Cooling upgrade question
 

Would this be accurate hierarchy (albeit inverse...in that the higher the number, the better the capacity) in "cooling capacity" of an miata? (assuming NB miata)

1) Stock radiator
2) Stock radiator + SM hood louvers (SMHL)
3) Stock radiator + reroute(RR)
4) Stock radiator + SMHL + RR

5)-8) repeat with additional capacity with CSF 42mm
9)-12) repeat with additional capacity with Supermiata cross flow 31mm
13)-16) repeat again with TSE radiator 76mm

Is this correct? There's probably some interweaving that could go in there. For example...a stock radiator with reroute and singular louvers, would possibly cool better than a CSF 42mm without a reroute or louvers, etc.

For a car that's running n/a within little to no track duty - what cooling setup (assuming radiator is shrouded properly on all 4 sides) would be more than sufficient for, say cross country trip with mountain inclines and 100F degrees outside - while having fun on windy roads, etc?

If I had $400 to improve my cooling system (stock rad, stock shrouding, no reroute) - what would be the most cost effective path to getting better cooling? Reroute ($250) + stock rad replacement ($80)? Stock rad ($80) + louvers ($200)? CSF rad ($220) + louvers ($200)? stock ($80)+ louvers ($200) + shrouding (...?)?

If you only have $400, i'd put my money on re-route + ebay 55mm radiator + stock fans. Replace later with swag radiator.

I'd vote for coolant reroute + ebay aluminum radiator and a single Spal fan. A 2nd one can be added if needed. Proper shrouding required as well.

2 votes for qmax reroute and ebay radiator...$250 and $150 respectively. Ill have to trim the stock fans to fit the thicker radiator correct?

It was tight, but I did not have to trim anything to install this one: https://www.ebay.com/itm/GPI-Aluminu...kAAOxyVLNS5HVQ

Depends on your sway bar, in my experience. It's not a huge deal either way.

Another vote for a reroute, aluminum radiator, and stock fans. Add venting later.

I’ll throw in another option, the koyo hyper V core 32mm. Fits like stock, with extra capacity and great cooling. Sounds like you’re shopping on the supermiata site exclusively. Which isn’t bad, but they make race car products. Although they all work on the street as well, the reroute has a decent sized bypass hole that slows warm up time, especially if it’s sub 50 degrees. And hood louvers are AWESOME, but let rain and dirt get in your engine bay. For instance my pulley rusts cause the belt rubs any paint off and the vents allow water in. little things like that to keep in mind.

Personally for a naturally aspirated street car id put on a brand new under tray and air guide, a koyo radiator, and call it good. I do have some experience with a 150hp NA with AC like this, in 100* weather, but not a bucket load of daily driving, so others may chime in saying it’s not enough.

Thanks for this. Yeah shopping around in goodwin and supermiata. I was looking at qmax primarily for easier install alongside "better" for not much more.

Goodwin still has a sale on those csf...radiator, so thats still tempting at 42mm while being $80 more than the ebay ones.

Good notes on the vents. Damn. Though it doesnt rain THAT much in socal, definitely a thing to note. I should do an experiment to see how well a stock type radiator cools with SMs louvers.

Sway bar is still stock, so it seems the ebay radiator should be minimal trimming if any.

Tray is still in good condition...will inspect the current airguide though.

Yeah in Southern California, you probably won't have too many issues with rain or cooler weather like me.

I've got a hyper v that I bought used from another member on here probably two years ago. I had it on my 99 for about a year but got a deal on a supermiata csf and threw that in with a q-max last year. Still in good shape but would reccomend a good flush. Anyway I'd be willing to let it go for pretty cheap. Shoot me a pm if you're intrested and I could send you some pics. Located in AZ btw.

Thank's Nbcavolo! All good for now. I'd rather have a brand new or VERY low mileage one.

Indeed...it rains a weensy bit more in Oregon.

No sweat man figured I'd throw it out there just in case :)

I have one of the setups you mentioned so I figure it was worth commenting. I have a track-only NB with CSF 42mm radiator, coolant reroute, and the Singular Motorsport hood louvers. Stock N/A power, no rad ducting, and stock undertray.

I can't get the car up to temperature with this set up unless it's a hot track day, for example a typical August day in VA of like ~90 degrees and 90% humidity. Pretty much anything less than that and the car runs cool even at full send. This past weekend was ~65 degree ambient temp and my water temperature was between 136 and 142 for the entire session. In the morning sessions I couldn't get out of the 120s. As soon as I get some air flowing through the car the water temp plummets.

The reason I say that is because I agree that an upgraded radiator and coolant reroute and decent fan should be more than enough to keep your non-tracked car perfectly cool even with some spirited driving. I was very surprised by the efficiency of the hood louvers when I added them, which is great for cars that need the cooling efficiency. In my case, however, the louvers have pulled me out of the car's desired temperature range. I'll probably start having to tape off part of the radiator or louvers on cooler track days to see if I can get back in the 175-190 degree range where the car is tuned to be from the factory.

Thanks Quigs. That's actually exactly what I wanted to hear. From all this, reroute + louvers + stock radiator would be more than enough. I guess that's also what supermiata was going for with their lightweight system. More of a... if there's air freely flowing through the radiator, you actually don't need that much radiator - emphasis on the "freely flowing".

That is what thermostats are for.

Definitely reroute before hood louvers, but remember that reroutes are more for even cooling than for overall cooling. You haven't said (or I missed it) what year your NB is.

Bbro, some reroute-equipped cars let enough coolant by the tstat that in cooler weather they can struggle to get up to full operating temp.

My car has this problem, and it's due to the fact that I drilled two small holes in my thermostat to increase flow to my remote-housing tstat.

running myself a N/A 1.6 track rat car for now. Its missing the radiator shrouding and tray. and has no condenser. and 180* thermostat with bleed hole.
down here in florida it gets a little warm out on the track after a while. it has also never really liked highway speeds unless i turn on the A/C to get the fans to kick on.
it does take for ever to get to temp. but I made the bleed hole a bit large on purpose to prevent spiking and to allow some wiggle room in case the thermo sticks closed.
I would also never need a heater in florida.

I Am going with Vraptor hood lourvers for aero benifits and then the LRB radiator should tray. to replace the missing one.

It might be over kill but the car is only driven to and from the track. and some spirited sunday funday drives.
and i think the louvers will benefit me also with reduced front end lift.

I'll give another example. On our Champ Car (NA with BP4W @ ~140whp) we run a stock (Koyo brand) radiator, with a reroute, stock fans, and ducting with no water temp issues. We have small hood vent, but its over the header (we were attempting to draw out exhaust heat).

I've not had a problem with either of my cars coming up to temp in even as low as 40F weather (They do take a couple minutes longer, but they get there with no problems). The only reroute i've ever had that would prevent operating temp in normal conditions was the Begi Racer Reroute. If your car is exhibiting the same symptoms of that POS, then something is wrong.

In my opinion. If a vendor is telling you that their reroute has the same symptoms, then listen to them i suppose. But i don't have that problem with their reroute. ;)

Ebay rad should be under $100. I just ordered one for $93.

I have one of those group buy spacer rerouts. No issues with warmup, my car comes up to temp quick abd sits right at 183-185F (180f thermostat) with the stock fans and SM crossflow (that is being replaced with the ebay rad since it is leaking where the tubes meet the end tanks after only 2 yesrs and 10k miles. Cools super well though).

Edited my post for clarity.

MY car has this problem, with the old MTuned reroute. I had put in a new thermostat in the remote tstat housing, and I was getting a significant temp spike before the tstat would open. I took it out and drilled a hole, realized I did it in the wrong place, drilled another small hole. This solved the temp spike, but now my car has a hard time staying up to temp when it's cool outside. Coolant plumbing to turbo could also be an issue here, hadn't thought of that before this moment though so not sure.

@Quigs , which reroute do you have? I didn't read your post carefully enough before - shouldn't have any issue getting up to temp while cold when under load, that's for sure.

I've got a 1999 Miata. Indeed - I'd also like to have "even" cooling. I even thought that would be the natural progression of things... radiator...reroute...louvers. I would be wondering if all you had was a regular radiator setup + louvers, would you delta from front to back be even greater, or would the engine run generally cooler (since it's always getting much cooler coolant on the intake) - with similar/unchanged delta temps.

Your mod process is correct - Radiator, reroute, louvers. Some may say even doing the reroute very first, then radiator. Again, this is about even cooling more than overall cooling. Doing hood louvers with a stock-flow cooling system on pre- '01 Miatas is sortof like mounting wide hoosiers on stock wheels. You're skipping a step.

I live in the south where it can get fairly hot in the summer. I'm running an aluminum radiator, two fans (one for A/C the other for cooling), reroute, 180° tstat, and SM hood louvers. Just installed a turbo a few weeks back so I am not sure of how it will do in the summer however I did run all the cooling parts pre turbo and never have had an issue. Now I get to see how everything will hold up with the heat.

I have an OEM 195* thermostat. The car gets up to temp at idle no problem and idles between 190-205 exactly as it should. As soon as airflow at track speed is introduced the temps plummet. Not as much in August, but in March and November ambient temperatures at the track don't get much above 55-60 at the peak of the afternoon with near freezing morning sessions. A lot of guys tape up radiator openings in the cooler months that don't have the increased airflow of the hood louvers, so I'm sure some taping in both places for me should help get the temps up a bit higher. Just haven't experimented with it yet.

DIY reroute with Bell Tuning spacer, Kia thermostat housing/water neck, unmodified OEM 195* thermostat, and upper radiator hose that matches the one on my tow rig (2004 Silverado 2500HD with Vortec 6.0). CSF down flow radiator, OEM "shrouding", and distilled water with a splash of Water Wetter.

As others have said I would do reroute first, radiator second, and ONLY if you absolutely need it then consider the hood louvers. An aluminum aftermarket radiator provides more benefits than simply cooling efficiency or increased capacity. Most importantly they don't blow up because of old, brittle, plastic end tanks.

There is also the MSM stock radiator if you want something better than stock as far as more capacity and inexpensive. Ditch the AC if you have it for more flow and ducting.

I can't brain a scenario in which a functioning cooling system with a thermostat would over-cool.

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A thermostat closing in a stationary engine will prevent it from over cooling. Not a moving vehicle with unregulated airflow. More capacity and more airflow is going to lower the temp if the thermostat closes. I had a 1.6 with proper reroute, meizer inline T-stat(not ideal), bypassed heater core and two different radiators(pwr and SPM csf) and used 2-3 different thermostats. Vented hood and had a unbeatable overcooling issue. It got up to temp fine but once moving temps dropped fast and would stay at 150-160* unless romped on continuously.

Tstats don't care if your moving or not. They function purely off of water temps. Dropping from 190f to 50f that suddenly sounds like a bad tstat sticking wide open to me. Even if the water in the radiator is 50f, the tstat *should* snap closed again once the heated block coolant has passed through and it sees the ice cold radiator coolant. My $0.02.

Yeah that sounds broken to me. The only time i've had a car overcool, ever, is when a thermostat wasn't working, or when i had a Begi Racer Reroute, which literally simply just bypassed the thermostat.

So wait... what I'm hearing here is that regardless if you had, for exaggeration's sake, a 100x capacity radiator (we'll just call it a huge tub of fresh room temperature coolant), starting up and warming up the engine should take the same amount of time since the thermostat's closed. Once it hits temperature it'll start opening up, and out goes the HOT coolant, and in comes the ~70F coolant. At this point the thermostat would proceed to close up again...only to repeat the process.

Does that mean, a system with high heat capacity just results in a thermostat that works "less?" Since it'll always be supplied with nearly ambient temperature coolant? So the time between needing to open, closing and opening again increases thereby causing the thermostat to do "less work?" Vs a system that's undersized, and even if the thermostat was stuck open, there wasn't enough cooling available...?

How fast does a thermostat open - and close? Its reaction time then would dictate the possibility of overcooling especially if the coolant on standby can maintain a nearly ambient temperature...no?

Reaction time wouldn't have any bearing on a consistent overcooling condition. Bad reaction time would cause swings, yes. But not consistently 50F below target.

Consistently below target = something is wrong.

To highlight this (basically effect of "weak actuator" on a control system) here's a graph showing these overshoots. I'm not a huge fan of this paper as a whole, and obviously the rpm/head of the water pump and heat generated by the engine will have a significant effect, but a picture says a thousand words.

https://cimg7.ibsrv.net/gimg/www.mia...15c6afb785.jpg
(Source: 10.11113/jt.v78.9667)

Thermostat is not a switch. It is an analog Proportional control only, once it opens the first time. Hence, initial warm-up goes above normal temp, and then things settle.

The ups and downs are caused by the fan, which is a digital control with a set operating high and low limit.

Correct. Ok - it's a spring. The fan's primarily have its job during idle and standstill...since when you're up to speed, that flow is generally >> the fan. Ok so in this case, after warmup - thermostat's open - albeit a little late due to its response - so there's the initial temp spike. Fresh coolant comes in...and the thermostat closes a little - accordingly - depending on the resultant temperature. So quigs is talking about his water temperature staying around 140F during those colder days with 65F ambient. So in this case, are we to assume that the coolant, radiator combo, thermostat position reached steady state at that temperature of ~140F? Let's just for fun's sake say the thermostat is effectively ~50% open at that temperature. Between the coolant coming in at 65F, and the water leaving out (I'm assuming this is where the sensor is) at somewhere north of 140F, being completely cooled back down to 65F (ish), is this effectively what's happening?

Standard Tstats for miatas open at 180°. That's when the Tstat STARTS to open. So remaining below that for any amount of time indicates a Tstat sticking open and not regulating correctly.

I see...so effectively, whenever the coolant goes below 180F for any reason, that TSTAT should be closing, etc. correct...? I haven't checked diagrams in a while, is there any source of bleeding that allows some coolant to bypass the thermostat? But regardless - it would still stand that a stock radiator, and a radiator with 20x capacity (exaggerated on purpose) SHOULD then warm up at the same amount of time since the thermostat's closed, correct?

When it opens though - out goes the hot coolant, and in comes the cold coolant............(let's assume 65F coolant)............will the thermostat close again, to allow the coolant to absorb more heat before heating back up to 180F and thermostat STARTS to open again?

Your bypass is the heater core. Warmup time is the same. Larger radiators only allow the water in them to cool for a longer period of time.
Your Tstat will will only open slightly if head temp is 180* and coolant is 60*. Its not an on/off switch, it opens in increments. Properly functioning Tstat will open only just slightly so that a small amount of very cold coolant will enter, keeping the coolant temp in the head at 180*.

*** it only drops that low once race-pace air flow is introduced on the cooler days AFTER the addition of the hood louvers. At idle or low speed driving in the paddock the thermostat operates exactly as it should. Temps comes up to 195*, thermostat opens, temp gradually rises to 205* or whatever the temp is that the fan comes on at a slower rate, fan comes on, temps drop to ~175-180*, fan cuts off, repeat.

Some Miatas were spec'd with a 195*, some with 180*. Mine has a 195 in it.

I appreciate you guys providing input that suggests my car is broken, but I assure you it is not. The only reason I posted in this thread was to advise the OP that the hood louvers were WAY overkill for a street driven car due to what I've seen with my car with the same radiator he was looking at getting. Prior to having the hood louvers installed and all else exactly the same the car would be right in the proper range of ~180-205* while on track as it should be. I added the hood louvers due to an assumed underhood temperature build up issue that I THOUGHT was present due to continually cooking my CPS on track. It turned out that what I thought was excessive heat build up and cheap CPS replacements was not the actual culprit as the cause was that the CLIP for the CPS was faulty. Put a new pigtail on and problem went away. However, I had already installed the hood louvers, so I can't exactly take them off...nor do I feel the need to source a different hood.

My point was that the hood louvers increased air flow so much that while moving at race pace, and ONLY while moving, during a cooler month event (March and November) then my car overcools. The rest of the year it settles in 10-15* degrees below target exactly as it should with the increased airflow of the hood louvers. This past weekend in particular was so cold in the morning that some of the Spec Miata guys were taping their radiators, indicating that they, too, were overcooling. I'm willing to bet that taping up my louvers will bring the temperature at race pace back up to 180-190.

At the end of the day I wish I didn't have the hood louvers as it was unnecessary money spent on top of being an unnecessary modification now that I have found the cause of my CPS issue. I simply did not want the OP to make the same unnecessary mistake I did. I'm sure I will, however, thoroughly enjoy the louvers if/when I decide to build for SPM S1 and/or NASA ST4 and add a heat generator under the hood haha.

If you are referring to my example, it's dropping from 190 to 150. I would agree that a delta of 140* would be majorly effed up haha.

Perfect. Also it seems that my choice of words makes it keep coming off like I think it's an on/off switch without intermediates - my bad on that part :inout:

And thanks for the info Quigs. It seems that the reroute + upgraded radiator + louvers would definitely be overkill for a street car. With this in mind, I was tickled with the thought of having the reroute with a stock radiator, and louvers. I do just generally like the idea of having the engine bay be cooler overall instead of being warmed by the stagnant-ish air.

Regardless, cost savings of getting the m.net glorified amazon tyc special - seems to be a moot point now that it seems the generic ~2" core aluminum radiators are "trusted" while being just $20 more. So it'll be that with contemplating getting a QMAX installed in the back with the engine still in the car. Any have experience installing that withOUT removing bolts off the PPF to tilt the engine forward to get more clearance during install? I fear that I'm not particularly secure in bolting it back (the PPF) in place with the right alignment, etc. afterwards.

I didn't mess with the ppf or anything when I did mine for the same reason. I ended up deleting egr because I couldn't get the pipe to fit. Maybe I would have been able to keep it if I had more space to finagle it but I'm on megasquirt so I just yanked it and blocked it. :bigtu:

Overall it wasn't that horrible, it took a whole day but I suck at cars so take that with a grain of salt. Two recommendations though, get a thin socket for the bolt that goes into the head it's a tight fit. Replace the heater core hose that connects to the housing. I about shit myself when it started leaking a day later, I was convinced I botched the gasket maker on the q-max and was going to have to pull it, but it was just the tired old hose.

It's easy to do without loosening the ppf. did nine in under an hour I just removed the heater hose and the coils.

You say you have a proper reroute. I would question that. I'm guessing the overcooling has something to do with the design of your reroute.

And to the other question, boats have an unlimited supply of cool liquid and use a thermostat to regulate their temperature. A properly working thermostat and water pump does not allow it to over cool or under cool.

Additionally, thermostats are not a binary device that are either 100% open or 100% closed. They can open gradually if exposed to a slow warming near their target temperature and close gradually as well. It is possible to have one just slightly open if maintaining and even temperature right near the opening value.

Perfect.

Sixshooter - I like the boat example. Good good.

Also - random question. Back in the day, there used to be a brand or something called "failsafe" thermostats (aka...when it fails, it fails open) - are all thermostats today, that way, now? Or do I need to specifically look for it to be called out?

Today's thermostats are generally reliable. Nothing is fully failsafe so check gauges on straightaways.

Anyone have a particular "favorite" ebay radiator vendor...on ebay? Thanks xD

I go with the cheapest all aluminum one I can find. Don't think I have ever used a vendor more then once.

xD damn shuiend.

I've had good luck with my CX Racing radiator, but its 5+ years old, so they've likely changed manufacturing plants since then.

Now I want to see a lake filled with thousands of boats until the water boils.

I’d recommend koyo 32mm and really any reroute, I’d like to see the new flying Miata one on a car to see if it worth it haha