Who suggested it would???

As for the rest, you are ONLY adding 2 extra blades , your analysis is a little WOT in this case.
Comparing to aviation is not a comparison..really RX-8 don't fly...do they.

 

The extra blades are disrupted by the airflow from the rest of the disc so the gain would probably be marginal anyway, if mazda stuck a 5 bladed one in there it was probably for a reason - same as the blades being so wide and thick will be there for more pressure/chord speed to overcome the blockage behind the radiator at the expense of outright airflow.

 

Yeah it is called noise..reduction

 

Doesn't really wash, more blades is usually less noisy for the same design perameters. Usually you'd just change the strut spacing or the rpms if you were getting an audible harmonic from the blades passing the casing.

 

Actually, it makes perfect sense from the standpoint of harmonics and resonance. If the fans have the same number of blades, then they have the same tone. Two sources of the same tone, or a multiple thereof, can cause a resonance that is drastically louder than the sum of the two sound sources.

 

Unless the motors or airflow were perfectly matched the chances of the tone being exactly the same would be fairly slim anyway, although the overlap could be close enough for it to be a consideration, but then, if the fans are running then outright cooling would probably be a priority over a little noise?
Anyway, as I said, it would make more sense just to move a support strut to alter the tone from one fan if the 7 blades really did have an airflow advantage. I think it's probably more likely that it was simply that a 5 bladed fan suited the airflow at that side of the engine bay on a standard car.

 

I guess where MAZDA have stated that they REDUCED fan blades to REDUCE Noise means NOTHING????

The blades in question are NOT RX-8 specific and are used on many other Mazda models, Tribute for one...and the 5 blade fan is about $7 cheaper for Mazda to use.

The Series 2 use the exact same two Electric motors with the S1 5 and S1 7 blade fan, , so what about the harmonic distortion and load because it is spinning another 2 blades with the same motors...OOh! watch out..!...your flux capacitor will blow out.


"Oh no its not.."

PIA...

 

What's the same motor got to do with anything? Doesn't mean the load or chord speed will be the same.

 

Ah it's clear now, I thought you were suggesting to add another fan in front of the radiator; I stand corrected. Air is air, to cars, airplanes, and living room fans. Do you know if the rpm is the same between series I and series II fans? If noise reduction is the goal, and the fan diameter is the same, adding blades will allow, up to a point, the same volume to be moved at a lower rpm hence less noise. The fan+shroud comes close to what's called in a wider sense, a ducted-fan. If the design is clever enough, the fact that the edge of the opening is close to the blade tips, plus forming somewhat of a cylinder, the gap can be adjusted so that the "induced drag" of the blade moving through the air is reduced. Almost without exception, fans work more efficiently the larger their diameter, so a single large fan may be more effective (depending how it fits in the space available) than two smaller ones.

 

Where did I say about adding another fan IN front of radiator??

Change the existing 5 blade to a 7 that is all, nothing more nothing less.

Series 1 has same FAN Blades as S2, but different size motors (S1 see pic), do they spin at same RPM??

Series 2 has upgraded (all new not used in any other Mazda's like S1 Motors) same two fan motors, do they spin at same RPM?, one would think so.

So, my suggestion was ONLY to use the same 7 blade fan and put on the Left where the 5 blade fan is...see S1 pic

 

Plenty of people--but lets keep this thread uncluttered.
od

 

I'm going to suggest a variation:
1. REmedy pump to minimize cavitation in stop and GO traffic where you have higher revs than average but lousy air flow
2. small ancillary EWP to boost flow under low rev, high heat conditions where you have more STOP than go

I'm sticking with Evans coolant so I don't have to worry about corrosion and I can even out the heat load if there's a defect in my deduction. Also, I can install it and forget it, without the hassle of changing it out and finding a legal disposal for it.

 

Understand your thinking.

I THINK I MAY HAVE IDENTFIED SOMETHING.
I am just a backyard shade tree work on car fool- Ok.
But last night as I was installing a super secret, black opps, completly unauthorized thermostat housing and thermostat, I noticed something.
Its hard to explain but I will try.
Currently I am measuring the coolant temp at the top radiator hose. My gauge is accurate to 2-3 degreesF. Now also I have the Pettit set up and we have an idle speed at 1.1K
I no longer have a coolant bypass system and I have primary coolant flow all the time.
I noticed something at warm up that may have been masked before by the by pass system?

At idle the engine was warming as expected. NP. But while keeping a close eye on my coolant gauge i would give the engine just a little gas--maybe to 2K and then immediatly let off the throttle so it would go back to idle speed.
When I did that I notice that my coolant gauge would bump up about 2-3 degrees. That little extra surge of coolant flow would hit the sensor and that coolant would be hotter than the coolant being normally circulated. This is NOT the result of momentarly increasing the engine heat by higher rpm--- the coolant cant react that fast and the increased heat would be minimum to none.
So that got me to thinking AGAIN---Oh God here i go--right?
Is the mechanical water pump circulating enough coolant at idle and low rpms? Is the increased temperatures during stop and go driving a result of poor air flow to the radiators, or inadequete cooling flow during idle and low rpm operation? Or is it both?
Interesting.
My 1st impression was and is at this time, the pump is not flowing enough at low rpm to properly cool? I have nothing to prove this other than my own observation, but it kinda makes sense. Stop and go driving is where most people have trouble with engine temps. Right? IF the pump is not flowing enough at idle and low speed (less than 2K) and we have poor air flow through the radiator its the perfect set up for overheating/hotspots.
The poor air flow has already been discussed and recognized. The possibility of poor coolant flow at low speed has not really been identified as a concern. My oridginal idea/thoughts did not include this. I was thinking more about proper and stable temps.
IMHO this is more casual evidence toward a anxcillary low speed operation only EWP and a better thermostat?

 

you stll get some corrosion with the Evans coolant. I was a bit surprised at the amount with the most recent change out. Otherwise this has once again become another RX8Club thread on arguing pointless minutiae ...

 

How often do you change out your Evans coolant? I'm not asking to start or continue an argument. You have more experience with it than I do, so I want to benefit from your observations.

 

What is pointless about trying analize as best we can how to obtain proper and stable coolant temps?
Who is arguing?
You know I am not in a real good mood this morning and your comment is just not resting well with me--not that matters to anyone.
Some of us try things, see some things, try to figue out the best we can how to address some issues, share our observations/thoughts/ideas in an attempt to correct or improve our surrent situation and then you come with an asinine remark about how once again this thread has become pointless.
IMHO there is something basically wrong passing judgement on others thoughts and ideas without explaining why those thought and ideas are not the way to go. Its almost sadistic.
One time you gave me some helpful information concerning not posting unless you really had something to contribute. I appreciated that . The Evans coolant finding you did share was great. But then you had to add the other didnt you?

 

I think you're onto something. I know there are other cars where low engine speed coolant flow is so bad that the owners' manual will say not to let the car idle for more than 5 minutes (I believe it was the early 1990 something Ford Escorts that were notorious for catching fire if left to idle too long).

Do you have the OEM coolant pump or something else, OD?

 

OD, Interesting observation, but I think you're missing something here: there's a thermostat. Plus, consider this for a moment, the cooling circuit is not only moving heat, it's moving information. In any condition other than the one where the thermostat is fully open, it adjusts the water flow based on its target full-open temp of 180 deg F. (Ideally, the feedback loop would look at the OBDII engine temp and keep that at 180 F.) What's your information flow look like? {radiator} --> {lower hose} --> {engine heat added (OBDII sensor)} --> {thermostat} --> {upper hose}. Increasing the rpm increases water flow, which pulls more heat from the engine, sending a burst of warmer water to the thermostat, then the upper hose and to your sensor. The thermostat reacts in a few seconds by reducing flow - and then you see your temp sensor drop down again. Note the phrase "pulls more heat from the engine" is judgment neutral. The goal is to keep the OBDII at 180 F.

My add-on gauge sensor is in the lower hose, eg., the water feed to the engine. When I'm cruising, the feed water is running around 165 F or 15 F under the target of 180 F. In > 80 F weather, then traffic stops suddenly and I'm then at idle, the input water temp rises over a couple of minutes, but the OBDII temp stays at 180 F until the input temp reaches 175 F, then the two temps will rise together with 5 F or less difference. (An idling engine doesn't generate all that much heat). If there were a flow problem at idle, it seems to me that there would be a bigger difference between the incoming water temp and the OBDII temps. (Note: I do have the Mazmart WP - things may be different with the stock one). When I get around to it, I'm gonna add a second WT sensor in the upper hose. That should give a more complete picture of the cooling system. In principle, with the second sensor and the flow rate were known, one could take a thermodynamic snapshot of the cooling system.

 

thanks for the info---good observations. If I understand correctly the difference between your post radiator temp and your hot temp is only 15 degrees F? 180-165=15?
So the radiator is only cooling your coolant 15F?
I thought there would be a broader difference between the hot and cool temps?
Wow.
I understand what you are saying about thermostatic function. The example I used of the temp "bumps" was something that I did not expect to happen. I thought it was a smooth gradual increase in coolant temps. Maybe I didnt explain well enough but these little bumps occured multiple times--whenever i would just slightly increase the rpms. I did stop at 185F hot side. It sure looked like when the coolant flow increased just a little the temp would jump--if i kept the rpms up to 2K the temps didnt jump like that--it was a smooth increase. If coolant flow is adequete there shouldnt be a difference--should it?

I have never measured temps from the cold side. Thats good to know.

 

180-165=15F. yep, silly math error (I edited my post to avoid future confusion). It may be off by a few degrees, but yeah, the small difference surprised me too. I did the "boiling water" check of the gauge sensor and it was right on at 212F, but of course if the calibration slope isn't quite right, it could be potentially off a bit at 165 F. But a clue that the calibration about right though is how the temps connect with the rise in the OBDII which results from the 180 F thermostat being open all the way.

There's no question that the flow rate is lower at idle than at cruise. Ideally, the heat load (rotor housing) should be connected directly to its heat sink (radiator). Instead, it's connected by water flowing through several feet of hose and radiator tubing, so many seconds connect the "information" of heat from one end to the other. Additionally, the sink isn't clean, because heat is lost not just there, but in the paths between. With no flow at all, the radiator will eventually get warm (long after your engine fries). The quicker the flow, the more "firm" the connection between load and sink becomes. You might repeat the test, and note the OBDII temp - is there also a blip there? Does it occur a little before the blip in the upper hose? Knowing the distance between the two, the time offset should give a way to estimate the flow velocity.

Really though, if the OBDII temp isn't showing much variation, I'd conclude the idle flow velocity is adequate.

 

/\..Wow.you have WAY too much time on your hands...

Well yeah, frankly, you wont find any real revelations for 99.9% of your driving, unless you are stuck in a traffic jam for more than 15 minutes in 90+ outside temps without moving (Air Flow), mods are a waste of time and money.

 

also remember the stock radiator sucks. It doesn't provide much time or the correct angles to allow the fluid to flow great.

The alternatives force the fluid from left to right back to left at 45 degree slopes, where as ours just flows from top to bottom.

 

Ok new observation.
I installed a custom thermostat housing that I modified to accept the Stewart barrell type racing 180F thermostat. The thermostat as three 1/16 holes to allow flow before the 180F temp is reached. That also allow any air in the coolant a way out.
I no longer have the coolant by pass system.
I am running regular over the counter antifreeze. Oem radiator cap.
WITHOUT my secondary radiator set up.
Ambiet temps right now is 75-78F with humidity of 40-60%

Warm up was only very slightly affected ( that surprised me).

Interstate running ---- i am running too cool. At 140--155F. (My oil temps are ok)

These temps are per obdII and my top radiator hose sensor.

In town/stop and go driving---170--180F.

My radiator is 7 yrs old. I have the mazmart pump.
Now what this tells me several things
1- the OEM radiator is good as long as it gets good air flow.
2- the mechanical pump is pumping too much for ordinary driving on the interstate at those temps. (Wasted energy).
3- the OEM radiator should not be a factor in whether or not the EWP works?
4- a better thermostat will only work much better as part of a cooling package.

Plans--- this thermostat has three 1/16 holes for constant flow, I am tempted to close one at the time to see if that gets my interstate temps where I want them. Goal is 180F--in town interstate and track. It may end up as simple as that and then during the extreme temp season (+90F) just hook up my secondary radiator (takes 5 minutes).
Then during the hot season--see if it holds during stop and go traffic. I have a feeling thats when the axially ewp and better fans will be needed?

 

Without reading the whole thread I'm not sure if anyone actually has tried an electric pump or not ?

A local here fitted one recently and is a regular race competitor - can find out more details if anyone is interested ?

 

i am..