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theres no reason to do this. why are you considering it?
the engines make best torque/power at around 70 C coolant 120 C oil temp as proven by race boat guys who run at continuous WOT doing dyno testing where they could control each independently.
There is a reason modern ecu fuel models take in both intake air temp and coolant temperature and charge transit time through the intake manifold and head/plate/housing. Cooler block means denser charge. I noticed bottom end torque improvement on my JDM car which has a lower factory thermostat than US, I imagine there would be a significant improvement over the US thermostat set point.
I have a Billion brand thermostat, Marcus Read also sells them if you have issues with Japanese retailers and you are on Facebook, although I imagine someone in North America stocks them.
the engines make best torque/power at around 70 C coolant 120 C oil temp as proven by race boat guys who run at continuous WOT doing dyno testing where they could control each independently.
There is a reason modern ecu fuel models take in both intake air temp and coolant temperature and charge transit time through the intake manifold and head/plate/housing. Cooler block means denser charge. I noticed bottom end torque improvement on my JDM car which has a lower factory thermostat than US, I imagine there would be a significant improvement over the US thermostat set point.
I have a Billion brand thermostat, Marcus Read also sells them if you have issues with Japanese retailers and you are on Facebook, although I imagine someone in North America stocks them.
Hmm I did not know that the JDM version comes with a lower opening temp t stat, you know what the opening temp is for the JDMs?
Originally Posted by cr-rex
theres no reason to do this. why are you considering it?
I just like to keep the temp low, currently I set my fans to kick on at 87 and off at 85, if my t stat opens at 82c then my prefer operating temp would be too low for the t stat to be fully open; just a personal preference.
Also during the summer in the traffic, my coolant temp sometimes jump up to 90+ (I know that's within range), but I just prefer to keep my op temp in the 80s even in hot days.
Last edited by BrianZhong; Jul 23, 2022 at 11:31 PM.
the engines make best torque/power at around 70 C coolant 120 C oil temp as proven by race boat guys who run at continuous WOT doing dyno testing where they could control each independently.
What MIGHT be evident in a rotary powered boat living its life at WOT and for a mostly stock to mildly modded car engine on streets doesn’t necessarily translate too well.
The OP probably doesn’t need it.
And no personal experience but last I heard/read, Marcus Read was the Aussie equivalent of Sal at Elite Rotary.
What MIGHT be evident in a rotary powered boat living its life at WOT and for a mostly stock to mildly modded car engine on streets doesn’t necessarily translate too well.
The OP probably doesn’t need it.
And no personal experience but last I heard/read, Marcus Read was the Aussie equivalent of Sal at Elite Rotary.
this here.... not all practices translate. For a street car that spends more time at a stop light than under race conditions, running that cool has no benefit. Them temps you describe are excellent and what my own car runs at. I don't ever seen 9Xc unless I'm doing back to back to back pulls and even then after cruising for a minute or two it drops back down to the 80s.
Our coolant temps are so much cooler than stock in these ranges theres no reason to make it colder. What you should be more concerned about in doing this is your oil. Oils have a heat range where they works the best. Run it too cold and you're running cold oil lol. Leave your cooling system alone. Its working fine...... better than fine actually.
My understanding is that stock Eng. Coolant Temp (ECT) is set to be Pareto optimal between performance and emission. From a racing perspective (i.e. 100% performance), Mazda Motorsports' recommendations may be worth a gander:
Mazda Comp - Coolant and Oil Temp / Pressure Recommendations
I think that coolant fan duty cycle and the associate current draw is also worth considering. The higher the set point, the (non-linearly) lower both are due to increased system efficiency. Stock FD "High" fan setting isn't till 226F!!!! And the oil and coolant systems are complementary systems.
That said, I defer to this august body for actual thermostat recommendation.
Yes, see how broad the normal coolant temp range is in the Mazdamotorsports chart- we have some leeway.
For a race only rotary you do want to be at the bottom of tjat range to maximize the thermal input available before reaching tje top of the range and having to dial power back.
My experience on the street-
from 2001 to 2014 I put ~40,000 miles on my 400hp FC racing, dailying and cruising.
I started with lowest available t-stat at the time (60c?)
Streetport and tuned Haltech.
After several years put in higher 80c thermostat because driveability and emmissions are so much better with the rotary warmed up. Kept noticing how much less fuel and how much nicer the car ran once heat-soaked a bit.
This was a car with a huge NASCAR radiator that operated at the bottom end of thermostat opening. On a stock or otherwise more compromised cooling system it might be a different story.
A real race only rotary will have the t-stat removed (point of failure and flow restriction) and the waterpump housing bypass plugged.
I highly doubt there are race cars doing lap after lap with a temp below 180F. I just don't see it. No background in racing but I do know that would be quite an outstanding feat in heat dissipation.
Regardless of what that chart says, what does the real world data say? What are those cars actually running at? For a street car with a license plate and a "normal" amount of power the temps described by the op are perfectly fine. No further cooling modifications are needed.
Theres no reason to run your car that cool. Its likely to cause more problems than it is to help. Keep in mind your oil performance at these lower temperatures but with a high load/demand. I'm sure there is a weight that would make sense with an associated water temp in the 7xC range but...... why? Also keep in mind that water and oil temps move together so lower water temps equal lower oil temps. Then oil temp and oil pressure also move together.
Not implying it will be the end of the world or a catastrophe if you pursue further cooling but there's just no point from a functional standpoint. Diminishing return is the phrase to summarize this pursuit.
For most street-driven cars I think a little more headroom is nice… ala the FC thermoswitch or stand-alone adjustment to lower fan threshold. But more leg room from a lower t-stat isn’t really needed imo.
If the OP is really into cooling mods maybe consider a boost-activated water-injection system. Water carries a lot of heat out with the exhaust which reduces load on the coolant and oil. It also all but eliminated the temp spikes I saw after periods of hard boost. You’ll also probable see less knock and carbon.
Well, I am not trying to run my car as cool as possible, nor am I aiming for a 7x temp; ideally I'd like to keep the temp in mid to low 80s because I do notice my temp spikes up to low 90s on a hot day, taking off from red like after sitting in traffic, it will eventually comes back to high 80s after enough air move thru the rad but whenever that spikes happens, it makes me nervous.
On top of that, my first FD suffered from overheat after a fresh rebuild which cost the water seal to blow, so I am just extra caution when it comes to cooling on my current FD.
your temps are perfect. paranoia is fine but you have achieved peak cooling performance for a street driven car. what you have just described is a perfectly working and efficient cooling system. you can end your pursuit. you have achieved victory.
