any temp data from yours yet? Mine are sub 100C in 10-15 minute sessions with ambient temps around 20C.
Yeah I remember when I was looking to go full flow, I emailed K&N asking what would be the equivalent with a built in bypass, useless tech support had no idea... My point exactly, but I need to do more testing, I'm not flat out yet. And the big test will be turn 1 at Eastern Creek :br: Certainly for street use or your average track day, I'd leave it stock, just fit a bigger cooler.
Thinking a bit more about your oil pressure, are your oil cooler lines actually the stock parts or just stock sized? I'm wondering if yours actually have the restrictor in them, I don't the the restricted versions would flow enough that the pressure stays the same from 3000rpm to redline. From Z1 motorsports:
Yep, stock, the only difference is a larger cooler and a K&N filter. Actually one of the hoses to the cooler is not stock, but I'm pretty sure the stock one that remains does have the restrictor in it. Will check and confirm on the weekend.
Just checked a pic of the front with the bar off. The stock hose is definitely the one with the restrictor in it, can see the bulge in the hose in the pic. I actually have this on the opposite side of the cooler to stock though. Because it's a bigger cooler, the stock hoses don't fit as per normal. So I have a new hose on the far side, and the far side hose with the restrictor on the near side (to the hard lines).
