No thermostat!!!Good OR BAD???
 

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..??

no thermo = bad

why is it bad??

^^ 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.

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.

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.

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.

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

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.

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.

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

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.

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...

I have an even better idea :D
FIX WHATS BROKEN
:D:D:D:D:D

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

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 :)

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.

Yeah i never did mention that i run evans NPG

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?

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.

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

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.

I have 6 years in engineering physics.

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

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.

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.

thank you everyone for your feedback
i am gonna run a thermostat!! no matter what
just get one that opens a little lower i guess like that mazda factory race.
also i am gonna run EVANS..
with a 13lb stant cap..
THANKS

Yeah, you do that. However, please allow me one thing... if you should come to find that there is no magic racing thermostat offered by reputable sources such as Mazdaspeed, Racing Beat, and Mazdatrix, then please entertain the possibility that you should either use the stock thermostat or properly modify the car for track-only use with a gutted thermostat body.

Here are the Mazda factory race recommended tips for track-only cars for those who would like to know what the big boys really run as opposed to the internet BS that always seems to surface on this subject:
http://www.mazdamotorsports.com/weba...ubject=cooling

With credit to the fc3s.org mailing list: (Steven Fooshee)
/Quote/
Okay, physics lesson. I've heard this "coolant doesn't get hot enough" bullshit too
often.

Q = A * m * (To - Ti)

Where "A" is a constant determined by about 30 million factors of the system; basically
surface area, heat capacity of the materials in the system, and corrosion layers on the
transfer surface.

Heat transferred (Q) is the product of the constant (A) times the mass flow rate (m) and
the temperature difference between the medium's (outlet minus inlet temp). As the mass
flow rate goes up, the temp difference will go down but the heat transfer at least stays
the same. It'll actually go up a little bit, since the average temp difference between
the engine and the coolant goes up.

Also, as you bump up the flow rate, the laminar boundary layer gets thinner so the "A"
constant gets bigger.

Anyway, the next time someone tells you that the coolant's not getting hot enough you'll
at least know better. /quote/

And for even more info (I love cut and paste, gives my old, tired, fingers a break)


http://yarchive.net/car/radiator_diagnosis.html

The pupose of a thermostat is to maintain an engine at a specified temp. When you remove the thermostat (for daily driving) the engine will spend most of it's time below the optimum temp, and fuel economy will decrease, engine wear will increase, and power will suffer.
Generally, the only time you would want to operate without a thermostat, is when the engine spends most of it's time under high load conditions (racing).

THANK YOU AGAIN!! =)

Did anyone see the word BYPASS in my earlier post.

About 1" under the stat in the housing is a BYPASS port.

The stat is supposed to cover the BYPASS port along with regulating flow to the radiator.

With no stat much of the hot exit flow BYPASSES the radiator and gets sucked right back into the block.

WOW! This is a lot of effort for a very simple question. The engine is designed to run with a properly functioning thermostat, either OEM or after market. You should install a thermostat designed for your rotary engine. Or don't and live with whatever consequences result, it is your car and your choice. All we can do is advise. Good Luck

thermostat mod
 

I drilled 4 1\8 inch holes into the thermostat to help cool the car better since it's under hotter , racing conditions.


Who thinks this would be good or bad..?
Opinions please..

https://www.rx7club.com/attachment.p...postid=2715722

Well lets see here is a list of upgraded thermostats

Nippon racing thermostat

SARD cooling thermo link:
http://www.bulletproofautomotive.com...il.php?ID=2949

buy anyways i found out that running any lower than 180 degrees with a stock ecu isnt good so ill put in a stock thermostat..
i will only run without it or a modified one after i get a standalone ECU for my turbo II

Hmm, lots of good info, I am going to re-install my T-stat.. I had read a lot of conflicting info abut after reading some of the symptoms of running without, I am expieriencing most of them... Hot spots, poor mileage, long warmup times.. ect.. Thanks all..

Why do people ALWAYS think they're smarter than Mazda engineers?

because some people do not feel that 182BHP is sufficient.

The only reason I was running without was due to the fact that I was too lazy to buy a new one when I put the motor back in, I kept saying, "next time I go to Autozone/mazda"

Well after some of the cars they put out and some of the issues they have had, questioning the merit of a certain design isn't always stupid. For god's sake if everyone just took what the engineers said as gospel then the Pinto/Fiero/Corvair,ect.... would still be on the road. THey are human and make mistakes. Not in this case so much but innovation is the key to Grassroots Motorsporting...

well i do agree that you should only run an OEM thermostat but i have run a cored thermostat with no problems aside from extended warmup periods. i have however run into quite a number of customer's cars that were running warmer than they should and low and behold they had aftermarket thermostats in them and once i swapped in OEM thermostats the engine ran at normal temps again.

Pinto = American
Fiero = American
Corvair = American

There's the problem right there... :rlaugh:

Pulsation Dampner on the Rx-7's........

But I do agree, American Cars have MORE eng. issues then the Japaneese counterparts...

Okay, there's a lot of BS here and a LOT of writing. I don't fully understand the cooling system myself but I do know the simple answer (and part of the reason why but I'll skip that):

1. It is okay to run without a thermostat, but it will NOT cool as well. You have to block the bypass like the thermostat does. Racers can give you info if you want to do this.

2. Get an OEM thermostat. The ones in stores are sucky.

God forbid a 10+ year old part fail :). I'm anti-Ford ever since the minivan we had as a kid was recalled SEVERAL times for potentially FATAL design flaws.

Newho... just put in a new Mazda thermostat.

Oh yes, I totally forgot about the upgraded $97 Toyota Altezza thermostat in a fancy package. I'm sure that would give at least a 50hp increase in an RX-7, and it should fit and work with no problems because an RX-7 is pretty much the same thing as an Altezza.

Nippon Racing is also very well known in the RX-7 world. I think they hold the record for winning the most endurance races with RX-7's, and they make an uncountable number of high quality RX-7 performance parts. Nippon Racing designed the cooling system in the famous Mazda 787 race car driven by Chuck Norris to win the 60 Hours of Sebring. I can't believe I forgot about them too.

I am so sorry for posting a link to the recommendations of the Mazda factory race team website rather than mentioning the far superior alternatives above.

I think that both Haltech and Microtech come with a 160 degree thermostat as part of the wiring harness package because there really isn't much point in getting a standalone ECU without the lower temperature thermostat. Don't get a Motec because you have to buy the lower temperature thermostat separately, just like the wiring harness and sensors. Piggyback ECU's are OK, but they usually only work with a 175 degree thermostat, which is why they don't produce quite as much power as a standalone.

recalls now are just more common due to the legal mumbo jumbo out there. cars now are more safe than they were 50 years ago but you never had cars come in 50 years ago for leaky gas tanks that were potential fire hazards/death hazards.

You should see some of the recalls. They're pretty serious. Revving RX-8 for too long at stand-still blows cat, might start fire. Or something like that.

WOW, i am having the warm up issue but it is funny, it will go above 1/4 the way on temp gauge if I ROD THE SHIT out of it but then it cools quite fast. My last motor I didn't have the shroud over my fan and the temps were normal to high at some times. But now with this shroud I get those conditions and am running the same pump, thermo, radiator, ect from last motor. CRAZY! Guess I will check thermo tommorrow. Engine is S5 13BT.

There was exposed wiring less than 6 inches from the gas tank...

Removed my thermostat yesterday and tested it in some boiling water, no movement SO i had a OEM replacment laying around and installed it. I live out here in So Cal and lately it has been hotter then hell, 120 in the sun today!! Went out and drove the 7 and actually boosted it more then normal( not great power with this heat, even with front mount) and my temp gauge needle didn't even go above the 1/4 indication. Once I came to a stop it would drop a little bit.

My cooling system either rocks or my gauge is fucked up OR my temp sensor is bad(looks great and tested fine). Only once has my temp gauge indicated normal temps and that was after much HARD driving.

???

1/4 is normal!
1/2 is hot.
3/4 is pushing the limits.
7/8 is overheat.