James Crisp

So next weekend I'm taking my 8 for some spirited sideways driving for the first time, I'm just trying to find out, what should be my coolant temperature limits, and oil pressure limits to where I need to abandon the run?

My reading so far has led me to the understanding coolant reaching 110 Celsius is pretty catastrophic for a rotary, so I'm figuring at the point of reaching 105, I abandon the run and let it cool (if I ever do reach the point), are my numbers correct?

and for oil pressure, is there a minimum/maximum limit that if I exceed I should abandon?

Jedi54

iTrader: (7)

Thread moved to RX-8 racing sub-forum in hopes some of our more seasoned track junkies can chime in.
You are correct though, for city driving 110° C (230°F) is definitely in the danger zone in terms of coolant temperatures. Speaking of which, how are you measuring the temperatures?

James Crisp

Thanks for moving it I'm still too new to post elsewhere.

I'm using Torque Pro and an OBD reader. I plan to put guages in, in the not too distant future.

Loki

iTrader: (1)

Same question for oil pressure, how are you measuring it?
It's a bit of a weird question, oil at speed should be around 80psi, and it's regulated there (I'm assuming you're not tracking under 3000rpm). The only way to exceed or underrun that is a hole in the engine or failure of the oil pressure reg... in either case it's too late to abandon the run, but it should also never happen nor can you do anything about it?

James Crisp

by the looks of it I can't actually, Torque doesn't seem to be able to monitor oil pressure for my 8, it doesn't see the data point.

I wasn't sure whether with high temperatures whether pressure would become an issue, buy if that isn't a major problem i won't worry about it as much.

TeamRX8

iTrader: (25)

the dummy oil gauge on the dash is actually a minimum oil pressure monitor that will limit engine performance if it’s super low. What’s commonly referred to here as “limp mode”. Otherwise unless the engine has aftermarket oil system mods it’s generally not possible to overpressure the oil system. If anything it’s too low from the factory. Higher oil pressure generally benefits a rotary engine more than a reciprocating engine even though there’s no camshaft, valvetrain, etc.

You’re maybe overthinking it some. High engine coolant and oil temps should be your main concern.

James Crisp

Oh I can guarantee you I'm probably overthinking it.

Hence my asking for advice for what I really need to be monitoring, I know temps are a major concern, due to the lack of airflow in drifting, am I in the right ballpark to back off if I hit 105 Celsius, or should I be higher or lower?

I there anything else I need to be monitoring, I'm running 10w40 (I'm in the UK and ambient temp is looking at be around 20 celcius for the event), going to have fresh gear, engine and diff oil for the event.

Federico Zylberglajt

I run 20w50 and the car runs significantly cooler than with 10w40. You may loose some HP but i've done 10 consecutive laps at Suzuka without stopping and water temps were around 95c and oil around 105c. I do have the biggest Koyo radiator they have for the RX-8, dual factory oil coolers. Radiator is fully sealed.
This is with ambient temps of 28c.
Oil does a lot more cooling in a rotary than in a piston engine.

Snox801

Yep agree with what’s said keep an eye on coolant temp and you should be fine.
these guys will steer you right.

zli944

@James Crisp Curious what your temps ended up being at your event.

I ran a track day with ambient around 36 C and coolant temps were hitting 110 C and for a bit of the lap, even higher. Definitely not something I want to do again but the car did survive, probably from dumb luck.

blu3dragon

iTrader: (1)

That is hot, but normal for those temps on track in my experience. The challenge is figuring out how to reduce temps, because you are right in that you don't want to run hard for long at those temps.
There's quite a bit of temp data in this thread: https://www.rx8club.com/series-ii-af...r-48mm-245281/

James Crisp

Sorry for the delayed response, mine is a slightly different situation to the average track day as I spend alot of time at high RPM with little airflow, I usually got to around 105 and i'd ease off, a few times I pushed it to 110, but by the time I started to hit those temperatures we were usually on the final lap of the course anyway, we only do about 2/3 minutes out on track at any one time.

The car didn't seem to mind those temperatures, it was happy until I blew the slave cylinder on the clutch which was completely unrelated it'd been playing up for a while.

I only just got around to stripping it down yesterday to remove the slave cylinder as i'd had real life things to deal with, but I hope to get it out again soon.