diabolical1

iTrader: (3)

Okay, here's the deal ... I've spent the last 90 minutes looking through the archive and through old threads. I'm trying to find some info so that I can decide what to do with my cooling system.

I've noticed that a lot of guys seem to be having one cooling issue or another lately, and I guess it makes sense because it's summer now.

So here goes ... I want to see if we can all get some good Q & A going here, so that all this info can be archived and easy to access.

Obviously, i can't practically think of "EVERY" single problem or question so just add anything that i miss.

1 - We all know that the air-type oil coolers [(79-82), (84-85 GSL-SE) and Gen II] are better than the water-type coolers (83-85 12A) ... that shouldn't be an issue any more! anyone disagree?

2 - Define "row" as it applies to radiators.

3 - People say that 3-row radiators are recommended for increased HP applications. What HP level is decided on as the threshold for being considered "increased"? Does this mean the that the "shorter and thicker-style radiators (79-82) are better than the taller and thinner-style, including the SE?

3A - For the guys with 20Bs, turbos and superchargers, I don't know what kinds of radiators you run, but feel free to fill us in. Stock radiators, T2 or Gen III radiators, aluminum racing types (e.g. Fluidyne, etc.) - others? Let us know ...

4 - We all know that there is a disadvantage to running too hot (unless, motor meltdowns are considered a "good" thing ) ... but what are the disadvantages of running too cool? (aside from those people that live in places where winter is brutally cold and need their choke and heat) Are there any disadvantages?

5 - Proper cooling maintenance is probably better than waiting for something to break. That means changing the water pump and antifreeze regularly - at the very LEAST. Also checking and changing the thermostat when you do the water pump.

6 - Dual pulleys are not absolutely NECESSARY, but would be "highly recommended" for those that don't run an air pump. It prevents high RPM belt slipping and as long as the pulley is smaller diameter than stock, it will fight high RPM cavitation.

Special Note: I read a thread that Mitsubishi makes an alternator with the twin-sheave pulley (it costs about $5 as opposed to the $50 or $60 that it costs from RB/Mazdatrix ... I got this info from the thread "Mazdatrix claim true?" by ncmn) - no Mitsu part number given.

Special Note 2: Actually that was the thread that got me to stop looking through the threads and start this one.

7 - Run an antifreeze coolant mix - NEVER straight water! The actual mix will depend on where you are and what you use your car for (daily, weekends, racing, whatever) ... The reason I got was that plain water will promote water pump degradation, because the glycol in antifreeze helps to lubricate it.

7A - Redline Water Wetter would be nice to add to your antifreeze, but is NOT NECESSARY. It helps with water's specific heat absorption.

7B - I've noticed the arguments for and against the use of green vs. orange/red antifreeze. However, it's still not an argument with a conclusive decision ... so I guess use what you wish at your own risk.

8 - Electric fans are a great upgrade, especially when your stock fan clutch craps out! From the threads I've read, it seems like Black Magic get the vote from most people on this forum, but others have been mentioned. (I don't know what prices are like, but I got a price quote of $189.) They will also release about 1 HP!

9 - Aftermarket gauges are not NECESSARY, but can't hurt to have them for water/coolant temp and oil temp.

10 - Invest in the lower hoses with the metal ring or else high pressure molded silicone hoses to combat the lower hose collapsing problem.

Well ... as I said, guys, feel free to add whatever you can think of. I hope that I covered most of it, but I'm sure there is a lot more to be said. Also, if I've misled anyone, then please, those in the know, make the corrections necessary.

I don't know who is charge of the site, but I hope this thread will turn into something that we can ALL use and learn from, and be a "good" reference for the "newbies".

Thanks all!

diabolical1

iTrader: (3)

I knew I would think of something right after I submited this thing ...

Also, when getting a radiator, and you have the choice, get the one for the automatic-equipped cars.

Directfreak

iTrader: (2)

I didn't know there was a difference. I about to order a new one froma radiators.com to replace my SE one, any expereince with them?

jeremy

iTrader: (1)

running too cool will hinder combustion.

you can buy a product that "cleans" the radiator from deposits that keep it from being effecient. i need this.

high horsepower should be translated into bigger bang. basically the bigger bang is going to create more heat and more heat needs more cooling. our na engines, especially 12a nad 13b 1st gen specific, are not going to have a high enough cmopression in na form to need a massive radiator.

auto equiped radiators are not always larger as the trans (ex. 3rd gen rx7) has a seperate cooler or the manufacturer felt that due to costs and assembly reasons, one radiator would be fitted to all models. only differences are the two extra openings to run to the trans that you now have to plug.

it is also known that the stack radiator and oil cooler are better then an oil cooler mounted in front of the radiator (thermal dynamics).

with the age of our cars i would definitely recommend a water temp guage to be on the safe side.

green antifreeze is obviously just cooler then red/orange cause its green.

diabolical1

iTrader: (3)

well, i've never lined an automatic radiator and manual radiator over side by side for comparison, but i've always heard that the ones on the automatics are thicker since they have to cool the tranny fluid as well as the engine. i know automatic trannies get really HOT, so i figured there was some merit to the "hearsay" ...

diabolical1

iTrader: (3)

thanks jeremy!

this is exactly what i'm hoping this thread will accomplish. see, i didn't know about the combustion thing being hindered by the temp.

anyway, is there a general interval for use (that stuff you would use to clean the radiator)? or do you just use it when you think the radiator might be getting clogged. is it the same thing as radiator flush?

the_real_bill

I just bought a Hayden 16" electric fan today for $113cdn (i love company discounts )
Regular price: approx. $155
From what hear, (please correct me if i am wrong) electric fans work better as a "puller fan" not a "pusher fan".
Also the Hayden 16" fan fits perfectly in the rad. It's extremely easy to install. I do however recomend installing a 30amp relay though!
Oh, and i'm pretty sure it frees up more than 1hp. I don't know the actual specs that an electric fan changes, but there is a HUGE difference in acceleration with the electric as apposed to belt driven. As i said though, i'm not sure how much HP it frees up.

Anyhoo... that's my $0.02



Vince

Denny

One of the upgrades I did to my SE was to switch over to a 2nd gen clutch/fan. It's bigger, noisier, but more effective.

That Retro-Cowboy,
Denny,
From the 'ol corncrib....

mar3

iTrader: (8)

Oh my...the Cannucks will come pouring out of the ant mound any second now....

diabolical1

iTrader: (3)

thanks for the info on the Hayden unit, the real bill
and thanks for the idea about the Gen II fan, denny!

but, what's this???
i haven't heard anything from the people "down under" yet ...
where are you Australia???

Manntis

[qoute]2 - Define "row" as it applies to radiators.

3 - People say that 3-row radiators are recommended for increased HP applications. What HP level is decided on as the threshold for being considered "increased"? Does this mean the that the "shorter and thicker-style radiators (79-82) are better than the taller and thinner-style, including the SE[/quote]

To define rows in a rad, don't think in linear or two-dimensional terms. Rows are added fore-to-aft. Think rows in a choir: front row in front (obviously), second row behind that, third row behind that, etc.

Each row of vertical pipes then runs top to bottom with horizontal cooling fins binding them together.

Hot coolant pours into the top of the rad, flows down the pipes, and radiates the heat from the coolant into the cool air rushing past via the horizontal cooling fins
(hence the term Radiator - neat, eh?)

A 3 row rad just exposes a greater surface area of pipes and fins to the cooling air versus a 1 or 2 row of similar height and width by adding a row of depth.

Excess cooling CAN adversely affect combustion (which is why there are cold-start valve setups that preheat some of the air before it enters the engine under cold conditions) but we're talking very cold air. To artificially cool the air so much it causes poor combustion would require elaborate refrigeration which is highly unlikely to occur as a byproduct of other mods.

Just my 2 cents.

jeremy

iTrader: (1)

ah but you forget the use of a choke do to a cold start. and this is even during 90 degree days.

Manntis

"The use of a choke do to a cold start"

um, what?

RotorMotorDriver

iTrader: (1)

If there wasnt a difference, why would they ask you which one you want .

~T.J.

PS - Yes, I know, it could be physical differences, but I just thought Id point out that fact

RotorMotorDriver

iTrader: (1)

Oh, and I just checked with some "factory manuals" I have, and they dont list different capacities for auto vs. manual tranny rads. Its all the same.

~T.J.

fatboy7

So, we know that having the coolant temp too low has a negative impact on combustion, what is the best coolant temp for power and reliablity on a 12A, or 13B? I asume the thermostat is what has a large deal of control over this, so is there any thermostat upgrades?

diabolical1

iTrader: (3)

thanks rotormotordriver ... i guess it's been a myth all this time. i also guess that i should have gotten off my lazy *** to research it, but at least we ALL know now.

i guess the reason the shops ask is because of the two extra lines at the bottom of the radiator that connect the tranny to it. that's just for all those who didn't know already.


i don't have an answer for fatboy7's question, so i hope someone out there has some numbers. i'll try to research this, but if anyone gets the answer before me, then by all means ... answer it.

jeremy

iTrader: (1)

mazda engineers will have spec'd the thermostat for the engine's optimal operating temperature. so i don't think an "upgrade" would be necessary as long as it is working to factory spec. i believe temp range was 160-190/195. 205 and your asking for trouble.

Manntis- what i'm saying is that every engine when started cold needs to be choked and fed a little more gas until the combustion chamber has warmed up some. obviously if temperature wasn't an issue for combustion purposes then this wouldn't need to be done. i'm not going to pretend i know exactly why, though.

also to note that the optimum temp range is necessary for the proper expansion and fitment of the various metals in the engine.

diabolical1

iTrader: (3)

okay ...

i just got the RB manual (p.64) and here goes:

they said the factory thermostat opens at 82*C (that's 180*F for those of us stuck in the stone ages )

engine coolant temperature should NEVER exceed 185*F under "NORMAL" circumstances, but the engine will live if it rises to 200*F - the catch is, the engine will live only if the temperature rises slowly!!!!

now, i'm guessing that all of this info was meant for stock 12A cars, making stock power. going from that assumption, as long as the car hasn't had any major carburetion or timing changes (retard, mainly) then the same temp ranges should apply.

however, i don't know about any variants from stock, like streetport, bridge, peripheral, turbo, supercharger, etc., etc. ... i would imagine the temperatures should be kept in the same range as stock, since the metals in the engine are not changing with the mods we make ... but my view may be oversimplified ... or just plain SIMPLE

all you guys gifted with more knowledge of thermodynamics, please chime in ...

jeremy

iTrader: (1)

well it stands to reason that a variant giving more power creates a bigger boom and thus more heat. but this doesn't matter as the materials are still the same. what will kill a na will kill a turbo or streetport.

the killer of a fast temp change is that there are various metals with various densities. a less dense metal, such as aluminum, will expand when heated much faster. due to being pinned to steel, some parts can't expand as well while some can. so there is cracking and then as the temp falls, warpage due to the fact that inbetween the dowels was able to expand further, and the center section seeing the worst now allows oil past, etc.

this is from mazda motorsports:
RECOMMENDED TEMPERATURE, PRESSURE & COMPRESSION
BREAK-IN RANGE, NORMAL RANGE, MAXIMUM LIMIT
Coolant Temperature
(Outlet Side) 160° - 175° F, 160° - 195° F, 205° F
Oil Temperature
(Oil Pan) 160° - 175° F, 195° - 230° F, 250° F

Manntis

One thing overlooked is most factory turbo engines have different blocks than their n/a cousins. Different cooling jackets, oil passages, materials thickness, etc.

Back to coolant temp/combustion chamber temp - a hotter combustion chamber gives more efficient combustion as the sparkplug doesn't have to work so hard to ignite the fuel/air mix. This is also why intake air is often preheated by radiant exhaust heat under cold conditions, and why diesel engines, which have no spark plugs, require glow plugs to start in cold temperatures.

However, these startup conditions are for engine blocks (and therefore combustion chamber walls) that are very cold, relatively speaking. Once the engine has warmed up to operating temperature cool clean air is preferred over the hot dirty stuff exposed filters suck in, and cold coolant is better than warm.

Remember that the ethylene glycol/water mix in your radiator is not a refrigerant, but simply water and a few additives to keep components from rusting or freezing. Liquid, once heated, takes time to radiate its heat (large lakes at night often still have much of their daytime heat and thus seem warmer relative to the air) and while a radiator and fan do a decent job, you're in litle danger of getting your engine 'too cold'.

Along a related line - where are the frost plugs on a rotary?

WackyRotary

That is inacurrate to some extent. Stock carb intakes are heated to keep the fuel mixture from falling out of suspension on the walls of the intake runners and not staying in vapor form. EFI engines usually never heat their intakes since theres no need when the fuel is injected right next to the port so there is no chance of the mixture getting out of suspension.


But heres a more important statement about this whole radiator debate which is silly to me in the first place. Firstly, manufacturers have certain temp ranges for a reason. Normally running a engine too cold ends up causing a faster mrr(metal removal rate). I can't remember the figures but i think its like 1/1000inch per unit time I can't recall. But its greater when its too cold. When a engine is run too hot, parts tend to warp on the extreme side. Running with in a certain range between too hot and too cold yields best fuel economy. Then running in even a more spefic range of that yields their better emissions which the manufacturer is most concerned with. Usually running slightly below 180F will give better power, but generally will also ware down the engine quicker. But a engine can run from a really low temp to around 210F effectively, however, keeping the temp lower helps you have a buffer zone if a failure occurs so you can stop the engine quickly without damage.

Now with all that said, oil temp is best kept well up also, because thiner oil has less friction then cold viscous oil. Ofcourse there is a upper limit to not stray too much above, which is why its good to run 20W-50 in 70F+ weather.

Somewere between 200-220F is usually good. It gets the water evaperated out which gets in it at start up and boils off quickly then, except in cold climates were its important to not run the car for short periods. Running the oil above 220F tends to boil off the lighter components in the oil and ages it quicker.


Finally, I run a older radiator from a '70's rotary, it has a small diameter pressure cap but fits the '85 rx-7 chassis the same. But I also run a front mount oil cooler from a 2nd gen TII instead of the oil/water cooler. I have never had any overheating problems related to conditions were it would be a problem: sitting in traffic, idling on a really hot day. This is with a 12a bridgeport by the way. Driving it hard doesn't raise the temp above stock needle location except at really low speeds.

The only time the stock engine(when I used it had a problem was at sustained high speed with the oil pressure dropping when I still had the stock water/oil cooler due to too little cooling capacity of water/oil cooler.

diabolical1

iTrader: (3)

okay ... now just bear with me a little ...

i know you said that running the engine too "cold" will have a negative effect on the MRR (metal removal rate) and then you did cover oils and the fact that their effectiveness is temperature-related, but wouldn't the MRR be more affected by the temperature of the oil (since its the buffer between metal surfaces) rather than the water/coolant temp?

i mean, yeah, it stands to reason that the coolant temperature will affect the oil temperature directly since combustion heat is, indirectly, being absorbed and dissipated by it, but i think there is also going to be a point where the coolant temp will not be able to have an effect on the oil's temperature since the oil is the only fluid that is actually inside the engine and touches the parts that are involved in the combustion process (e-shaft, rotors, etc.) as opposed to being limited to the outer edges of the motor casing, like the coolant.

could you explain this just a little bit more?

diabolical1

iTrader: (3)

oh ... and by the way, whoever gave this thread the rating, i want to thank you!!!!

Manntis

I see you're in Minnessota. I don't know how cold it gets there in winter (I thought it gets quite chilly), but Canadian spec cars, even with EGI, often have a mechanism to preheat intake air in cold weather. For example in my current location winter starting temperatures of -40 Celsius are not uncommon. Without a bocl heater keeping the antifreeze somewhat warm, a battery blanket keeping the electrolyte from freezing, and an intake air preheater the car would be impossible to start.

It is true that there is no need to preheat the air to avoid the condensation/deatomization you mention, but there are other reasons.

Don't presume that one person's driving conditions are everyone's driving conditions.