Lower Temp Thermostats. Whats the deal?
#1
Lower Temp Thermostats. Whats the deal?
What is the purpose of a lower temperature thermostat and what are the pro's/con's of fitting one?
Ive recently been reading into people fitting lower temperature thermostats in their cars/Scoobys and wanted to make a discussion about them.
First of all, is the following accurate in terms of how a thermostat works in a car?
* Car is started from cold and thermostat is currently closed.
* Engine starts to warm up.
* Coolant temperature in the engine block increases and reaches xxx degree's.
* Thermostat opens at xxx degree's and coolant circulates through the radiator.
* Thermostat remains open until coolant temperature drops and closes again. Eg, when engine is turned off.
Am I also right in thinking that once a thermostat reaches its opening temperature, it will not close fully or narrow its flow because the engines normal operating temperature is higher than the thermostats. For example, the thermostat opens at 80 degrees but the engine's normal operating temperature is 90 degree's (or maybe more with 'spirited' driving) so the thermostat will not begin to close again until it drops to 80 degrees which probably means the engine is turned off and slowly cooling down.
With this in mind, back to the original question...What is the purpose of a lower temp thermostat?
Does it simply open sooner and circulate through the radiator meaning the engine takes longer to reach normal operating temperature?
Ive recently been reading into people fitting lower temperature thermostats in their cars/Scoobys and wanted to make a discussion about them.
First of all, is the following accurate in terms of how a thermostat works in a car?
* Car is started from cold and thermostat is currently closed.
* Engine starts to warm up.
* Coolant temperature in the engine block increases and reaches xxx degree's.
* Thermostat opens at xxx degree's and coolant circulates through the radiator.
* Thermostat remains open until coolant temperature drops and closes again. Eg, when engine is turned off.
Am I also right in thinking that once a thermostat reaches its opening temperature, it will not close fully or narrow its flow because the engines normal operating temperature is higher than the thermostats. For example, the thermostat opens at 80 degrees but the engine's normal operating temperature is 90 degree's (or maybe more with 'spirited' driving) so the thermostat will not begin to close again until it drops to 80 degrees which probably means the engine is turned off and slowly cooling down.
With this in mind, back to the original question...What is the purpose of a lower temp thermostat?
Does it simply open sooner and circulate through the radiator meaning the engine takes longer to reach normal operating temperature?
#2
Scooby Senior
iTrader: (41)
Yes pretty much Roger Clarks sales pitch is...
You have various options. OEM is 78, Zerosports is 71 and Cosworth is 68 to name just a few. With the 68 and an oil cooler you will struggle to reach consistent operating temps and will run perhaps too cool as a regular drive. The 71 I ran in 2 of my Subarus was fantastic and it ran much cooler across the usage than the OEM Stat. I am convinced my 2.5 ran without issue as I fitted the cooler stat at 7k miles
It's also important to point out that the 'uprated' stats are designed to fail in the open position to avoid over heating, whereas the OEM stats are not
With a low temp thermostat in place your engine coolant is allowed to circulate around the engine much earlier which allows overall engine temperatures to be reduced sooner than they would normally occur. Ultimately your coolants job is to carry heat out of the engine, take it through your radiator (where the actual temperature reduction will occur) and then flow back into the engine at a reduced temperature to when it left. This entire process is activated by a door opening and closing (your thermostat), so if this "door" is opened earlier than would normally be expected then the coolant can get a head start on taking heat out of the engine.
It's also important to point out that the 'uprated' stats are designed to fail in the open position to avoid over heating, whereas the OEM stats are not
#4
Scooby Senior
iTrader: (41)
Mine ran consistently cooler and the idle temps are certainly lower. I had some numbers I posted ages ago when this was discussed before I will have a search On my S202 with the oil cooler and 68 stat, it was so effective it was hard to keep it over 80 degrees. That's on the road and I only really use the 202 on track which is fine
#5
Scooby Senior
iTrader: (41)
Here you go
Zerosports is a 71dg stat and works really well. On my 2.5 it cruised at 78-84 and idles after hot runs a 88-92 peaking at 93 full boost on track
The Cosworth one I have now I bought for track use only and is too cold for road really on a year round basis. It cruises at 74-80 and with the eom oil cooler doesn't get a great deal hotter ideal for track but not on an everyday car
I run the Zerosports on the classic I have as well and I've never had one fail or a system that's got too hot. The benefit of a stat like a Zerosports as well is that should they fail they fail in the open position. OEM stats fail closed. This is an added safety benefit with the worst that can happen is a cold system, preferable to a cooked one
The Cosworth one I have now I bought for track use only and is too cold for road really on a year round basis. It cruises at 74-80 and with the eom oil cooler doesn't get a great deal hotter ideal for track but not on an everyday car
I run the Zerosports on the classic I have as well and I've never had one fail or a system that's got too hot. The benefit of a stat like a Zerosports as well is that should they fail they fail in the open position. OEM stats fail closed. This is an added safety benefit with the worst that can happen is a cold system, preferable to a cooked one
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#10
Hmmm interesting, im toying with fitting an oil cooler as im seeing oil temps of 95 - 100 on spiritied driving, im wondering if a 71d cooling stat would reduce oil temp also by 5 or 10 degrees ?
#13
EDIT: Do peeps use gauges to monitor their temps or gadgets like Scangauge?
#15
If i could guarantee it would lower my oil temps as well id go for it, but running my coolant at 71 or 77 degrees doesnt worry me too much, its watching my oil temp hit 100 on a hot day that scares me lol and an oil cooler i can get for around the same money which i think will benefit me more, i was jusy hoping a lower stat would cure my oil temps as its alot easier to fit than an oil cooler
cheers
cheers
#18
Former Sponsor
iTrader: (9)
If i could guarantee it would lower my oil temps as well id go for it, but running my coolant at 71 or 77 degrees doesnt worry me too much, its watching my oil temp hit 100 on a hot day that scares me lol and an oil cooler i can get for around the same money which i think will benefit me more, i was jusy hoping a lower stat would cure my oil temps as its alot easier to fit than an oil cooler
cheers
cheers
If you're only getting to 100C, don't fit an oil cooler, it's not going to help with protection.
Cheers
Tim
#19
100C is nothing to worry about with oil, in fact it's ideal. Assuming you are using a good 5w-40 or 10w-40, that will be fine up to about 130C or slightly higher peaks. Under about 80C, not all of the additives in the oil are doing their job properly and the oil is not flowing as well as it should.
If you're only getting to 100C, don't fit an oil cooler, it's not going to help with protection.
Cheers
Tim
If you're only getting to 100C, don't fit an oil cooler, it's not going to help with protection.
Cheers
Tim
Cheers
#21
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That's interesting.
Where does that information come from?
Is it your own findings or manufacturer's specs?
Is it real world usage (i.e. on track) or is it laboratory environment testing?
I'm genuinely interested.
Where does that information come from?
Is it your own findings or manufacturer's specs?
Is it real world usage (i.e. on track) or is it laboratory environment testing?
I'm genuinely interested.
#23
Scooby Regular
iTrader: (13)
My oil temp sits at 130degrees on track, with a 16 row cooler fitted with proper fabrication so the air flows straight through and is pushed out the back. (it is a wet system with a baffled sump and a 11mm oil pump)
Harvey used to say to me he never worried until about 140degrees....he used to run Royal Purple.
I have also run Fuchs Pro S 10/50 at 130/140 degrees for about 15mins flat out with no problems.
Cheers
Steve
#27
Scooby Regular
iTrader: (6)
Just on the oil temp thing.....mk1 golf gti manual used to state if oil temp hits 140 to slow down/allow car to cool...and thats going back to early 80's!
As for the cooler stats surely the car will still get to its operating temp eventually? Std stat may be 78 but car operating temp is around 90 and fans kick in at 96....or so it did on my hawk sti using the psi3 to monitor
As for the cooler stats surely the car will still get to its operating temp eventually? Std stat may be 78 but car operating temp is around 90 and fans kick in at 96....or so it did on my hawk sti using the psi3 to monitor
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