MazdaManiac

iTrader: (3)

Either way, it is wrong.
Changing the ratio has nothing to do with "thickness" or flow.

Then do it. You will be surprised by the actual correlation.

Pretty much none whatsoever until you are above the 1000 HP range.

Entirely different scenario.


Spraying and intercooler is NOT the same thing as spraying a radiator.

Do you proof-read anything you write before you hit "submit"?

dannobre

iTrader: (3)

Strange you say that about the transmissions. I have monitured the transmission temps on my car...and I am way over what I would consider OK after about 1 hour on the track in the summer. I would imagine that those of you in Phoenix and Vegas would find the heat too much a lot faster than that.

Had a nice Voodoo metal **** that I couldn't hold with my bare hands...and barely with my Nomex driving gloves

MazdaManiac

iTrader: (3)

Interesting.
My tranny case is usually right about the same as my engine temp.
That said, the tranny doesn't really care that much about how hot it is until it starts seeing something north of the 300° mark.

DocBeech

iTrader: (1)

No of course not, anti freeze is much thicker than water. So reducing the amount of anti freeze in the system wont help you at all. It makes no sense what so ever. Anti freeze also doesn't have the same amount of heat transfer properties that distilled water does. The more distilled water you can get in the system, and the less anti freeze you run. The more fluidity it has, and the more heat trasnfer capability it has.

I actually have a carbon fiber hood on my car, thats how I know. Its been on the car for a couple months now, and the engine has been staying a little cooler under normal operation. My next step will be to add a sprayer and then to do the fan install on the oil coolers. It gets hot here, When I get home I will post the photo where I had an in car temp gauge reading 130 on the highway. Anything I can do to lower car temps I will do.

As for the Transmission cooler. My buddy Jay had to install one on his Corvette, and its running at about 750whp. His situation was also a must do, not just something he wanted to do. If the rear rotor on our car is serving as a problem, then cooling the transmission surely wont do anything but help, with the exception of in the winter.

Now Im not sure exactly how much of my post you read, spraying and the intercooler are the same thing when its the system I am talking about. I am talking about the intercooler/radiator systems that spray nos to help with cooling. <-- we are on the same page about this right? To clarify I have never used NOS in the throttle body or inside the intake. Only as a cooling tool.

MazdaManiac

iTrader: (3)

This is completely wrong on several levels, but it has already been discussed in several places.

Also discussed to death and the data about how air moves through the engine bay demonstrates how coincidence is a deceptive indicator.

Those systems are NOT designed to be sprayed on the rad, just the intercooler.
The temperature differentials and the thermal loading are completely different in those two systems.
I've watched more than one radiator virtually explode when hit with tap water after a hard track run.

DocBeech

iTrader: (1)

These numbers speak for themselves to me. Water is second only to Mercury when it comes to the ability to transfer and move heat.
Thermal Conductivity of AntiFreeze = .14
Thermal conductivity of water = .67

On a second note the viscosity of distilled water around 70 deg is 1.0 where as for Antifreeze at the same temp its 17.8. So nearly 18 times thicker than water. Heres the chart if you want to read it: http://www.engineeringtoolbox.com/ki...ity-d_397.html


So coincidence or not my car is running cooler after the install. That was the only mod that was done on the vehicle that month as well. Obviously the temps on the car now would be obsolete being that it was in the 85 deg range for a month and a half, and now its in the 40 deg range. I understand that much, but I am talking about the drop in temps I saw when the hood was first installed.

Never had a problem with a spray system. I had one installed on the 427 before I bought the super charger for it. Ran it for about 8 months then just moved it to the intercooler. The system never had any problems, and the radiator never exploded. I drove that vehicle in both SoCal and Arizona. Had to use the system numerous times to prevent engine damage. So from my experience I have never seen that kind of problem with this system.

MazdaManiac

iTrader: (3)

Thermal conductivity is only a small part of the overall equation.
Thermal inertia (effusivity) and flow rate are more important.
Also, viscosity (or, what you really mean - fluidity) ratings (in mPa·s) are not linear in their relationship to flow, not to mention that 17.8 mPa·s at 70° is roughly the viscosity of honey.
I'm pretty sure you've seen antifreeze. It is nowhere near the viscosity of honey.
Pure ethylene glycol is about 16. Mercury is 1.5. Do you believe ethylene glycol flows more slowly than mercury?

DocBeech

iTrader: (1)

Yes antifreeze does flow a lot slower than mercury. Just because its heavy doesn't mean its not fluid. Put them both on a piece of paper and see which one flows faster. Anti freeze is thick. Mercury switches are very sensitive. Pure antifreeze is thick, what most people touch is 50/50 which cuts it in half. Making the viscosity a bit under 9.

The important part is heat transfer. The whole purpose of the system. Anti Freeze doesn't transfer heat well at all. .14 vs .67? your talking about a huge difference. The fact that water transfer heat so well, means it can absorb more heat in less time as well, and move that heat to the radiator.

Mercury Viscosity is .118, just slightly higher than water.

MazdaManiac

iTrader: (3)

I think there might be a date with an IR thermometer and a concentration meter in your near future...

EricMeyer

Well I've got a couple of guesses and their exactly that---guesses.

Alec, what is:

1. The need to circulate a coolant through the entire motor to maintain a constant temperature in all areas to dissapate heat / avoid hot spots.

2. Engine bay packaging (the radiator is almost always in the front and why take the long path over the river and through the woods to grandmothers house. An extra long hose weaving through the engine bay would add more design constraints to the other required automotive systems (steering, brakes, emissions, suspension, A/C, other). Thinking about V-8 motors of the past, typically there is nothing else in front of belts and/or behind the radiators (and there shouldn't be) so therefore that spot is pretty open. Seems plausible, yes?

3. Probably some obvious reason that I/we have yet to learn.

My gut says this is not rotary specific. Thinking back on the oldest auto engines I can think of, in and out coolant hoses always appear to be entering/exiting very near the radiator.

My gut also says that somebody on this thread is going to seek out and find info on this and share with all. I left a post it note on Henry Ford's headstone yesterday. If his ghost gives my Ouji board the answer, I'll let you guys know.

EricMeyer

Both of them?

EricMeyer

We ran a tranny cooler with -10 lines to the rear of the car to a small oil cool rad with a fan blowing air through it. Still ran 250F when she was hot. Interestingly enough, the temps didn't dramatically decrease without the cooler. The old SpeedSource RX-8 Grand-Am ST cars never ran one of these. We did it in hopes of making the 04-08 trans 3/4 syncho and shift fork last longer-----negatory. Keep in mind this was with headers/exhaust running right along side the tranny case too (which I would assume would have soooome heat transfer) Maybe. Perhaps?

All the other RX-8 Grand-Am racers/SpeedSource car owners never ran or tried a trans cooler. Like us, they just carried a crap load of spare tranny's with them.

The big boys will REM or WPC (or some other type of microfinishing treatment) their gears and this does lower temps. We may have experimented with this in the older transmissions and found reduced temps and higher power on the chassis dyno. But it didn't cure the 3/4 design problem.

Side note: The 09-10+ tranny is near freakin' bulletproof. We have 4 of them now and they are rock solid. They weak link is the input shaft which is about 1/2 the diameter of the 04-08. But you can shift that sucker as fast as you can and she works great! 30 hours of everything I could throw at it (trying to break it on purpose to finds it's weak link) and the synchros were barely worn. This thing is awesome compared to those old POS that we would rebuild every 5 hours or so with damn near all new parts.

DocBeech

iTrader: (1)

The reason I know the change in antifreeze works is because of what we would do on vehicles when I worked for GM. Guys would move from up north where they were selling cars that had two row radiators. The cars sold here were 4 row radiators. Same vehicle its just where the car was thought to spend its life. They would move down here and have over heating problems. Well we couldn't always convince them to change to the radiators that would come stock on the cars from here. So we would change out the anti freeze ratio. We would do a custom mix to 0deg F which its never hit here in Dallas. This always solved the over heating problem they were having. Up north they are using 60/40 where as we can get away with 25/75 here. 25/75 protects you to zero deg, then you can add water wetter on top of it to improve heat transfer.

nycgps

iTrader: (1)

like I said in 9k's thread ... you guys are thinking too much about the heat issue ...

olddragger

iTrader: (3)

Now my reasoning for this thought is to help protect the apex corner and the side seals.

To continue with the same coolant path yet have a major change in the position of the exhaust ports which exposes critical parts of the engine to higher temps than ever before is basis for some thought especially after the number of early engine failures this design has seen?
In 1995 Mazda did some research of a side port design and of course in 2004 they did this again. Thats knew that the side seal was in trouble and they came up with the new design that supposes to eliminate carbon from getting under it. They also designed the omp injector so it would weep as close to that area as possible in efforts to lubricate and COOL it.
That was a failure as we all know.
They also increased clearances in the side seal/corner due to the heat factors. Thatwas a failure also.
They probably could not redesign the coolant passages due to expense. The entire package would have to be redone?

Now coolant temps at the heater hose site (drivers side by the knock sensor) is only about 10 degrees cooler that it is at the radiator feed hose. I have monitored both. This means the returning coolant IMHO is not picking up a lot of heat?
There are 2 exits for coolant in the rear of the engine
heater hose supply --drivers side
one for the throttle body--passengers side--its very small

Water versus antifreeze--lets not go there. For those interested read some of Evans coolant theory papers.

A redesign again imho may not be that hard. Electric water pumps have come a long way. One could be placed at the rear of the engine to pump coolant thru the engine toward the front, coolant exit would be close to the radiator and then a long hose from the rad to the ewp? The internal coolant passage modification that would be neccesary---IDK?
I wish I had the means to try this.
OD

dannobre

iTrader: (3)

Heat transfer is mainly due to the delta between the coolant temp and the temp of the parts they are cooling. The greater the delta..the more the heat transfer

If you think about it...the cooler side of the engine gets the coolant first when it is cooler...therefore the largest gradient in temps...

The hot side gets the warmer coolant...but is already warmer to begin with....so the gradient difference will still allow good transfer towards the coolant...and it then immediately exits the engine and goes to the radiator.......much better than the other way..that would result in the charge getting more heated during compression than needed...and trying to mimic a diesel

HiFlite999

iTrader: (2)

A few points:

1) If hot radiators in general explode when water is sprayed on them, they would also do so in a sudden rain or splash of water from a puddle. If such occurances cause massive metal fatigue, street car radiators (the ones not made from plastic anyway) would fail quickly. An exception might be if a modder is foolish enough to rigidly bolt it to frame members with no provision for expansion/contraction of the cooling tubes.

2) Water spraying works primarily through evaporation, and not via the heat capacity of the liquid. One can easily see why this is so from the attached pic. (Copied from here: http://hyperphysics.phy-astr.gsu.edu...rmo/phase.html ). It shows the amount of energy it takes to heat water through the ice/liquid/gas phases. 0 C to 100 C takes 420 J/kG. 100 C to 101 C takes 2300 kJ/kG, or ~ 5 times as much. Chilling the sprayed water beforehand is pretty useless. 0 C to 101 C will give you 5% additional cooling compared to 30 C to 101 C.

Of course moving air will also evaporate water and at temps well below 100 C. Still, it's well established in the HVAC world that a water (primary circuit)/water/air heat exchanger is vastly more efficient than water (primary circuit)/air one. Virtually every large building has heat exchangers on the roof that work with water evaporation this way. If you want to experience the effect first hand, go outside on a hot day and spray your AC condensor with a garden hose - the effect inside is immediate and dramatic. Don't do that on a regular basis though, cause you'll get scale buildup on the fins and reduce your long-term efficiency. This is also the downside of routine water spraying car radiators/intercoolers.

As far as the -8, most of the reported non-track cooling problems come from low-speed or stopped conditions which water spraying will be of limited help solving due to the lack of airflow. Otherwise, why not use it when needed?

HiFlite999

iTrader: (2)

I've not experienced it and the couple of reports I ran across didn't specify which one, but I'd assume it would be on the suction side (lower hose). I doubt if this occurs with new hoses and the factory configuration, but there are two elements of the stock layout that may help. The first (according to CW) is that the stock water pump (assuming stock pulleys) cavitates at high rpm effectively putting a limit on the amount of suction the wp can generate. Second, in the middle of the stock hose is a metal fitting which supports the hose in a rather long staight run. Going to a more efficient, non-cavitating pump will generate more suction. Getting rid of the metal fitting in the interest of simplicity or pusuit of the Golden Idol (flow) may either alone or together with a better pump result in hose distortion or collapse.

Note I'm just speculating (hence the original question) wrt the RX-8, but not so in other cases. In the good old days, we used to run into this problem fairly often. Hoses were pretty bad back then and often had metal coils (spring-looking thingies) inserted into long straight hose runs for support. If you pulled it out, the hose would suck right down flat when revving the engine.

HiFlite999

iTrader: (2)

Heat transfer, big time! Since it's all radiative however, a simple piece of thin aluminum blocking the line-of-sight between the two will cut it down to almost nothing quite easily.

How easy is a swap to do? (Street car). I'm already having some trouble with 3/4 at only 21k miles on the car. I'd hate to get the stocker repaired only to have the problem show up again in another 20k miles.

olddragger

iTrader: (3)

i run the 09 trans--and have been for over a year. bolt in swap.
Its heavier and bigger-so it does put it closer to the exhaust--like you say just shield it.
Also you cannot refill the trans fluid from up top --you have to do it the normal way.
Get a syncro saver and you can really jam the gears with no fears. The space between the throws is a little wider than the S1 model, the 3/4/5 gears ratios are much closer making accelleration and downshifting easier. You dont need a short shifter with it, the oem one is just fine. Reverse is in the right spot also.

Dan--didnt understand youre post? My thought was no hot/.cooler coolant. All coolant when it enters the engine would be same for both sides combustion and exhaust.
Per just laser surface temps--not very accurate i know---the exhaust side surface of the engine(not header!) is always hotter than the combustion side.-20-30 degrees F and thats on the surface.
OD

MazdaManiac

iTrader: (3)

Except for the PPF, which is a deal-breaker.

dannobre

iTrader: (3)

Not worth the price of admission Cheaper to find a working used one. The parts are stupid expensive...even if the labour is free


I have 2 spare that I have picked up for $500 or less each...one with 3200 miles on it...and the other with about 20 ( idiot wrecked it on a test drive )

MazdaManiac

iTrader: (3)

LOL.
I have one of those, too!

dannobre

iTrader: (3)

Wish I could have gotten that engine

jasonrxeight

you people are soo obsessed about running engine cool. sure you should not let it overheat, but running it too cool is not necessary good otherwise thermostat would never be invented.
if a rotary can do 100k miles with stock setting like some people have done, means its got enough cooling.