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What if i told you that one of the cars I logged (turbo) had reached 260F peak and ran several laps around that 240 mark .... and lived to tell the tale ?
What if i told you that one of the cars I logged (turbo) had reached 260F peak and ran several laps around that 240 mark .... and lived to tell the tale ?
not only that ..... but he must have put 30 liters of water into it during the day . I was sure he had blown it ...... Yet he still drives it daily now with no ill effects ... months after
I found I needed to physically hold the bottom foam in place or it just gets blown up and out of the way ..................
For now, it is glued to the bottom of the radiator with hi-temp RTV. I plan to keep an eye on it to make sure it stays there. If it doesn't, I'll explore more physical strategies. Perhaps the wifey can help with the physical stuff.
Originally Posted by Brettus
I have logged half a dozen rx8s at the track , most of them purpose built race cars . All of them have been running at around 105C and none of the owners thought there was any problem .
I dunno. That equates to 221F. I have hit 219F in the Texas heat without any problems. Of course, that peak temp is one of the things that helped me rationalize the cost of a more efficient replacement radiator...
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Last edited by Steve Dallas; 06-16-2015 at 09:17 PM.
Well mine just went in, along with a rebuilt motor
It was tight, actually I took out the AC condenser to make it easier - the ac lines were already disconnected elsewhere, but it would have been possible without doing that if I'd thought about it a bit instead of just pulling everything out the way.
I re-used most of the original foam, but looks like I have already lost one of the small pieces. I used double sided tape, so I guess I need to put a new piece in with something a bit stickier.
I also noticed a crack in the fan bracket when I was putting the undertray back on :-( Not sure how it happened, and I think it is fine, but be careful when getting the fan tray to fit back into the slots behind the bottom of the radiator.
Previously 210-230F was typical for me on track. I'm looking at a few of my logs. Intake is close to ambient since I am running at speed:
So, the difference is 134, 126, 133. I'll report back on temps once I have run the new setup on track. Will be a few weeks at least...
No noticeable issue running the coolant up to 230F for me, although I am sure it was not ideal for engine life. There was nothing untoward spotted in the tear down. I did start to lose a little coolant through the blow off once things got that hot though. As part of the replacement I also put in a new reservoir cap.
Looking forward to your data stvnscott. If you have, and can post intake temps we can do a direct comparison (assuming you are still on the stock intake).
Last edited by blu3dragon; 06-16-2015 at 01:23 PM.
Here is why I may have wasted my money on this radiator. This is a chart of data from almost exactly one year ago, when I was running the OEM radiator. Look at the recovery times achieved by the fans in grid and by the cool-down lap at the end of the session. I probably did not need to improve on recovery. The true average temp while on track is about 213 rather than the 208 listed on the chart. Obviously, I am very interested in my future running temps on the track with the new radiator. C'mon Koyo! Give me a true average temp of 208 to make me feel like I accomplished something! [At least I know I won't have plastic parts failing on me in the future.]
I do log my intake temps and am still running the stock intake with OEM filter. In this particular data set, min is 91.4, max is 131, and avg is 97.8. The delta is 124F. My max intake temp was reached while sitting in grid for an unusually long period of time. My min intake temp was reached on track. The average is pretty skewed all around as a result. Meanwhile, my min and max coolant temps were reached under almost opposite conditions.
Here is coolant temp juxtaposed against intake temp:
Oh, and tape will never hold that foam in place. You need high-temp glue of some sort with an assist from friction at the very least.
Last edited by Steve Dallas; 06-17-2015 at 07:23 PM.
Reason: gramm&rs and sp3llins
I'm not too worried about recovery temps. Not really sure how that helps, although if it offers better cooling then the recovery should be faster too.
What matters to me is peak temp while lapping at full pace, and I expect it will reduce that due to the greater surface area. I guess we will find out soon...
The intake temp delta comparison is only valid at speed. You can see a pretty constant delta in your chart once the temps have equalized. As soon as you slow down, then the ECT will drop as the system is no longer overloaded, and IAT will rise as the intake air speed slows so it has more time to heat up, and under hood temps rise as well. A better way to do this would be if you had an air temp sensor in front of the car, but without that I think the IAT is probably the most accurate measure we have.
Looks like your delta is around 120F. That's already better than my results above.
Another thing to keep in mind with cooling is that past a certain coolant temperature the car will start making less power, as the ECU starts to make less power in order to try to preserve the engine.
My bad. I had an old version of Torque running on my tablet. You don't have to download the extended PID packs anymore. Just install Torque Scan and run a deep PID scan, then go back to your logging PID list, and it should be there. Or at least that's how it worked on my phone with the latest version of Torque.
There is one bit of bad news though. Well, bad for the test, but otherwise good for the car and me.
The weather forecast called for sunny weather with a high of 95, which would have meant the 2:45ish PM conditions should have been about the same, with an ambient temp of 91ish. The high was actually 88, and it was overcast, so there is a 3 degree temp differential with different conditions at 2:45ish. Alas.
The changes I made to the car between June 21, 2014 and June 20, 2015 are limited to a BHR midpipe and this Koyo radiator. Everything else that might affect cooling stayed the same.
On to the charts.
Repeating the chart from 1 year ago for easy comparison.
Chart from yesterday.
You can see the temperature climb as I am sitting in grid. When the fans come on at 203F, the temp quickly falls. It takes a good amount of time to climb to 205F once I am on the track. Part of that is my warm-up lap, but I drive those pretty hard, so I attribute part of it to more efficient cooling. Min, max, and mean temps are all significantly lower. The true average track temp is the 208F I was hoping for. Coolant temps are only above 210F for a short period of the 20 minute session unlike before. Interestingly, recovery does not seem to be any different. Once I throw it up into 5th gear for 1.5 laps of cool-down, the temp drops very quickly to a level where I am very comfortable shutting off the car in the paddock.
Speaking of the paddock; on the previous chart, the starting temp is much higher, and the fans come on immediately to bring it down. I knew the temp would rise after shutting off the car--sometimes as much as 20F. So, I would try to bring it down as low as possible--yet it would still climb. Yesterday, however, once the temp was down, it pretty much stayed there. I have no explanation for that. I purposely did nothing different, and the sessions were timed the same way--almost exactly 1 hour apart.
But... Since the ambient temp was 3 degrees lower, portions of this chart need to be scaled up by some unknown amount to make a true direct comparison, so I can't really draw much of a conclusion as to whether this radiator is a worthwhile upgrade in terms of cooling capacity alone. Aww, who am I kidding? Or course I can! I'll just use a little confirmation bias and call this radiator a worthwhile reliability upgrade. My butt thermometer sez so.
Last edited by Steve Dallas; 06-21-2015 at 08:54 PM.
Yep, the issue is the engine running when the car isn't in motion; no cool air to the intake or engine bay, coolant temp increase, low volume flow through intake tube, stagnant hot air in engine bay
Really nice data, thank you for posting. Interesting too. Firstly that the ambient air temp tracks intake temp so closely. Good to see that, although I am not quite sure what to make of the fact that is also tracks so closely when the car is parked.
It does look like the coolant temps take longer to rise and stabilize when lapping, which is good, but the peak is only 3 degrees lower, which is the same as the difference in air temps... so, hard to say the radiator is helping, although at least I think we can say it is not making things worse.
I think we can assume there is a linear relationship between air temp and coolant temp, at least for small changes. Other variables exist though:
1. coolant/water ratio
2. wind speed & direction
3. humidity?
4. track and driving style
The effect of those is probably small to negligible, except perhaps the first if there was a big change.
The ambient air temp sensor location explains why it tracks closely with the intake air temp. It is located on the driver's side between the wheel well and the oil cooler. It is susceptible to picking up heat from the radiator, oil cooler, asphalt, engine compartment, etc.
I am not necessarily going to agree that there is a linear relationship between air and coolant temp. It is unlikely an entire system responds in linear fashion. However, even if I accept that premise and scale the entire chart up by 3 degrees, the car still stays under 210F much longer.
As I said before, I am not really willing to draw any conclusions about this radiator as a cooling upgrade for a NA car. I do like it for its all aluminum construction as a reliability upgrade.
I may be a glutton for punishment and hit the track again on July 14. If I do, I'll log some data and see what it does in some real Texas heat.
I'm not too worried about recovery temps. Not really sure how that helps, although if it offers better cooling then the recovery should be faster too.
Recovery matters when you are afforded varying distances for cool-down. Sometimes I get 1.5 laps. Sometimes I get 0.5 laps. At some tracks, I can jump onto the highway for some additional cool-down. At some tracks, that is not an option. The faster the system cools down, the better IMHO.
However, your overall point is well-noted. I just like to track all of the available variables. Sometimes, data shows surprising results.
06-15-2015, 09:06 PM
