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Know this topic has been rehashed quite a bit but wanted some clarification on the numbers I'm seeing.
I have an oil temp sensor in a filter pedestal and recently also installed one in my turbo feed line (BNR twins).
The turbo feed line reading is significantly lower than my pedestal reading. This could definitely be due to the sensors being different, but the difference is too large to chalk up just to this.
Where the pedestal might read 80-90 C, the turbo feed might see 60 to 70 C.
The flow diagram below is also a bit confusing to me. How exactly does the oil flow post sump > pickup tube > oil pump?
My setup will look a bit different since I'm running dual coolers with a 180F thermostat, but I believe the oil feed for the coolers and oil return are at the same locations in the front housing and oil filter pedestal respectively.
the diagram seems to show the turbo feed Teed off the route through the block (from rear iron to front), which logically would also point to the turbo feed being hotter.
"which logically would also point to the turbo feed being hotter."
i agree.
a sensor at the oil filter is measuring oil directly from the coolers whereas the turbo feed line takes that oil and runs it thru the two upper dowel pins located within the block. certainly at a minimum the dowel pins would be the same temp as the coolant which is often 87 C. my guess is the sensors are the cause.
We discussed it in another thread but came to the conclusion that it doesn't matter where you get the oil temp reading from. Its all relative. 90c is a little warm but still good.
You're looking for some reasoning here it seems but its kind of one of those things that has no end if you pursue it. Its more likely to have you doing things you don't need to just for some closure. Maintain monitoring your temps at the hotter location
It can be tricky when you have two devices showing different measurements. If you only had one you might have assumed it was always correct.
I agree it makes sense to test each sensor. If you can temporarily move the sensor to sit in a pot of boiling water, that may be a useful reference since water will always be about 100 degC the entire time it's boiling.
This is barely related, but I pointed a thermal camera at my RX7's engine bay after an autocross and the oil pump outlet area on the front cover looked hotter than the oil pedestal. I didn't get a clear view of the turbo oil feed line in that video, but that side of the engine near the water pump and airbox generally looked a little cooler than the oil lines on my car (stock single oil cooler, max temp at the oil pedestal was 105 degC).
Also, I added color to an oil flow diagram to highlight the various passages. The colors don't really mean anything, I just switched colors when I thought it made sense. I haven't had a rotary engine apart, hopefully an expert will correct if I have any of the passages wrong.
Exactly my next steps, the pedestal sensor is harder to pull, so I'll test the turbo feedline sensor first.
That one is connected to a SPA technique dual gauge which i like, the pedestal is connected to a PLX multi gauge, which i no longer have mounted in my gauge pods.
Will update once I check the sensor.
I double and triple checked the oil thermostat and my dual cooler plumbing, it seems to be correct, Mocal 180 F thermostat has black Allen's that indicate a side and I remember when I was fitting the thing in, I checked religiously to make sure it was oriented correctly
I checked my coolant sensor (TB coolant line) and oil temp sensor (turbo feed) in some hot water and they read correctly (within a couple degrees of reference reading).
Not so worried about the oil temp being different between the oil filter sandwich plate and the turbo feed, I figure I'll keep the alarm around 95C and go from there.
My TB coolant sensor also reads about 5-6 C lower than my OEM temp sensor as displayed on the PFC but I think I'll do the same, set an alarm at around 90C for my gauge which should mean around 95-96C on the PFC (my fans are set to come on at 81C).
The turbo oil feed line tube does look similar to the power steering oil cooler tube- might be something in that
Are you measuring oil temps exiting the front housing on the way to the turbo or on the other end of the tube entering the turbo?
I'd say it's pretty midway. The hardlines on the twins are stock, then I used adapters for a short 4AN run to a turbosmart t40 which is mounted under the UIM (using the same bolt where the EGR block off plate is). The sensor is in the T40. The remaining feedline to the front cover is all braided 4AN
fans coming on at 81 C will basically run the entire time putting extra load on the electrical system, mine are set at 90 C.
The fans mostly work at low speeds or stopped; once driving at highway speeds the air velocity is enough.
fans coming on at 81 C will basically run the entire time putting extra load on the electrical system, mine are set at 90 C.
The fans mostly work at low speeds or stopped; once driving at highway speeds the air velocity is enough.
agreed. i remember tuning an FC turbo years and years ago. it was basically stock except the exhaust and ECU, and i was really surprised at how steady the temps were. we could make run after run after run and water temp wouldn't budge.
basically it would run 190f or 88c +/- 1 F.
i set my fans to mimic that plus a little laziness, mine are at 93c
fans coming on at 81 C will basically run the entire time putting extra load on the electrical system, mine are set at 90 C.
The fans mostly work at low speeds or stopped; once driving at highway speeds the air velocity is enough.
Hm, interesting. Stock fans (with the FC switch) come on at 85C no?
On track with a slightly thicker core stock mount radiator I have definitely seen my water temps climb above 95C
I'd rather replace an alternator and fan motors than a block, but I guess there is a limit with it like all things. I might bump it back up to 85C but will try it like this for at least one track day and try and log some temps
FC fan switch is 97 deg. C. Stock fan switch is 107 deg. C. Yes, really.
A PFC or other aftermarket computer can set the ECU fan temp to 85 or so, that will kick the fans on low and if you have the AC on the fans will be at medium. The FC fan switch is the high point so if things get REALLY hot (super hot day, stop and go traffic, AC on) that will kick the fans to High to really get temps down.
09-04-22, 03:09 AM
