I'd like to replace my stock thermostat with a higher temp version so I can improve efficiency and power. I'd like to find a thermostat that opens fully at around 205 - 210 degrees. Does anyone know where I can find one?

 

Higher? You mean a thermostat that opens at a lower coolant temp? I know j's racing, spoon, mugen and possibly mishimoto/koto have thermostats. You should also get a fan switch. I think the numerous vendors on this site should be able to get them.

 

I definitely don't want a colder thermostat. I bought one for my previous S2000 because it seemed like the cool thing to do (pun intended), but then I learned about the physics of combustion, and realized it was a rediculous mod. Cooling systems in general are a necesary evil, and just extract precious energy from the combusion chamber instead of letting it push down on the cylinder. The biggest reason why companies still sell colder thermostats is mostly because people buy them whether they need them or not. At best, they are a bandaid for an under-engineered cooling system.

I want my cooling system to run as hot as it can while stiaying just below the detonation point. To do this, I plan to run colder spark plugs, less antifreeze (more water), higher pressure radiator cap, and Redline Water Wetter.

 

This is absolutely untrue. Engine power is directly related to the density of incoming air. The higher the density, the more power the engine can make. Hot air is less dense than cold air so, the lower temp 'stats, removing the throttle body heater and insulated the intake manifold gaskets are all intended to reduce the heating of the incoming air inside the intake manifold.

This change you're making MIGHT improve fuel economy but, it's not going to make more power. If nothing else, it'll make the engine more prone to detonation so the ECU will have to pull timing over a lower temperature engine.

You know that engine coolant temp is just an average right? Coolant temps in the areas next to the combustion chamber can be much higher so, you get temperature spikes and localized boiling that also causes detonation.

You might want to look into something like Evan's coolant. It's polypropylene glycol based, has no water and boils at something like 340 degrees.

 

AP2 replaced the fan switch with a sensor tied into the ECU. I'm not sure cooling system mods are a good idea.

 

I totally agree that colder air is bettter for power, and I also totally agree that keeping the throttle body and intake manifold cool helps with that. However, if you install an insulator like the Hondata intake manifold gasket that also blocks coolant flow to the throttle body and intake manifold, then there is no benefit from having colder coolant temps. The colder thermostats do NOTHING to improve cooling efficiency, and they do not lower the peak temps that the coolant reaches (like on a track). All they do is reduce the temp of the coolant when the engine is under light load, which is useless. They also increase the amount of temperature variation (between the peaks and valleys) that occurs under regular driving, which isn't good. It would be better to maintain a constant temperature, even if it is near the upper limit of "normal operating temperature". Oh, and It also increases wear on the engine since it causes the oil to heat up slower after a cold start.

I think you missed my point about the coolant. I don't want to use any more antifreeze than I have to since straight water makes for a more efficient coolant. I just want to run the minimum amount of antifreeze necessary to prevent freezing during a Dallas winter.

 

this is a new idea, i will be reading up on it.

 

Read up on the Evans, they specifically address localized overheat and boiling in the areas of the head near the combustion chamber. Interesting thing is they don't use much pressure in the cooling system. On a stock cooling system with normal fluid, the anti-freeze increases the boiling point to 230 or so and the additional pressure of the cap bumps it up to 255 or so. With the Evans boiling at over 300 they don't need any of this.

To me, this is like the 100 mpg carb and the stupid hydrogen injection thing. If it really made a huge difference, the car companies would already be doing it. They spend millions trying to improve these cars.

I think you should go ahead and try it. Might want to wait till you get the flashable ECU stuff so, you can change the FAN on temps in the ECU. I did that in my suby but, the opposite direction, I put a cooler 'stat in and re-programmed the ECU to turn the fans on at 195 instead of 205. You'll probably want fan on temps in the 220 range.

 

If I have a boiling problem, then I'd consider the Evans coolant, but I don't expect to have a boiling problem any more than the next guy. As I said, a hotter thermostat wouldn't increase the peak coolant temps. It would just increase the minimum coolant temps.

There is truth to what you say about car companies spending millions to improve their cars, but surely you agree that they build safety margins into everything at the cost of performance. They do this with ignition timing maps, air fuel maps, and coolant temps. If you want to maximize performance on a particular car, you can do this by tweaking with all 3 of these things to find the optimum mix. Everyone know this, but most people think they are getting higher performance with colder coolant, when that is really the opposite. Going with colder coolant is like retarding timing or enrichening the fuel mixture.

If it was possible to "tune" the thermostat as easily as the fuel and timing maps, so that the engine is always operating just below the detonation point, then we'd be seing more power.

 

You're missing my point. You ALREADY have a boiling problem. We all do. The coolant that touches the aluminum on the head closest to the combustion chambers is already flash boiling and condensing when it hits a cooler strata. This causes combustion chamber temp spikes because the boiling coolant insulates the metal from the liquid coolant. It happens when you drive the car hard. I was thinking that by increasing the coolant temp, you're just going to make it worse. Since the Evans boils a some much higher temp, it's not subject to the same process. Lets say it's more resistant to it.

I really think you should try it. I just don't think you'll see measurable gains. Hell driving in traffic, the engine is already running at 196-200 degrees because that's the temp the cooling fans come on at. The 'stat sets the lower threshold for temp but, the fans set the upper.

The ECU already compensates for engine temp. Both the intake air temp sensor and the ECT sensor are used in the timing maps to retard timing if the engine or intake air gets above a certain temp.

How are you planning on testing it and what do you expect to gain?