sammytcl

iTrader: (1)

We had a few rx8s running this past weekend at Street of Willow. The ambient temp was around 80+ F. Here are the mods on cooling system on the 3 rx8s we are comparing:

sammytcl - turbo at 8psi, 8 gal 100 octane mixed with 5 gal 91 octane, koyo rad, mazsport cooling fan relay, mazmart Re-medy water pump, mazdaspeed 1.3kpa radiator cap, 4 quat racing coolant mixed with 1 gal water & 1 quat antifreez, vented hood, relocated battery and removed intake tray & box

skyse3p - na, 91 octane, stock rad, mazsport cooling fan, stock coolant, greddy 1.3kpa radiator cap

mazdaexe - na, 91 octane, koyo rad & aftermarket coolant, stop radiator cap

After 7-8 laps of total around 13-15 minutes of wot, all 3 of us reached 230F in coolant temp.

Here are some video showing my coolant temp vs rpm vs speed in real time, and the three videos were lap 2, lap 4, and lap 7 within the same session:

Video 1
http://www.youtube.com/watch?v=4g_M3LneGLg

Video 2
http://videos.streetfire.net/video/S...rbo_161090.htm

Video 3
http://www.youtube.com/watch?v=RG02H5UFLxE

Flashwing

Since I am stuck at work (Evil green screen on vidoes) I can't see the video so I'll have to wait until I get home.

Track data with your specific mods and those of others on the track is something of interest to me. There has been some research into how effective the Koyo radiator is in removing heat from the motor. I've had at least one local RX8 owner swap back to a stock radiator and experienced a DROP in temperature over the Koyo.

Any possible Oil temperature data?

Since I have not had the chance to see any major track time since I installed my gauges and radiator i've not been able to provide any worthwhile data.

Any additional information would be great!

sammytcl

iTrader: (1)

my oil temp reached 240F max.

here is my theory on koyo rad:

if you just put a koyo rad on a stock car with stock battery location, stock intake tray in place, and stock hood, you will most likely see a higher water temp over stock rad, due to more heat being dissipated by the koyo but trapped inside the engine compartment and eventually heats up the engine event more.

the only way to prove it is by doing the following comparison on the same car, same ambient temp and same running conditions:

1. record water temp reading on stock rad
2. record water temp reading on stock rad with battery relocated, intake tray & box removed, and install a vented hood
3. record water temp reading on koyo rad with battery relocated, intake tray & box removed, and install a vented hood

I might be wrong.

Flashwing

No that type of data gathering does sound correct. I appreciate your opinion as I've had the Koyo in my Rx8 for about a year now and even survived the hot Phoenix summer with no issues.

Currently I'm also sporting a vented hood and a race battery so there's more open space and venting than a stock car. So far those items have helped cooling wise.

I'm looking forward to watching the video!

Red Devil

How is your intercooler mounted, and what are its dimensions?

mysql

You can emulate the koyo radiator by blocking off half of your stock radiator with some plywood.

TeamRX8

iTrader: (25)

racing coolant?

sammytcl

iTrader: (1)

It is in the original greddy kit location, but my whole front grill is drilled out, and the lower half of the reinforcement was cut. The entire intercooler is getting fresh air.

MazdaManiac

iTrader: (3)

I recently switched back to the stock rad from a Koyo and saw my average coolant temps drop nearly 20°F.

sammytcl

iTrader: (1)

jeff, do you have your battery and intake tray still in the stock location? what is your average coolant temp before and after the koyo? my average coolant temp on a 80+ day street driving is around ~185-195 on local, and 181-186 on freeway.

Jedi54

iTrader: (7)

subscribing.

What's racing coolant?

Schimmle

Subscribed. Just ignore me. Nothing to see here. Hey look. Its the personification of utopia on the wall behind you!

sammytcl

iTrader: (1)

Fortec Racing Coolant:

http://members.jcom.home.ne.jp/fortec/list3.htm

sammytcl

iTrader: (1)

one more piece of information:

during the 3rd session, the ambient temp was high 90F, skyse3p and mazdaexe both ran for around 7-8 laps.

mazdaexe ran around 4 laps, and coolant temp reach 240F max!

skyse3p ran around 8 laps, and his coolant temp reach 230F max.

i was not running on that session as my brake cracked, so no comparison between na vs turbo / koyo vs stock.

sky and steven, correct me if i am wrong about the data.

MazdaManiac

iTrader: (3)

No. Battery is in the trunk and the airbox and tray are gone.
I have an aluminum shroud that projects the fan out into the engine bay with only a fairly aerodynamic deflector to keep the rad air off of the intake tube.

I would see 205°F just tooling around and 217° - 225° on the highway at 95°F ambient.
Now I have 185° just cruising and 190° - 205° on the highway.
Today, its nearly 100° in my area and I can cruise on the highway at 90 MPH with the temps holding steady at 208° with the A/C on.
With the Koyo, that was simply not possible as the temps would immediately climb into overheating and shut the A/C off at 230°+.
Nothing could abate that other than opening the windows, cranking the heat and slowing down to less than 70 MPH in 6th.

I'm running 90/10 mix of distilled and Prestone with 1 bottle of WW.

Razz1

Sorry I only checked mine once and it was at 190 degrees after that session.

Only time the fans came on was when i left the track early on the last session and didn't do a cool down.

I believe all of you have the stock front bumper.

I have the large opening up front on the RE bumper.

gr8rx

could it be that a lot of the heat issues occur from the placement of the stock fans, all the hot air that they pull off the radiator is pulled right into the engine bay. I would think that mounting the radiator towards the engine instead of away, and put the fans underneath expelling the hot air towards the road surface would be much more efficient

LionZoo

Sorry Sammy, for some reason I didn't quite understand completely what you were saying on Saturday night, or else I'd have told you this then, but as of now I have to type it out. Maybe it was just that I was more sick Saturday night, so my brain wasn't working completely...

Anyway, your theory about the Koyos needing extra flow to be effective does not quite measure up to thermodynamics. This is because if the Koyo were rejecting extra heat, it would produce a lower coolant temperature or at the very very least the same coolant temperatures. This is because though the extra heat rejection might be choked by lack of proper airflow through the engine bay, it would not produce higher temperatures since the net heat rejection rate of the system would not be lower by installing a more efficient radiator and so the coolant temperature, the source of the heat energy being rejected, would not increase.

xsnipersgox

there is a possibility that the koyos radiator has a much higher surface area to dissipate heat, however, in the pursuit of maximum surface area, they have choke the velocity of the air going through it to the point of having a negative effect? just a thought.

sammytcl

iTrader: (1)

like i said before, i might be wrong. i am too lazy to swap back the stock radiator to prove anything, instead i am going to proceed with the v-mount to see what will happen.

MazdaManiac

iTrader: (3)

That's the best way to do it.
At some point (maybe when I have some other reason to dismantle my engine bay), I'm going to do the same.

Mazmart

iTrader: (12)

This is an excellent thread. The more proper real world data gathered, the better it will be for the community.

Paul.

olddragger

iTrader: (3)

also keep in mind here that their track is a relatively low speed track. So fans become more of an issue say than on a track in which you have a lot of time over 70mph. Very good data. Yall have the same front clips?
Great vids by the way---love the intergration ---shows how smooth the rx8 is on the track.
Charles Hill and I (and many others) will be on track at roebling this coming w/e to flog his intercooler for the Pettit system. We will post the data to share---keep it coming!!
Anyway you can show the intake air temps?
olddragger

costello

If the coolant temps get up into the 230F range and then you pull off, the fan will be on correct? (190F for fans right?)

I'm running a stock car without any gauges, but I don't recall my fans coming on that often at the last Sebring event. I know they work since they do come on driving around town. Temps were in the low to mid 80s at the event. Yeah, not a great way to keep track of temps, but I figured if the fans aren't coming on then things aren't getting too hot. Plus I do some cooldown for half a lap or so and the Mazdaspeed front end seems to have a bigger opening in the front.

Sebring has some long straights and it's more humid in Florida. Does higher humidity help in cooling?

What type and viscosity oil were you guys running?

MazdaManiac

iTrader: (3)

207°F for the first fan and 214°F for the second.
That is one of big the problems with the stock cooling setup.

I turn mine on at 185°F and 195°F with the AccessPORT.


Immensely. Water has a much higher specific heat than air.
That's one of the problems of living in the desert. The ultra-low humidity makes the airflow issue significant.