DaveJackson

iTrader: (5)

This is not a good idea. "Coolant" isn't designed to keep the engine as cool as possible, or they'd use a substance that went through a phase change. The engine is supposed to run quite hot, just not too hot and that is regulated by the thermostat and the thermo-switch for the fans. Cooler is not better. Cooler is only better if you were running too hot and having problems with boil over, etc.
Cooler will translate here to increased carbon buildup and other undesirable side effects. I trust the mechanical engineers who specialize in heat transfer working at Nissan on this one. Sorry, but unless you have a degree specializing in transient heat transfer analysis, I'd put that thing back in.

superchargedg

iTrader: (4)

This is not the 60's when a lot of muscle cars did this...totally different engines nowadays....what a foolish idea.

Z1 Performance

iTrader: (564)

Some people are under the opinion that if its cooler, its automatically better. Not sure how that all got started exactly.

On older cars with primitive ecu's, coolant temp was a reference point for things like head temperature sensors (ie early fuel injected Z's). Doing a colder thermostat made the car run richer. These cars are smarter though, because look how quick AFR stabilizes even after a cold start in the dead of winter - its what, maybe 30-45 seconds before it starts oscillating around stoich? Not only that but the ecu moniters how quickly things get up to temperature, including the coolant. So, perhaps in a summer climate, something like this "works", in a colder one it won't. I remember on my own Z, I did the NISMO thermostat - and every single winter, my car would throw random CEL's that had an unspecified code, and some that had a coolant related code. Eventually I tossed the thermostat out, went back to a stock one, and problem solved. Car never ran worse or better with the NISMO stat, and aside from it opening earlier, it didn't even change the net coolant temps by any meaningful amount (maybe 20 degrees).

While the colder is better theory holds true for intake temperatures, on NA or FI cars, it doesn't hold true for things like coolant and oil. These fluids are designed with certain operating temperatures in mind. Exceeding their limits is bad, as they aren't able to perform their job as intended (nor as the components they service are intended). Go too far the other direction and the same thing happens - bad stuff.

How on earth coolant temps that are now 10% lower than before helps anything, god only knows. I mean, it's cool and all that you did it, but it would be beneficial for someone else looking at the thread to say why you it and what benefit you realized yby doing it. At least if the OP had some sort of datalogs to show any sort of net change - timing, fuel, torque, hp, something. But no such data exists. So it's one of those things that is somehow better because it's different than it was before, absent empirical data showing it's different and better

rdrfronty

A couple comments on the thermostat issue. I'm not sure if anybody is aware, but Nissan puts a cooler thermostat in the vq35 than they do in some of the other vq engines. The vq40's have a 82C stat. versus the 76.5C that the Z's vq35 has in it. Because of that, the Z stat is a popular mod for frontiers and Xterras. Anyway, my point that I think Nissan felt the Z might benefit from the slightly cooler stat.
Now personally I am a fan if the 350Z Nismo stat, which is a 54C stat. I've had it for 1.5yrs without issue. Now I do live in SE Texas which I feel helps to justify the cooler thermostat. And it's not that I feel it's good for your engine to run cool, I just feel the Nismo stat helps keeping your engine from running hot. In summer weather my coolant temps stay in the 170-180F range, regardless if hard running or just putting around. I feel that keeping the coolant temps moderate helps performance by keeping the overall underhood temps down. If those temps are down, it can only be a benefit.
Another reason I feel the Nismo stat is a good choice is from my personal experience at Uprev. Traditionally, lots of tuners and dyno testers tend to let your temps and engine cool off some before doing one final dyno pull for your peak hp numbers. This slight cool off will usually gain a few horsepower compared to the numbers obtained doing back to back dyno runs(when the engine is usually hotter). My engine always pretty much did the same on my old dyno sessions. However, on my last few trips to Uprev to get retuned, which also happens to be after my Nismo stat install, Uprev has commented a couple times that a cool down wasn't really needed with my engine because they observed that I had more moderate air and coolant temps even after a bunch of dyno runs. When they tried the "cool down" it gained no hp. And these last two Uprev trips also happened to be in hot Texas summer weather.
So what this means to me is that I can run hard in summer weather, and with my Nismo stat keeping me under 180deg, I do not experience the power loss that a hard running perhaps 200F 350Z engine has or the even more loss that a 210F hard running stock Frontier stat equipped truck would experience.
One last thing. I feel the main reason that the hotter stock thermostats that come in the vq35 and especially the vq40 is not installed to keep the engines runner safer. I feel the key reason is for obtaining peak mpgs. For Nissan (and most manufacturers) getting the high mpg readings is one of the key factors in many of our engines design and tune features. And I think most people will agree that a engine running 205F will almost always net better mpg than an engine running 175F. And from MY personal experience, a engine running 175F will usually net more HP than an engine running 205F.

1sick350z

iTrader: (3)

I know this post is couple months old but my thermostat malfunctioned on me and was stuck therefore causing my car to begin overheating. Called around and no one had the thermostat in stock so as a temp solution i did what the OP did. During my wait for the thermostat to come in i continued to drive the car. The car threw a check engine light, dont remember the code but it said coolant temperature reading below threshold. Did removing the thermostat cause it maybe or maybe the sensor went bad when engine began to overheat. I cleared the code today and will see if it comes back on with the thermostat installed. Anyone run into this issue?

DaveJackson

iTrader: (5)

Very likely due to running with no thermostat. Read up on how a thermostat world's and it might make more sense to you. If it's permanently open (removed), it is sending fluid to the radiator that wasn't hot enough to require additional cooling.

1sick350z

iTrader: (3)

Well after clearing the check engine light and new thermo installed the light came back on, would a slight overheat cause the sensor to go bad?

gshadyz

iTrader: (4)

x2 way going to say that

binder

iTrader: (8)

you do realize when the coolant moves faster through the engine it picks up less heat from the engine therefore the coolant temps will be lower BUT the temps of the engine itself will be higher which is more important.

Nobody cares how cold the coolant is, it's how much heat you can pick up from the cylinders that matters. So yes, you can log lower coolant temps all day long and still have the same or even higher cylinder temps. you would have to use probes on the cylinders or even use EGT's as a measure.

iheartmyz

iTrader: (3)

after an engine teardown, i was having SERIOUS issues bleeding air pockets out of the cooling system. I tried everything and my car would still occasionally overheat. My hypothesis: hot air won't open the thermostat, hot coolant will (go figure). I did this exact mod about a month ago and walllla, engine runs nice and cool. I take a few more minutes in the morning warming the engine. I took a mini road trip from San Diego to Las Vegas a few weeks ago and the car ran just fine. Up in the mountains on the way home, i did throw a P0128 code which i found out was engine running cooler than normal. still i have no issue with that. Oh and btw, liquid does not need to sit on something hot for heat to transfer better. Heat transfers regardless, but obviously the waste coolant will be much cooler if its a constant flow. I don't have a degree specializing in transient heat transfer analysis but I do work on multi-million dollar weapon defense systems and their cooling agents for a living.

binder

iTrader: (8)

it's basic physics. The amount of heat transferred is directly proportional to the contact between the 2 materials transferring the heat.

Simple test, tap your hand on a hot stove burner. Now hold it on there. Notice the difference in how much heat is transferred? I don't think anyone needs to quote equations to understand that process.

DaveJackson

iTrader: (5)

Just reserving a spot with this gem until I get to a computer sometime tomorrow.
Prepare your Angus...

(Edit: see Post #34 two above)

binder

iTrader: (8)

oh i love a good physics rape

DaveJackson

iTrader: (5)

OK, so I'm just going to break down the game footage, here.
So, removing your thermostat somehow gave you the ability to follow the bleeding instructions correctly and actually bleed the system?!

Well then, BAM! Case closed. Quick!! Inform the patent and Nobel offices immediately and get ready for the cheques to roll in. Man, do we look stoopid. I would have sworn that the car would roll over, lock the doors, disable the window motors and burst into flames after doing this mod, but here we have a car with a removed thermostat driving a few hundred highway miles as conclusive proof that this mod works! I can't believe that the first person in automotive history to think of removing a thermostat is right here, in this forum. You'll be president of Nissan by the time this is done.

Then you unleash this pair:

"Oh and btw, liquid does not need to sit on something hot for heat to transfer better. Heat transfers regardless..."

"hot air won't open the thermostat, hot coolant will"

Umm... Yeah.
It's unclear what you're trying to get at, here but I think you should take a gander into something called specific heat capacity and convection.


Then you try to call me out with this??! What's that about?
If it's your goal in life to make your engine run as cool as possible, get off of your **** and design a heat exchanger that uses a compressed refrigerant that goes through a phase change in the condenser and you can have icicles under your hood in no time.


OmFG, are you seriously playing THAT card!!?
What's your goal here?! I don't care if you're the love child of heat exchanger magnates Hudson and Tranter, there is so much drivel in this post it is painful. Don't get me wrong, I am fine with being yelled at when I have said something that is complete garbage, but if you're going to spout at me like you're the show because you make ice at Lockheed Martin when you can't even comprehend what your car's working temperature is
I mean, you're going to (at least) work for the "number one so-and-so in America" before we take you seriously, here.

iheartmyz

iTrader: (3)

1. You CLEARLY have WAY too much time on your hands, OR you care WAY too much about your e-uberinterwebzmustpwnnoobsopplthinkimcool points.

2. When I used the word "everything" describing the methods I used to bleed the air out of my coolant system, it encompassed following the FSM instructions and bringing my car to a Nissan Dealership where they vacuum tested the system and its components. I apologize for not specifying.

3. Me citing my trip to Vegas was by no means an attempt to add credit to me or my actions. I was merely stating that I made a 650 mile round trip, and I was reporting my findings (which after a couple thousand more miles, are still the same). I would say your reaction was melodramatic to say the absolute least but I think I covered that in my first point.

4. I can see how it'd be hard to comprehend my post when you take it out of context and out of order. Hopefully the easy numbering system I've chosen will alleviate any future confusion. The first comment I made describing the relationship between hot air, hot coolant and the willingness of my thermostat to open (or the lack thereof [for clarity purposes]) was obviously a poor attempt on my part to paint a picture in the readers mind of an air bubble not being able to open the thermostat. I'm sorry the "(go figure)" didn't help my effort of stating the obvious. Furthermore my comment on a cooling agent not needing to be stationary to transfer heat was aimed towards a random post I saw earlier in the thread. I'm sincerely sorry if you somehow took personal offence to that.

5. It's hard to address specific issues you had with my original post when you continue to take sentences, chop them up and try to discredit them by acting confused and aimlessly ranting about who knows what (as seen in point 4 as well). I will still give it my best shot despite your valiant efforts. I can promise you it is not my goal in life to make my engine run as cold as possible, and I honestly don't know how such an observation can be derived from my comment. I was just making a point that it helps in the heat of the Southern California summer to shed a few of those unwanted degrees from my engine. Apparently that means I want icicles under my hood. I can see how the second part of my sentence can frustrate you seeing as it brings YOU no credit or glory but again, but I was honestly just piggy-backing that off of the previous sentence.

And LASTLY (or 6. if you're already confused) I find your plethoric use of "smilies" to either entertain, captivate or motivate your benighted forum cohorts, humorous. So in the effort of honoring your tradition, please place these as you see fit haphazardly throughout my post.

P.S. Please take this as it was intended, a friendly response to a misguided post, and feel no obligation to: one-up, prove me wrong, make me look dumb, discredit my ideas, glorify your ideas or whatever ulterior motive you may construct because I can assure you that I do not care.

DaveJackson

iTrader: (5)

^
1. Removing your thermostat is dumb.
2. Next time, use a thesaurus in your word processor to come up with even more S-M-R-T words and it won't take you 4 days.
3. I'd respond better, but I'm too busy working for a major, multi-national, multi-billion dollar, mega weapons consortium as the ChiefLead DesignGineer managing their cooling programs.

Andrei

iTrader: (7)

No one will argue with that. But coolant travels through a motor for a lot longer with or without a thermostat and is in constant contact with hot parts until it gets to the radiator.

The coolant temp being too low I also get the code but that only happens under 65 degrees. This is a perfect mod for anyone that has an FI motor or that drives in hot weather.

Also with a thermostat installed I see temps as high as 222 degrees after repeated street pulls and I cant have that.

DaveJackson

iTrader: (5)

^ Not sure I'm following you. An open thermostat creates the condition of a removed thermostat in terms of the coolant flow path. When appropriate, it closes and this adds a valuable level of control to the system.
It seems like removing the T-Stat from your house A/C and leaving it on all the time (day and night) just because you live in Phoenix. Sure, it's hotter than Hell during the day and you are up and active; but, eventually as it cools off at night and you're just trying to sleep, you're going to be miserable.

binder

iTrader: (8)

How does it travel through the engine a lot longer with the thermostat open? It's the same path. There isn't a magic path it travels through unless it's closed. So the only difference would be during the sub-optimal warm up times. After that the flow path is the same.

As stated below. Once that thermostat is open it is the SAME THING as no thermostat. So after the fully opened temp there is no difference in flow between a normal thermostat and a removed one.

They don't get it Dave. It seems as if someone thinks the coolant is doing something special when no thermostat is there verses a fully opened thermostat. Maybe people think the thermostat keeps opening and closing really fast even when it's at full operating temps? I'm not sure. It seems pretty basic to me. If the coolant flows the same path open as a removed tstat then there is no difference in cooling.

It doesn't magically make the coolant absorb more energy from the engine. Matter of fact, people have the results all backwards anyways. If the coolant was absorbing more heat energy then their coolant temps WOULD GO UP since it contains MORE HEAT due to removing it from the engine.

On top of that the ONLY THING that removes heat from a cooling system is the transfer of heat back into the environment via the radiator. That's it. You can either increase the surface area of the radiator (what removes the heat from the coolant) or you could use a more efficient cooling medium that transfers heat faster. Adding more chambers to flow all around the block or any weird crap like that might cool the cylinders down but it will not change how fast the heat from the coolant is dispersed from the radiator. So measuring coolant temps is actually the wrong way to measure how much cooler an engine is running. Combustion temps must be measured or direct measurements from the engine itself.

binder

iTrader: (8)

For people that are getting lower temps without a thermostat. That's an easy answer. With the thermostat in place it is difficult to properly remove all the air from behind it causing it to not function correctly. When you remove the thermostat it becomes very easy to bleed a system.

So your change is due to the fact that your cooling system is now properly bled when before you probably had trapped air. Pressure bleeding or using a spill free funnel over a period of time is the only way to remove all the air. Until you have done that you will have suboptimal cooling. I know because i always had poor cooling until i properly bled it WHILE STILL KEEPING THE SAME THERMOSTAT and magically I now am 652hp and can do dyno pulls for 2 hours with coolant temps never breaking 200*. On the same thermostat before proper bleeding i was up in the 230's only at 540hp. More hp, properly bled cooling system and my temps went down.