First of all, I did search. I read through a bunch of posts and there wasn't really a difinitive answers. So onto the question. Is a bigger radiator necessarily better? A koyo radiator is actually bigger than a fluidyne, but everyone seems to agree that the fluidyne is better. Is this just because of fitment issues with the koyo? Has anybody gotten better use out of one or the other.

I'm about to upgrade to a single turbo and realized that I haven't replaced the radiator yet. Trying to decide between the 2-row and the slightly smaller fluidyne version. I'll be using some sort of FMIC, haven't decided which yet. Any help would be appreciated.

 

At some point, the radiator will be too thick to flow enough air through.....the Fluidyne works extremely well and has less fitment issues.

If the Koyo cost as much as the Fluidyne, it wouldn't be nearly as popular.

 

i have a koyo radiator i did installed it my self and im not really the type to get my hands dirty besides the basics. It took me about an hour to install it my self. as far as single turbo goes im not sure how fitment is im curently undergoing single turbo but im not working on my car. its at a-spec so im not sure.

 

This what I got out of my research on it:
Copper is most efficient. Koyo has a copper version but that's not the one listed anywhere.
Plastic end/water tanks are bad because they are prone to crack. Aluminum radiators have aluminum tanks.
Fluidyne and Mazdacomp are more efficient then Koyo and don't need to be as thick.
Koyo has a triple pass racing version that cools more then the two row but racing stuff isn't better on the street.
Fluidyne fits just like stock.
Single turbo 7's don't need stock fitment.

 

Ok, so what makes fluidyne or mazdacomp more efficient than koyo?

 

Every car seems to be a little different. Fluidyne has less fitment issues, but not zero.
Would one be a better choice if he intends to run a fromt-mount?

 

It doesn't really explain "how" or "why" it's more efficient but AWR is 1.25" core and Koyo is 2.08" core and they both claim about the same cooling range with nothing specific to FD. I'm not shure how much thicker their tripple pass is or if it is. Not shure if this helps any.

http://www.awrracing.com/pages/cooling.html
http://www.awrracing.com/pages/btu.html

 

With a FMIC fitment will not be an issue as it will be mounted differently unless clearance is an issue since Koyo is 3/4" thicker.

The 3-row turn flow is 2" & 1/16"
http://cgi.ebay.com/ebaymotors/KOYO-...QQcmdZViewItem

http://www.good-win-racing.com/mazda...ml?id=mQpUXpme

 

I noticed that the proprietary radiator that comes with the knightsports V-Mount kit (which looks to be the nices available) is some 70 mm thick, and four pass. It was built for them by Ron Davis racing radiators who ought to know their stuff and use quality cores.

i'm not sure the threshold of "too thick" occurs between the thickness of the fluidyne and the koyo. Perhaps the efficiency difference, if there is any, is in the core/fin design? Also, I believe the fluiydyne (I have) is a single pass.

 

[QUOTE=GoRacer][I]
Fluidyne and Mazdacomp are more efficient then Koyo and don't need to be as thick.

I and " No Cones" have found the Koyo triple pass solved our track overheat issues. We both ran the Mazda Comp for years prior and found after all the cooling mods and still running to hot, the Mazda Comp was the weak link. I was at Lime Rock Park on Monday, peak water temp per PFC 89C, that's with Evans which tends to run hotter.

 

i got a fluidyne and it works really good.. it fixed my overheating problem

 

Before deciding on a radiator, you need to let us know how you will be using the car. If you are not going to be road racing, a smaller capacity radiator will be fine. I assume that you won't be road racing since you have decided on a front mount intercooler.

 

1.) Keep your goal in mind.
I think it's safe to say that our goal is to keep our engines from overheating. Don't get distracted by extra information, just focus on acheiving your goal.


2.) The BEST setup is different for each car.
If you're building a car for track days and competitive roadracing, you'll be at full throttle for longer durations than most other cars, which generates more heat. If you're doing a lot of street driving, it's unlikely that you'll be at full-throttle as often, so you might not be willing to spend over $600 on a radiator, when a $400 radiator will work perfectly for your needs.


3.) Efficiency vs. Volume:
For radiators, efficiency is (Heat Dissipated) / (Radiator Volume). If two radiators are the exact same volume, the more efficient radiator will dissipate more heat. However, you're not likely to find two radiators that are the exact same volume. The thicker radiator will have a larger volume, which might (or might not) compensate for its decreased efficiency.


4.) Other Factors
Efficiency and volume are NOT the only things make a radiator work well. One of the most important factors is airflow. The radiator cools the engine by transferring heat to the surrounding air. Cooler incoming air will make the radiator work better. Faster airflow across the radiator will make the radiator work better. Many people have proven that ducting and fan control can be more important than radiator choice.
Another thing to consider is the OEM thermostat isn't fully open until 204F, which means that you're not using your radiator to its fullest potential until 204F unless you've modded your thermostat. If you want your car to run cooler than 204F, you might want to consider thermostat modifications before radiator upgrades.
There are quite a few other factors that I haven't mentioned, but I think these are the most important (in this exact order): fan control, ducting, thermostat, radiator volume.


If you're going single turbo, don't forget your oil cooling either. If you've got a single OEM oil cooler, you should upgrade that as well.
-s-

 

If you have an upgraded SMIC (like me) and choose to go with an aftermarket rad,then the fluidyne is a must due to fitment issues.

 

A lot of people assume a thicker core is better. But if you study the heat transfer equations, temperature deltas, fin thickness, fin density, channel spacing, etc, it's actually pretty complex. Every change is a trade-off. Radiator and heat exchanger manufacturers have computer programs to calculate the performance of a particular design, and even their application engineers never quite know the results before the numbers are run.

Bottom line is that I've never seen a true comparison of the radiator designs out there now, so the only thing that's reasonable is that the bigger aftermarket radiators do better than stock. There's really no way to know which aftermarket designs are best without serious calculations or strict testing.

Dave

 

To Quote Scotty-

1.) Keep your goal in mind.
I think it's safe to say that our goal is to keep our engines from overheating. Don't get distracted by extra information, just focus on acheiving your goal.


This is exactly the first step. Koyo and Fluidyne are both good upgrades for the FD's stock radiator which has plastic endtanks. Both of these radiators fit fairly easily in to the FD with little to no extra effort. These radiators make a great stock replacement for cars that see mostly street driving with a little track use. That being said, If you're car sees serious track time- you will want a larger radiator, better fans and larger oil coolers. Remember that the rotary engines' number one enemy is heat and build accordingly.

 

I concur with Scotty305 in his post (above).

I will emphasis that Airflow is the key, especially for the FD. From a thermodynamic perspective, it is airflow, not radiator core size, which is the limiting factor in heat exchange for all but the most extreme conditions. Anything you do to improve airflow through the rad will improve its cooling. Thicker radiators tend to reduce airflow (but do hold more transient or specific heat), so there is a balance to be struck.

For my money, I would stay with the stock or intermediate size rad, improve the airflow and spend my upgrade $$ on an improved oil cooler.

 

Great points there guys, I think I'll be going with the slightly smaller radiator instead of the 2-row. I'll be on the street mostly, with maybe a track day thrown in here or there. I hadn't thought about oil coolers either, so I guess that's where the extra money will go to. Thanks for the help guys.