Yep, have this in my own car and it is effective. Be aware of increased oil pressure though.

 

I run a 65 degree thermostat and i don't experience what you mentioned .. even on coolest days lowest i see is around 65.. even on the coolest days its logically impossible to be below what the thermostat is set to open.. unless its a short drive..

you won't have uneven idling .. just higher than normal.. the ecu keeps thinking you are in the coldstart cycle and basically keeps the idle high..
your fren may have other problems not because of the thermostat

one of the primary reason is actually for track.. the harsher track condition warrants a cooler engine

 

It sounds incredible, but that's what happened. The coolant temp literally took a nose dive to 50 degC when on the move and went back up to 80 degC when the car came to a stop.

There is uneven idling because the car is at normal operating temperature but the thermostat is fooling the ECU into thinking it's in cold start.... this is different from a true cold start; pulse widths, injection phase, cranking enrichment, additional fuel decay and spark advance values are all different.

Yes but if the engine is not in any danger of overheating in the first place, there is no reason to pressurize the cooling system and cause overcooling.

 

I guess this was my car in question :P

And yeah, it did drop to around 50-60 deg C when cruising on the highway (usually off/low boost) in Malaysia.

 

Guess this happens very late at night ?? I do see exceptionally low temps, but never that low and I have a lower temp thermostat .. granted I don't have the 1.3 bar pressure cap ..

actually .. the thermostat doesn't do that .. it's a physical device .. it opens at the predetermined temperature .. it has no connection electrical or what to the ecu.. you're mistaking the temperature sensor ?? which causes turns on the fan and start or terminate the cold start cycle.. if the temp sensor never leaves cold start, logically the engine never reach normal operating temp ..so something is definitely wrong with that car..

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Sometimes, some people think 1 or 2 track days a year is harsh enough .. there's also the safety feature built into the standard ECU that's not used in aftermarket standalone. when you reach certain temp on the coolant, the ecu actually goes enrich the fuel .. I found this out when playing around with a piggyback .. I can never get the AFR constant after a couple of runs .. I'll get it spot on for the first few runs then it'll go pig rich .. then if I tune to the new AFR, I get too lean when the engine is not running as hard .. think it's mentioned here somewhere also this phenomenon.

 

the short answer is this: unless you are tracking your car alot and have a programmable fuel setup, don't bother. All the low temp t stat does is open sooner -with an otherwise stock cooling system, you are not going to see dramatically lower temps on any datalogs.

The pro's are that it opens sooner, meaning it cycles coolant through the motor more often. Great for road race guys or guys in super super hot climates that flog the hell out of the car, pretty useless for everyone else

Con's - car is going to run INSANELY rich at idle and part throttle especially...some cars will even throw a CEL because the ecu under OBD2 moniters how long it takes for the t stat to open. So, unless you have some means of fuel control in the car, or can flash the car right after you install the t stat, the money would be better spent on the other cooling system upgrades (larger radiator, better fans) and using the stock t stat

 

At idle the coolant temperature will be controlled by the engine fan.
We are talking about 9ºC cooler than stock. So, How 9ºC cooler will afect the performance?
Why Did Ralliart make it? just for marketing? Why Did Ralliart put this thermostat in the all Ralliart modded Evo? Why HKS KANSAI recommend this thermostat together with a performance ECU? It is hard to believe that they recommend a "hurt performance" part

 

On a DSM if your coolant temp is too low, you will lose a degree of timing advance. Plus combustion won't be optimal. Not good for power. I suspect that the control on an Evo is similar.

 

coolant temp is not determined by the engine fan - the whole system works together...the efficiency of the radiator, the amount of cfm's the fan push, the pressure of the rad cap...all works together. Nothing operates in a vacuum.

Why does Ralliart make it? Simple - part of it IS marketing. Every company offers "low temp thermostats", and as such, Ralliart does as well. Same reason why every company offers "high pressure rad caps". I did not say performance is lowered in every instance; I said performance will be affected by simply swapping thermostats and not datalogging and making the necessary adjustments to the fuel and timing curves that will certainly happen as a result. The mere fact that Ralliart sells it in Ralliart equipped Evo models and that Kansai recommends it with their reflashed ecu is telling you the EXACT same thing I am - that it most certainly does affect the fuel and timing tables, and you need some way to adjust for that, or the car will not run optimally.

 

Thanks Z1.

I will install the ralliart thermostat in few weeks and I will post my impressions. The only reason why I'm changing to a lower temp t.stat is that my car has a Ralliart ECU. This ECU, I think, has an optimized air/fuel ratio and timing, as Z1 wrote.

 

Allow me to rephrase. The thermostat is fooling the water temp sensor which gives the ECU the wrong reading. Thought that was obvious, apparently it wasn't so. And nothing is wrong with the car... everything went back to normal when the aftermarket thermostat was replaced with the original.

I don't know which standalone you're talking about but any standalone worth their salt has engine temperature compensation tables for fuel and ignition.

 

whatever dude.. you are the best..thermostats and temp sensor doesn't fool.. thought that was obvious too.. the temp IS lower HENCE the engine IS running colder..



standalones have all the features they don't have the experience..the POINT here is 10 years of tuning by MMC with codes thats been refined.. no standalone can beat that..

 

No, it doesn't. The lower temp thermostat opens at a lower temp. Nothing is getting fooled. The ECU is getting the correct reading.

 

No the engine isn't running cooler. The water temp sensor is reading cooler due to the thermostat. Big difference.

Whatever dude... you are the best... no wonder all the high powered cars are running stock ECUs eh?

 

Edit: I just read what I typed in the previous post and I really meant "fool the ECU" instead of "fool the temp sensor". Maybe the following paragraph will clear things up.

Why does the ECU get into cold start mode? Because the water temp sensor says the engine is cold. But is the engine cold? No it isn't. And that's the point... because it's been running for the last several hours, cruising and stopping periodically. Am I saying that the sensor is wrong, inaccurate or faulty? No. Am I saying that the thermostat is the cause of the problems? Yes. So can it be said that the sensor's reading cannot be relied upon in this particular instance? Yes. That's what I mean by "fooling the ECU", because the ECU trusts the coolant temp sensor reading completely. And this is partly why it's a good idea to retain some form of manual control over things.