kam

Hi i was wondering if the stock rx7 rad is good, i just got another brand new stock rad, because of my minor accident, but do i need to really upgrade the rad?? isnt the stock good enough?? another question, isnt the coolant in the filler cap normal to go low???

cash money

actaully is more cars, you wouldn't have to upgrade the radiator until you get a few mods and start running real hot, but the FD has an insuffecient radiator, it is terrible,
you can take cure of alot of problems by running evans coolant, but if you starts modding it alot, you will have to upgrade, i don't know how much a new Radiator costs from the dealership, but im pretty sure you could have gotten an upgraded one for the same or less money

Brent Dalton

iTrader: (31)

The main "weak link" is the AST....you can buy a aluminum one....but I would just pay $25 and eliminate it... just my $.02

pp13bnos

iTrader: (1)

If you use the evans, you can just take the line that goes from the ast to the overflow, remove the ast, and plug the overflow line into the filler neck one. Then just plug the line coming out of the bottom on the radiator. This will work, because with the evans, its a 0 pressure system. CJ

RonKMiller

The stock rad is perfectly fine (unless you are runnning a lot of extra hp) except for the fact that over time the plastice end tanks tend to crack and weep.
Lots of guys race with them with no problems. There is a general mis-conception that a "bigger" or "thicker" or "shinier" rad is going to work better. It's all about air flowing past the fins, and some of the thicker ones actually are worst since they impede air flow volume at lower speeds which is when you really need it the most!
Almost ALL cooling problems on third gens are not caused by the "inadequate" radiator. Double or triple flush the sysytem and change coolant yearly. I would buy a new OEM thermostat and replace all your hoses. Reuse the stock clamps. A pita and pretty expensive but this is the best insurance you can buy to stay running cool. The Evans is total overkill unless you are racing. Save your money for other mods like a dp.

pp13bnos

iTrader: (1)

Why is it over kill if it saves your motor? spending $80 for a case, vs buying a new thermostat, coolant, triple flushing etc...Its just more time effective, and cost effective in the long run to just run the evans. Not to mention, no more worring about the plastic ast or radiator blowing up. Jus my .02 CJ

djantlive

I think it's subpar. A car should have a cooling sys that will keep the car from overheating at idle. Obviously, FDs do not handle heat very well if it idles too long. The stock fans are pretty amazing in pulling airflow though.

If your stock one is busted, I would definitely go with a fluidyne one. Cooler engine last longer.

pweizman

I was just faced with this same question. My radiator went bye bye because of a failed plastic end tank. I was lucky I didn't overheat. It happened at home...and I was watching my digital water temp gauge closely....

I ended up getting an aftermarket OEM style replacement. However, it is NOT the same as the one that was stock in the car. It is an all metal radiator, and a bit thicker than the stock one. However, it is copper/brass construction...not aluminum.

This is a good alternative for someone that wants to keep the car mildly modded. The only draw back to the copper/brass radiator is that it is heavier than the stock one. A copper/brass radiator will cool just as well, if not better than an aluminum one with plastic end tanks. It just weighs more. I guess I will have to get a smaller battery to make up for the weight increase...

The cost was good too. I got it from a guy on the forums for $205 shipped. 1-800 Radiator had OE replacements for $231. Who ever said it would be cheaper to buy a Koyo or Fluidyne was right...if you bought the radiator from the dealer....but who would do that?

It should be fine for my car. I only put about 2000 miles a year on the car, and I think my mods won't go past DP/CB (currently)...and ECU/Intake in the future.

Later,
Patrick

artguy

the stock rad is NOT fine. It is incredibly inadequit and will spell doom for your seals when you run to hot. Ive been thru two motors on stock radiators...get the fluidyne or comparible...it will save you thousands later.

had I done it Id have a brand new friggen paint job..a huge intercooler and the radiator too...not another engine rebuild.

good luck

jason

GsrSol

Insurance probably bought your new radiator right?

I had a stock radiator, got into an accident and insurance bought me a new OEM radiator. I could actually see that the needle went down just a tad with the new one and haven't had any overheating problems with the Texas heat. If you have a brand new OEM radiator, it will be fine for a while, just flush it once-twice a year and run distilled water in it w/ a little antifreeze.

DamonB

My stock radiator started leaking from a tank a while back. Replaced it with another stocker from 1-800-RADIATOR. I live in Texas and the car never overheated in summer with the a/c on and the original lasted 8 years and 85,000 miles. I don't feel that is subpar performance for a radiator.

With a highly modded car I would certainly lean towards an aftermarket one with more cooling capacity.

technonovice

1. Stock radiator: It is adequate for casual applications, but if you can afford to replace it with a Fluidyne unit (~$500) it would be a purchase you should feel good about. My stock radiator breached at the end tank as well with about 90,000 miles on it. I think the heat and harsh vibration takes a toll on it. Tuner tests have shown the Fluidyne to perform well in cooling things.

2. AST: My feeling is that you are better off removing it than leaving the stock plastic AST, but the best action is to replace it with an aluminum unit. Why? The best reason is that the FD cooling system has a very limited amount of coolant and removing the AST alltogther reduces the the coolant capacity by about 1/2 liter. May not sound like much but the full capacity is only 8.8 Liters. That is almost 6%.

matt_ledbetter

A new or low mileage stock radiator is fine for most people... Over time the stock radiator is crap. The coolant passages are very small and will eventually pick up enough crap to hurt flow. Crack open one with 70k miles and you will see what I mean.

You can try to flush it, but it most likely won't help.

A new one from mazda is good... a new mazdacomp, SR, etc is better...

-Matt
'93 Touring

juliof

Upgrading the rad is the best thing you can do for the FD probably will add life to youre motor.I also think going with the expensive Evans coolant is just over kill save youre money , if you change the coolant every 2 years or so you will be fine.If the thermostat is original change it, seal area around the radiator for max air flow, straightened oil cooler fins and add another oil cooler for more cooling.

jspecracer7

I was having EXTREME overheating problems with my FD before I bought my power FC. I had my friend hook up the datalogit equipment to it to turn the fans on at a lower temperature, and after a full night of railing on it, my water temp never got above 93(And I railed the **** out of the car).

My opinion is that the stock radiator/fans are fine, but the ECU turning on the fans at 96 was STUPID. I used to get to 110 C before we turned down my fans.

artguy

I will say it again. The stock radiator is NOT fine. It is a piece of ****...... it simply does not keep the car temps low enough under duress or fun driving. It doesnt even keep the thing cool at idle (open the hood and feel it for yourself lol .......ouchy?).

its the best mod you can get because you wont have to buy a new friggen motor due to high temperature damage (those O rings sure are strong arent they?)

Im on my third...Ive seen at least a half dozen fd's at the shop all because of heat damage....all costing thousands of dollars...and not all were heavily modded.

shoulda done the radiator first I tell ya!

j

why do most rotaries fail. one answer HEAT. ..either coolant or a fuel issue....either way its heat...so rid yourself of part of the equation...you bought an ecu didnt you? do the rest.



jason

artguy

double post..delete this puhleeze.

Smilez

If you had a down pipe and exhaust and a street ported engine, which is the better reliability mod? An ecu or radiator?

Thanks!
Jeff

technonovice

You are going to hear two different opinions on that. If it were my car, I'd replce the AST with an aluminum one and get a Fluidyne radiator. This would be the wise and safe route. You can also do the nearly free fan mod so they come on after the car is shut off. You can also wire them to switched on manually.

However, I don't think it would be unreasonable to get the Power FC for future to prepare for future Mods. Though you don't really need it right now.

Smilez

Thanks, I plan on doing both of them over the next 3-4 months, but I want to do the one that will help the most first. The ecu draws me because of the knock control and doing any fuel tuning to make sure fuel will be right, but with summer around the corner, I'm concerned with the heat and don't want to take any chances.

technonovice

If you plan on doing them anyway then it could be a matter of what gets shipped to you first.

RonKMiller

Let's see... I live in Tucson where the temperatures from May 1 until October 1 are usually damn hot, and the pavement temps are around 140 degrees F most of the time in the afternoon. I've owned my FD3S since new, April of '93, and have 75,000 miles on the STOCK radiator. I run an intake, dp, cat back and upgraded M2 ECU. I figure that's good for about an extra 30 hp over stock. Distilled water and Water Wetter only in the cooling system. I've never overheated - even sitting in stop and go driving with the AC on high for an extended period of time. I call that more than adequate. If you are burning up engines there is another reason, it sure as hell isn't because the stock rad isn't up to the job. A dp will get rid of more heat than any other mod. Like I said, if your're running higher than 300hp by all means upgrade the rad, but then you are getting into tons of other issues to keep things under control as well. A faulty thermostat and/or burst AST are the BIG issues when it comes to overheating and are cheap to fix and need close attention. What's the number one way ANY internal combustion engine is cooled? Gasoline. What kills more O Rings (rotaries) than anything? - running lean. Buy a dp and dual sensor EGT - still less than a Fluidyne or Koyo. The dp prevents heat and the EGT let's you keep real time track of your engine should you start to run lean - no more guessing. Is my radiator on it's last legs? Probably. But I also pulled it (really easy) power flushed it and tested it last year (really easy and cheap - $14.00 at the local rad shop) and everything is fine. I'll replace it with an aftermarket for $200.00 WITHOUT the plastic end tanks when it's time......I've seen more people waste more money on **** they really don't need while neglecting basic maintenance. Ya, the Fluidyne is nice and shiney but who sees it once it's installed? For most owners it is total overkill, and the Evans coolant is also.

DamonB

I will just add once again that my car is daily driven in Texas in rush hour with the a/c on and never has had cooling problems. It also did 22 autox's last season; a bunch of them with the pavement hot enough it felt like your shoes would melt. No cooling troubles at all.

ttpowerd

just upgrade to an all aluminum....the stock endtanks are plastic and crack causing more problems then you want to handle bc overheating is not something that you want to face with a rx7

rotary-tt

No overheat problems with stock rad. Was getting a little warm until I figured out that 1 of the radiator fans was burned out. Replaced it and now it's fine. I can understand how the heat could make it brittle over time but I run my FD very hard without problems. And it does get hot here in the summer.

Make sure both your fans are working...