your car looks track only in the avatar. If true, no need for it.
A thermo doesnt keep water in the radiator to cool, then lets it in the engine.
It just keeps water in the engine to let it warm up quicker. once it gets to temp it starts to open, and CONTINUOUSLY circulates water through the radiator to block back to radiator. lack of a thermostat will do nothing but extend the warm up time of a car, unless your having issues with running to cool, where you would need a thermo to help keep temp UP.
Eyal

 

Lack of thermostat also leaves the bypass open in the throat of the waterpump, causing some coolent to recirculate within the pump. Huntley used to make a plug for bypass port so he could run without the t-stat and without recirculating a percentage of the coolant inside the pump. As I said, though, I've run without a t-stat and without blocking the bypass, and the car overall ran cooler.

 

I have run without the turbo thermostat for years without any ill effects.

 

I am taking my plastic Turbo thermostat housing off the spare engine and taking it in for fitting. Maybe a new aluminum part will come out of this.

 

Wouldn't running your car without thermostat make the computer compensate for the colder temps. by making it run richer?

Colder temp.= More dense, thus more oxygen=leaner misture

now computer kicks in to even it out

Kinda makes sense

 

In non-freezing weather, the coolant temps don't generally drop all that low. Now if you ran around without a t-stat in frigid weather, then it may create some issues.

 

The 944 Turbo cars have 2 coolant thermostats, whereas the 944 NA models have only one, the main thermostat! This thread is about the "secondary turbo thermostat" found only in normal 944 Turbo models. This 2nd, smaller thermostat, is designed to allow the turbocharger to come up to operating temperature as quickly as possible from a cold start when it is closed. The turbocharger water cooling system on the 951 (aka 944 Turbo) is very clever - when the engine is cold and the auxiliary turbo water pump is not running, the water flow path for the turbocharger is blocked so that little or no water flows through the turbocharger allowing it to heat up quickly as the engine starts running. As the engine block heats up, the secondary turbo thermostat located at one of the water pump's inlets, begins to open and water flows from the passenger side of the radiator to the T-hose located below the expansion tank, then passes through the not-running auxiliary turbo water pump (!), through the turbocharger, then through the secondary thermostat and back to the water pump inlet then back into the engine block.This "turbo cooling" water is allowed to flow through the block and then back to the driver's side of the radiator completing the path. Note that since this secondary thermostat is located just inches away from the main engine thermostat, it heats up along with the engine block - except that it is housed in a special nylon housing. Why nylon? Because unlike a metal housing, the nylon housing offers a thermal de-coupling from the metal water pump and the engine block. Why de-couple the secondary thermostat from the heat of the engine block by using a nylon housing? So that this secondary thermostat will operate partially as a function of the water temperature passing through the turbocharger and not merely as a function of the engine block temperature.The turbocharger does operate at a very different temperature than the water pump housing. So why all this German engineering bother to keep the turbocharger temperature in a happy place?
The life of a turbocharger can be greatly extended if upon cold start, it is allowed to come up to normal operating temperature before user nails the accelerator and demands that a cold turbocharger suddenly fill with Hot Exhaust and start compressing intake air. See warnings in your 944 Turbo Owner's Manual. Hot exhaust gases impinging on a cold turbocharger causes thermal shock - a rapid expansion of hot metals bolted directly to cold metal parts. Gaskets, O-rings, bearings between the two sections of the turbocharger get really stressed and can wear quickly in this scenario, So for longest life of your dear turbocharger, Porsche recommends that the driver does not request significant turbo boost (high power) until the engine has properly warmed up to "Normal". Note that after the engine is turned off the auxiliary turbo water pump turns on (30 seconds typ.) and circulates water from the T-pipe at the bottom of the expansion tank through the turbo then back into the upper side of the expansion via a one-way valve. With engine off and when the aux turbo water pump runs, some turbo-cooling water may also flow in a parallel path from the turbocharger outlet through the (open) secondary turbo thermostat then through the engine block and back to the radiator and on to the aforementioned T-pipe. In the case when the secondary turbo thermostat closes, the aux turbo water pump simply recirculates water from and to the expansion tank.The turbocharger has its own water temperature sensor to control the aux turbo water pump so that the turbocharger can cool down at a controlled rate (to prevent cooking the bearings, seals and lubricating oil). By the way, the oil flow path through the turbocharger (engine running) also provides additional cooling effects.
944 Turbo cars can be operated without the secondary turbo thermostat installed in its housing, likewise, turbo cars can use a metallic secondary thermostat housing - just be gentle during warmup.

 

FWIW I have been running with no Turbo T-stat on my track car for a couple of years.. Additionally I also dont have the secondary after run waterpump on the turbo... I just make sure the car is up to operating temp before I nail it.. Usually let it warm up for about 10 min, fans come on ect..

 

Quite the 15-year-old thread resurrection for a first post, and interesting point about the nylon not transferring heat!

On a related note, I recently changed my water pump and thermostat. I previously had a low-temp (71 degree) main thermostat and my car usually ran about a quarter of the way up between the two middle white lines, if that. I couldn't find a low-temp thermostat locally this time **, so figured I'd go with the default PCNA part, which came rated at 83 degrees. I figured it shouldn't matter since the t-stat would be open either way once the car warms up. however, the car now runs just above half way up, despite adding Water Wetter and using a higher water to coolant ratio than before. The only thing I can figure is that the new thermostat doesn't fully open until even hotter and is restricting the flow (and allowing more bypass) until the temps get up into the middle of the gauge. It did open before the water boiled when I tested on the stove, but I didn't measure the water temp to see how hot it was once the t-stat was fully open. I dunno, but I ordered a low-stat Wahler t-stat and will be putting that in as soon as I get it. Nothing wrong with running in the middle of the gauge I suppose, but with a history or HG failures I just feel better with a little breathing room....

** Napa did have a low-temp version listed for the 944 turbo, and it was only $9. But...the opening where the coolant flows through was noticeably smaller than the Wahler/stock thermostats. I suspect these are actually built to VW specs and cross-referenced for the 944 because they physically fit despite flowing less. Buyer beware.

 

You want to run 100% coolant for the best heat protection, 68% coolant/32% water for the best freeze protection. Adding more water to the coolant only drops the heat and freeze protection of “antifreeze”. Antifreeze is actually the best heat protection due to it doesn’t boil off like water.
And holy Resurrection.

 

Google says 60% antifreeze creates the lowest freezing point, for what it's worth, at -63F. It's never freezing here, so I could probably run straight water like the racers do, but I want the anti-corrosion and lubrication properties of the coolant. There's no doubt that the boiling point goes down when you add water, but is that effect enough to make much difference? A 60/40 water/coolant blend has a boiling point of 220F. An 80/20 blend boils at 216, so there's only 4 degrees of extra anti-boil protection to gain in that range -- yet the coolant is noticeably cooler on the gauge at 80/20. I'm in the 25-30% range now. I'm no expert, but if I can run the car consistently cooler, but with a boiling point 4 degrees lower, that seems like a better trade off than watching the car run up to the upper white line all the time just to get 4 more degrees without boiling? If a higher boiling point is really more important than running temps, per se, I think that brings us back to the old Evan's coolant debates that entertained us all for a while a few years back... That stuff boils at 375F so is in a whole different league, but it doesn't cool as well by all reports... So I dunno. I'm just getting a lower t-stat and calling it a day.

 

I noticed a drop in temperature going from 100% coolant to a 50/50 coolant/water mix.

 

I have no doubt. It needs the water to carry the heat. Racers often run 100% water to get max cooling ability. Also, weirdly, you need to add water to lower the freezing point. Straight coolant freezes somewhere around -10 to +10 degrees, whereas a 50/50 mix doesn't freeze until some crazy low temps. The magic of chemistry I guess...

 

Water is over 2.5 times better at conducting heat than ethylene glycol (coolant [antifreeze]). So running a higher water to glycol ratio will increase the cooling system's ability to absorb and reject heat.

 

Well I replaced the 83 degree thermostat with a 71 degree version today and once again can confirm that the car just flat out runs cooler with the lower temp thermostat. 96 degrees out today and I drove around, boosted, went up and down hills, etc., and the car stayed pretty consistently just above the first (80 degree) line. With the 83 degree thermostat, it ran about 1/2 between the lines (and at times as much as 3/4). Go figure.