Nismo Thermostat For Rb25det Neo

[satanic]

Hi all,

Just purchased a Nismo Thermostat off the forums... came off a R34GTR and is rated to 62 degrees...

I've had a ask-around and have received varied opinions on what these things do to your car; from what I gather they:

1) Make for more complete burning?

2) Make your car run colder?

3) Make warm up times longer on a cold morning?

4) Good for track; crap for street?

* I know absolutely nothing about the thermostats etc so yeah

What I want to know is whether or not the PROS outweigh the CONS and whether I should be putting thing on my car (R34GTT). I also want to know if it is one of those things that you put on and get your car tuned with it, or one of those things that can just come on / off the car and not affect the tune.

Thanks in advance

Stan

[RB SANDY]

Interested in the post

[paulr33]

a similar side note we witnessed an r34 gtt radiator explode due to excessive water pressure + heat. it was later found the owner had an aftermarket apexi radiator cat, which was likely to be the catalyst. it held the pressure in, whereas the stock one would have just popped instead of holding it in. well at least thats how i think it went

so aftermarket is not always good

[Beer Baron]

all it does is open at a lower temp than the stock one. the stock one i believe opens at 72C. this will only really be usefull if you have cooling issues atm. if you dont and your car is holding a steady 75-80C water temp then I wouldn't bother. as it opens sooner your water will take a little longer to reach 75c. It wont affect perfromance directly at all. wont affect tune at all so nothing to worry about there. wont affect power output at all.

[satanic]

At the moment my car is runnning with the water temp at 85-90degrees... this is during driving (tame and solid)

Is this reccomended as it's at peak 10 degrees higher than what you have quoted BB.

Paul; do you mean radiator cap? What's a radiator cat?

[discopotato03]

If it worries you Id be looking at the cooling system itself ie radiator/std thermostat/viscous fan hub . If there is a cooling system capacity problem the lower temp thermostat probably won't change that , it'll just take a little longer to get there . Understand that once the thermostat is fully open its up to the cooling system to waste the heat so it doesn't matter if the thing opened at 62 or 75 . There must be sufficient reserve cooling capacity if the thermostat is to regulate water temperature .

Cheers A .

[RB30-POWER]

all early rb's are commence open at 76.5degC and full open at 90degC.

the R34 GTT RB25 is actually hotter, the thermostat, (all new cars run hotter water temps as it makes the engine more efficient and past emissions) as you know the 25NEO is a low pollution engine.

you don't want to change the thermostat, unless you have a valid reason, do you?

i can get the exact figure for the NEO engine thermostat to for you, can't remember off hand but is deffinately warmer then the early RB engines.

cheers

[RB30-POWER]

ok, just to confirm the NEO engines are commence open at 82degC and fullu open at 95degC.

so in theory your engine is always meant to run inbetween the thermostat open and full open temps. It can get warmer though on real hot days AC on and stuck in traffic, but you get the idea.

[Kinks]

all early rb's are commence open at 76.5degC and full open at 90degC.

This is the reason why you'd run a colder thermostat - if you need more flow at operating temp to keep the temps from rising further. Thermostats don't open like an on/off they are a mechanical device so they operate gradually.

In most cases you shouldn't need one. There's nothing to be gained by running a colder thermostat on the street.

[FATGTS-R]

Your car would take longer to reach normal operating temp so the ecu will see these lower temps and keep the car in its cold start enrichment cycle longer which is only a waste of fuel

[Busky2k]

Changing theromstats ranks up there with lightweight pulleys and earthing kits as rice for more power. Leave it to the VTEC boys.

Whats mentioned is correct. It'll take longer for the motor to warm up for short trip driving. Thats deterimental if anything.

[Cubes]

I mentioned this earlier..

I've had a play with both genuine thermostates and different brand aftermarkets (auto shop aftermarket cheap crap).

The genuine thermostates open much less and take longer to do so. On the car it is up to operating temp within 2km's from a stone cold start and no idle warm up. coolant temperature stays nice and constant with very little fluctuations.

The aftermarkets (both brands I tried) opened up much quicker and a greater amount. On the car it took forever to warm up. It ran cooler even though its little stamp of 76.5degree's was the same as the genuine thermostat. I didn't get a chance to test the aftermarket thermostat in summer as I didn't leave it in there long enough as the long warm ups gave me the poos.

My sisters VL.... It had a small overheating issue when climbing willunga hill (some of you SA blokes may know this hill, big arsed and long)

I replaced the radiator with a new 3 core and a new aftermarket thermostat. I noticed the temp ran nice and cool in general cruising conditions but giving it a boot full or hitting willunga hill I saw fluctuations in temperature and it took forever to warm up.

I decided to throw in my old genuine nissan thermostat.

It warmed up much quicker and ran a little warmer, but the most interesting part was engine temps stayed consistent. And the best part... No more overheating heading up willunga hill.

My only conclusion was that the aftermarket thermostats open a little too much causing the water flow to be too great through the radiator possibly causing it not to transfer heat OR the large thermostat open some how prevents flow due to lack of vacuum or soemthing who knows..

The car now doesn't overheat in summer when cruising around the streets witht he a/c on where as with the aftermarket temps would creep over half way. Now they always stay under half.

[satanic]

OK so the temps in my car (as read from my F-CON) are normal for the NEO motor... nothing to be worried about.

The above statement coupled with what you have all said = thermostat not viable

Hmmm...

Thanks heaps guys!

[mad082]

what thermostat fits in a rb25 (from a 33)? does a vl/r31 one fit? my car takes about 1.5-2km longer (about twice as long) than my SSS pulsar to come up to temp, and it anoys me because i only live about 2km from work and the needle has only just started moving by the time i get to work, whereas the pulsar is fully up to temp by the time i get here. i only drive the skyline to work about twice a month.

[Cubes]

The VL item fits but if you grab an aftermarket item from the local auto store it will *chances are* have the long warm ups I experienced.

You need a genuine thermostat for a quick warm up.

I requested an R32 RB20DET thermostat. It might be worth checking if the part numbers are the same. (r33).

All the thermostats are interchangable.

Getting the car up to temp asap saves fuel.

[nuffsaid]

I'd say if your not having issues at the momment, leave it out. I have heard stories about constantly fluctuating water temps with low temp thermos. I'd much rather a consistent okay temperature, than surges between low and normal temps.

RB30 has a good point.

If you wanna have better cooling capacity, maybe a radiator upgrade would be a better alternative?

[J_Red33]

Just thought I'd give this thread a bump as it is quite usefull, & add a few comments.

I was looking at getting an ARC 68 degree thermostat but was really unsure on the need for a lower temp one. I may just get a genuine one from nissan if they are not too expensive.

I went down to Autobarn to get a price on a Tridon 76 degree thermostat & they wanted virtually the same price (will have to get a couple more quotes), but if they have trouble with temp regulation I'm not so sure.

I have used a Tridon thermostat before without any issues on an old 87 Telstar, but I was told one trick by a friend highly experienced in the trade & that was to pull off the little bleeder valve to the side of the main thermo valve so that there is always a bit of coolant flow. This may be all that's required to get deacent temperature regulation. However I don't know at this stage if the RB25 thermostat has this bleeder.

Have to look into it though as my thermo is rooted & the car never gets to full operating temp in the cold weather unless you absolutely thrash it for quite a while. At least I know it won't overheat

[Cubes]

Hey Jazza... Long time no see.

I've tried the aftermarket tridon and another german brand thermostat in mine some time ago.

Both resulted in very slow warm ups; both also never went over 75degree's on cruise; if I were to give it some stick it would quickly rise up to 80-85degree's. The slow warmups and lack of the almost instant heater was enough for myself to put the genuine back in.

The genuine warms up extremely quickly, within 1-2km's, holds a consistent temp of 83-85degree's regardless if Im giving it heaps or just cruising.

I've experienced the same in the old VL's BUT the vl's would overheat with aftermarket thermostats on long pulls (willunga hill for example), the genuine item held coolant temp cooler up willunga hill and more consistent.

Beats me why... Possibly the water pump has issues sucking through the aftermarket thermostat that opens much much wider than the genuine.

[discopotato03]

Hi Cubes , I went through all sorts of contortions years ago trying to solve the FJ20ET in Bluebird cooling issues .

What you will notice with some OEM water thermostats is that they seal properly when closed on an O ring type seat . Aftermarket thermostats often don't have this and are relying on a metal to metal seal . The easy way to see if they seal is to put your mouth over the top of it and try to blow through it . If its airtight it should regulate ok . If your breath flows through it then don't use it because it won't close up .

That little jiggler valve is there to let air out when you fill up an empty cooling system , the little ball tit thing closes so that it doesn't flow any appreciable amount of water but will let air escape in the system to help prevent air locks .

I don't like drilling holes through thermostats because this then lets water flow through the radiator and that extends warm up times . I don't agree with this need to let a little through all the time idea , if the thermostat sticks shut the extra hole won't prevent the engine overheating because it won't pass enough water . If a thermostat won't seal shut then it can't regulate water temperature its a simple as that . If it leaks then temperature will be dependent on how much water gets through and how much and what temperature the air is running through the rad core .

If I had my way engines would have two thermostats , one high temp one to get the heat into the oil sooner and another to run the system at a more appropriate temperature the rest of the time . Who knows , maybe one day we'll have an ECU controlled valve that opens to use a cooler thermostat under high loads and reverts to the higher one for light loads and in theory better fuel consumption . An oil temp sensor could tell the ECU when its cool or a little too toasty as well .

See ya , cheers A .

[Ronin 09]

I have a nismo 62 in my GTR and it warms up to 70 fine before 5 mins.

Also have a 40mm Race Radiators alloy rad.

Have not booted it, but it holds temps at 72ish quite nicely.

Also, for completeness, I have a Serck oil cooler without a thermo and after 5-10 mins both water and oil temps dont budge from 70ish.

These are defi gauges so should be pretty accurate.