Rb25 Operating Temperatures

[nicr4wks]

Hi All,

I've been trying to find safe/normal operating temperatures for an RB25det, a good idle seems to be about 80c, but what is considered a safe temperature when you start pushing or tracking the car?

After just fitting a replacement engine to my 33 I've been watching the temps very carefully, my dash gauge never moves above 1/4 no matter how hot shit gets so I've been using a consult cable to read from the ecu, currently running water through the system as the engine has only been in for a couple of days and I'm checking for leaks etc. City driving sees 80-86c, I was at wot in 3rd for 15-20 secs heading up a steep hill right after a spirited drive and temps reached 98c, obviously water becomes fairly useless at this point so I just coasted down allowing it to cool.

Is +100c normal for an RB being driven hard? If so I guess I should switch to some coolant asap.

[R31Nismoid]

You talking stock radiator? I wouldn't be tracking with a stock one. I mean you can in a stockish car, but its not really ideal.

With a aftermarket radiator, my RB25 and RB26 both sit between 67-75 putting around. Only giving it an absolute gut full will see upwards of 80+

IMO invest in a radiator if you are see 98, thats up there.

[iseekool]

Hi All,

I've been trying to find safe/normal operating temperatures for an RB25det, a good idle seems to be about 80c, but what is considered a safe temperature when you start pushing or tracking the car?

After just fitting a replacement engine to my 33 I've been watching the temps very carefully, my dash gauge never moves above 1/4 no matter how hot shit gets so I've been using a consult cable to read from the ecu, currently running water through the system as the engine has only been in for a couple of days and I'm checking for leaks etc. City driving sees 80-86c, I was at wot in 3rd for 15-20 secs heading up a steep hill right after a spirited drive and temps reached 98c, obviously water becomes fairly useless at this point so I just coasted down allowing it to cool.

Is +100c normal for an RB being driven hard? If so I guess I should switch to some coolant asap.

I have an R34 - usually runs 85-89c - on hot days it runs 90-103c depending on load.

Hard driving on a moderate day is low 90s

I'm running Castrol 33% coolant.

My car is stock.

Edited April 1, 2011 by iseekool

[bubba]

Normal street driving on belter hot days, the highest I've seen in either car was 95deg, nothing to worry about.

The 32, on a 40+ day and a good 2 min skid, the highest I've seen is 105deg which was fkn hot but still didn't throw any coolant.

Coolant, under pressure, isn't going to boil until about 110deg. If you're seeing about 100deg or higher on the street or highway, then you've got issues that need addressed.

From my experience, RB's like to operate at about 80deg (RB20/25non-neo/26), they run a 76.5deg thermostat. The neos seem to want to run a bit hotter (probably due to emissions reasons) and they run an 82deg thermostat.

Edit: I also had way better results from a stock GTR radiator than the 50mm chinese alloy thing I used to have.

Edited April 1, 2011 by bubba

[jrm]

I have an R34 - usually runs 85-89c - on hot days it runs 90-103c depending on load.

Hard driving on a moderate day is low 90s

I'm running Castrol 33% coolant.

My car is stock.

It's worth noting that R34 have a much higher thermostat than the R33 (off the topic of my head I beleive it starts opening around 80-82C and fully open by 95C?). I believe these hotter running temperatures were done as part of the LEV modifications (ie: lower emissions) ..

My R34 sees similar temperature ranges as above on a stock radiator (using tectalloy 100 coolant), fresh thermostat, recently changed fluid, etc. Planning to put a bigger radiator in within the next few weeks. I will note I saw much higher temperatures (105+ on hot days stopped in traffic) when I had a nismo radiator cap fitted - not sure why that is.

[The Dan]

Coolant doesn't make your engine run cooler, all it does is increase the boiling point. In fact, due to Ethylene Glycol being an oil product, it actually reduces the thermal efficiency of water. Only products that reduce surface tension are going to reduce temps

[Tangles]

I boiled all the water/coolant at my last track day. Would have been 120degrees PLUS.

Hopefully my dedicated RB26 r32 sedan track car never sees boiling point, not a nice feeling wondering if youve ruined your engine.

If I didnt have a thick headgasket on my RB25 (stock bottom end, ported head, gt3076) Im sure it would have shagged the engine......

It could be your stock radiator is blocked with sludge. best to replace it with a thicker dual/triple core aluminium 'race' item. The one in my

RB26 is from ASI in melbourne @52mm thick, the RB25 radiator is a Koyo 40mm thick item

[nicr4wks]

Thanks for the replies guys.

I have an R34 - usually runs 85-89c - on hot days it runs 90-103c depending on load.

The NEO does run a bit warmer than the earlier 25's, my thoughs were inline with R31Nismoid and bubba, for a '96 RB25 I was expecting to see 80-90c but had never monitored it after a hard drive to know for sure.

Current radiator has had various mixtures of chemiweld and oil through it in a previous life, even though it's been flushed it's probably rooted. I guess I'll be looking at an aftermarket radiator for peace of mind

[lachlanw]

isnt rb25det 76 degrees and neo is 82 on the thermostat ?

i figure if it deviates much from your thermostat temperature you have issues you need to adress

[pipster11]

trident lists the 25 as 82 and the neo as 87

[JonnoHR31]

nissan thermostat for all RBs except 34s is 76.5C, but the thermostat is in the bottom hose (coolest point), temp sender is in the top hose, which is the hottest point of the system.

i see the same temps as nismoid, high 60s to low 70s, but thats not normal, seams to be a 31 thing.

[R31Nismoid]

I always thought it just to be a 31 thing with added space in engine bay and around the front of the car aiding airflow.

My GTR does as well though with a decent after market rad, which I found interesting and dispelled that one.

[Mayuri Krab]

Mine sits at ~82 during a normal day without A/C & will go up a couple of degrees when stuck in traffic.

In a 38C+ day with A/C on, it will go over 90C when stuck in traffic but will drop back down to about 85 when moving at decent speed again.

This is with a stock radiator, recently got the plastic top tank repaired & rad cap and thermostat replaced.

[BrynDETT]

so is it pretty much fact that smaller then standard engine bays have a direct effect on engine temperature?

[discopotato03]

Yes thats a given , if air won't flow too well through the engine bay then it won't flow too well through the radiator core .

A .

[rad100]

Just sitting there idling in my shed for 15mins my car (built 25 with stock rad) saw 82deg.

[drifter17a]

so what is the maximum water temp that is considered dangerous ? 110+

[Dose Pipe Sutututu]

Yeah