The only reason I EVER put lower tem thermostats on cars is for when they are having cooling problems due to lack of airflow to the radiator. In most cases, a FMIC that is thick enough to restrict airflow is usually a good case for doing this mod, other than that, you are not doing yourself any good. Save your money for other things.

 

Let me stimulate the discussion and ask a question
If the best operating temperature in the s2k is 98C (as AusS declared), why did Mr Honda let you VTEC at 2 bar of temperature ie around 80C+/- 5.

My understanding is that most engine has an ideal coolant operating temperature of 82-98 degree. This engine might be special but why would Mr Honda do such odd thing ? I've been using a Mugen thermostat for more 1 year without any problem. I don't live in the desert and don't always thrash my car. However, my engine is far from stock.

 

Engineer in trainning but my dad is a mechanical engineer who's taught me a lot over the years. He used to design diesel engines with his team for a couple of years.

By 2 bar, the clearances might be "ok" enough to get into vtec load and RPM's without as much of a concern. If there wasn't a problem at all with temps there wouldn't be all the limters imposed in the first place.

Just because your engine is running fine for a couple years doesn't mean there hasn't been any damage done. It's all about chance and possibilities. Running the car hard under cold temps increases the odds of a problem occuring and wear happening. I'm also 100% sure you dont have the OEM piston to wall clearance at room temperature of 0.001". The bearing clearances being tight (looser is better upto a certain point. A bearing clearance of .02" is said to be optimal) ....upto .007" tight for the main bearing clearance doesnt allow for a thick enough layer to pass through. If your OEM motor came with extremely tight clearance (you would never know unless you took it apart and checked it) it's highly possible to put wear on the bearings since the oil is so thick there wouldn't be much of a free flowing layer for the crank to float on top of.

BTW, I'm running the mugen thermostat but like some of you, we actually need it. Especially with my turbo being a water cooled one.

 

we are not talking about extremely cold temp kane
I never vtec my engine until my oil temp and water temp are warm. I use my brain to control the gas pedal and not rely on some factory limit mate

Some more food for thought too
Standard thermostat open at 76-80C
Mugen thermostat open at 68C
Spoon open a little bit earlier.

I used the mugen because I don't like the rapid change in water temperature, with my sc and now turbocharge application, and I always take precaution to warm up the car properly.

BTW if you use one of these afermarket part, test if before installation. It will be a pita to replace again if you are unfortunate enough to get hold of a defected one, not to mention the possiblity of engine damage.

 

That's one of the two reasons mugen is one of the few JDM companies I like. I doubt I have to worry about it being defective. If I get a chance, i'll have it checked out though.

 

put it in a bucket of boiling water and you will find out for sure kane

 

Title does not dictate knowledge. You're an Engineer, YAY, I'm happy for you. O wait, so am I...
O wait, you're 'In Training", whatever that means. Just because your Dad is, does not make you.

As for clearances, where in the hell are you getting this from? Considering these thermostats still keep you temp range in 80-100 degrees, I don't see your argument on this.
There is really only one main advantage to an aftermarket thermostat... At idle, you car will run a bit cooler, or as you come to a stop after hard driving, your engine will cool a bit quicker. But as soon as you step on the gas and create heat and energy, it's going to rise to the same operating temps as with a thermostat that opens at 90 vs 80 degrees. I have seen it via my AEM EMS on my Civic, which has a Mugen thermostat installed. Even when it's been 30 degrees outside, the only significant changes I see are stopped, idling. When I am accelerating, or driving on the highway, my engine temps have stayed in the 80-100 degree ranges. So.. again your argument about clearances, simply holds no water.
Engine temperatures change too quickly and so often, that there is no way to state an aftermarket thermostat will mess up your clearances. Especially considering they run at the same temps with stock or aftermarket. I'm sure I can find some old data log information from my Civic to support these claims.
And if you're trying to refer to the properties of metal expanding and contracting under heat... Remember, Honda uses ALUMINUM for their block and heads, not steel. You're not going to see any signifficant clearance changes over 10 degrees of operating temp, unless you are getting in the 100+ degree ranges.

Someones opinion/ and personal experinces is never WRONG and you so stated.
Until you can provide hard evidence of these 'clearance changes' you are in no position to state anyone is wrong or right.

O ya... One last thing, i did state that in the winter I saw lower temps while cruising, but they were honestly on a few degrees. And since I installed the Mugen, not spoon like I said before, thermostat, i saw more consistency in my operating temps than with the stock. Meaning the rise in temp was not as drastic, and cruising temps were only a few degrees differnet, not enough to screw with any clearance specs that you are so worried about.

 

You have never seen the block apart and to think they can use aluminum for the whole engine??? There is steel, carbon composites, bronze, copper, etc. You cant be serious when you say that the block - which only provides structural support for the internals - is aluminum and that clearnaces dont matter.

At a stop, your engine is hotter than it would be while cruising on the highway but cooler than after hard driving because of the oil temps not being as high anymore.

The temperature differences with the OEM and aftermarket cooling system is significant. It's not all in the same range unless you got a defective system. I'm sure I can get numerous people to state that their engines are running a good bit cooler under normal driving with the aftermarket.

Go search the net. There was an article I read a long while back that explainned things pretty well about race motors which rely completely on specific clearances and temperatures. The engines are designed to run at a specific temperature. I've seen the full spoon cooling system run the car ~30+ degrees colder on the AEM EMS while cruising.

You dont have to take it to heart. It's your car, drive it like you want to. My friend has been driving his car hard in cold climates right upon start up and his rings dont seal much anymore. I used to get piston slap on my civic driving the car hard right after start up. BMW imposes a rev limiter that progessively goes up as the engine warms up. F1 cars are warmed up before they are even started because of their clearances being so specific.

Like I said, do whatever you want to do...it's your car. I'm personally running the mugen cooling system as well. I wouldn't run the spoon just because I saw it run very inconsistantly to what it should have. I dont want to have you or anyone arguing about this. I'm sure there's enough professional support for both sides for only a few degrees. My original statement said that it's not necessary for the average car and conditions. Like all aftermarket parts, company claims on parts isn't always accurate and I personally saw the spoon system running very cold to what it should.

 

All I'm saying is that if Mr Honda got it so right why do we feel we have to change it?

And I don't mean that as a statement but as a question. No one has given a really concise reason why there is a deficiency in the stock thermostat that is somehow alleviated by an aftermarket one.

 

My 50 cents.