JunpoweR

iTrader: (1)

Well everyone what do you think??

Running no thermostat is bad or good??

i think it helps cooling but it just takes longer to warm up
and the fuel mixture goes out of warm up mode later on because engine takes longer to warm up the coolant..

with the thermostat the coolant will not flow untill the engine reaches the tempature required to open up which warms up faster but the opening is smaller..
and the coolant flows slower.!! because when i took it off of my GSL-SE it lowered the coolant tempature it never got over 1\8 on the stock meter..

someone told me it will let the coolant pass through too fast and it wont cool down enough but i think otherwise . because i explained my tempature meter readings were lower then with the thermostat .. he said the stock tempature meter isnt reliable and isnt linear..i think it is just dosent have the temp. numbers on it.. but does go through a linear tempature range on the stock dash..

am i right or wrong..??

Project84

no thermo = bad

JunpoweR

iTrader: (1)

why is it bad??

krazydru784

^^ read...flow too fast..possible hot spots...i dont have a thermo either..and i was debating this too. i still see 1/2 meter temps though..but i live in southern cali where its lik 96 degress outside.

bingoboy

basically with no thermo the coolant can possibly move through the block too fast to absorb the heat needed to cool the engine properly. i have heard of some people punching out the center of the thermostat however i don't know if that is a good idea or not either. if you had a seperate oil temp gauge that would probably let you know if your engine is cooling properly or not.

also, if your engine isn't cooling properly due to no thermo, you most likely wouldnt be able to tell (until your car overheated or something broked) from the coolant temp gauge as the coolant would not be as hot as the block.

Fingers

The coolant moves too quickly through the block with no thermostat in place to restrict flow. What results is the actual coolant being a lower temperature, while your block's temps skyrocket. Very dangerous. Coolant doesnt get enough time to transfer heat.

SureShot

ATTENTION - Have you noticed the bypass port that's about 1" below the stat valve position?

There is a spring loaded disc on the stat that extends below to close that port.

If you must run without a stat, then you must plug that hole with something.

Rotorific

iTrader: (1)

FIRST OFF I have a radiator from a 929, an electric fan that pushes 50% more than the Fiero Fan and no thermo.

Im going against the flow because I have done this for 2 years now and still have not seen a problem. I do not run a thermo during the summer time months here in GA May-Sept if you need to know the months and the temps are above 90 and never below 85 during these times and lets not forget the humidity of 90% or more... With a thermo in, it would run 1/2 all the time. Without it, it barely reaches a quarter of the way. I drive my car hard well I drive it very hard. The first year i did this i had a stock radiator and the fan i run now and the needle never got past 1/2 while drag racing or drifting/burning out for long periods of time. This year the needle will rise a hair above the 1/4 line and stay there no matter what i do to the car.

Im not disagreeing with what you guys say because you guys have some knowledge on me, Im just saying that it can be done in moderation without consequenses.(sp?) I have the mods to cool the system efficiently, Ive had no coolant seal issues, and I thought the coolant temp was read from the block near the oil pressure sensor. I could understand it reading wrong if you had an external temp gauge where it read near the water pump housing because it would be reading the coolant outside of the block and if the coolant moved to fast then yes it would be reading low or exremely low. But since its reading from the block im still lead to believe that the temps are right on the money. -Gabe

c-squared

The coolant temp that reads on the gauge comes from a thermocouple placed into the water jacket, thus effectively reading the coolant temperature and not the block temperature. It is located beneath the oil pressure sending unit.

I challenge to install an oil temp gauge, even a shitty Walmart mechanical gauge will suffice, and then run both with and without a thermostat.

You will notice your oil temperatures increase while running without a thermostat, while your coolant temperatures decrease. Thus, your oil cooling system has to work that much harder to effectively cool the engine, since your coolant is not.

I have done this, and seen the proof. So, if you insist on running without a thermostat, at least install a restrictor plate.

Icemark

If the engine is running at 1/4 orf the temp gauge, it is too low and you are:
#1 lowering your overall engine efficency
#2 creating hot spots (as mentioned above) in the engine.

The stock system was designed to run at around 200F. If it is running at 150 or so, then there is a major loss of thermal effcency of the motor.

I imagine your gas mileage is pretty low too, well alone the loss of HP.

Rotorific

iTrader: (1)

The coolant temp is still read from the block as in the coolant is right there in the block passing through.

I see what you mean with the oil temps but was your car stock though? I didnt really press the issue that I wouldnt dare do it on a stock car nor would i do it when not needed like the fall, winter, spring, months. I have the mods to compliment the coolant temps so im not worried about that but I might buy an oil temp gauge to see if that is trully a problem. -Gabe

c-squared

It does not matter if the car was stock ( it was not), what matters is relative oil temperatures. Without a thermostat, the oil temps increased while the coolant temps decreased.

The coolant temp is not measured from the block. The coolant does not see the same temperatures as the block. Effective equilibrium of temperture is never achieved between the coolant and the block... the coolant simply is not present long enough for an equilibirum to be established.

The coolant temps would not reflect block temperatures even more without a thermostat, since the coolant would pass by the block even more quickly, and less heat energy would transfer into the coolant. Make sense? the transfer of heat energy takes time... Think about putting your hand is some warm water, and then taking your hand out right away.... your hand will not experience much of a change in heat. Now stick your hand in, and leave it there for 1 min. Now, if you take out your hand, it will be warmer. Same thing here. The coolant does not have the time to absorb the heat from the block, so the coolant remains cooler, while the block remains hotter. you can see this most easily with an oil temp gauge.

deadRX7Conv

Good idea with the oil temp gauge. This will easily prove which is better.
The 'stick your hand in water' and 'equilibrium' is a good and simple explanation.
The question is whether the stock designed water pump is at a point where the equilibrium is affected.

The water pump has an efficiency curve. It is very possible that there is one perfect RPM with the thermostat and another perfect RPM without it.
At low RPM(poor pumping), lack of a thermostat might improve cooling since water flow is restricted by engine RPM and pump pumping efficiency. At a certain RPM, the cooling curves(thermostat vs no thermostat) will intersect and as water flow increases, more time will be needed to absorb heat. Whatever this fictional RPM is, might help in determine whether you should(n't) use the OEM thermostat. This is one reason why we use the thermostat. It variably opens/closes to maintain the equilibrium cooling point over a wider RPM curve VS. one perfect cooling point without a thermostat at ONE rpm point.

Another thing to consider is a coolant flow restrictor. A washer or hollowed out thermostat should work. And, this too can be proved with the oil temp gauge(monitoring oil temp for extended periods of time at any given RPM and charting a graph). The flow restrictor should improve the cooling curve or can be sized to pick a different perfect cooling RPM.

The little thermostat valve bypass port thingy is something that must be understood and could be enough of a reason to keep the Mazda thermostat.

Also, I'm wondering if an underdrive pulley can reduce the water flow enough that it still has sufficient time to absorb heat from the engine. This might improve the efficiency curve for people without thermostats. It might also help with cavitation where the efficiency curve becomes a cliff and drops hard.

What does the factory ECU reference for engine temp? Not running the thermostat could create instant inefficiency and could possibly reduce power, decrease MPG, and increase emissions. Think "carbon buildup"!

I say the best way to improve cooling is to:
Replace the radiator with a griffin/k2rd/koyo/fluidyne........ Bigger radiator is like having more cooling in the bank that pays a higher interest rate(surface area).

Improved airflow-- its your decision to argue the pro/con E-fan argument. Oil/water temp gauges will decide if the one you are using works best.

Improved aiflow2-- whats up all those claims that a front spoiler can help scoop air into the radiator/oil cooler. Shrouds are also mandatory.

Bigger oil cooler or improved oil cooler circuit--- who here has tested the thermostat in the cooler? Its mocal thermostat and factory race oil cooler time.

New water pump. I could only guess that new OEM is the best. Never had faith in store bought rebuilds. 10-15 years takes it toll on water pumps. Same can be said about the cap and thermostat.

Synthetic oil-- this again if for you to argue with yourself. Synthetics help reduce friction, help remove heat, and maintain a more consistent viscosity curve.

Coolant improvements--again, argue the ratios with proof. Either go all water+additive or go all coolant(non aqueous). If you're like me, 50:50 seems to work perfect.

Additives: Redline/TowKool/RoyalPurple/Kemopro/Lubegard/NOS/kwickcool/synergyn/... make coolant additives that improve cooling, lubricate pump, refresh antifreeze, and keep everything squeaky clean...

Fingers

I have an even better idea
FIX WHATS BROKEN


Better than any SuperGardExtraPerformanceProtectionPower thermostat superrestrictor, or coolant additive that you can buy/make/steal.

Fingers

Oh yes, please, if you do a flush, please, do not use cheap antifreeze. EVER. Use only Prestone or Evans ... and only the green stuff.

It has corrosion protection, and it won't turn to gunk as easily as shitty coolant. I learned the hard way, learn from my mistakes

steell

I think there are a whole lotta people here who should study some physics instead of repeating old wives tales.

If a car overheats when the thermostat is removed, it is due to water pump cavitation, not "coolant moving to fast"!

I am not going to wear out my fingers typing all the details, just do some research before making silly statements.

Rotorific

iTrader: (1)

Yeah i never did mention that i run evans NPG

stevensimon

iTrader: (11)

so whats better? an autozone thermostat, or oem? i heard somewhere that they are different. whats the differences? why should i pay 22.50 for oem, when i can get generic for 2.50?

jsotelo

OEM for 15.00 from Mazdatrix. Basicly it won't fail and it's a higher quality, opens when it's supposed to and closes when it's supposed to.

Dana, Rotary Racer, who knows more about cars than I ever will told me to never buy anything but an OEM one for a Rotary car. Said the rotary is a lot more sensitive to even a few degrees of temp.

Yeah this is second hand knowledge but if Dana says it then it's pretty much gold.

Wankel7

I remember reading on the Mazdaspeed website that if you are using your car as a race car you are good with thermostat. There didn't back up their statment.

They didnt say anything about street racing

James

NZConvertible

Well I studied quite a bit of physics and thermodynamics, so I don't consider this an old wive's tale. Without the restriction of the thermostat, the coolant moves faster. This is easily proven. All heat transfer takes time to occur, and the longer two susbstances are in contact the more heat transfer that will occur. The rate that the coolant is moved through the engine has to be a balance between the rate the heat is asborbed from an area by the coolant and the rate that the heat is removed from that area by the coolant's movement. There is an ideal flow rate that will maximise heat removal. When a cooling system is designed, many variables are taken into account to ensure that the system operates near that point. Changing one of those variables, in this case coolant flow rate, is going to affect that.

With the thermostat removed and the coolant moving faster, the engine is usually overcooled at low load, because the small amount of excess heat is removed when it shouldn't be, and undercooled at high load because the coolant is moving too fast to effectively remove heat.
Please explain why.
If you're going to make statements like you have, you have to be prepared to back them up, otherwise they're worthless. If you think we're wrong, tell us why. Nobody's going to believe you're right just because you say so.

c-squared

I have 6 years in engineering physics.

RunningDeer

Mazdaformance.com (Mazda dealer) $11.44, the place for all OEM for less money

Icemark

Although there is some truth in what you say, cavitation is only just one part of the equation.

Either way, without the thermostat (as covered countless times) the coolant looses its ability to properly cool the engine.

And most people do not know what water pump cavitation is and how it is caused.

So here is a small lesson for them:
Cavitation means that cavities are forming in the liquid that we are pumping. When these cavities form at the suction of the pump several things happen all at once.

We experience a loss in capacity.
We can no longer build the same head (pressure)
The efficiency drops.
The cavities or bubbles will collapse when they pass into the higher regions of pressure causing noise, vibration, and damage to many of the components.
The cavities form for five basic reasons and it is common practice to lump all of them into the general classification of cavitation. This is an error because we will learn that to correct each of these conditions we must understand why they occur and how to fix them. Here they are in no particular order :

Vaporization
Air ingestion
Internal recirculation
Flow turbulence
The Vane Passing Syndrome

We can pretty much rule out Vaporization, Air ingestion and Vane passing (as long as the pump has been designed with the proper clearences) in a properly maintained, running and filled automotive system, so that leaves us with Internal recirculation, Flow Turbulence.

Internal Recirculation

This condition is visible on the leading edge of the impeller, and will usually be found at the discharge tip working its way back to the suction. It can also be found at the suction eye of the pump.

As the name implies the fluid recirculates increasing its velocity until it vaporizes and then collapses in the surrounding higher pressure. Again, if that was not clear... the system flowing though too fast will cause this issue.

Turbulence

We would prefer to have liquid flowing through the piping at a constant velocity. Corrosion or obstructions can change the velocity of the liquid and any time you change the velocity of a liquid; you change its pressure.

Of course with different RPM that the pump works at; the constant velocity is almost impossible in an automotive system. Yet with enough restriction properly designed into the system, the velocity can be lowered.

This is the most common cause of cavitation in a automotive system. The pump simply out pumps the restrictive design of the system. Removing the thermostat, simply changes the optimal RPM for the pump to operate at to avoid cavitation as well as fails to prevent lowering of the fluid pressure, which increases the possibility of turbulence.

Rotorific

iTrader: (1)

Mark...I still have yet to see poor MPG but i would like to see my OIL temp which would be in the red zone to say the least.