RedDragonRX8

I went to an autox for the first time today and was thoroughly enjoying it. towards the end of the day i was waiting in line and noticed my car was steaming at idle. I looked at my gauge, noticed the water temp was at 3/4 the way, turned off engine, opened hood and noticed the coolant was boiling in the reservoir. I let it cool down and got more coolant. It started fine and didnt overheat again. Should I be worried.

Charles R. Hill

iTrader: (7)

The RX-8 has a notoriously under-engineered cooling system, especially if you live in the Sun Belt. The first thing you can do is a system flush and replace your coolant with a 70/30 mix of distilled water/coolant. I try to stay away from additional modifiers like Water Wetter and such, but some swear by them.

mysql

- You can run distilled water + water wetter, and get rid of antifreeze, that will increase your cooling capacity.

- You can get the accessport or mazsport cooling fan mod and lower the temp that the radiator fans kick on.

- You can upgrade your radiator to a larger one from BHR.

- Finally, you can replace the radiator fans with ones that flow more air.

Charles R. Hill

iTrader: (7)

I tend to beileve that my rad renders the other equipment mods (except maybe a RE-medy water pump from Mazmart for the trackers) unnecessary. With the better airflow the BHR rad has across it the fans cool just fine and to have them turn on earlier isn't needed as the thermostat is what regulates the engine temp. The ideal thing would be the coolant mix you describe(my personal opinions aside on that matter), a BHR rad, and a 180-degree thermostat.

RedDragonRX8

thanks for the quick replies!!!

I was worried i might of killed my engine or something. I have never had an overheat problem until now but it is starting to get warmer here. What do u think of a hood scoop?

mysql

vented hood is not going to help you as much as you think.

Charles R. Hill

iTrader: (7)

There are many discussions about airflow under the hood and all that. The reason I am using the core in the BHR rad that I am is because it allows for a LOT more air to flow across it. I hate to sound like I am pressing you and simply selling my stuff but I came out with it for a reason. There are several who are using it in the hotter climates, even while boosted, and they have measured improvements. Ask 09 Factor and marsredr100 what they think.

nycgps

iTrader: (1)

CRH knows his stuff, Get his rad and ur overheating problem will go away

RedDragonRX8

ill have to wait a couple of months to gather some money but it does sound like a good idea. does the radiator cost 575 with shipping?

nycgps

iTrader: (1)

Im telling you, For the price, its TOTALLY worth it.

Charles R. Hill

iTrader: (7)

$550, shipped. Thanks for asking.

Spin9k

The car should not just overheat for no reason. Sitting at idle in a line of cars isn't any stress on the engine. The fans should deal with that no problem. The typical reason it might not however is that the system cannot maintain pressure...and the coolant will then boil at a lower temp. This can happen if you radiator cap is not holding pressure, or isn't on tight, or you have any kind of coolant leak anywhere in the system, maybe a hose fitting bad, or something like that. The leak will relieve the normal pressure build up as the temp goes up, and you'll get boilover without the pressure in the system. Otherwise, did the fans come on? If not perhaps a fan relay or fuse is gone. Perhaps have you done any mods where you worked on the coolant system at all?

All the mods mentioned would be nice, but just from what you describe, they shouldn't be needed.

RedDragonRX8

oops my bad. I meant to say i had just finished my second run at the end of the day on the course and parked where i needed to be in line to run again. i was in first gear the entire day. it was a novice training course.

Razz1

1st gear only..

Jasonawojo

iTrader: (2)

1st gear rocks ^ - I always dread the shift to 2nd when autocrossing, takes away that instant punch/spin

I haven't had any overheats yet, but from watching my scangauge I'd have to say that the highest coolant temps occur after each run idling, due to lack of airflow over the various coolers.

nycgps

iTrader: (1)

1st gear ? ....

MazsportScott

The single most effective product you can buy to lower the operating temps of the RX-8 is the Mazsport Cooling Fan Mod. In situations such as autocrossing, there is VERY little airflow across the radiator due to vehicle speed. This mod will eliminate the airflow problem regardless of vehicle speed.

Mazsport.net

MazdaManiac

iTrader: (3)

Auto-X is a funny beast, especially if you live where you live.
I spend a fair amount of time in second, but my power delivery will be a bit different than yours.

The single most effective thing you can do for your cooling system is to make sure it is all properly set up for life in New Mexico.

The coolant mix should be almost entirely distilled water and the system should be completely flushed every year. You would be surprised what comes out of the drain and the engine drain (there are two places to drain your coolant - make sure you use both).
You should use either a surfactant/lubricant like Water Wetter or about 2 pints of anti-freeze along with that distilled water.
Switching up to a 1.1 BAR cap is also advised, but be sure your hoses are all in good shape because the slightly increased pressure will stress them a bit harder.

A fan mod (either a simple switch or a controller like Scott is talking about) will make your fans come on earlier, but it won't stop the heat from going into the system. The OE fans are pretty decent - it takes a lot to flow more air then they are designed to do - but simply having them on full when there is no moisture in the air and the ambient temperature is above 90° will do very little.
Desert conditions are tough on the cooling system.

Razz1

Only for warming up the engine. Other than that its wide open.

MazdaManiac

iTrader: (3)

Hmm, kinda.

Hmm, sorta.

The OE thermostat is an interesting beast. It is a "180°F" unit, but that is just its cracking temperature.
It doesn't achieve full lift (as minimal as it is) until 205°F.

Calling that effective temperature regulation in a motor that can swing 20°F in two or three seconds is a pretty optimistic outlook.

MazdaManiac

iTrader: (3)

Well, the minimum operating temp is pretty well set by it, anyway.
Once that thermostat starts to open, all kinds of things come into play.
When I install my new water pump next week, I'll be trying some experiments with the t-stat.

Easy_E1

iTrader: (2)

The thermostat when it is wide open also acts as a flow metering system. It will regulate the amount of coolant flow through the radiator and maintain proper engine temps. Without this restriction the faster the coolant travels through the radiator the less cooling effect the radiator has. No time to cool the coolant. The coolant gets back to the engine with out being cooled sufficiently and therefore the coolant is reduced in it's capacity to remove more heat out of the engine and continues to get hotter. Causing a boil over.
That's why thermostats are there, not just for warm up.
This is a big problem with a high revving engine like the Renesis.
That is a good reason to have a radiator with more than sufficient core capacity to cool the fast moving coolant. That's why the BHR radiator works so well.

nycgps

iTrader: (1)

If u track a lot

BHR's Radiator + Mazmart's improved water pump = a Must !

I have the Pump and Aftermarket Rad. I think Im ok for now

RedDragonRX8

thanks for all of your advice!!!!!

I think i will save up and just get all the cooling applications mentioned.

the BHR's Radiator,
mazmart improved water pump,
Mazsport Cooling Fan Mod


i think the cooling system is worth 900 bucks. Since I dont have that ill just buy piece by piece. time for a second job

ken-x8

The thermostat controls the temperature until it opens all the way. Above that, the system finds its own equilibrium. Until the electric fans come on

Idling is a tough cooling condition because there's no air flow - which is where fans come in.

FWIW, if you want to quantify the benefit of a different radiator or coolant (or grill, etc.), there is a standard way of doing it. You block the thermostat in the full open position. (Generally means you're going to sacrifice one.) Then you drive at a fixed speed, measuring both the coolant temperature and the air temp flowing into the front of the car. Do that for each configuration, always running at the same speed. Difference between inlet and coolant temp tells you which is working best.

Ken