Nismo Thermostat: Swapped Silvia/180sx Allowed?

[Neejay]

I've researched and I've noticed that there are a lot of people against using the Nismo thermostat on a street driven car. Temps here are about 30-32C and my temps reach up to about 88C (FMIC, apexi cone filter, 3" turbo back exhaust, stock RB25 turbo, 10-11psi). My coolant system is a new water pump, R32 aluminum radiator, new OEM thermostat, 1 gallon 50/50 coolant/water mix, distilled water, 1 bottle of Redline Water wetter, dual 12" Flex-a-lite puller fans.

I've seen the argument that the nismo thermostat could cause closed loop mode (dumping fuel), but that's about it. Is it not recommended on a R33 GTS-T because it's a STOCK? Would it be an exception if it's in a silvia/180sx chassis since the RB is crammed in there?

[femno]

Depending on what loom you have running the Rb25, it shouldnt be an exception.

Whats wrong with 88deg?

[mad082]

ok well firstly closed loop is when it runs leaner, open loop is when it uses more fuel (but doesn't dump it in). pretty much any time you accelerate at over about 1/3 throttle you will be in open loop.

secondly the thermostat won't be affecting closed or open loop, it will be the cold start enrichment (basically the same as what a choke does on a caby engine). however i doubt that the slightly lower temp of the thermostat will have an effect on that. you car normally runs a few degrees above the actual thermostat temp.

why are you wanting to change it? if your car is running at 88 degrees with your current thermostat i see no need to change. that is by no means high. you could get them up close to 100 degrees and still not be too worried.

[TiTAN]

or if the heat is an issue get a better radiator.

[Neejay]

Depending on what loom you have running the Rb25, it shouldnt be an exception.

Whats wrong with 88deg?

Oh, for some reason I was under the impression that the temp shouldn't get over about 82C. I just searched more on here and see some people run 90C+...guess I was mis-informed.

ok well firstly closed loop is when it runs leaner, open loop is when it uses more fuel (but doesn't dump it in). pretty much any time you accelerate at over about 1/3 throttle you will be in open loop.

secondly the thermostat won't be affecting closed or open loop, it will be the cold start enrichment (basically the same as what a choke does on a caby engine). however i doubt that the slightly lower temp of the thermostat will have an effect on that. you car normally runs a few degrees above the actual thermostat temp.

why are you wanting to change it? if your car is running at 88 degrees with your current thermostat i see no need to change. that is by no means high. you could get them up close to 100 degrees and still not be too worried.

Ah, cool. Thanks for the correct information.

or if the heat is an issue get a better radiator.

There's already hardly enough room as is. This radiator + e-fan setup is already running cooler than the other thicker radiator I originally had.

I guess I'm not getting too hot then. Thanks a lot guys! I'm going to re-bleed the motor just in case.

[TiTAN]

the stock thermostat will be fully open at ~80c

[mad082]

Oh, for some reason I was under the impression that the temp shouldn't get over about 82C. I just searched more on here and see some people run 90C+...guess I was mis-informed.

Ah, cool. Thanks for the correct information.

There's already hardly enough room as is. This radiator + e-fan setup is already running cooler than the other thicker radiator I originally had.

I guess I'm not getting too hot then. Thanks a lot guys! I'm going to re-bleed the motor just in case.

i had an issue with my car running hot and it was sitting at 93 degrees and the std clutch fan wasn't fully engaged at that temp.

if you are starting to run hot you will hear the roar of the clutch fan as it fully engages. but even it fully engages well before you are at critical temps.

[Neejay]

i had an issue with my car running hot and it was sitting at 93 degrees and the std clutch fan wasn't fully engaged at that temp.

if you are starting to run hot you will hear the roar of the clutch fan as it fully engages. but even it fully engages well before you are at critical temps.

I don't have a clutch fan, just dual 12" Flex-a-lite fans.

I had to raise the rear of the hood/bonnet. It helps when city driving, but causes the engine to run hot @ 93C on the highway. I pulled off the exit and raised the hood with the car running and you can instantly see the temp drop via aftermarket water temp gauge.

I don't have the stock heatshields on the manifold or turbo (need to buy some) and I'm going to have take the bumper off until I can get my hood vented or buy a vented hood.

[discopotato03]

I'm curious to know what you're using to control the fans and more importantly what temperature they switch on/off at .

A lot of people don't agree but I see it like this .

For the radiator to control the engines water temperature it must be able to cool the water in it (rad) to a LOWER temp than you want to run the engine water temp at , I think too many people with elec fans try to control the engines water temp with the fans switch settings and it ends up being a tail chase .

Provided you can get the switch sensor in the radiator , not the engine , it can be made to work properly .

In a nutshell you use the fan/s to control radiator temp and the water thermostat to control the engines water temp .

It was explained to me that the engines water thermostat is there to control its minimum running temperature not it's maximum , I had to think hard about that one .

Lets just say that you had the guts cut out of your thermostat and it had full flow all the time , under normal circumstances the engine water temp would be low because there is nothing to regulate its proper minimum running temperature .

If the coolant temp gets high then the thermostat opens up and blindly hopes more flow will bring the temp down again .

As an experiment try running the fans all the time and leave the std 76 deg © thermostat to control the actual engine water temp . It's probably not so different to running around in the winter time because its the THERMOSTAT that's trying to control the water temp not the fan switch setting .

Also some people fret about the fans not switching off sometimes for reasonably long time periods (in warm running conditions) - so what - they're doing their job .

I'm not suggesting you have your elec fans run 100% of the time but this is effectively what the std mechanical one does . It also pushes air through the engine bay all the time which is not a bad thing .

From cases I've seen engine conversions and high engine/bay temps go like this .

Fit bulkier engine than the manufacturer intended which alters airflow characteristics through the engine bay .

Fit elec fans because there is not enough room for the factory viscous hub one .

Fit two small fans rather than one big one in the belief that they cover more of the core . Fit behind the core .

To make a radiator transfer heat the post rad air has to have somewhere to go and that's through the bay and out around the gearboxes bellhousing and off underneath the car . The very best radiator in the world won't do a real lot if there is nowhere for the air to flow behind it .

A GTR radiator is probably tall enough to get two fans on but I reckon at least one needs to be the full height of the core .

People try to set the fan on temps at some mythical upper cooling temp because they think Ok the fans come on and cool the engine water temp down . What they succeed in doing is ensuring that the whole cooling system temp is up there and when the fans switch on dumping all that heat into the engine bay .

Had it been a std engine in a std bay there may well have been sufficient airflow through the system at speed to maintain a workable engine temperature but things have changed and air may not pass through so well unassisted .

Now if you have the fans switching on at a temp below your engines normal temperature you have a reserve of cooler water in the radiator , when the engine water temp rises for whatever reason the thermostat can open up and take advantage of the reserve cooler water . If there is no reserve then the whole cooling system rises as does the temp of the air going through the core .

To my way of thinking you need to get in early and ensure that the temperature of the water in the radiator is reasonably cool and then let the thermostat do its job .

It's on the cards that the fan/s are going to have to work longer because it's harder to get air through a core and more specifically an engine bay with more flow restriction in it .

Beyond this the only other thing you can do is consider oil cooling and cash in on the fact that generally the difference between oil and air temp is greater than cooling water and air temp so better chance to reject the heat .

My 20c , cheers A .

[Neejay]

Hmm...I have one fan that comes on with the ignition and one that's on a manual switch. I typically turn the second one on at around 170. I've taken my front bumper off and I never get over 180f now. I'm thinking about getting a vented hood now.

[mad082]

what sort of shrouding do you have around the fans? that is usually the biggest issue when people fit thermos. if the shrouds aren't very good then the fan doesn't suck enough air.

you say it's a r32 aluminium radiator, did you buy it new or second hand? if second hand i would look at getting it cleaned. also it could be the water pump causing the issue. if it isn't working as well as it should then the water is staying in the motor too long and getting too hot which puts more stress on the rest of the system.

[Neejay]

what sort of shrouding do you have around the fans? that is usually the biggest issue when people fit thermos. if the shrouds aren't very good then the fan doesn't suck enough air.

you say it's a r32 aluminium radiator, did you buy it new or second hand? if second hand i would look at getting it cleaned. also it could be the water pump causing the issue. if it isn't working as well as it should then the water is staying in the motor too long and getting too hot which puts more stress on the rest of the system.

Fans are dual 12" FALs, has its own shroud. It's a brand new R32 aluminum radiator. Water pump is brand new oem (done at the time of the swap, less than a year ago.

[mad082]

sorry, missed the mention of new water pump in the first post.

is it possible to get pics of the setup?

may also be worth looking at changing to a single 16" fan, or looking at getting the fans and shroud of a car that has them stock (such as a late model falcon, magna or pulsar) as they have nice big blades on them and have properly designed shrouds so are going to work much better.

but the issue could be due to the fact that there isn't enough room in the engine bay to allow the desired air flow from having a 25 crammed in there, in which case the vented bonnet will help a lot. but get pics of the fan setup if possible.

[discopotato03]

He's in Atlanta USA and the RB's in a USDM 240SX S13 , don't think they got Falcon Motor Co rubbish over there .

I know it goes against the grain having elec fans in front of the radiator but how are you off for space there ? Over here Davies Craig say that their elec fans move more air in pusher mode that puller mode .

Years ago a feller I know here had a ginormous elec fan on the front of an equally huge intercooler in the nose of a Datsun 1600 (510 in the US) and a bulky engine (FJ20 Turbo - DOHC EFI) compared to the std carby 4 cyl L16 .

The radiator was from a Pulsar SSS (Sentra SE/R in US) and it worked well . Previously he had two small elec fans behind the radiator and it was always running hot .

I think provided all the air going through the large front mount IC also goes through the radiator all's well .

Cheers A .