Hi Guys,

Just a quick update with the latest track results! I spoke with Tim after the SCCA event at VIR 2 weekends ago and we were again quite pleased with the the results! The car ran in the low-mid 190's all weekend and only once did it get to 200f briefly in traffic. :icon_tup: Btw, these results are with stock OE Mazda pulleys, we would see further improvement if we were allowed to run our own underdrive set but rules are rules.

I would also like to say congratulations to Tim for setting the pole position time and on the back to back win's Saturday and Sunday! Well done sir!

Nice ! I'm of the opinion that by keeping temps at that level , a little extra power is available which may have helped with that great result.

Exactly right Brett! The lower temps also make the engine produce a bit more torque as well. This gives the car a bit stronger launch coming out of the corner which typically leads to a bit more speed down the straights. :rock:

I just did a weekend at Spring Mountain, no data to compare it to, but ambient temps were in the high 70s - didn't see over 210. I think with the stock t-stat, it's building heat and opening at 203... the temp rises to about 210 as the t-stat opens and circulates through the radiator, and then the temps drop back down to the 190-200 range before going back up. It seems to cycle through on and off with the t-stat opening and closing...

no issues at all -

PCS

Thanks for the feedback pcs, glad to hear it's working well! I believe we can get those temps down even further if you like =-) Send me a pm if your interested.

I'm good for now. Next step, if needed, will be better oil cooling - I don't anticipate actually needing it though. we'll see - i'll try to get it out in the heat to do some tests...

went out in 107* and 103* this weekend...

on the 107* day, temps still creeped up to 230* - not sure there is much that can be done about it. Ended up cruising the track in 4th & 5th instead of 3rd & 4th - almost like a self imposed 6500rpm redline to avoid going past 225...

on the 103* day though - for the most part was able to go WOT, and at the section of the track where the temps ended up being the highest, never really got past 221-225 except for one lap where it spiked to 228 - it was a little higher than I wanted, but in that heat, I thought the radiator did very well.

For comparison, in 90-95* temps, I was getting up to 230 after a few laps (i didn't notice it until my stock gauge moved and I got an OBD reader last year). temps are under that this year in higher ambients... and I'm driving the same track 2-3 seconds faster than last year.

seems to work well, but heat is still an issue. next step may be better oil cooling or following up on the hood vent thread from escapedan...

Glad to hear about the improvements and improved lap times PCS, well done! I am confident we can get your temps significantly lower, what track were you running at this past weekend?

Buttonwillow - looking at better oil cooling and hood vent as a possibility in the future, but for starters, I've decided not to go out in 100+ temps anymore, hahaha

Well that's one solution I suppose pcs, lol. Kidding aside, the issue however is not the radiator, track day turbocharged cars running this radiator are not having the same results, they are running cooler. Let me know, I'm here to help if you want to resolve it!

Let me know pcs, Scott

interesting - the temps recover pretty well, but i wonder how much of that has to do with turbo'd cars probably having more access to air than the limited amount I have coming from the front. I've been looking into vents or opening up the front to promote airflow through the radiator, just haven't committed to it yet.

"track day turbo'd cars" is pretty vague. A turbo car should have more cooling issues due to the higher engine loads and the intercooler blocking the path to the radiator. But of course you also have to look at the whole specific setup when making comparisons.

What are you running for coolant and what mix? Stock fans?

Airflow makes a huge difference. When I vented the hood it was a huge difference in how heat soaked it got.

I think the oil coolers make a big difference as well....the oil cooling also keeps the system more nimble and able to react faster

Altering your fan on/off Temps makes a difference and depending on speed can really help a lot

My car with a similar Rad. (Ron Davis) vented hood and 2 big Setrab oil coolers and a custom from Air intake for the rad at 550 rwhp turbo runs at 86-90 degrees as long as ambient is below 90. Above that it tends to stay close to ambient give or take a degree. That's running 30 minute sessions. If it's hot things can get marginally warmer after that...but I think the warmest I have gotten with this setup is 105 degrees and only for a few minutes before I gave it a bit of a rest and it was back down again.

I also run coolers on the tranny and diff....they get super hot without them as well.

Are you mixing up degrees C and degrees F in that last post or am I going mad ?

I apologize for drifting off topic, but could you elaborate as to the hood venting, or perhaps share a picture? There has been some debate about where to vent the hood for maximum effectiveness. It sounds like you have it in the right place.

Oops...threw in the 90F ambient temp # ....sorry should be 32C 😊

What about when stuck in a traffic jam on a 95F+ day? That seems to be the biggest issue with these cars.

stop & go at 95* put me at about 195-208, with an occasional 210 popping in there. To me that seemed like the thermostat was partially opened, temps rose, thermostat fully opened, temps rose a little more before coming down, then t-stat partially closed... and then the cycle repeated...

The fans turn on after 206F. I think that's what happened. Did you have the AC on? The AC forces to fans to go on high at that temp.

In 95F after an hour of traffic, my car hits 215F :sad: Once it was 99F and the car hit 220F and didn't go down until I turned off the AC. I have a stock radiator btw. This is the battle most stock RX-8 owners (who monitor their coolant temps) fight. People who don't monitor them have no idea how close they get to overheating :hahano:

Keep in mind track and driver make a difference as well. I probably run 10F cooler at Sonoma where there is a lot less full throttle than Laguna Seca. I also run hotter now that I am faster than I was a year or two back.

Also, fans are key on the street, but at speed (on the track) they don't help.

I need to see if there is something I can do for my next track day as I'm expecting air temps to be 100F. I'm thinking opening up the vents behind the oil coolers is my next step. Hopefully that helps my front brake temps as well since they are too high right now.

I could try an experiment with hood venting if a certain other member on here is willing ;-)

That seems more likely to be fans cycling. Tstat should open at around 183F. Personally I would not worry about 210 or even 220F in stop and go.

That's all fan efficiency and turn on temperature. If you have the fans turn on early then you can easily keep it at ambient temps give or take a degree or 2

The problem with the car stock is the idiotically high temps the fans turn on :(

i thought the t-stat opened fully at 203?

Ya...but it starts about 180...so it has quite a bit of flow before full open..

You can also get a Mazmart one that opens earlier...doesn't do much though unless you change the fans

Because I have the AC on, the fans are on high speed all the time. At these ambient temps, when the AC is in auto, it's almost on max. That forces the fans to go into high speed. They literally turn on when I start the car. My car hits 220F while the fans are on high speed, and they've been on high speed since the coolant temp was 170F. The real problem is that the fans don't spin fast enough. I still can't believe Mazda went ahead with these fans while knowing that they're incapable of keeping the temps below 220F, and that these engines don't tolerate heat very well... :dunno:

dannobre - sent you a PM regarding the vents, can you share any of the details regarding yours / research on pressure zones / etc? Been looking for useful data, but haven't been able to find much on the 8, though there seems to be quite a bit on the miata...

I am using a Carbon Vented hood from Seibon, Don't have any airflow data I am afraid...just observations from the hood

I was going to use a smoke grenade in front of the grill....but though better of it ;)

aahh i see. Which did you opt for? TS? TSII? TT?

TS i think ..been a long time since I bought that 😊

so I lied about not going out in heat anymore. Looks like I'll be out this coming weekend in 100+ temps again, ugh. Saturday's forecast calls for 112???

I added some copper pipe insulation on the top and bottom of the radiator put air through the radiator, left the sides so that some airflow gets through, and am working on getting the Singular hood louvers installed to create more of a pressure differential from the front to rear of the radiator.

Fingers crossed!

Do let us know the coolant temps once you get the hood louvers installed. Always wondered if it really made a difference...

Hi pcs, I'm curious, which track are you headed to this weekend?

Also, I would like to help you get your temps further reduced, would you email me a few underhood pic's of your current setup when you have a moment.

Thanks pcs, look forward to helping, Scott

was going back through this thread and missed this. Was running FL-22 originally, but when I changed the radiator, didn't remember to use FL-22 and ended up with about 75% distilled 25% green coolant (not sure which one anymore).

Stock fans, yes.

Well I have finally bitten the bullet and ordered one of these. Will post some experience, data, etc when I get it running.

^thanks

Thank you Dragon, we appreciate your business! Sorry if I missed it, are you running the stock fans, pulleys and thermostat currently?

Everything stock right now, but AC removed and it is an s2 motor, so s2 water pump.

Is it an S2 model or did you do a motor swap into an S1?

S2 motor in an S1 chassis... https://www.rx8club.com/rx-8-racing-...3/#post4780096

Datapoint with the stock (series 1) radiator: https://www.rx8club.com/rx-8-racing-...3/#post4780452

Hey Guys, I wanted to let you know we just finished up another build run of these and have three units not spoken for as of yet! Thank you for your business and support, Scott

Hi guys,

Spring will be here before you know it and we have been getting emails from guys who are prepping their cars for the better weather and a new season of motoring! Emails regarding our dual pass radiator have been coming in and we are currently in a build run, if you have been putting off picking one up there's a couple spot's left in this next run.

The last one in stock is being shipped out to Ric Shaw Racing in Australia for a full on S2 track car build he's putting together. Thanks Ric! :wavey:

You know who you have to call 😎

I have yet to install mine and would be happy to take some measurements of it if needed.

You already know this of course, but it's BIG :) Troubleshooting this right now...

I just inferred you got the dimensions from Scott already, so you know the size of it. Troubleshoot was a bad term. I just mean it's get dirty install time. i went with the performance fan at the same time and have a tip from Scott just in case we need a touch more clearance to the cross member.

EDIT: it's in, just need to foam.

We currently have a just a few of these remaining in stock and ready to ship!

If you have any questions guys don't hesitate to ask!

Thank you, Scott

Anyone have photos or diagram on how to connect the fan assembly as it does not have the standard connectors?

https://cimg5.ibsrv.net/gimg/www.rx8...8ee2220e48.jpg

Perfect fit

Finally got around to wrestling this bad boy in with the stock fans and intake yesterday. Just need to find a pipe to connect the reservoir tank now and hopefully all set.

Big thanks to escapedan because I'm pretty sure I would have given up and ordered some new parts without the pics he posted earlier in this thread.

A few tips:
1. If you don't have an assistant, get one. Otherwise be prepared for a good workout as you lift this thing in and out of the car 6 or 7 times.
2. In place of an assistant, an axle stand can be used to support the bottom of the radiator.
3. You are going to need to trim the oem fan shroud down some. Start with the right hand (looking from the back) edge and then a few other edge pieces to get it as flush to the radiator as possible.
4. You will need to trim some of the fan shroud to get the upper coolant pipe on. I recommend doing that now so you don't forget and then have to take the thing out one more time just when you thought you were almost done (guess what I did?)
5. It might be possible to do without completely removing the passenger side fan connector leg that I did. Instead, try shaving it down with an angle grinder, leaving most of it in place. I did this on the 2nd one. I didn't remove any from the passenger side, but I did shave some down a bit.
6. You will also need to notch the left and right edges of the fan shroud to accommodate oil cooler pipes and the front of the fuse box.
7. I don't drive the car any more than I have to between track events, so I'm not too worried about losing the pipe through which the fans pull air through the ecu box. I guess I will find out how well it and the small battery I have get on with the heat when the car is stationary.

Assuming it all works when I get the final pipe on, I'll be testing at LS next week :-D

https://cimg1.ibsrv.net/gimg/www.rx8...7116d8b71e.jpg

Hacktastic radiator install