funny, all this fuss about ducting & thermostats and few people do whats important:

1) maintain their coolant system (dump old for new)
2) bleed their system properly
3) run an ACCURATE water temp gauge

i removed the lower tray, run stock radiator and have vdo gauges for oil, water, etc... temps were always good (~180-190) and on super hot days out here in socal.. ac on, off, uphill runs.. all the same.

as for running with no thermostat, well.. if you generate that much heat you're better off just getting a lower temp thermostat.

Myth.

Indeed. The fans are going to turn no matter what. If the force of the incoming air is all there is to turn them, then they will effectively offer resistance against it. If you give 'em a little electric oomph, they will help it along.

I thought the consensus was this ISN'T a myth.

Heck, the newest MS-iii firmware is going to add a trigger to prevent fans from running at WOT.

IIRC,

In WWII airplanes, it was discovered that propeller aircraft, when in an engine failure or engine off condition, actually required a much steeper glide path, when the propeller was spinning vs. a more shallow glide path when the propeller was halted. A halted propeller offered much less wind resistance than a free flowing propeller, and it allowed the aircraft to better maintain airspeed and kinetic/potential energy. In order to counteract this, some later aircraft engines were designed to stop the propeller from spinning in an engine failure/engine off mode.

Until the speed of the fans approach the speed of the air passing through them, the actual effect is more wind resistant than aerodynamic. At full on, the fans are pushing what? 25 mph? 35? How does that compare to track speeds?

Just sayin...

quote from fogger 03: If you've raised the back of your hood (cowl induction?) then put it back down. Mazda put the rubber in there where your hood seals to the rear of your engine bay for a reason. That's a high pressure area and will serve to significantly reduce airflow through your heat exchangers.

now i've stated this before, and i don't know if it's because of my setup (cutout frt. bumper, splitter,etc....) but on MY car, the raised rear of hood allowed alot of heat to escape! yes, in the very center of the hood the air flowed in, but on each side there was hot air coming out at speed as you can see in the video below. and in traffic, when the fans are on there is incredible amounts of heat coming out all across the hood.
lastly, a magazine tested this concept with air and coolant temp sensors all over the place and in fact used a miata as the test vehicle, and there were significant drops in under hood and coolant temps.
personally, i don't like how it looks, but it worked great until i was able to install a drop vent/headlight delete hood recently.

http://www.youtube.com/watch?v=ejPk2eBnr7o

I've done the same and my strings got sucked in after 40mph:




that magazine test was bogus, there were so many flaws in the test method. and i keep asking: why does it matter if your IM's surface temps are 190*F vs 200*f?

like i said, my car might be different with the splitter and big cutout in the bumper. but i did notice that it looks like you just pulled the rubber seal and didn't lift the hood at all, so that might make your results different also. i also noticed smoke coming out from my hood once at the track. i was doing over 100mph and had a oil leak from my catch can make a smoke stream that went up and over the corner of the car.

:laugh: What turbo are you running?

wawaweewa!

Agreed. When I manually activate my fans on the highway the coolant temp drops.

Reality > theory

C

pick a car

point being, you're better off looking at your losses than doing useless stuff like thermostat removal or reroute to cool your motor. sealing off the radiator, larger radiator, maintenance & proper bleeding would be more advantageous. if you're still running into high coolant temps, then get a fuckin setrab oil cooler and be done with it.

i cant understand how anyone judges temps with stock gauges. theyre practically useless (moreso on the nb)

The one that you removed the undertray on, and are running the stock intercooler. You know - The car WITHOUT A TURBO.

Sorry, coolant reroute is proven. Please try again. An oil cooler for my coolant? You do realize the the specific heat of water will absolutely blow oil away every day of the week for the purposes of cooling, right?

Stock gauges are far from useless. Granted, we're not going to tell exactly what temperature the engine is operating at, but a person can tell the difference between 11 o'clock and 1 o'clock

run an oil cooler and tell me what happens to your high water temps


undertrays are overrated. in case you didnt realize, the factory calls them splash guards. they dont tend to do much of anything

The tray keeps high pressure turbulent air from reducing radiator flow. My tray goes back to the steering rack for a reason.

you should never remove a t stat by the way, it will actually increase engine temp... the t stat is designed as a restriction to water flow on the radiator, without it the water will flow too fast thru the rad and will not let it cool down

I don't think that is true. Yes the radiator inlet/outlet delta would be less if you flow faster, but the faster you flow water through the engine & radiator, the more heat you will extract from the engine.
The goal is more engine heat extraction and a cooler engine and not delta between the radiator inlet and outlet.

People who remove a t-stat usually see cooler operating temperatures leading to the motor running in 'warm-up mode' making the car run rich longer.

Wow, really? Do you realize that by using your concept, I can throw money into a fire to become rich!?!?!? STFU, and learn to think logical thoughts - thermostats were designed to INCREASE engine temperatures. That is their primary purpose in life.

It's not possible to extract 'more' heat from an engine by changing the cooling system unless the change in the cooling system fundamentally increases the heat energy generated. Does your theoretical thermostatless setup produce more heat energy than an identical thermostatted setup? Two otherwise identical engine setups that run at different operating temperatures will produce identical quantities of heat energy. The cooling systems will extract identical quantities of heat energy. The setup that keeps the engine cooler is simply able to extract that same amount of heat energy with a lower delta relative ambient air temperature.

Just to chime in here - past weeknd I flogged my car at Road Atlanata in 97F ambient temps in 20min sessions. NEVER saw the temp gauge rise past halfway (yeah, stock temp gauge) and ran long enough to get 184.5F tunnel temps by my foot - was not comfortable. I run a 180 thermostat with 4 1/4 holes drills in the top of it, with a reroute, ebay Godspeed rad, 25row oil cooler... and mad ducting. I also added a splitter this weekend that goes to the rack.

Also, I've heard the same thing with running w/out a thermostat - coolant passing too quickly to absorb max heat. Don't know if it's true for our engines, but in the refrigeration world I work in it's true, too much refrigerant flow will not allow enough time for heat transfer...

Once the evaporator is covered in ice, warm air is not allowed to pass through. Ice will actually insulate the evaporator. Also, it's a huge waste of money to run a refrigeration system quickly because of the vast amount of power that the compressor consumes. You want to get the most cooling possible out of every cubic inch of refrigeration that goes through the compressor. It is therefore much more economical to run refrigeration slowly, and the cons of frozen evaporators suggest that little to no cooling capacity is to be gained by overclocking the compressor.

i removed the thermostat on my 99 mustang with an 03 cobra swap and used it for dd and track never overheated but took awhile to heat up lol

Originally Posted by fooger03 : I experimented pulling 1 fan relay, then driving on the freeway at 55 mph (it was hot and traffic was a bit heavy). It overheated. I then reconnected the relay, overheating gone.

Bill Cardell observed the same thing driving through mountain passes. Fans help even at speed.

https://www.miataturbo.net/showpost....7&postcount=23
http://www.jaycorptech.com/pc-62-14-...th-shroud.aspx
http://www.jaycorptech.com/images/PRODUCT/medium/62.jpg

You don't count.

edit: or maybe you do. How much of that shroud is 1-way flaps?

You do not recall correctly.
 

This hypothesis is wrong.

In the situation you describe, when the propeller isn't turning, they feather the prop so that the blades are parallel to the oncoming airflow, offering the least resistance. If the propeller cannot be feathered, and it cannot turn, it is an enormous speedbrake.

A spinning fan will offer less resistance than a non-spinning fan (unless it is being actively spun in the opposite direction against the airflow, which is not the situation we are talking about).

It has to. For a given airflow speed, there will be a fan revolution speed which is a net zero impact to that airflow. If the fan spins faster, it will begin to produce thrust and speed up that airflow. If the fan spins slower, it will begin to create progressively more drag the more it slows. Extend this to zero rpm for the fan and you end up with the most drag.

Another way to look at it - a non-spinning fan will create the highest perpendicular delta-v to the airflow. The air has travel across the width of the airfoil. If the fan is spinning, that distance will be less (because the blade is moving out from underneath it as the air is traveling, reducing the distance), therefore less energy will be taken from the airflow (less resistance to the airflow).

Edit: does anyone know if the cooling fans are speed-governed? If they aren't, and there's just a voltage applied across the motor, then they are going to spin much faster at speed than they do with zero incoming airflow.

Its five pages long, its late so I will post my universal bullet proof experience:

Coolant as usual, the bigger the radiator the better and the best fans that push the most volume of air.

One thing is I have a switch to turn on the fan on demand.

Stock radiator or aftermarket aluminum no difference, just the largest radiator with the most rows available.

I ran 10@1 with 2 layers of the head gasket removed, 215 compression, NGK 7 and never went past half the temp gauge on hot FL summer weather boosted at 15 psi.

Wow, really???? i sure sound like a retard... anyhow, by dyno testing a turbo mustang we've seen increased engine temps when running with no t stat compared to a cooler or even stock t stat installed... so from field experience and also by talking to a former colleague, running with no t stat is not recommended to anybody, if you really think about it the flow restriction is necessary on the cooling system to keep everything working in balance.

i almost forgot, a t stat is designed to achieve optimum engine temp in the fastest time possible, not to increase engine temp :loser:

I think I will replace the fans next with fan relay, and add another small fan infront for the A/C coils.... what so special about this fan?

Sigh I have replaced all the coolant hoses and changed to aluminum radiator, but im still overheating...sad part is my car is not even boosted.... i bet somewhere its leaking coolant

Do you have the Mishimoto radiator? If you have, check the cap. The Mishimoto caps seem to leak very often. My first Mishimoto cap leaked all the time and the second one leaks on the track on a hot day. I just ordered the 22-24 psi cap from FM.

And by the way I do not have the T stat. I did a minor change, instead of removing the whole thing and having a big hole for water to go through as I have read some resistance is needed to prevent cavitation.

So the T stat was stripped out on the middle, but the flange is placed on the CH. Only the center part of the T stat is missing, it creates some resistance, not to much flow as when not having anything and not to restrictive when having the whole thing. To me, in my case, in this specific situation, it works for me and is the happy medium.

That is all wasted breath, it's been extensively tested and proven:
http://www.google.com/search?btnG=1&...ling+propeller

The major variable on whether this is true or not tends to be propeller pitch, so in cases where the aircraft has an adjustable pitch propeller, It may be possible to set a very steep propeller pitch to negate the effect; however, on aircraft with fixed propellers, it is very nearly ALWAYS advantageous to have a stationary propeller vs. a freewheeling or "windmilling" propeller.

In case you've forgotten, we're talking about track driven turbocharged miatas...

Not your dyno queen. The cooling factors going 0mph on a dynamometer are outrageously different from those at 60-140mph on a race track.

If your experience is that running thermostatless increases your engine temperature, then:
A: Stop running antifreeze
B: Add a bottle of water wetter
C: Please post results of your controlled experiment, with multiple and identical runs for each setup in identical conditions.

damasodeljr, don't get your panties in too tight of a bundle. We both agree on the point "Always run a thermostat"

JasonC SBB above has posted an example of an extremely good, absolutely relevant, argument. Had he not been running a shroud, I would have almost immediately dropped my argument. Since he is, I'm not sure.

i like turtles.

This is true if you consider only a single trip through the radiator. If you consider the entire, closed loop, continuously circulating enigne/cooling system, it is nonsense. In the latter context it violates 2 laws (and 18 more minor regulations, statues, and executive orders) of thermodynamics.

M.

I think I can contribute here. I have some experience with power plants. I'm going to oversimplify a little.


On a typical power plant:
The pump to cool the heat source has multiple speeds.
The pump to cool the water/water radiator also has multiple speeds.

When there is large heat production both the heat source pump kicks into high speed and the radiator pump kicks into high speed. It's never only one or the other--water has to move faster through both the heat source and the radiator for it to work.

I suggest that removing the thermostat is akin to kicking the heat source pump into high speed. It can only work if airflow is also increased through the radiator.

Guys, you need to stop thinking of removing the thermostat whatever your gauges tell you. Removing the restriction on the engine outlet will reduce fluid pressure inside the block/head. The boiling point of the coolant will be lower leading to vapor pockets which in turn cause hot spots in the head. Just as Hustler pointed out on page 2 and delcbr on page 3... According to the book Four-Stroke Performance tuning by A. Graham Bell the pressure supplied by the pump is 30 to 40 psi at higher revs unless you remove the restriction.

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Perhaps I just don't understand the point that you're trying to make, but here is my counter-argument:

I'm not sure how you get that the water pump can function at different speeds based on how hot the engine is. I'm also not sure where you get two different pumps at. There is a single water pump, which is entirely dependent on engine speed. If we want a pump which pumps faster as the coolant gets hotter, then we need to install an electric water pump. Coolant temps are generally load based, not speed based - If I'm doing 80mph up a 20% grade, my engine loading, and therefore the heat produced, is going to be far greater than if I'm doing 80mph downhill, the other way. In both cases, the water pump is moving at the same speed. We compensate for this with a thermostat. The coolant will get hotter, the thermostat will open farther, the coolant temp in the radiator will increase, the surface temperature of the radiator will increase, and once that happens, the difference between ambient temps and radiator temps increases, which literally translates to a greater cooling effect at a greater load, all while maintaining the same engine speed and fluid 'pump' speed.

sup

did you fix this ?

Well I haven't done any serious driving since 2010 :( I moved and have been deplyed for the last year. Planning on a 1.8 swap soon hopefully. I did go all water/water wetter though which worked for the track day I made this thread for.

duct your radiator next time damn it. ;)

Yeah I imagine I will do that when I take everything out.

You have to duct it or it won't work on the track when you learn to drive like a man. Buy a roll of plastic from speedway and a bunch of rivets, thank me later. I'll take detailed pics of my oil cooler set-up if you promise to play handball with me.

In fairness, by "power plants" I suspect he was talking about commercial power generation or some other industrial application.

That said, removal of the thermostat is indeed evil. Yes, it will increase the rate of flow through the system. But removing that restriction also takes away the key element which causes the coolant pressure within the engine itself to run 1 or 2 atmospheres above the coolant pressure in the radiator, and this increase in pressure does increase the boiling point of the coolant within the engine, which retards the nucleate boiling process.

:eek3dance


Good info here, never thought of it that way.

Thats why you gut it instead (great explanation btw Joe! prop ;)). Get ducting first, thats wayy more important than maximizing flow.

It has everything to do with flow, of air through the fins of the rad ;)

As with the powerplant example, there is little use to increase the flow on only one side of the heat transfer, especially if the flow on the other side is the one that needs fixing first.

Does anyone know what the pressure difference over the Tstat is at high (but non-cavitating) revs?
Just curious of how much higher the pressure is in the head compared to the rad cap.

I spent 2 days under my car - bumper removed - to do a proper ducting...

Before that, I tried everything I could think of to get the car to cool off - it would cruise at 215* easy at 80mph, I was cycling the A/C off so that it wouldn't go above 235*

Now that everything is sealed up, I'm willing to bet that my ~160* thermostat is very rarely full-open. On a 95* day, at 80mph, with the A/C on full blast, I think I was able to get the water temp up to 192* once. I realize it's not track driving, but compare the before-after of doing a proper duct job with that...

Ducting the radiator is much more important than a gutted thermostat. I am not sure what you are trying to say.

Just that, nothing more, nothing less.

Speedway has it for sale right now. Just bought a roll.

Speedway? Link to sight please

http://www.speedwaymotors.com/Garage...eet,35873.html I guess.

would removing the AC condenser have an effect? Seems like it should increase the amount of air that the radiator sees by a good amount, what with all the bent fins that they all must have by now.

Massive effect.

FYI, removing the thermostat is not a good idea. The pressure gradient produced across the thermostat is what moves water through the system. I run a gutted thermostat in Theseus, so you can do that if you want, but don't just remove it.