Radiatorworld.com radiator assessment
 

I am condensing a couple of posts from another thread, and at the end I'll show what I found.
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I replaced my stock rad (it was still working well, but this was for preventive maintenance purposes since it was 15 years old) with the one you (bajaman) recommended (brass OE replacement rad from radiatorworld.com), and my FD now requires the cooling fans to come on more often to keep the temps down. I sealed along the sides of the rad, etc, so I don't think that's the problem. The temps now also seem to creep up on hard pulls when the ambient is above 80F. It never seemed to do that with the stock OE radiator.
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Quote:
Originally Posted by Sgtblue
I'm not defending bajaman, but there are a couple of questions that come to mind that might explain your experience OTHER than the radiator change...
1. What's your coolant/water ratio and is it the same as before the change?
2. Where are you getting temps?
3. Are you sure you comparing at roughly the same ambient (time of year)?
4. Any other changes in tuning or mods?

1. 50/50, same as before
2. Stock location, same as before (linearized stock gauge) - did not change the calibration
3. Yes - even at warmer temps with the stock rad, I did not see these temperature variations, and the fans (I have the Miata thermoswitch) came on only while sitting still.
4. None, although I did replace the WP with another stock (remanufactured) one from Malloy at the same time.

I'm even using the same type of gasoline - Sunoco 94-octane.

Add'l info - I lose no water, and the engine runs great otherwise. Other than noticing more temperature climb, and the fans coming on more often, there are no problems related to this.
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Actually, I did do one mod at the same time - I put a restrictor in the water line off the bottom of the Pettit AST, the same size as the restriction in the stock AST.

EDIT:
My guess as to the cause of the temperature increases and increased cooling fan use:
The OE rad is denser (more closely-spaced fins) than the radiator.com brass rad, and thus requires less airflow to get the same amount of cooling (or conversly, with the same airflow, cools better). With the stock AC condensor and the stock hood in place, there may not be enough air-flow to make the radiator.com version work properly. The brass may conduct heat better, but the problem here appears to be not enough surface area to transfer sufficient heat to the air.

Therefore, I infer that going back to the denser stock rad, or a thicker aluminum aftermarket rad (Fluidyne?) would probably solve this.
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bajaman,

Thanks for your concern and your PM.

I am certainly not placing any blame on anyone for the temperature increase I'm seeing. I just didn't expect this result. I'm just trying to get to the root cause of this before I do anything that costs more money (like getting a new stock or aftermarket rad like a Fluidyne), and maybe won't fix the problem.

Since this is not causing a huge problem, I think my next move, when I get the time, will be to pull everything (PFS IC duct, IC, air intake, etc.) off so I can make sure all the areas where air could sneak around the radiator are completely sealed. I think it is sealed as well as it was with the stock rad, but I will inspect it VERY closely this time to make sure.
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RESULTS FROM MY EXAMINATION OF THE RADIATOR AND THE INSTALLATION:

The sealing around the new radiator was good. However, estimating the fin area was quite revealing: the OE rad had fins ~ every 0.052 in. The radiatorworld.com rad had fins every 0.087 in. Even with the r-w.com rad being ~1.25" thick, compared to the OE 0.97", this gives ~21% less fin area on the r-w.com rad.

Bottom line: Even thought the r-w.com rad is thicker and made from copper/brass, the reduced fin area does not give enough heat transfer to the air, and this is the cause of my running warmer with the new radiator.

I will probably have to go to a new OE rad, or to a Fluidyne to get the temperatures back to where I want them.

Thanks for everyone's help and comments.

i got the rw race rad, works great

Before you put a OEM radiator on let me tell you what happend to me today.

Leaving my parking lot, there was an accident on either way I left, so I had to wait in traffic at one of them for about 10 or so minutes. It was extremely hot out today, so I put up the windows and turned on the A/C, I noticed it was not blowing very cold at all but figured it was because it was so hot out. As I neared my house I caught a glance of my PFC, which was displaying 8 variables so its pretty small to see, but my coolant temp was 103C!

Now I have a Koyo radiator, and since installation, Its extremely rare that I ever even see the fans turn on (while at a cruise on a normal day it hardly creeps a few degrees above where the thermostat opens!). I pulled into the garage and popped the hood, than went and flicked the A/C figuring the fans would cool it off......my fans were NEVER running! No wonder the A/C didn't blow cold, stuck in traffic and no fans moving air through the condensor! My fuse blew and cut both of the fans off, I drove atleast 30 minutes mostly in traffic on a 95F day and only hit 103C. If I had been on the stock radiator my engine would have been toast, the koyo just paid for itself atleast ten times!

The duct on my PFS was to close to the fan wiring and rubbed a couple of them until they were bare enough to short.

Since you have the radiator out already, why not just get a real radiator and never worry about temps period?

I also have the radiatorworld brass OE replacement raiator. I have noticed that the water temps on the Power FC with the stock radiator took longer to rise past83 deg C than with the radiatorworld unit. I have my fans set to turn on at 89 deg C, but I have noticed that once fans come on, the temps seem to drop more quickly than with the stock radiator. I don't know if it is because brass/copper transfers heat more efficiently than aluminum, but it could contribute to it. I think it is a great radiator for daily driving, which is what I do, but if you are going to be making hard pulls often, I would go with radiatorworld's race radiator, or if you have the money a Fluidyne or Koyo. Just my .02

Fluidyne
 

I just ordered one from "Turbo Import."

$435 incl shipping.

Dave,

Fluidyne makes a good product. However, I have seen 2 different lengths of tubing on the inlet from the upper radiator hose. The longer tubing fits the fan shroud better, but raises the height of the upper radiator hose. This caused a fitment issue for my friend who had a stock airbox. The airbox would not sit low enough to be bolted down completely. My Fluidyne had the shorter tubing it fit fine with the airbox, but didn't fit the fan shroud. I would up having to cut away some of the shroud to get it to fit. The intake fitment may not be an issue for your setup. The rest of the installation was pretty easy. I also wound up cutting away part of the casing for the AC drier. I cut away the front part so that it would come out easily if I had to do this again. At the time, I didn't know to remove the radiator from the underside of the car ........ as the FSM recommends.

Good luck, Adam

The PFS air filter housing fits the stock upper radiator hose placement like a glove. The PFS filter box is within 1/8" of the hose. So, if the rad I get has the longer tubing, is that likely to cause the hose and the filter box to interfere? I can't make the filter box smaller in that area, since the K&N filters inside just barely clear now.

What else is different about the Fluidyne that might make it not fit?

Thanks.

Dave,

The longer tubing makes the stock airbox sit higher. I expect that you will likely get the radiator with the longer tube. I'm not familiar with the PFS intake, or how it is mounted. If it uses the stock mounts, and "expects" to be at stock height, it won't fit like it is supposed to. If this is the case, you may want to have the tube cut, and welded to a shorter length. This will mean the you will need to cut away some of the fan shroud to get the fans to bolt up to the radiator. The fan shroud is pretty hearty. Cutting away part of it will not compromise it. I cut mine, and have had no issues since I did it about 4 years ago. A second alternative would be to put some spacers in at the intake mounts, and raise the intake slightly. Hopefully, this won't cause any issues with hood clearance, or anything else.

As far as other issues, there was nothing significant. I do remember cutting away one side of a washer on one of the airbox mounts. No big deal.

Its been about 4 years since I installed mine, so my memories are not that fresh. One other thing: The drain plug on mine was a two piece brass plug. The outer part of the plug is not intended to be removed. The inner part is a valve. As I recall, the inner part goes upward (into the radiator) to drain the coolant. This means turning it the opposite way that you normally would to loosen it. Mine had to be turned clockwise to drain coolant. Be careful with it, so you don't break it ......... like I did :D

Adam,

The PFS filter enclosure would maybe be the problem on my setup. It's sort of free-floating, located by the hoses that attach to it. However, it can't be raised further, because it would then interfere with the PFS SMIC and also with the stock hood support rod (in the "down" position).

I think that with these possible problems and the success I had with the stock OE radiator for 15 years, that I will probably just get a new one of those, and avoid further fitment issues. Right now I've got too many things going on and don't need any more unforseen problems. I will cancel my order for the Fluidyne.

Thanks for your help.

Dave, I had the PFS intake and SMIC with the Fluidyne. Yes, the upper hose is a tad higher which makes the intake come up a little bit. There is no problem with the IC or hitting the hood support rod. The only problem that I experienced was that the very front tip of the PFS intake rubbed on the underside of the hood a little bit. I do not have this problem with the rx7fashion intake I'm now running.

The right-front-top corner of my PFS filter enclosure originally rubbed on the bottom of the hood when I first installed it, so I had to bevel that corner as it was to get it to fit properly. It also barely fits under the hood-support rod now, and raising it would make it interfere. Note that I did modify the PF intake and the PF IC duct somewhat when I installed it, so just becuse your Fluidyne fit well doesn't necessarily mean that mine will.

I am afraid that raising the filter enclosure even a tiny amount would cause more trouble than it's worth, considering how well the stock radiator worked for me for the last 15 years.

Thanks for the advice. I do appreciate it.

Gotcha. I think the stock radiator is unjustly vilified. It works great and is light. The end tanks obviously wear out over time (although a lot of other cars use plastic end tanks too), but other than that, there's not much wrong with it.

Yup - the possible problems with the end-tank seals was the only reason I replaced it at all. The radiatorworld.com rad was recommended, and it seemed like a cheaper alternative. Live and learn...

Thanks, again.

Isn't there a Mazda Comp. radiator that is stock size without the plastic end tanks?

Dave, Why don't you call fluidyne, and ask about the length of the upper tube? If it is the shorter one, you won't have any issues with your intake.

RP (rx7.com) has an all metal radiator for $300....don't know about fin count and such.

OE Radiator
 

Just ordered the OE radiator from Ray. It'll be here next week.

Thank you, adam c and rynberg, for your help and suggestions, however, in this case, I just decided to keep it simple. I know 1st-hand that the OE version meets my requirements, and there will be no fitment issues

Your advice was much appreciated.

Any time Dave :).

On another subject...
Sure glad I didn't take the FD to work today - we just had a severe thunderstorm with baseball sized hail. Everyone's car, including my Focus (which I don't really care about - it's just a car) has pretty bad hail damage. The Focus has at least a dozen bad dents.

I have read that the stock radiator fin style is superior to many of the aftermarket designs, as it transfers heat very well. The main issue is the capacity of the stocker.

I have to disagree, yes it works....but I think its a hell of a stretch to say "it works great". I'd say a majority of cars use plastic endtanks, but than also consider a majority of cars will never see 95C in their lifetime, which most of our cars see daily.

What do you mean by capacity? It's water volume, or its ability to cool?

I disagree with that statement. VW normal temp is 240F, on Toyota its 235-240F or greater than 100C. Main reason is emission.

On the VR6, there is a secondary electric water pump that continues circulating water after the engine is off. I have that on my car.

The plastic tanks is the main reson to replace the OEM radiator. Our cars do not survive overheating. It's not worth the risk of o-ring failure. You don't have to get a thicker Fluidyne or Koyo. Copper does work better then aluminum. That would be a better OEM replacement for a stock FD. All you have to do to reduce heat is replace the thermosensor for the FC version.

i just had my radiator dump all my coolant while i was driving the other day....but luckily the second the buzzer came on i shut the car off and rolled it to a side road where i would pop the hood to get a face full of coolant.

i have pics and a vid to detail the exact cause of the failure...but needless to say it was an all metal replacement for the OEM that failed due to a kink in the tubes.

I was about to purchase a radiator from radiatorworld (the copper one) and i just wanted to hear more long term testimony from others who have purchased from them.

That's one of the main reasons I posted on this subject - to alert others of my experience.

I will post the results (on whether the temps go back to normal) when I get the new OE rad installed. Should be within a couple of weeks.