mishimoto thermostat

[HFPcivicSI]

Hey, is anyone running one? Found one online for like $65. Wondering if people are noticing the 15-20 degree cooler temps they claim.

[Jacksond]

What type of driving are you doing? If your car is a DD I would strongly advise against this. Most people think "Hey cooler engine, better performance!" while this is true to an extent (for example cai's), you can actually lower the temp to a point where your ecu remains in "Limp" mode indefinitely because it things that the engine isn't reaching running temp. If you are boosted this is a different situation, however, because they run far warmer than a N/A car. There are several other threads pertaining to the Mugen thermo and spoon fan switch. If you do end up running a cooler thermo please post results as I would like to see how it affects the ecu.

[HFPcivicSI]

My old porsche mechanic said the same thing back when I had my 944 funny enough. He said the motor makes more power the hotter it runs (N/A) and to always make sure the cooling system worked perfectly. But there are people that say the other side of the argument too, that if you can cool it down a few degrees it will perform better... Thats why I am posting this lol, not sure which side of the fence is right..

For my application, its a DD, and N/A with IHE (lol). However my plan is in the next month to drop it off to get kpro tuned, and I was going to add the hondata gasket. My clutch+flywheel will be here monday.

[tinman5]

Unless you are seriously pushing the engine, boosted or N/A, just stick with a stock thermostat.

What you need to understand is this: the engine (all engines) is going to generate X amount of heat. This temperature varies from engine to engine, but the results are generally consistent within families and down the line. Your engine will generate X amount of heat. What does the thermostat do? It keeps the engine running at what the manufacturer concludes is the optimal temperature for performance, reliability, emisions and longevity. What does a lower temp t-stat do? It simply opens earlier and stays open longer.
At best you may see a 5* drop in coolant temps. Why? Because the t-stat is at the mercy of the radiator. The stock radiator is capable of shedding only so much heat. It too will work on a consistant temperature range, thats where your fans and general airflow come in to play. All the while the water pump is keeping things moving, combined with heat, pressurizing the whole system.

Now, run your engine hard and we are in business. A screamer like a Honda will generate even more heat through shear friction. 8k rpm leaves very little time between strokes to cool things down, THIS, this is where your lower temp thermostat comes into play. Even at this point your engine temps will be at stock levels, perhaps a tad higher. The whole point is not to lower the running temps, but to help keep them consistent when driven hard.

You will see no, to minimal benefit running this on a daily that only gets driven hard for a few moments at a time once in a while.
Did some testing on this with my 240 years ago, it wasn't until we upgraded to a proper aluminum radiator, independently controlled fans and some ducting that we were able to corral the higher boost levels. There would be up to 40* spikes in coolant temps in brief bursts. Reigned in the power a bit, cleaned up the tune now she will get from 10 to 15 degrees over stock temperatures on long runs consistently. A drastic improvement over a simple thermostat upgrade by itself.