demon

I've recently installed some Defi gauges in my 8 and have been observing water temperature with some interest in regular driving. Typically my water temperature on the freeway is in the ~70 celsius range (158F). When sitting in traffic however (no AC) I've seen temperatures as high as 95C (203F) which seems awfully high versus the temperature with constant airflow.

This leads me to believe that the fans are inadequate - clearly cooling is effective when airflow is high (freeway) but not enough air seems to be flowing through the radiator in traffic situations. Does anyone have any data on the CFM of the stock fans or any other experiences?

Cynic10508

Are there any aftermarket solutions such as Flex-a-lite that work on the RX-8? I guess they work for people who really want to replace everything but I wonder how effective they really are especially in stop-and-go (or should it be go-then-stop) city driving.

PUR NRG

Before you decide where you want to go it helps to figure out where you are. What does the factory consider normal operating temp ranges for the car, at speed and during idle? What is the overall max and min temp and at what point does the OEM needle get into red?

A quick google reveals the average boiling point for pressurized radiators is around 123C.
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Kitchen Measures

demon

That's pretty much what I am getting at - without having a FSM at hand I don't know any of this info. I would love to know the suggested "safe" operating temperatures of the car. All I can compare to is other vehicles I have owned which have always operated in the low 70C range in most conditions - I don't remember what my FD ran as it was many years ago.

I don't really care about the OEM gauges - my experience with Mazda gauges is less than stellar. It seems the stock RX8 oil pressure gauge is basically an on/off switch as discussed elswhere on this forum, and who even knows what the range for the water temperature gauge is. If it's anything like the FD it's "ok" and "blown engine".

therm8

I believe you are correct. My temp needle never moves past 2 tics to the left of center. But I can hear the fan running occasionally, which means the coolant is at least 185F. I hate dumbed down gauges and the stupid average car owner that makes Mazda feel they are necessary.

PUR NRG

That belief is unfounded without any baseline data, and asking about stock CFM airflow seems meaningless in that context. CFM only has relevance if you want to find a fan with higher throughput.

The only time you can say a fan is clearly inadequate is if radiator temps continue to rise during idle, eventually boiling the fluid. That simply doesn't happen with modern cars. The fact it levels off and remains constant indicates a balance is reached. Again, you have to know the intended operating range and compare that to known boiling points to see if the margin for safety is adequate. Asking about CFM rates is getting ahead of yourself.
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Weed

demon

Agreed, but I still am not comfortable with the car running so much hotter at standstill than at freeway speeds. Having said that, this car is mostly for track use than a daily driver so it's ultimately not a huge concern - I thought it might lead to an interesting discussion though.

PUR NRG

I didn't ask about the range of the OEM temp gauge. I asked what is the temp at redline. There is a difference.

Modern radiator temp gauges are designed with average (ie. idiot) drivers in mind. Therefore the needle will stay relatively motionless during normal operating temps so drivers aren't needlessly worried. The means the only useful info that gauge provides is whether the temp is too cold (at or near blue zone) or too hot (at or near red zone).

That's why I asked what the temp is when the needle's at red. Simply knowing the normal operating temp range isn't enough--it's also useful to know at what point does the manufacturer consider the temp high enough to be a critical danger. The difference between the two indicates your safety margin.
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HERBAL VAPORIZER

PUR NRG

I would think the opposite--track cars heat up a lot more than daily drivers and the ability to cool down after you get off the track is critical. Even after a cool-down lap you don't simply drive into the paddock and shut the engine off.
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Ipad Accessories

rotarenvy

I've noticed the same things with my defi water temp gauge.
85 C is the temp when on the highway and 95 C is stop go, but if you drive the car briskly you will see temps of 105 deg C and above at idle. on the race track temps are at 110 deg C for 5 lap sprints but are stable. these temps are in the return pipe just before the thermostat.

I'm wondering what would be considered dangerous temps? I was told by some FD guys that above 115 deg C would cause damage. if I'm seeing 110 C after the radiator how hot is it near the combustion chamber?

the other thing I'm seeing is that the thermostat opens a long time after the std gauge says it is at 'normal operating temperature'. it seems to open round 75 C and then temps stabilise at 85 C. on cold days this can be up to 10min at 3000rpm. idling would take much longer.

rotarenvy

what can you do in the pits to cool the car down if the fans arn't up to the task? pop the bonnet and cross your fingers?

still at 110 C the std gauge hasn't moved from 'normal' so I guess it is normal.

PUR NRG

I didn't say the fans weren't up to the task, simply that you don't immediately shut the engine off. I've tracked the car at Laguna Seca in hot weather w/o problems simply by letting it idle for five minutes after coming into the paddock.
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NEXIUM SETTLEMENT UPDATE

ZoomZoomH

iTrader: (1)

what I did when I had my FC, after a track session, coming off a cooldown lap into the pits, I would actually drive SLOWLY around the pit area for a lap, and then park the car, pop the hood/bonnet, KEEP THE ENGINE RUNNING for about 2-3 minutes, and then shut down, but still keep the hood up until the next session comes around.

demon

Again agreed, however stop-and-go traffic conditions and long periods stopped were primarily what I was referring to.

If the "redline" of the stock water temp gauge is anything like the FD, we are in alot of trouble. I would like to know what the number is though - it sounds like it is above 110C which seems suspect.

Sounds like you have your probe in the same place - I am using the Blitz Cooling Performer (basically a replacement silicone radiator hose with a bung for a sensor) coming into the thermostat. Are you using the stock radiator? What coolant and mix are you using?

r0tor

iTrader: (1)

Has anyone noticed that one of the flashes seemed to have readjusted the amount of time the fan is actually running?

I remember on hot days right when i got the car 2 years ago the fan would stay on for a good 5-10 minutes after the car was shut down. Now, I'm left wondering if the fan is ever on because i almost never hear it even running (and it now never runs after the car is shut down)... but the factory temp guage doesn't say i'm overheating

olddragger

iTrader: (3)

one of the reasons that the fans dont need to run long after engine shut down maybe is a one point I remember there was speculation about the fans blowing a LOT of hot air past the coil packs and some people where having problems with those packs and having to replace them.
olddragger

Razz1

All the more reason to get a vented hood.

After more research if you really find traffic temps to be a problem then why not drill holes in between the diamond mesh of the front grill?

Keep in touch with those Vegas guys, as traffic is bad during rush hour.

Maybe the Arizona guys can help us out too.

I know here in Calf the traffic sucks and it gets preety hot near the end of the year.

rotarenvy

std radiator with Mazda .au ~30% coolant mix. I have the sensor in a custom adapter on the stock hose like the knightsport one. I had a look at some workshop manuals after the operation and it looks like there is a metal joiner further towards the radiator that I should have taped and used :o

idling the car in the pits is next to useless you have 110 C on the track and 103 C idling where as slow driving will have it down to 85 C. if you have gone for a highway drive you actually increase your engine temps if you idle down :D

takahashi

WRONG!

Vented hood does nothing to water and oil temp. https://www.rx8club.com/australia-new-zealand-forum-37/who-said-vented-hood-rice-prove-side-56k-beware-63019/

Time to get a new radiator

Another gadget you can get is a fan controller but I now doubt it has any effects on the temp during operations.

rotarenvy

the fan controller would be great for in the pits. my hot fan dosn't seem to come on

takahashi

Well. Billion make one of those. As I said the fan will not make a BIG difference in the water temp, since I think the radiator is getting enough air and at its limit on the track.
http://www.billion-inc.co.jp/vfc_series/vfc2/index.html
Application list
http://www.billion-inc.co.jp/data/vfc_matching.html

It WILL make the engine cool faster while not running though. :o

takahashi

BTW it is my favourite radiator



Forget bigger single layer rubbish.

This is 3 layer BASS radiator and it s only $1500! :o BTW that is from FEED 112000 yen

PUR NRG

Mazda Motorsports sells an aftermarket radiator for $600. It's supposed to offer 3x stock cooling performance. Unfortunately I don' t know who makes it. Yet another reason to autocross--it allows you to buy all sorts of goodies at way cheaper prices.
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Honda crf series specifications

demon

I have one on order, I'll keep you updated on its performance. I'm also going to experiment with different coolant/water/waterwetter combinations and see what the ultimate effect is.

olddragger

iTrader: (3)

interesting keep us informed
olddragger