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.

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-oil_5w20-5w30-20w50.gif



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).

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-coolant_5w20-5w30-20w50.gif



Engine Oil Temps:
Oil temperatures at constant velocities of 55 and 80 MPH

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-oil_5w30.gif



Engine Coolant Temps:
Engine coolant temperature plot at 55 and 80 MPH

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-coolant_5w30.gif



Engine Temps at 80 MPH:
Engine oil and coolant temperature plot at constant velocity of 80 MPH

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-80_5w30.gif



Engine Temps at 55 MPH:
Engine oil and coolant temperature plot at 55 MPH

http://i126.photobucket.com/albums/p88/bucketelf/rx8_temp-55_5w30.gif

Interesting post, I'm putting in oil temp, water temp and oil gauges in the immediate future to keep an eye on my temps.

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.

There are some aftermarket oil coolers for this car. but I wonder how do they fit (is it perfect fit?) and how does it perform? (compare to stock)

Dunno, never heard of anyone that has an aftermarket one.

... 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.
Yeah, but wait til the heat of summer rolls around ... it hasn't hit 100+ F here yet :cool: Extrapolating the oil temp curve, 100F ambient will give me around 210F oil temp at 80 MPH :uhh:

What do the colored diamonds represent?

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

What do the colored diamonds represent?
The blue diamonds are the coolant data, the yellow crosses are the oil temp data.
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

...
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
Yeah, I read that post of yours ... quite an interesting mod. You're probably right in that you're getting a little better cooling since you've decreased the frontal area of that support --- I think :)

Going off topic, but how do the Nordskog gauges look in the dash? Do you have any pics?

Going off topic, but how do the Nordskog gauges look in the dash? Do you have any pics?
The pics are buried in the Racing Beat Gauge Pod Update thread ... http://www.rx8club.com/showpost.php?p=1658142&postcount=186

Results look pretty close to mine.

For some reason my car seems most peppy at 200 oil and 200 h2o. Could be just me though.

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 :)

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 ...

very nice. dont know how i just found it..

i would love to see the same tests without the rb screens...

food for thought..


beers :beer:

wow - how did I miss this .....
Well done - very interesting .

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

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

You are going to incur the wrath of the "experts"---what you say can't happen!
(of course ,like you I know it does)

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. :eek:

it looks like your thermostat is working ok, not much else to glean from that data

I never realized that the front bumper rotary symbol had a direct affect on thermostat operation, imagine that ...

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.

Yes, I agree ... it's always good to have information like that.

Thanks heaps elf!

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.

good point,,

i would be happy to lend my mazsport cooling mod if you what to test elf. the greater good..

beers :beer:

do you think the RB screens could be blocking some airflow?

do you think the RB screens could be blocking some airflow?

there have been a couple of ideas on this.. i have a set of hymee screens i have not put on yet..

beers :beer:

any screens block a certain amount of airflow. Think about it. It is material in front of other material.
very crude demostration--take a piece of screen ---place it between a regular fan(thats on) and a strip of paper you are holding in the airflow. watch what happens.
rotary symbol is attached to the thermostat --just like that 1981 Z-28 camaro automatic transmission that would not shift into high gear because the left turn signal light was burned out. Go figue.
Screens --are a judgement call---some people because of the enviroment they drive in really need them.
olddragger

any screens block a certain amount of airflow. Think about it. It is material in front of other material.
very crude demostration--take a piece of screen ---place it between a regular fan(thats on) and a strip of paper you are holding in the airflow. watch what happens.
rotary symbol is attached to the thermostat --just like that 1981 Z-28 camaro automatic transmission that would not shift into high gear because the left turn signal light was burned out. Go figue.
Screens --are a judgement call---some people because of the enviroment they drive in really need them.
olddragger

Yeah..............as far as the oil cooler screens go..........I guess one could argue that if you didn't have them your cooler fins are gonna get bent and therefore loose cooling efficiency. So the screens protect against that but at the expensive of airflow. I haven't noticed my screens damaged in any way(so far), but when I put screens on, I did spend about 45min straightening out the cooler fins first.
Tough to say which is really better in the long run. :scratchhe Guess I believe that the screens are best or I wouldn't have put them in, but I do know it's not an install and forget item. So......................... I'll be looking at them to clean or straighten IF I need to do so.

How much screens decrease the effectiveness really depends on the geometry and void area of the screens. I have some homemade screens that have a much bigger void area than the Racing Beat screens and are positioned a bit in front of the oil coolers. The screen is a bit filmsy and its main purpose is to prevent bugs and pebbles from bending my fins; I don't think it'd stop a decent sized stone, but it might slow down the stone enough to prevent it from puncturing the cooler. Still, I feel comfortable in saying that the screens do not decrease the cooling to the fins by an appreciable amount as the cooler itself is a much bigger obstacle to airflow than whatever the screen will be. I feel the pressure drop across the coolers are magnitudes bigger than that through the screen. I suppose I can run some simulations to offer partial validation of my hypothesis, but I've done airflow design quite a few times and so am comfortable with my judgement.

Interesting that the RB screens are right up against the fins whereas the Hymee screen covers the opening in the bumber .....
Which is better ? :dunno:

^^^id also like to know

^^^id also like to know

Looks like we'd have to find somebody with the ability to run the temps(like Elf) and then provide hin both Hymee and RB screens and ask him to run them. :uhh:
Would be interesting still to see how the Mazsport cooling fan mod does as well.
I put that in about two days ago and am going to write them and see if the damn thing is supposed to cycle about 4 seconds on and about the same amount off! Seems like an awful lot, although I haven't really gone on any drives yet. The above was just at idle! :banghead:

Interesting stuff. Whenever I've collected data with my scan tool my max water temp has been 199-200. I'd also be interested to see a comparision with the racingbeat flash.

nice data and thanks for contributing!

Great work elf. Thanks for sharing. Looking forward to your winter data, although I don't expect you'll be able to get it down to -30C (-22F) where I drive sometimes.

Question: I assume the oil flows from the pan, through the filter, and through the oil coolers before being delivered to the engine components. Where is your oil temperature sensor located? What about the coolant temperature sensor. Is it reflective of an inlet, outlet, or some internal temperature?

I'd like to see how the oil cooler/AC screens affect the temps too :) , but as OD stated, it's a judgement call to install screens because of ones driving environment. Before I installed the RB screens, I remember having to pluck out about eight or nine pea-sized pebbles from each of the oil coolers, and then having to spend about forty-five minutes or so straightening out the fins. The AC condenser fins fared a little better because of the small OEM screen. Still, I may do a "with/without screens" comparison anyway.

Great work elf. Thanks for sharing. Looking forward to your winter data, although I don't expect you'll be able to get it down to -30C (-22F) where I drive sometimes.

Question: I assume the oil flows from the pan, through the filter, and through the oil coolers before being delivered to the engine components. Where is your oil temperature sensor located? What about the coolant temperature sensor. Is it reflective of an inlet, outlet, or some internal temperature?
If I had started this little project in February of this year, I'd have data down to 12F at 55 and 80 MPH. I think -30C (-22F) may require a dog sled team or something :)

I'm using the RacingBeat coolant and oil sender adaptors, located in the heater hose and under the oil filter, respectively. I was using a set of AutoMeter mechanical gauges previously, and the electronic digital gauges I'm using now agree with what I was getting with the AutoMeter gauges. I suppose it would be ideal to could get the temp readings from the rotor housing, but this was a simple and doable (and available) solution for me to do.

Hopefully, other rotorheads with different brand gauges and installations will chime in to compare temps. Mine may very well be way off :uhh:

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. :eek:

Zaino Master, you don't even want to know what temps I see in those driving conditions (well, mid-90s so far). Maybe that's why Mazda decided to use a coolant temp gauge that doesn't move much.

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.
Yeah, the cooling fan mod is interesting. I may just put this on my to-do list.

Also, depending on the local police, remove your front license plate if you can. That frees up some airflow.

Yeah, the cooling fan mod is interesting. I may just put this on my to-do list.

it is a big big plus..

beers :beer:

Updated the plots (more data) and added a new one comparing 5w-30 and 20w-50 oils at 80 MPH.

Finally, it's hitting 110F or so around here. Not as bad as what you Phoenix, AZ folks are seeing --- I hear you guys are going to be (if not already) in the 115+ F range or so. I suppose I can head into Death Valley, CA to get some 120+ F readings :)

This is great infomation... one question for those who has the water and oil temp gauge, what is the peak that you set? 100 C or 102 C for water and 110 C for oil ?

dont set a peak--dont have a peak type gauge.
i would recommend that peaks are going to be dependant on your situation. on track i do something when oil temps hit 235-240F coolant at 220 F.
my cruising temps are different than on the grafts here. Great info by the way!
i cruise at 80 same rpm and mid 90 weather--- coolant temps are around 190 and oil temps 195 or so. that is with 5W30 RP oil.
my car is set up like this
1- coolant at a 65/35 ratio
2- no screens
3- even have removed the rotary shaped thing from the air damn--not for flow --just for looks--but i believe it did help flow.
4-- agency pulley--so water pump is underdriven--therefor doesnt cavatate as much
5- rb flash which turns the fan on at 180F --HIGHLY recommend--even makes the a/c better!
I no longer have cooling concerns.
Hell ---I IDLED in a parking lot(blacktop) for 35mins --ambient temp was 97F coolant temp got to 195 and oil temp about the same. AND i was running the a/c! The fan was working well.
olddragger

Olddragger, what guages are you running or what method do you use for your measurements?

these temps were with autometer mechanical gauges and I am runniing the rb adaptors.
Good point in that temps will vary from the location it comes from. On the 8 with the rb oil plate adaptor i think the temps are pretty close to true, on the coolant and rb adaptor (heater hose)--it is probably a little off from true--but not by much--it will not "show" as quick though.
olddragger

these temps were with autometer mechanical gauges and I am runniing the rb adaptors.
Good point in that temps will vary from the location it comes from. On the 8 with the rb oil plate adaptor i think the temps are pretty close to true, on the coolant and rb adaptor (heater hose)--it is probably a little off from true--but not by much--it will not "show" as quick though.
olddragger

Good instruments and locations.

I guess one of the only probs with the mechanical guages is not being able to datalog but if you have the time to check them that's great.

Updated the graphs in the first post to include data for 5W-20 viscosity oil. Wish it would've stayed hotter (+110F) here for just a few days more for me to get the higher ambient temp data --- oh well, maybe next year :dunno:

See everyone at SSX! :)

Xcellent work, very professional! Nice to have some factual data rather than anecdotal info about temps.... esp as you cover such a wide range of ambient conditions. It doesn't really appear that anything is amiss under any of the conditions you have tested, which is reassuring. Again thanks for the graphs...I don't know how I missed this earlier :)

ps I use the red digital Cyberdyne gauges and get similar readings from what I can see but of course I'm not recording everything as you have done. I use 10-30 oil and very nice to see the effect you show of different weight oil.

Bump.

Great thread, interesting how the data differs with the ambient temps. Going to 0W-40 I really didn't see any diff in oil pressures or temperatures. Am I reading something wrong? The coolant temps and oil temps seem high for cruising speeds. But I will have to wait until May or June to see.

Major bump

Good topic thou

Bump.

Great thread, interesting how the data differs with the ambient temps. Going to 0W-40 I really didn't see any diff in oil pressures or temperatures. Am I reading something wrong? The coolant temps and oil temps seem high for cruising speeds. But I will have to wait until May or June to see.

I have data for 10W40 oil but I haven't updated the graphs yet. Just a quick look at my data suggests that I will see little or no changes in oil temps through out the ambient temp range. Seems like the 20W50 oil has the most affect, especially at the lower ambient temps.

For me, the coolant and oil temps creep up at bit, then stabilizes after about 4-5 mins. of steading driving (at 80 MPH; never again will I drive at 55 MPH -- too slow LOL).

Wow. I'm running mobil1 0w-40 synthetic oil. 9krpmrx8 where did you send your oil? how much did you need to send? and how much to get it tested?

do not exclude the oil pan exposure to the ambient temps as a factor of cooling.
someone told me that recently ---i had never thought about it.

Wow. I'm running mobil1 0w-40 synthetic oil. 9krpmrx8 where did you send your oil? how much did you need to send? and how much to get it tested?

http://www.blackstone-labs.com/

Just request a free kit, they will send it to you with directions. It's about $22.00 to get it tested.