Engine Temps
04-30-2007, 09:46 PM
#1
What pointy ears?
Thread Starter
Engine Temps
Here's what my engine temps look like at 55 and 80 MPH. I've begun to add engine temps for ambient temperatures in the upper 90s, low 100s (F) now that it's started to get hot around here. You can pretty much ignore the part of the curve that falls below 45 F ambient on all of the 55 MPH curves since I don't have any data in that region for now (have to wait until winter).
UPDATE 070921: Added data for 5W-20 oil in addition to the 5W-30 and 20W-50 oils in the first plot, and affect on coolant temperatures in the second plot. Unfortunately (for this project), the weather started cooling off so I don't have enough temp data in the +110F region for the 5W-20 oil. I suspect that its curve would cross over the 5W-30 curve somewhere above 210F (near the cross-over point of the 5W-30 and 20W-50 curves). But until I get that data, this is speculation. Also, I'm still gathering data for ambient temperatures below 50F for 5W-20 oil --- so ignore the upturn in its curve (and the upturn in the 20W-50 curve for that matter) below 60F for now. I may have to separate the curves into another graph --- the data points really make these plots busy LOL.
Recording Conditions:
* Vehicle at speed for 10 mins or more.
* Level road
* Wind speed below 27 mph
* Relative Humidity 20 or below
* Engine oil always kept near full mark
* Tire Pressures at 35 psi cold
* RB A/C and oil cooler screens
* Stock NA engine
Cowardly Disclaimer:
* Don't know the accuracy of the Nordskog Digital Street series gauges
* Ambient temperature read from the OEM center console LED display ---
don't know how accurate that is either
* Wind speed is a guesstimation --- I live in the desert, so if you see
the creosote bushes bending in the wind, it's probably below 27 mph.
If you see the creosote bushes bending in the wind AND you're getting
sand-blasted AND you have to dodge tumbleweeds the size of your car,
it's above 27 mph.
* And finally, the behavior of my engine may not be representative of the
NA RENESIS engine. Any similarity between my RENESIS and other
RENESISes, whether fictitious or real, is purely coincidental --- so there.
Engine Oil Temps:
Oil Temps at 80 MPH for 5W-20, 5W-30, and 20W-50 viscosity oils. Extrapolating the curves in the higher ambient temp region, the more viscous oil will run a little cooler. You'll probably benefit using a higher viscosity oil if your driving conditions constanly keeps your oil temperature above approximately 210 F.
Affect of Oil Vicosity on Coolant Temperture:
Using 5W-20 or 5W-30 viscosity oils affect the engine coolant temperature identically (taking into account the gauge error). Seems to be some benefit (lower coolant temperatures) using a higher viscosity oil at the higher ambient temperatures (or higher loading conditions).
Engine Oil Temps:
Oil temperatures at constant velocities of 55 and 80 MPH
Engine Coolant Temps:
Engine coolant temperature plot at 55 and 80 MPH
Engine Temps at 80 MPH:
Engine oil and coolant temperature plot at constant velocity of 80 MPH
Engine Temps at 55 MPH:
Engine oil and coolant temperature plot at 55 MPH
UPDATE 070921: Added data for 5W-20 oil in addition to the 5W-30 and 20W-50 oils in the first plot, and affect on coolant temperatures in the second plot. Unfortunately (for this project), the weather started cooling off so I don't have enough temp data in the +110F region for the 5W-20 oil. I suspect that its curve would cross over the 5W-30 curve somewhere above 210F (near the cross-over point of the 5W-30 and 20W-50 curves). But until I get that data, this is speculation. Also, I'm still gathering data for ambient temperatures below 50F for 5W-20 oil --- so ignore the upturn in its curve (and the upturn in the 20W-50 curve for that matter) below 60F for now. I may have to separate the curves into another graph --- the data points really make these plots busy LOL.
Recording Conditions:
* Vehicle at speed for 10 mins or more.
* Level road
* Wind speed below 27 mph
* Relative Humidity 20 or below
* Engine oil always kept near full mark
* Tire Pressures at 35 psi cold
* RB A/C and oil cooler screens
* Stock NA engine
Cowardly Disclaimer:
* Don't know the accuracy of the Nordskog Digital Street series gauges
* Ambient temperature read from the OEM center console LED display ---
don't know how accurate that is either
* Wind speed is a guesstimation --- I live in the desert, so if you see
the creosote bushes bending in the wind, it's probably below 27 mph.
If you see the creosote bushes bending in the wind AND you're getting
sand-blasted AND you have to dodge tumbleweeds the size of your car,
it's above 27 mph.
* And finally, the behavior of my engine may not be representative of the
NA RENESIS engine. Any similarity between my RENESIS and other
RENESISes, whether fictitious or real, is purely coincidental --- so there.
Engine Oil Temps:
Oil Temps at 80 MPH for 5W-20, 5W-30, and 20W-50 viscosity oils. Extrapolating the curves in the higher ambient temp region, the more viscous oil will run a little cooler. You'll probably benefit using a higher viscosity oil if your driving conditions constanly keeps your oil temperature above approximately 210 F.
Affect of Oil Vicosity on Coolant Temperture:
Using 5W-20 or 5W-30 viscosity oils affect the engine coolant temperature identically (taking into account the gauge error). Seems to be some benefit (lower coolant temperatures) using a higher viscosity oil at the higher ambient temperatures (or higher loading conditions).
Engine Oil Temps:
Oil temperatures at constant velocities of 55 and 80 MPH
Engine Coolant Temps:
Engine coolant temperature plot at 55 and 80 MPH
Engine Temps at 80 MPH:
Engine oil and coolant temperature plot at constant velocity of 80 MPH
Engine Temps at 55 MPH:
Engine oil and coolant temperature plot at 55 MPH
Last edited by elf; 09-21-2007 at 09:47 AM. Reason: Updated data for 5W-20 viscosity oil
05-01-2007, 06:19 AM
#3
Registered
I can see why the RX-8 has 2 oil coolers. That oil temp max is about 20 degrees higher than my RX-7 runs. To be fair, however, I installed gauges in the RX-7 over the Winter and have not stressed the engine yet in hot weather. The factory manual for the RX-8 essentially specs the oil temp at 100 degrees (C) [212 degrees (F)], so you're well within spec.
05-01-2007, 06:41 AM
#5
What pointy ears?
Thread Starter
Originally Posted by Go48
... The factory manual for the RX-8 essentially specs the oil temp at 100 degrees (C) [212 degrees (F)], so you're well within spec.
Extrapolating the oil temp curve, 100F ambient will give me around 210F oil temp at 80 MPH 
Last edited by elf; 05-01-2007 at 07:34 PM.
05-01-2007, 10:18 AM
#7
good post man--I have done a good bit of looking at engine temps over the past year or so. on the track and on the street. Biggest thing for me was switching from 5/20 oil to 5/30 because with the 20wgt the engine could not mantain factory recommended oil pressures. AND on the track i now run a 10/40. All synthetic---they DO run cooler.
The 2nd thing that became apparent was the lack of good airflow through the radiator and the oil coolers. Get the fan turned on and your steet coolant temps will never see 200 (within reason of course!) Oil temps--thats another story.
Oil needs to be at the 180-190 mark. Even though there is a lot of discussion concerning oil temps (many people on the track in the 8 and other type cars will go over 250F) I dont like to go over 230F even with syn in.
Therre are a lot of things that you can do to help with temps. If you are running screens BE SURE that the screens are actually touching the coolers---if they are not --then the airflow will be restricted. I dont run them anymore.
One you probably havent heard about---i recently cut the rotor symbol out of my front air dam--just added a support where it used to be---I cant prove it--but I swear my temp gauge runs about 5 degrees cooler now during in town--non congested driving. I really think it blocks more air movement--or causes some type of turbulance --i dont know--but during certain times the car is a LITTLE cooler. People will probably roll their eyes about this. Dont care i like the way it looks also.
keep up the good monitoring---add oil pressures and rpm observed during those times
olddragger
The 2nd thing that became apparent was the lack of good airflow through the radiator and the oil coolers. Get the fan turned on and your steet coolant temps will never see 200 (within reason of course!) Oil temps--thats another story.
Oil needs to be at the 180-190 mark. Even though there is a lot of discussion concerning oil temps (many people on the track in the 8 and other type cars will go over 250F) I dont like to go over 230F even with syn in.
Therre are a lot of things that you can do to help with temps. If you are running screens BE SURE that the screens are actually touching the coolers---if they are not --then the airflow will be restricted. I dont run them anymore.
One you probably havent heard about---i recently cut the rotor symbol out of my front air dam--just added a support where it used to be---I cant prove it--but I swear my temp gauge runs about 5 degrees cooler now during in town--non congested driving. I really think it blocks more air movement--or causes some type of turbulance --i dont know--but during certain times the car is a LITTLE cooler. People will probably roll their eyes about this. Dont care i like the way it looks also.
keep up the good monitoring---add oil pressures and rpm observed during those times
olddragger
05-01-2007, 07:18 PM
#8
What pointy ears?
Thread Starter
Originally Posted by expo1
What do the colored diamonds represent?
The curves are just Bezier curve-fits to better visualize the data. I updated the plot ... should be a little clearer.
Edit: least-squares fit now
Last edited by elf; 05-31-2007 at 08:46 AM.
05-01-2007, 07:27 PM
#9
What pointy ears?
Thread Starter
Originally Posted by olddragger
...
One you probably havent heard about---i recently cut the rotor symbol out of my front air dam--just added a support where it used to be---I cant prove it--but I swear my temp gauge runs about 5 degrees cooler now during in town--non congested driving. I really think it blocks more air movement--or causes some type of turbulance --i dont know--but during certain times the car is a LITTLE cooler. People will probably roll their eyes about this. Dont care i like the way it looks also.
keep up the good monitoring---add oil pressures and rpm observed during those times
olddragger
One you probably havent heard about---i recently cut the rotor symbol out of my front air dam--just added a support where it used to be---I cant prove it--but I swear my temp gauge runs about 5 degrees cooler now during in town--non congested driving. I really think it blocks more air movement--or causes some type of turbulance --i dont know--but during certain times the car is a LITTLE cooler. People will probably roll their eyes about this. Dont care i like the way it looks also.
keep up the good monitoring---add oil pressures and rpm observed during those times
olddragger
Last edited by elf; 05-01-2007 at 07:35 PM.
05-01-2007, 10:28 PM
#11
What pointy ears?
Thread Starter
Originally Posted by Slick8
Going off topic, but how do the Nordskog gauges look in the dash? Do you have any pics?
05-17-2007, 09:43 PM
#13
What pointy ears?
Thread Starter
More data
Added a little data for 55 MPH and also added plots for engine oil temps at 55 MPH and 80 MPH; also engine coolant temps at those same speeds. Updates are in the first post of this thread. I'm constantly gathering data, so stay tuned
Last edited by elf; 05-17-2007 at 10:27 PM.
06-14-2007, 09:14 PM
#14
What pointy ears?
Thread Starter
Yet more data
I added some engine temps for ambient temperatures in the high 90s, low 100s (F) --- the plots in the first post reflect the changes. More to come ...
06-15-2007, 10:17 AM
#17
it would be really cool if vacumn readings were added also. I wonder????
This summer I plan on installing a oem header heat shield (not wrapping it), installing a heat shield on the intake and wrapping the airbox. I have the revi and cai. I also wonder if the coils could be mounted on the airbox. Possibily relocate the battery(have you seen how the bottom of the air box and the battery box blocks the airflow from the fans?).
Sorry for the thread hyjack--really good info man--keep it coming
olddragger
This summer I plan on installing a oem header heat shield (not wrapping it), installing a heat shield on the intake and wrapping the airbox. I have the revi and cai. I also wonder if the coils could be mounted on the airbox. Possibily relocate the battery(have you seen how the bottom of the air box and the battery box blocks the airflow from the fans?).
Sorry for the thread hyjack--really good info man--keep it coming
olddragger
06-15-2007, 06:34 PM
#18
Registered User
good post man--I have done a good bit of looking at engine temps over the past year or so. on the track and on the street. Biggest thing for me was switching from 5/20 oil to 5/30 because with the 20wgt the engine could not mantain factory recommended oil pressures. AND on the track i now run a 10/40. All synthetic---they DO run cooler.olddragger
(of course ,like you I know it does)
06-15-2007, 06:43 PM
#19
Administrator
iTrader: (7)
very cool info! I've been thinking about this a lot recently since I forsee plenty of 100+ degree days here while sitting in traffic on the fwy. 
06-15-2007, 10:23 PM
#21
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Join Date: Feb 2007
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Very interesting graphs. I like to see two more things at some point.................The oil temp difference with the RB screens and the H2O temps with the Mazsports cooling fan mod since I just installed it this evening.
06-16-2007, 01:18 AM
#24
Administrator
iTrader: (7)
do you think the RB screens could be blocking some airflow?