Thermostat temps

[FXMDBilly]

Don't forget that there are products out there that will lower the coolant temps too. I think that Royal Purple makes a product called "Water Wetter" or the likes there of. I have never used any of these, but know "Street Rodders" that swear by it. Check it out.
Brad

The Royal Purple-brand "water wetter" has been known to cause radiator damage, foam, and many other problems. Many radiator manufacturers do not recommend using the RP brand water wetter.

I myself have had said problems with the RP brand on a few street and race cars over the years.

Only use the original Redline-brand "Water Wetter".

I wouldn't expect that any respectable Turbokit builder will use other than a watercooled Turbo, afaik all modern turbo's are watercooled!?

The point is that this when pushed, will add a temp spike to the cooling system and the reaction of a partially closed thermostat will just be too slow so by the time the full cooling capacity is available, the system will be already be in overheating mode. As a low temp thermostat will react earlier, the temp spike will be flattened off faster thus preventing overheating.
Ask me how I know... I have a turboed MX-5/Miata

The best thing to do is just let the motor warm up to operating temperatures before revving the motor, 'boosting' on it, and stressing the motor. It's always important to let any car warm up (NA, SC, or Turbo) before you rev it high or cause a lot of load on the motor.

If you let the motor warm up properly, there is no concern about the thermostat opening prematurely due to excessive heat from the turbo. Just warm the motor up before you start beating on it.

No, most are using water cooled turbochargers. While there is thermal transfer between the turbo and the oil around the bearings, the oil's purpose is lubrication. A water jacket turbocharger uses chambers around the bearing to extract heat from the center housing (reducing transfer to the turbo's compressor side). This water jacket shares the engine's coolant circuit in most applications.

+1
Almost all turbos now are watercooled. Just like the days of the old air cooled Porsches going by the wayside, so have older non-water cooled turbos. While the turbo oiling system lubricates and also helps to cool the turbo, the water greatly improves the cooling efficiency of the turbo. While you can take a modern water cooled turbo and only plumb the oiling side, it WILL work, but it will also have excessive heat, which will affect the life/longevity of the unit and in extreme environments, could lead to a failure that otherwise wouldn't have happened if the water lines were hooked up.

I knew this would open a can of worms!

Here's one for you. why do 99% of purpose built race engines (not OEM based) do not use Thermostats?

Not really true. Many racecars use thermostats. Depending on the race series, regulations, and rules, either the stock location thermostat or an aftermarket remote water pump and thermostat are used. Thermostats on both the water and oil systems are VERY important.


Billy

 

[Daedalus]

1)The turbo runs off the exhaust gases of an engine creating back pressure between the heads and the turbo to push the wheel on the turbo, now the back pressure in the headers have more energy causing more heat then stock, therefor the heads of the car are at a higher temp now.

2) Since the turbo runs from the exhaust gasses the turbo spools up causing it to reach very high temps (i think over 1500 degrees), being it a watercooled turbo the coolant temps are pretty high now.

You stated that the coolant temp will increase at 3.3*c at WOT is this the same for NA motors and FI motor? Then is it same for FI motors at low boost as to high boost as to extreme high boost? I would like to know this because I have a turbocharged honda civic 2.0 GSR motor and I can go from making 300 whp to 800whp with a flip of a switch on the boost controller. It makes 800whp at about 32-34 psi of boost on a fairly large turbo so does the equation stay the same? The more air and fuel I pack in the cyclinder the the more power I make creating more energy that needs to be absorbed by the coolant.

First off, don't get attached to the back-of-the-envelope calculation, as it was intended to bound a problem and isolate whether there's a need for a different thermostat on an NSX, which is why this thread was started. I chose easy, worst-case assumptions just to prove a point; the number is unquestionably on the high side of reality. Actual temp fluctuations should be less (probably much less), and also non-linear, but it is more difficult to quantify. To do so, we would need to remove conservatism with more info, such as volumetric flow of coolant as a function of thermostat position (the calculation assumed 0), initial coolant temp, heat transfer capacity of the radiator, more specific opening speed of thermostat, etc.

The calc assumed a power output of 335KW (450HP), as this seems to be the "entry level" power output for turbo kits. A stock engine would output less, so the temp rise (again, only under silly assumptions) would be proportionately less. The results suggest you could double the assumed power output and still not have to worry about the thermostat, just a lot of other things. The amount of heat dumped into the cooling system is ballparked at 28%, and is the heat absorbed through the walls of the heads into the water jackets. I'm guessing the more power you make, the more this ratio might decrease, as a greater % of heat would exit with the exaust, since combustion temps wouldn't rise as much as pressure and exhaust volume. Some exhaust backpressure won't make much difference to this. There is some cam overlap, so the incoming boost helps to purge the cylinder of exhaust before the exhaust valve closes.

I wouldn't add FI to a car without measuring at least a few parameters while dyno tuning and/or periodically after...coolant temps, AFR, oil pressure, fuel pressure, etc. It's the only way to be certain of those things. Then you can spend your time worrying about the things you can't measure.

You stated above about using oil cooled turbos, the oil going to the turbo is not for cooling purposes, but the oil supply is for the bearing in the center of the turbo.

Lubrication is a given. "Oil cooled" is a term often used with older vehicles. My first motorcycle was an "oil cooled" '85 Honda. Without the temp moderation from the oil, the moving parts in the turbo would expand beyond what they're designed for. Water cooled turbos keep a tighter temp range, and thus see even less thermal expansion.

Now lets just take into account all the extra heat/energy we have added to the mix of a stock cooling system. So accordingly the cooling system need to be brought up to par, which would mean upgrading to a larger/more coolant capacity radiator and what ever else it takes to keep everything under good operating condition.

I agree that just changing the thermo to a lower *thermo is not enough but I think it gives many a peace of mind, also does having a lower temp thermo hurt the engine in any way? if not then its phycological insurance for the driver or builder and is worth the $50 or $60 to them.

Probably the worst thing would be slightly more internal friction and wear. Engines run better at higher temps. A lower temp thermostat can be right on the border of the min vtec operating temp.

 

[bluepearl92NSX]

OP, if you were to go with a lower temp t-stat, I would go with the Mishimoto.