DamonB

My car has a stock motor and radiator and the only engine mods are a downpipe and catback, still running the stock twins. I have added fences to the sides of the nose opening to force all air through the radiator and run an 80 percent water to 20 percent coolant mix.

Yesterday was 100+ degrees all day and I ran 8 runs at the autox. At the end of the day I started the car and let it idle for 10 mins with max a/c on while I hitched the tire trailer. Then drove the 25 miles home at 70mph with the a/c on max while pulling the tire trailer in 100+ degree heat. The car ran just over 205 degrees with highs about 210 when climbing hills. It didn't seem to wish to climb much higher than 210, even when pushed hard.

What are you aftermarket radiator guys seeing for engine temps?

Trexthe3rd

Fluidyne, variable temp fan mod, fan blade conversion.
Evens NPG+
185-190 at the t-stat housing with 95 ambient temp.

ZeroBanger

on a 100+ degree day climbing elevation 105+, on a cool day 85C. highway on a 100+ day 91C.

an aftermarket radiator does nothing to make your car run cooler, its just a reliability mod. Dont believe what the masses tell you.

DamonB

That's been my opinion but I wanted to see if I was wrong.

Forgot to add I run the Miata thermoswitch so my fans go to high automatically at 205 F degrees.

pomanferrari

iTrader: (1)

I don't know, empirical evidence seems to indicate that aftermarket rad like fluidyne does lower temps.

My normal temp with ambient at 95 degrees is around 200 on hwy no boost, 220-230 in traffic. Turned on fan earlier via Datalogit and got about 10 degrees lower.

With the Fluidyne it has never risen above 210 no matter how hard I flog it. This is w/o a good seal like the stock rad.

BTW the fluidyne is very heavy, almost three times the stock radiator weight. It has about twice the fluid capacity as the stock.

pluto

With this kind of heat, I see about mid 90's to about 102-103C when cruising with the a/c blasting. For some reason it seams to get warmer when maintaining speed on the highway at like 80 mph plus. I have a front mount, mazzdacomp radiator, no ast, and about 80/20 water to coolant.

DamonB

At 95 degrees outside with no trailer hitched to the car and the a/c on I can run 75+mph all day long and never hit over 200. Adding the load of the trailer and a passenger in 100+ degrees after flogging the car all day and still only hitting 205-210 empirically shows me that the stock radiator is just fine in controlling temps.

KevinK2

True for street use, not true for big track events. Even properly ducted, stock rad was not as good as mazdacomp rad. Fluidyne is even better (more front area vs mazdacomp, as well as thickness).

adam c

iTrader: (2)

My fluidyne radiator has a much larger capacity than the stock radiator. Than means more water is being cooled, which means the engine gets cooler water. Therefore, the engine MUST run cooler. That being said, the stock radiator with good fan controls is good enough for almost every situation. Examples of where it might not be good enough:

Hard driving on hills during hot days.
Road racing.
When it fails due to poor quality.

The last reason was enough for me.

1stand3rd

Put me in with the group that says an aftermarket radiator will not allow a car to run cooler. It will just allow you a longer duration of appropriate operating temps during extreme conditions.

I look at it this way...say you have a gallon of water in a pot on the stove that you want to bring to a boil. A 1 gallon pot won't take as long to bring to a boil as a 2 gallon pot. Eventually, they both come to a boil.

DamonB

That has been true for me too. Running on a road course constantly under boost raises my temps significantly higher (read as: slow down and cool the car). Unfortunately I have not run a roadcourse in real heat yet so I can't say how bad the problem is. I seriously doubt the stock radiator will let me run hard for much time if it's 100 degrees out.

Rated R1

DamnB this have been my observation with the Koyo. I run about the same temps as I did with the stock radiator, however I could lower the temps much faster with my fan mod. I have also found that running the car with the AC on keeps the water temps much cooler since it kicks the fans on. I was getting up to about 210 on the highway yesterday on the way home from an autox. This was in 90 degree weather in heavy traffic with no AC. Cutting on the fans my temps would quickly drop to the 185-190 degree range.

DamonB

True for your experiment, but not for a radiator. The radiator is constantly shedding the heat of the coolant into the airstream. As long as it does that efficiently enough, water capacity doesn't matter. That's why a bigger radiator doesn't necessarily lower temps even though it's bigger and holds more water. The radiator has to be more efficient to lower coolant temps.

1stand3rd

But using the same heat source and the same pot, doesn't this hold true? Lets assumue 2 different sized radiators in excellent condition. Eventually, wouldn't you reach the same operating temps?

Shinobi-X

I have the Koyo radiator as well, and share the same experiences.

DamonB

For pots, yes.

No. The difference between radiators and pots is that pots are not good heat exchangers and radiators are. A radiator is constantly releasing the heat of the coolant into the airstream and so controlling the temperature of the coolant. The pot has no way of shedding heat from the water inside it. If the radiator had no air passing through it then it would be horribly inefficient, as the radiator itself would just heat up along with the coolant. To make a radiator more efficent you can force more air through it, increase the frontal area of the radiator or increase the ratio of fin and tube volume.

As long as the radiator can shed the heat of the coolant quicker than the engine can heat it, then the coolant temp will stay stable.

RCCAZ 1

iTrader: (10)

The issue that no one has addressed yet is the engine's ability to flow coolant through the rotor housings. Jim Meder from Racing Beat and others claim that the inherent problem with the 13B REW is it's inability to adequately flow enough coolant through the engine block. Extra capacity helps, and yes, aftermarket rads DO help when it comes to adding more capacity and handling post shutdown system pressure, i.e., long-term reliability, but the real cooling culprit with Gen 3s is system FLOW.

1stand3rd

OK, I can understand your point on the ability of the radiator to shed heat. Maybe using pots is a poor comparison. I was simply (incorrectly?) assuming that only volume was the sole variable that has an impact on temperature.

RCCAZ 1

iTrader: (10)

The other thing I forgot to mention is the benefit of sealing the sides of your radiator/condensor shroud in the frontal area of the car. After sealing mine up I witnessed nearly a 10C drop in temperatures at highway operating speeds, which is HUGE! Also, if you haven't done so in awhile, it's definitely worth your while to get out your rubber mallet and pic tool and clean out the AC condensor. You won't believe how much grime and small debis will drop out of that sucker!!

GoodfellaFD3S

iTrader: (213)

Ihor, get off of Steve's account, you silly Ukrainian

On a 100 degree Texas summer day, I see between 85 and 90 while cruising, and creep up to maybe 94 during hard driving. I've seen temps as high as 112 on the road course, but that was after discovering that someone who shall not be named filled my rad with 100% coolant

GoodfellaFD3S

iTrader: (213)

I've found this helps, too

RCCAZ 1

iTrader: (10)

Yea, removing the condensor SHOULD help ALOT. I'm just not interested in purchasing an air conditioned full-body suit for cruising around Phoenix, and those salt stains would just ruin my nice R1 seats

DamonB

That would support the idea that on a hardcore race car the size of the radiator is fine since coolant flow is the limiting issue. Seems it has been said that Petit always raced with stock plastic radiators. I think my coolant temps on road courses are more related to the stock water pump pulley making the pump cavitate at high rpm. I find a big and instant difference in coolant temp between shifting at 7500 rpm and shifting at 6500 rpm. I plan to get an underdrive pulley for the water pump and run it on my daily driver only for track days.

scratchjunkie

i have a PWR radiator and i see 210f daily during city driving no matter how warm or hot it is outside. When outside temps are 100+ the lowest i see while cruising is 195f. The up hill drives do make my temps rise pretty quick, but on the downhill it really drops back down like a rock. I have also not noticed any difference from my stock rad temps to my aftermarket one. not trying to steal the thread or anything, but is it possible in 100+ degree weather having a temp gauge sensor drilled into the filler neck can become heat soaked?

RCCAZ 1

iTrader: (10)

Good point, and one that most people fail to realize. IMO, on street applications in extreme operating conditions (like summer driving conditions in Phoenix), the water pump underdrive pulley will cause your car to run warmer, which may be more trouble than the benefits from reduced cavitation and drag. Just my 0.2!!