Thread: How hot is too hot

whats factory and how they preform best are not always exactly the same.

generally factory is set for max life

According to my Tridon catalogue, t/stats aren't fully open until about 12*C past their crack open temp.

Originally Posted by rick130

According to my Tridon catalogue, t/stats aren't fully open until about 12*C past their crack open temp.

My saucepan test on a 82° thermostat showed that.

Simon

Small lesson in fluid mechanics for you all.

The thermostat/tap/valve only has to lift off seat a height of 1/3 its effective flow diameter for it to be hydraulically fully open.
for example, if the thermostat has an effective flow diameter of 30mm, then a lift of approximately 10mm is considered to be full open.

However in a cooling system, the velocity and flow of the water from the pump will top out when the thermostat is about 3 or 4mm seat lift as the waterpump does not generate either enough pressure or volume being a centrifugal type impeller and is a relatively constant flat rate of pressure and is a closed circular system to start with!
Plus a thermostat is there to provide some load to initiate more efficient cooling by slowing down the flow in the engine to allow more heat to be absorbed into the coolant and more time to expose it to the radiator cores to transfer latent heat.
An excessively high flowrate in your engine will not pick up enough latent heat nor will it transfer it out.

So basically it doesnt matter when the thermostat is fully open mechanically, but it does thermatically.

whats the difference for stroked motors running after market ECU's?

mine runs around 95ish, my mechanic who races his 4.4 (stroked 3.5) in a TR7 runs his round 105 to 110 on track

Originally Posted by def-90

whats the difference for stroked motors running after market ECU's?

mine runs around 95ish, my mechanic who races his 4.4 (stroked 3.5) in a TR7 runs his round 105 to 110 on track

If your running at 95 on road, its probably a bit to the higher side of where you want an aluminium engine to be. I would guess your running a std radiator also?? Would look at getting a bigger core radiator if thats the case and make sure you use good coolant. Redline Water Wetter is excellent.
As your coolant gets hotter, so does your oil and oil breaks down the hotter it gets. If you run it all day everyday like this, your oils going to carbonise and foul up quicker if you use mineral base.

In a race car its a different story. Running high revs and hard load all the time you are going to run hotter, nothing you can do about it, but the radiator wont be std and oil gets changed basically every meet.

Any performance setup will change normal operating parameters, you just need to deal with the changes......

Take into account also that using normal tap water, due to things like calcium, lime and other solubles, it actually lowers the boiling point of water, ie rainwater, de ionised or distilled water wont boil till 100 degC, but tap water depending where on the planet you are can boil from as low as 93 deg where high levels of soluble minerals etc are present.
Next time it rains, stick a bucket outside and get as much as you can, then put a saucepan of rainwater and a saucepan of tapwater side by side on the stove and see which one boils first!

Is the reason for the power drop off at higher temps due to increased bore friction as a result of piston expansion?

Originally Posted by mark2

Is the reason for the power drop off at higher temps due to increased bore friction as a result of piston expansion?

Not particularly.......
More so the fact that your inlet temp is hotter and hot air expands losing mass. Reason why intercoolers are used on turbo'd and in some cases supercharged engines.