Nismo Thermostat For Rb25det Neo

[mad082]

i discovered my thermostat was a factory nissan one and it opened MUCH further than the aftermarket one i bought. it would open about 15-20% more. it opened at similar temps, but it made the car run a bit cooler as it could flow that little bit more water.

cubes: what you said about the thermostat opening too far and not letting the water spend enough time in the radiator to cool enough sort of makes sense, but it works both ways. the less it opens the more time that water spends in the motor, so the hotter it gets. the hotter it gets, the hotter then engine is, and the longer it would take to cool the water down. that is why when you run the car without a thermostat it will run cold. by your theory it should run hotter without the thermostat.

[Cubes]

mad082,

Can you grab the part number off the genuine thermostat? Maybe the RB20 and Rb25 thermostats are slightly different.

The new genuine rb20 thermostat I tested really didn't open much at all. I'd say in total it opened 15mm off its seat.

The 2 aftermarkets opened all the way which appeared to be approx 20-25mm off its seat.

The aftermarket opened sooner, opened at a greater speed and also closed quicker; essentially it was more responsive than the genuine.

The genuine was sluggish in its movements and didn't open as much.

As I mentioned above on the road the aftermarket had the car running cooler on cruise and showed temperature fluctuations when u gave it beans. The genuine holds a solid 83-85ish degree's, essentially temperature warms up quicker and holds consistent. Much nicer than a swaying temp guage + it held the motor within the apparent fuel efficent 85degree temp range.

The r32 did get too warm like the VL with the aftermarket thermostat when hitting the big arsed willunga hill.

In the VL Willunga hill requires approx 1/2-3/4 throttle to hold 110km/h; the hill takes a couple of minutes to reach the top of. So its a fairly big hill.

With regards to running a car without a thermostat which makes it run cold... This is 'generally' true under light load BUT give it full throttle for any length of time and they overheat. I've experienced this back in the old carby days with 308's and mild 250 2v precross flows.

yes I did try no thermostat in the VL.. It ran stupidly cold on cruise and overheated up willunga hill to the point where i Had to back off and turn around; slap a genuine thermostat in it and it was as good as gold.

No thermostat was a bad thing.

Which brings me back to maybe there isn't enough suction or vac on the water pumps side to provide reasonable flow; maybe the theory regarding water flow speed through the radiator is barking up the wrong tree and all along it has more so to do with providing a vac on the water pump so that it pumps water instead of spinning it around and around.

Some one with a little more fluid dynamics knowledge would be able to look at the water pump design and know for sure.

Not that it is really applicable but remember.... The greater the temperature differential the greater the effiency of heat transfer/removal.

[Cubes]

So yer... thats my experience/observations. What yours people..

[RB30-POWER]

without a thermostat the water flows to fast through the radiator to remove heat once the coolant is saturated.

another function of the thermostat, which not many people know is that it causes a restriction in such a manner that the pressure in the block and at the cylinder head is increased above the radiator pressure. this is critical in preventing localised boiling and steam packets in this area.

lowering the thermostat opening temp is going to reduce thermal efficiency reducing power and economy, this is why cars now are usually rated at well over 100degC opening temp.

i don't suggest going higher then standard in the RB engines as temperature of the engine is also related to the metalurgy of the head as alloy heads are sensitive and can go soft it overheated beyond standard temp.

with regards to the nissan vs aftermarket, genuine nissan are same price if not cheaper then aftermarket, so why mess around with the cheap flimsy chinese crap, that has crap temp regulation and are prone to jambing open or closed.

[Cubes]

So its a little bit of everything then.

Comparing the aftermarket thermostats to the genuines the genuine looks and feels a hell of a lot more solid. Down this way aftermarkets are ~$25 each compared to the genuine nissan @ $49.

[RB30-POWER]

If you mention import, they might wack an extra $10 on

Just buy for RB30 R31, $39 retail, last time I ordered (not to say price has gone up)

Aftermarkets are like $40 here for RB30, can't get over it, every other cars is the usual $15, which is still overpriced for the quality they are.

Sent you a PM as well.

[Ronin 09]

well would you count a Nismo one as 'aftermarket' - they are probably made in the same place as the OEM ones so would behave similarly one would think

[Cubes]

I wouldn't.. The Nismo items are essentially nissan items.

The one I saw looked the same as the regular Nissan thermostat. Not skinny like the aftermarkets.

Thanks RB30-Powa. Looks to be a good read.

[J_Red33]

Hey Cubes, yeah it's been a while, was away in Europe for 5 weeks. Ran into your missus just before I went.

Well I this thread activity has suddenly exploded.

I ended up going to Unley Nissan today & got a genuine thermostat for $53 & FYI Cubes, the part number is 21200-42L06

It makes more sense for the thermostat to vary gradually with warm up instead of acting like a switch, I'd say that this kind of action in itself would mean that it regulates temperature better than the aftermarket ones. Going by what RB30-POWER also elaborates with the no thermostat situation, perhaps the aftermarket thermostats open up too much to keep sufficient pressure in the block for the pump.

Biggest thing that made me decide to go with the stock temperature thermostat was that my car fails to get to full operating temperature even when I'm driving it hard in this cool weather. Couple that with the fact I don't even have a front mount to cool the intake charge more, & I see little need for a low temp unless I was about to rebuild my engine for a serious power upgrade.

Very useful thread guys I wish more threads on here were just as informative, cheers

[Abo Bob]

Just do a search for "all posts by Abo Bob". It's all pure gold. Every other thread is crap.

Another vote for use the stock one.

[Beer Baron]

ronin, i reckon 70 is too low. ideally for the 32 you want the temps to stabilise arond 75-85 both water and oil when just cruising around. though it is winter, and you do drive like my little niece on her tricycle so that may explain it.

[Ronin 09]

ronin, i reckon 70 is too low. ideally for the 32 you want the temps to stabilise arond 75-85 both water and oil when just cruising around. though it is winter, and you do drive like my little niece on her tricycle so that may explain it.

fine mr baron. 8000rpm in second everywhere it is.

i do recall looking at the PFC controller that said 74.

btw, even on a tricycle i will dominate around the track!!

[Hardman69]

Does anybody have a part number for the R34 NEO RB25DET thermostat?

(The 82deg.C one) - My R33 takes FOREVER to get up to temp, I wanna go HAAAWWWWTTT ! !

[Hardman69]

Anyone?

[Adriano]

Umm, dont you have to go to nissan to get it?Why dont you just ask them.

[gtt23]

i run a sard lower temp thermostat in my 34gtt (amongst also an oil cooler and thicker radiator).

do some dyno runs on your car and see what results u get at different operating temperatures;

i found 80's were fine but once in 90's i was losing noticable power.

car now runs 70's - 80's in most conditions thus when i want/use the power (and the engine gets hotter)...

i don't loose that power as a result

[Cubes]

How do you find the sard brings the temps up?

Nice and quickly and once temps are reached they are stable for general driving with a little squirt here and there?

[Hardman69]

Umm, dont you have to go to nissan to get it?Why dont you just ask them.

They're usually reluctant to order stuff unless you give a part number, or your VIN, so they can be sure it's the correct part. Since I want a part from a later model car, I'd like to order with part-number in hand. :sorcerer:

GTT34: I do 98% of my driving in cruise-along mode, when I want every last drop of economy I can get. On the highway it's usually around 68deg. water temp (on the PowerFC). If I'm in thrash-mode, it's either for 1 or two corners (so temp won't have time to rise) or I'm doing a track day, so temps will never get below 100deg.C anyway. (i.e. thermostat wide-open all the time)

U know it makes sense!

[discopotato03]

Hardman I think I'd be removing the thermostat you have and making sure its working properly , ie sealing shut when its cool . I wouldn't think a coolant temp anywhere in the 70's and up should make any real difference to steady state fuel consumption . No engine would need enrichment by that stage so the only other factors I can think of would be possibly a little oil drag depending on viscosity and closed loop ECU settings . If anything cool air charge temps should allow ignition timing optomised around best mean torque rather than detonation protection I think .

Cheers A .

[Cubes]

Disco,

The PowerFC provides fuel enrichment for anything below 80degree's. As the Powerfc base maps closely reflect that of the std ecu's maps I wouldn't be suprised if the std ecu's values also provided fuel enrichment below 80degree's.