High Water Temps- Tried almost everything.
 

i orginally was planning on building my car for drag racing. i figured with drag racing, id have <13 seconds of actual racing and 20 minutes of cooling off. with this in mind, i went with a HKS FMIC and Fluidyne Racing Radiator. well, this dream quickly died once i found road racing and autocrossing.

on the autocross, i have a hard minute of racing with maybe 5 minutes of time to cool off between runs. ive tried popping the hood and letting it cool off between runs, cranking the heat at the end of runs, cranking the heat through the runs, shutting the car off after runs and leaving the fans on. nothing seems to work. with the power fc, once the heat starts to creep, my car starts acting possesed; the rpms bounce between 800-3500 rmps with me out of the car. i've seen over 110*c after some runs. i lay off the acceleration right when i notice it, so dont think im beating on it at this temp, please. my motor is not worth seconds off my time. with road racing, it's worse cause i am out on the track for 20 minutes at a time. i find myself having to upshift to keep my car out of higher rpm's in an attempt to lower temperatures. still overheating.

i've tried water wetter, a greater water to coolant ratio, different coolants, nothing. i'm still getting high water temps.

my final attempt failed. i bought a cf N1 vented hood with anticipation of it helping. granted, Massachusetts has been in the 90*s+ pretty much everyday since i got the car back with the hood, i still hoped it would help. nothing. i keep it out of boost, crank the heat, upshift to keep lower rpm's, and the heat still rises. i'd say 98*c while trying everything to keep it at low rpm's. if i boost it, it reaches maybe 105*c but slowly comes down.

everyone obviously suggests a v-mount radiator and intercooler set up, but i know there's a way to make this work. i'd rather save up and go single and lose some heat that way, then spend @$2,000+- on a v-mount set up. i have the power fc and i havent really tweaked the fan settings.

HKS Fan Controller? maybe a performance thermostat? higher pressure radiator cap? any upgraded fans that we can get?

im looking into cutting a vent in the R1 front spoiler and making a metal duct that shoots right into the radiator, but im gonna see what else i can do first.

any suggestions would be greatly appreciated.

i'm not sure if my mods matter, but just in case:
FMIC, DP, intake, HF Cat, CB Ex., SS Pulley Kit, Radiator, AST, PFC, & PFC Commander.

Change your thermostat if you haven't yet.

^Yup. Get the OEM one from Ray. Also make sure you're fans are running on all 3 speeds.

Definitely change the thermostat first, and if that doesn't fix the problem, do something to get the fans going more often.

Dave

thanks guys, will do.
i'm sorry (im probably going to look like an ass for not knowing this), but whose Ray?

sidenote- rx7rage: that's a goregous picture of your car, and did you notice any real difference with the N1 hood?

should i go with the Mazda Genuine Thermostat for $20 or go with a SARD thermostat for $85. Ari and Chris at Rotary Performance say "To regulate the temperature of the engine, we’ve never found anything superior to the genunie Mazda thermostat." Mazda Genuine 13psi or 16psi radiator cap or SARD 1.3kg/cm2 cap?

Ray Crowe of Malloy Mazda, Manassas Va. 888.533.3400. Let him you know you're a member of the forum and he'll give you a good price. Go with the OEM t-stat and get a new gasket. Don't forget to install the new t-stat with the giggle pin at the 12 o'clock position.

BTW, I've got alot of family in Fitchburg and Lunenburg.

You are going to have to do some custom ducting around/under that FMIC to bring direct air to your radiator. Either that or switch it for a large SMIC.

1. The OEM thermostat isn't fully open until 204F (95C). At coolant temperatures lower than this, some of your coolant will be bypassing the radiator. If you're trying to keep the coolant temps below 95C, you should drill your thermostat or you'll be fighting an uphill battle.

2. Change your PFC settings so the fans turn on at a lower temperature first, or run with the parking lights on. The stock ECU doesn't turn the fans on until 230F (110C). With the parking lights on, the ECU will activate the fans around 210F (99C).

3. Also install a 16psi radiator cap. I just bought a Stant pressure cap, it was less than $10. I think that pressure caps (in combination with the fan's activation temps) are more important than most people on this forum had realized.

-s-

The problem is lack of ducting to the radiator and air escaping and bypassing the radiator instead of going through it. Most front mounts leave a large gap between the core support and the radiator. At speed a significant amount of air will flow out through this gap and bypass the radiator. This is why many fd's with a front mount will be ok around town but the temps go up on the highway. I fixed this problem by fabricating a custom cover to seal this gap and also ducting air under the intercooler right to the radiator. I was going to make a run of them, but there was a lack of interest to make it worth my while. To get air under the intercooler, I spaced down my front lip and sealed the bottom of the undertray to the radiator with foam weather stripping. I also put the foam on the sides of the radiator and between the radiator and the shield on top. This made sure that all the air had to go through the radiator. When road racing I was able to do 20 minute sessions without the temps exceeding 105C. Other relavant cooling mods were a mazdacomp radiator, stock new thermostat, 70% distilled water and 30% coolant, 2 bottles of redline water wetter. I ran a switch to enable me to turn the fans on anytime I wanted. The motor also had the coolant mod performed to the coolant passages in the rotor housings. I also had a 99 spec front bumper which has larger air openings. I later further cut out the center cection from what is is in the pic.

ill start with the thermostat and a new coolant cap and tweaking the PFC and see where that gets me. anything's better then this.

again, i really appreciate all the help.

I also noticed you're running aftermarket pullies. Do you have the full unorthodox set? I've seen problems when people run both a main pulley and water pump pulley. The water pump gets too underdriven. Check out my myspace too.

You're running the undertray right?

I'm running a Billion 71* Thermostat and lower fan settings on my PFC my temps
are always low 90s even on traffic on a hot day and stock radiator.Got a RE Amemiya SMIC though.But you should change the fan settings on your PFC
thats the easiest option if you have or can borrow a Datalogit.

i ordered a genuine mazda thermostat and GReddy radiator cap today from RX-7.com. i do have a fc datalogit, i just need to get the software for it. i do not have the factory undertray, but i will make a wtb thread for that. i have the unorthodox racing ss pulley kit. thanks guys.

Installing a factory undertray should have been one of the first things you did :).

Biggest difference for me wrt to cooling on the road race course? Removing my a/c system. I am also running a SMIC which helps quite a bit.

Definitely look at the pics that Ihor posted, that 'shark mouth' mod will really make a difference.

i know i know. like i said i tried the 99 spec, but no luck. my mechanic has one sitting in his basement that doesnt fit his v-mount intercooler or dual radiators, so im gonna get that. a lil dremmel action should take care of it. everything 'should' look good after these mods. i just need to save up and go single.

This is probably the best answer here. ducting helps alot. My car used to got hotter on the highway and ran fine around town. I added a radiator sheild on top, temps went down some, I added a scoop under the car bolted to the bottom of the radiator directing all air into it from under the car, and problem solved. car now runs cooler on the highway then around town (which is cooler than before) like it should be running. I am also changing thermostats now and adding waterwetter for good measure.

the reason a front mount ic messes with the radiator so badly is at higher speed it creates a void of slow moving air and the air passes around it. this is kinda like the efect of a truck bed. behind the cab a void of air that does not move sits and actually causes the air passing over the truck to run over the bed instead of acting like a parachute. if you lay down the rear door of the bed it causes a whirl wind that spreads to the back of the cab in the bed and actually slows the truck down because all the air running over the truck suddenly goes into the bed. with the radiator question, we want the air to whirl in instead of creating the void. ducting is the best thing to help this... that is if the rest of your cooling system works good.

thanks rt turbo.

Sorry to jack the thread but the temp here today was about 111 and my temp reads about 88-95*Celcius, is that pretty good?

hey no problem, its relevant. what set up do you have? how were you driving it? that sounds good.

88-95 is pretty good I think.

I just installed a Greddy 2 row, and the biggest affect on my water temps was running the undertray. The first day without the undertray, I had temps up to 111 cruising on the highway. After putting on the undertray, removing my AC, and sealing up the radiator, it usually sits at around 90-91 under normal driving and 94 or so on the highway. On cool days or at night, it consistently stays at around 88-89.

I found the same thing with a friend's FD many years ago---the undertray makes a big difference at highway speeds. The temp will keep creeping up until the fans turn on, and sometimes creep up past that temp even....

I have a Koyo aluminum radiator, no a/c, fans are on as soon as i turn the key, i have a 28x12x3 intercooler on the front with a oem front bumper. I need to do some kind of undertray to get a little more flow to the radiator and i would like to upgrade the front bumper to a cwest because it looks good and it would actually be functional allowing more air flow to the oil coolers and the radiator/ intercooler. Anyone have a pic of their undertray so i kinda know what im doing when i make it?

Like several people before have said "DUCTING, DUCTING".

I left mine off because I was trying different things. I must
have drained my raditor at least five times that week. Anyways,
my temps went way up on WOT on a up hill run ( I think it
was like 5 to 10 minutes of WOT uphill ). The power fc saw temps of
110c. This was at night with temps a cool 60f. The factory undertray
and ducting make a huge difference once your car is moving.

After you have your ducting and under tray fixed and your still
having problems go with duel oil coolers.

Yah, one of my major problems was having too high of a antifreeze %. I was running 50/50, when it's not really needed in this kinda summer weather. So I dropped it down to 80/20 with more water. It definitely helped.