Maruha low temp thermostat

[track_addict]

I'm after some advice on low temperature thermostats for my SE. Since I'm getting the car ready for lots of track work I want to increase the cooling abilities as much as possible. A low temp thermostat seems like a logical place to start.

I have read that SE thermostats start opening around 92degC and are fully open at 100degC. I have also noticed that whenever I drive the car for longer than 15mins, whenever I stop the fans are on and the engine bay is very very warm. This is just after a regular drive, nothing fancy. I figure it will only be greatly exaggerated after being beat on at the track.

I did some searching and found that Maruha do a nice low temp thermostat that starts opening at 72degC and is fully open at 92degC and has greater flow. I spoke with my mechanic about it and he suggested I avoid one that opens so "early," as this will alter the engine parameters (AFR's etc) and cause possible issues.

The only issue I can think of is taking longer to warm up, which is not an issue for me. Am I right in thinking this?

What I'd like to know, is if he's on the money and it will in fact cause some issues? And other peoples experiences with the Maruha thermostat.

The car is my daily and does 50kms minimum a day.

[sailaholic]

I've got one. Yes it's entirely likely to cause issues on a stock ecu as it may leave the car thinking it's always in warm up mode.


Sent from my iPhone using Tapatalk

[cookie]

After doing lots of research on this I decided to stick with a factory one. A low temp one only prolongs correct operating temperature. Once there a low temp does nothing. If you wanted to try it out (for overheating) just remove the thermostat entirely...

[Magpie]

Lower coolant temp will increase horsepower, however the coolant system must be able to keep the engine at the lower temp, the thermostat only controls the minimum temperature. Further lower coolant/engine temp will increase fuel usage as well as wear!

My thoughts would be to make your current cooling system as efficent as possible by ensuring that all the air goes through the radiator. Look at Danny's 20B build to see the concept applied. Whilst it is not possible to acheive Danny's level of efficency at a street level (open to debate) preventing any air going past/around the radiator is easy.

At the moment my car (NB motor) runs at 91 deg C on the track, maybe goes up to 93. The plan is to make this more efficent by building a duct, this possibly means that the size of the mouth can be made smaller and therefore improve aero.

[sailaholic]

A low temp thermostat does not prolong correct operating temperature it changed what is "correct". It won't really help a deficient cooling system apart from allowing for more creep from "correct" temperature to fatal temps.

Peak power is made around 85 degrees which is where most Evo etc will run.

Mazda runs these engines quite hot (from a power perspective) but it does help efficiency.


Sent from my iPhone using Tapatalk

[Nevyn72]

My understanding was that is was the restrictiveness of the NA8 thermostat that was the issue in some MX5s, this was largely corrected in the NB series of engines.

The sales page from Maruha tells the whole story quite well so have a read to the bottom,

http://www.maruhamotors.co.jp/miata/par ... ostat.html

If overheating is a problem then allowing coolant to flow around when the engine is a bit cooler won't make much of a difference as the problem occurs when the engine is already hot.

You would be far better off focusing on making sure coolant flow is as free as possible (not really an issue in the NB SE), and improving the car's capacity to cool the water being circulated.
This could include such things as;
- Ducting and sealing the air path to the radiator.
- removing interference to the Radiator airflow, in other words AC delete.
- replacing the Radiator with something better, although the standard one is pretty good so you've got to spend some serious $$ for tangible gains.
- adding additional cooling systems, such as oil coolers.
- adding additional ventilation to the engine bay to allow hot air to escape more easily, ie. bonnet vents!

These are just some possible suggestions, I'm sure others might also have some ideas.

Have you replaced the factory intercooler yet with a larger one to reduce heat soak issues?

[Guran]

I have been experiencing ongoing overheating issues with my "new" 10AE over the last three months I've owned it. My initial focus was on the undertray and intake moulding (both were missing), but fitting new ones made very little difference. The waterpump has been checked and was in good condition. Next I replaced the radiator, but found that the old one was flowing well anyway. The solution was found when I discovered that a brand new thermostat was already sticking and causing the flow to be restricted. Such a simple little device causing so much trouble! On Saturday, I ran it at SMP GP circuit with no thermostat and the water temperature was perfect. The only downside I found was that the heater didn't provide much warm air for the very chilly pre-dawn drive to the track. Fuel consumption was probably a bit high for the street driving, but on the track it won't make any difference. I'm still intending to try another new thermostat to combat those cold morning drives to the track, but will keep a close eye on the temperature gauge.

[manga_blue]

You've got a cooling problem. Putting in a lower temp thermostat won't fix it. It will just upset your fuel mixtures and will mask the cooling problem until you put the car on a racetrack. Then it will probably run like s##t until it boils and fries your head.

Any track car does need a high quality, responsive thermostat though. MX5Mania used to sell one but I can't see it listed now. Look for a performance oriented one (i.e. fast opening, wide throat) but around stock temps. If you can't find one then get a genuine Mazda one.

[track_addict]

Thanks for all the informative replies guys.

How have we deduced that I have a cooling problem? Other than the fans being on when I pull up after a drive and a hot bay, I have no other indications of an issue. The temp gauge doesn't budge (shitty gauge I know, working on that) and doesn't use any coolant. The fans also cycle on and off as normal, as opposed to staying on all the time. What am I missing here?

As far as finding a performance thermostat, do I just get in touch with tridon etc and see what they've got? Or go to a speed shop or something?

I have upgraded the FMIC, which made a world of difference I might add, otherwise the engine is 100% stock. Adding an oil cooler is on the list of things to do, as is some kind of baffling which shouldn't be too difficult. The car has been serviced by Mazda up until my ownership so I doubt the cooling has been neglected. Never the less I'll chat with my mechanic and might give it to him to do a service on the cooling system/stick in a new thermostat as a precaution. Don't really have the money to blow the motor and rebuild to a more desirable spec.

[manga_blue]

whenever I drive the car for longer than 15mins, whenever I stop the fans are on and the engine bay is very very warm. This is just after a regular drive, nothing fancy. I figure it will only be greatly exaggerated after being beat on at the track.

The fans are only meant to cut in when the engine temp starts to get above its normal operating range when you're stuck in traffic and there's no normal airflow through the front. If the fans are switching in under the conditions you describe then either the fan switch is wrong or the car is running too hot.

[sailaholic]

I looked at depowering the factory mechanical water pump and adding a electric water pump that was digital thermostat controlled.

To do this obviously you remove the normal thermostat.

There was a lot of noise on the net about removing your thermostat will kill your engine because the water circulates too fast and overheats.

This all sounded like a heap of crap to me. The only reasonable answer I found was that the restriction of the thermostat can be used to control fluid flow in the head and prevent hotspots / localised boiling.

No idea if this is true or not. I tried emailing Davies Craig about it and got no response.


Sent from my iPhone using Tapatalk

[track_addict]

So I have some more info on this. I've not got an OBDII bluetooth reader and Torque on my phone. I really only bought this so I could get an accurate, digital readout on the coolant temp. It also does intake temp and other smaller, non important things.

So, basically what is happening is that the car warms up normally until it reaches 96 degrees, fan comes on, temp goes up to 97 while the fans start to get the air moving, they bring down the temp to 92 degrees and cut out. If I leave the car idling they cut in and out every 90-120 seconds or so. This seems normal to my general knowledge. Last Sunday I did a hill climb. So, sitting idling waiting to do my warm up burnout it would go upto 97deg. If it happened I was to do the burnout at 97 after the burnout it would creep upto 99-100deg. Fans are obviously running at this point. I'd go do the run (only 38 seconds but up around redline the whole time) and by the end of it it would be at 100-101deg. On the return road it would very quickly be pulled down to 90deg. Again, this seems normal to me.

I told all this to my mechanic and he also agree'd this seems fairly normal. He hasn't had much experience with MX5's other than what I give him but he's very experienced, plays with a lot of old english cars and has had some experience with MG race cars.

I'm fairly satisfied that everything is working as it should but I'd like to improve the cooling for when I do super sprints. So I figured I'd do the easy and simple things first. Ive gone and bought a high flow (but standard temperature) thermostat and some new coolant concentrate and will mix up a stronger coolant mix than normal. I'll also do some baffling. Namely a cooling panel and Ill make up a panel that seals from the front bar back to the OEM undertray.

Has what I've observed on the street and track seem normal to you guys with more experience? Do my plans for improving the cooling seem like a good place to start?

[manga_blue]

will mix up a stronger coolant mix than normal

Sometimes conventional wisdom for a road car is not the best for a track car. Nearly every coolant sold here is ethylene glycol. Ethylene glycol protects the engine against corrosion, lowers the freezing temperature and raises the boiling temperature. These are all good things for the daily driver and a strong mix is even better because then it will survive a few years of dilution by topping up with water without sacrificing the corrosion and freezing properties.

Unfortunately ethylene glycol also has lower thermal conductivity than water and is less dense than water. This means it does not absorb heat from the hot spots in the engine as well as water does, nor does it have the same mass to hold the heat as it carries it away and then it does not transfer the heat to the fins of the radiator for cooling as well as water. Basically ethylene glycol is a poorer performer than water under the stress of track days.

The general idea for track cars is to use as little additive as you can get away with. If you compete at Winton or Goulburn then you must have some antifreeze (count on -10 for safety) if you stay overnight. Otherwise if you're frost free then you need just enough glycol to protect against corrosion, or else you can use a performance improver like Redline Water Wetter with little or no glycol.

[project.r.racing]

There was a lot of noise on the net about removing your thermostat will kill your engine because the water circulates too fast and overheats.

You mean overcool and increases engine wear.

with no thermostat, the car will operate at about 60 degrees when moving. and go up to 90 when stationary.

[RS2000]

There was a lot of noise on the net about removing your thermostat will kill your engine because the water circulates too fast and overheats.

You mean overcool and increases engine wear.

with no thermostat, the car will operate at about 60 degrees when moving. and go up to 90 when stationary.

Apparently, with some engine designs, removing the thermostat allows the water to move too quickly thru' the engine, & there isn't enough time for the water to absorb the amount of heat it should.

Cheers