MazdaManiac

iTrader: (3)

The "break-over" point is about 96° - 98°F.
Under that, the motor will stay relatively cool.
Over that, it will overheat.
I don't know why, but this has been borne out again and again on a bunch of different RX-8s with different setups.

Removing the t-stat is, indeed, a bad idea. You can replace it with a restrictor disk, but it will only matter up to that magical ambient 98° or so.

The fan mod will only work below that temp as well.

BTW - the OE gauge starts moving at 231°F.

sammytcl

iTrader: (1)

i would like to know how much the bhr radiator is going to help with and without sealing the side and bottom gaps between the radiator & the shrould.

kinchu007

iTrader: (1)

Thanks for the correction MM...I've edited my previous post...my number was off, but I think my logic is correct...once the fans are moving at full speed that's as much as the cooling system can do...whether that starts at a lower temp (a-la cooling fan controller mod) or not doesn't much matter at the track...it matters more on the street where heat soak won't happen as often and so the fan controller mod will keep temps lower on average even though the car's cooling capacity has not been increased in any way, it's just being utilized sooner (at a lower temp).

MazdaManiac

iTrader: (3)

If you have all of the original foam (and your undertray is in original condition), it is completely sealed.

olddragger

iTrader: (3)

what adds to the weirdness is that in Ga(higher humidity) we have over 100F days(105F last yr) and we really did not have any bad cooling issues. Strange.
OD

MazdaManiac

iTrader: (3)

As noted earlier, humidity is tremendously effective at cooling the motor.
Water has a much higher latent heat than air.
That's why your water/meth works!

sammytcl

iTrader: (1)

I think this is why koyo (or some aftermarket radiators) is worse than stock in most cases, as most people/shops that I know did not put the original foam from the stock radiator to the aftermarket one.

My coolant temp peaked at 219F on a 18 mins run, and the ambient temp was 86F.
skyse3p's coolant temp peaked at over 230F on the same run session, and he has 1.3 bar radiator cap and mazsport cooling fan mod.

MazdaManiac

iTrader: (3)

I'll be doing a track day on August 16th. Its in the early morning, but ambient temps will be in the 110°F range by the time I do my last session.
I'll grab data.

olddragger

iTrader: (3)

Water=truth
I now skip august track days!
OD

MazdaManiac

iTrader: (3)

If I skipped all the "too hot" track days, I'd only run from October until March!

sammytcl

iTrader: (1)

I wish we can all go to the track (e.g. Laguna Sega) one day all together and have fund!!

kinchu007

iTrader: (1)

Sure we can...we're all getting to know each other better...this is not a far-fetched idea at all.

sammytcl

iTrader: (1)

which track are you going? how far is it from los angeles? maybe i will join you!!

kinchu007

iTrader: (1)

sammy, let's do Cali Speedway on the 26th of July...cheap autocross $80...SpeedVentures

sammytcl

iTrader: (1)

for some reason, i don't like autocross. sorry.

kinchu007

iTrader: (1)

I've never done it...would be my first time...I'll be at Buttonwillow August 8 or 9 not sure which yet.

kinchu007

iTrader: (1)

I just wanted to capture this so we have a record of it before it become impossible to find (will also try calling Buttonwillow next week to get their take on amb. temps and track temps...not sure if they provide this data).



Looks like the 104F trusty digital readout was totally wrong.

kinchu007

iTrader: (1)

So I just got back from Buttonwillow running 13CW this time...it was hot, hot, hot and I have some updates.

First of all, I got the water pump in there before the radiator (I'll update my opening post to reflect this).

Also I sealed the radiator gaps with foam.

And....it looks like they both worked wonders!

I didn't overheat one time, stayed under 225F!

Just in case you're wondering I DID NOT change my driving style by shifting earlier or by avoiding high RPM engine braking/throttle coasting (or whatever you call it)...I drove the same way, no adjustments. Looks like the water pump works and sealing the radiator gaps works, so that's good news! I honestly think you can stop here and safely summer track the car with the stock radiator, but I'm still going to go forward with the BHR rad.


Here's a pic of the max engine temp (much lower than the previous 240.8F)...




...and a pic of the weather data (only 2 degrees colder than teh previous 96F)...




...and finally a pic of my best time (Filip Craciun @ 2:17.2)...




...and here's a pic of the HOFF!




I still came out on top of my buddy's 135i even though he got Potenza RE01-Rs and Cool *****'s track pads.

My buddy's stock S2000 with Ferrodo pads was able to get a 2:22.8, which is very impressive for his first time tracking the car.

Linky: http://picasaweb.google.com/filip.cr...09Buttonwillow

olddragger

iTrader: (3)

i am now convinced that those of us that have to drive on days with +95F ambient(track and street) need a secondary radiator and a 180F thermostat(which I can now do.) My car is MUCH cooler now and I didnt really have any cooling issues before--i was just to close to the edge at times( like grid lock and backed up drive throughs).
OD

racewithroar

Hey Guys,

For those of you that track quite often - you should seriously consider replacing the stock fans with a single, larger fan.

What happens is at high speed the stock fans are actually restrict more air than they help to pass through. Getting a single fan mounted to one side of the radiator or the other will leave part of the radiator open for free flowing air at speed.

Plus, there are single fans out there that push more air than the stock ones. Look into SPAL fans.


As for removing the thermostat, it can be done if you block off the radiator bypass, either by fitting a sheet of metal over it and welding (or JB welding, which I saw in another thread), or by tapping it and putting in a 1/2" Pipe Thread plug. The second option allows removal during winter months if so desired. Also, you need to leave the sealing ring in place between the lower and upper portions of the housing.


I cringe when I see these track temperatures - our Alarm is set for 200 degrees, and we bring the cars if they hit 215, which is rare, thankfully.

-- Adam

OnRails

You mean 215 water temp or oil temp? I've seen 225 on the water temp many times on hot days at the track. You think this is way too high? Should we be looking to do a cool off lap when things get above 215?

Jedi54

iTrader: (7)

kinchu: great thread. Glald to see the water pump and Rad are helping you out.

racewithroar

Water Temp. Once it gets up to 215 you should probably definitely start thinking about a lap or two to give the car some time to cool down. If it keeps going up on your cool down lap, bring it in. Another thing to be careful about is following other cars too closely for too long. Try not to stay right up on people's rear bumpers.

We have seen rotor housings start to get warped at a water temp above 225 degrees. When that happens the motors will still run fine but we have seen a decrease in longevity of the motors. 240 is very dangerous. 260 is catastrophic.

Our oil temps on the other hand generally run anywhere from 10 degrees cooler to 5 degrees hotter than the water temp.


This is in motors with Ceramic Apex seals, and we run custom radiators and Setrab oil coolers. We get as much out from between the radiator and motor that we can and have a custom front end with ducting for the radiator and oil coolers.


Our temps probably aren't realistic goals on cars also run on the street with all of the creature comforts and without other engine bay modifications. But they do need to be better than what everyone is saying they are getting up to.

kinchu007

iTrader: (1)

Hi Adam,

The idea behind the BHR radiator is to space the fins apart a little more so the stock fans can pull more air through.

I do see your point about having one side open altogether.

You say your alarm is at 200F...that sounds awesome...can you please list all your cooling mods? I'm sure that would be more useful to all of us than avoiding summer track days altogether

-Fil

racewithroar

Sure:

Custom Water Reservoir, mounted in the space b/w the Passenger front wheel arch and the firewall.

Custom Front Bumper Assembly w/ Radiator + Oil Cooler Ducting

ReMedy Water Pump

Modified Thermostat Housing

Complete A/N Water Lines and Oil lines using Aeroquip Startlite Hose

Setrab oil Coolers

Custom 3" Dual pass radiator.

Spal Extreme High Performance Fan, turned on by a dashboard switch by the driver.

Remote HP1 Oil filter is mounted to the crossmember, behind the radiator.

And on top of that - removal of everything that isn't necessary. Our engine bays have much more space than stock.


-- Adam