DocWalt

FWIW the continuous high RPM usage in the above videos from Pocono, I was seeing ~194 F coolant temps on the start line and it hit 221 F right at the finish line. ~70 second autocross run with 50% of it above 7500 RPM. Even with a crank under drive pulley it gets hot pretty quick. Settles down immediately as we coasted back into grid, but still...

TeamRX8

iTrader: (25)

because there are other issues as well

DocWalt

Care to elaborate?

yardy8301

Would also be interested in response. Hitting 210-220 on the crawl back to grid after a ~40second course with short downtime between runs. I just lowered the fan on temps slightly, not sure how low I should go there. I suspect much lower than I am already (200 and 208). What are the "other issues" to look for?

RE-Vision

I have the MazMart Ron Davis radiator, and run distilled with a sprinkle of FL22 - I have never had issues with the temps, even on really warm days. My fans are set to 194/200 and never run for very long.

TeamRX8

iTrader: (25)

The OE radiator is more than adequate for autox purposes. Never really was a fan of the off-the-shelf RD radiator, but I suppose they now allow a radiator swap in STX relative to specific allowance limitations.

There are two factors that go hand in hand wrt to rotary cooling; coolant and oil.

To that point, the OE oil coolers are more than adequate too.
.

DocWalt

FWIW I have low temp oil thermostats in the stock coolers and have straightened the oil cooler fins. I also spray the oil coolers and radiators between runs. Not allowed to modify the fender liners in STX or I'd open those up a bit. I know the next step is fancy AN lines and a remote oil cooler thermostat on the oil cooling side.

This past weekend at Finger Lakes Champ Tour the peak temp we saw was 217 F even on a ~60 second course in high ambient temps... but never the same range of RPM used at Pocono. I'm pretty sure I'm cavitating the water pump, even with the underdriven crank pulley. Waiting on the custom water pump pulley now...

I have the Koyo S2 radiator. I don't see any benefit over a stock radiator, my temps still kinda suck. They do immediately cool down and fans run for ~30 seconds in grid. Leave the start line at ~194F or so on every run.

DocWalt

Unrelated, still really happy with the Shaftworks USA coilovers. I think I'm going to go to a little stiffer rear springs instead of playing with swaybars as that will only make the already mediocre stock diff perform worse. OS Gikens are on a long wait right now

RE-Vision

It was 90ish at Crows a few weeks ago and after a sustained run the car was about 205, then back to 195 when I got to my grid spot. Say what you will about the OEM radiator, but it never let me get away with this.

DocWalt

I have no opinion on the Mazmart radiator. Just stating that the Koyo doesn't seem to be anything special.

RE-Vision

It definitely isn't. It's an OEM sized radiator with aluminum side tanks, which doesn't really add a whole lot. the Mazmart RD is definitely thicker (it didn't really fit all that well) and, from what I can tell, works as advertised. I have tracked and autocrossed this car without worrying about temperature for 2 years now.

DocWalt

The Koyo S2 rad is thicker than stock with a "better" core but it still doesn't seem to be the issue for me. Considering how damn quickly the temperature climbs during an autocross when it's all high RPM versus lower RPM...

The Ron Davis rad is really nice and likely what I'd do and mess with S1 fan shrouds in my S2 to make it work

DocWalt

Amy & I drove the RX-8, tons of fun and we got to ride with each other which was fantastic. Great learning experience. Sorry about the audio, the microphone fell out of its mounting clip and was buzzing around inside the trunk. Amy finished 2nd in STX and in the top quarter of PAX too! I ended up first in PAX which was nice because we were on the slower Nankangs.

Amy's fastest run:


My fastest run:

yardy8301

I am also loving the Redshift coilovers. 13k/10k with no rear bar and redrilled front bar feels ok to me, but that doesn't really mean much since I don't really know what anything else feels like. I do notice some inside wheel spin (at least that is what I think it is) on tight slow turns.

This weekends run:

TeamRX8

iTrader: (25)

what LSD does it have?

yardy8301

Stock LSD.

DocWalt

I have occasional inside rear wheelspin like the final off camber turn in my above videos. 12k/8k springs on my Shaftworks USA coilovers, but Hotchkis RX-8 bars front & rear, both on medium. I'm going to try different diff oil now that I realized what I put in has friction modifier, so I'm hopeful that helps.

Still super happy with the coilovers, there were HUGE ripply bumps in the loop portion of my above videos and the car was really composed and easy to drive. I'm at the soft end of spring rates which surely helps, but still impressed!

Planning on doing 12k/9k springs to help the steady state balance, as well as the offset knuckle bushings for a bit more front camber. Tire wear is fairly even but I want a bit more front end.

DocWalt

You have the same wheelspin issues that I have. Mostly fine but sometimes wheelspin like crazy.

Car looks really good, nice run.

TeamRX8

iTrader: (25)

yeah, that’s why.

.

DocWalt

FWIW putting proper non-LSD additive fluid in my diff helped the wheelspin issues a lot. No issues with diff chatter or anything.

I whipped up a Brettus style intake that stays STX/DSP legal. Fairly cheap and should really help get hot air out of the radiator. Unfortunately still dumps into the fairly enclosed series 2 engine bay, but it is what it is. The series 2 undertray really seems to limit airflow out of the engine bay.

RE-Vision

Let us know how that works out. I personally don't think anything works better than the OEM airbox. Still having cooling issues?

DocWalt

Will do. I did a TNiA in ~90 degree heat and saw the temp gauge moving, logs show 235 F peak when I did a cooldown lap. Only a few laps into a session too

RE-Vision

That's wild, I've had my car hit 210 on a hot day at Streets of Willow, but the minute you stop driving hard and cool down the temp goes back down rather rapidly. Something is definitely up there.

DocWalt

Cools down rapidly for me too. I can make the temps climb quickly on the street too by just cruising around in lower gears, hence my continued desire to try slowing down the water pump more. If it doesn't work... well I tried.

Hoping the intake helps a lot on track, not too concerned on the street or for autocross. Does make cool noises, but MAF readings don't seem quite as clean even at high RPM and I have an airflow straightener.

TeamRX8

iTrader: (25)

that intake configuration was around long before then