low-temperature thermostats
 

I spotted a listing on eBay what claimed:
Available for all new style LS series engine that have a separate thermostat and water neck. These thermostats are available in 160, 180 and 195°F temperatures to suit any application. Mr. Gasket's 2005 Pontiac GTO test car gained 5 hp with the 180° unit.

Surely if you were testing maximum power on a dyno, the engine would warm up beyond the standard 195 degrees. How can it make a difference?
More likely the extra HP came from somebody turning off the aircon.

low-temperature thermostats
 

On 7/1/21 11:56 pm, Pedro Valdez wrote:
> I spotted a listing on eBay what claimed:
> Available for all new style LS series engine that have a separate thermostat and water neck. These thermostats are available in 160, 180 and 195°F temperatures to suit any application. Mr. Gasket's 2005 Pontiac GTO test car gained 5 hp with the 180° unit.
>
> Surely if you were testing maximum power on a dyno, the engine would warm up beyond the standard 195 degrees. How can it make a difference?
> More likely the extra HP came from somebody turning off the aircon.
>
The lower temperature thermostat would run the engine cooler by 15
degrees and that would increase intake air *density* resulting in more
power. For a performance application, the 160 thermostat might even gain
a little more power - for the same reason. Note too, running the engine
cooler means you have more leeway in the risk of auto-ignition of the
end gas meaning less risk of detonation. You can get away with either
more spark advance and a higher compression ratio.



--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

low-temperature thermostats
 

On Fri, 8 Jan 2021 00:05:24 +1100, Xeno wrote:

> The lower temperature thermostat would run the engine cooler by 15
> degrees and that would increase intake air *density* resulting in more
> power. For a performance application, the 160 thermostat might even gain
> a little more power - for the same reason. Note too, running the engine
> cooler means you have more leeway in the risk of auto-ignition of the
> end gas meaning less risk of detonation. You can get away with either
> more spark advance and a higher compression ratio.

Hi Xeno,

I do NOT profess to be an expert in this topic, not in the least, so be
patient with me if I state what seems obvious & logical to me but which
might not be the case in reality (for today's engines).

The thermostat, as I was taught way back in the early sixties, opens up
_once_ (in general), and stays open for the duration (until the engine
shuts down).

In fact, once an engine is "warmed up", I was taught you could completely
remove the thermostat, and you couldn't tell, from the outside or from any
measurement parameter, that the thermostat wasn't even there anymore.

At least that was way back when...

Fast forward to today and emissions controls, I understand that today's
thermostats may be much more finely mapped such that they might open up a
few times during a typical drive; but do they?

If they do, then my comments below are moot, as the "lower temperature
mapped thermostat" could perhaps maybe affect the engine temperature (if
it's constantly in the never ending process of opening and closing and
restricting coolant flow).

But if the thermostat opens only once (given an engine runs hotter than the
thermostat set temperature), then wouldn't a lower temperature thermostat
simply mean that it opens once, but at a cooler temperature than before?

low-temperature thermostats
 

Pedro Valdez wrote:
> I spotted a listing on eBay what claimed: Available for all new style
> LS series engine that have a separate thermostat and water neck.
> These thermostats are available in 160, 180 and 195°F temperatures to
> suit any application. Mr. Gasket's 2005 Pontiac GTO test car gained 5
> hp with the 180° unit.
>
> Surely if you were testing maximum power on a dyno, the engine would
> warm up beyond the standard 195 degrees. How can it make a
> difference? More likely the extra HP came from somebody turning off
> the aircon.

The LS factory thermostat is 186 degrees, plus unlike other engines it
is in the return side of the system not the water outlet. Normally the
LS runs right around 190-195 with the stock thermostat.
I know of a few folks who have pulled the thermostat just to see what
the thermal ability of the system is and on a 75-80 degree day the
coolant temps ran in the 170s at speed with 50/50 dexcool.

With some programming and the right tweaks I could see a gain with the
180 as that would put the coolant around the 185 degree range. I doubt
it would be 5hp but ? Would likely get more of a gain if you were to
reroute the air intake out where they were in high pressure areas and
insulate them from the underhood temps.

--
Steve W.

low-temperature thermostats
 

On 8/1/21 4:01 am, Arlen Holder wrote:
> On Fri, 8 Jan 2021 00:05:24 +1100, Xeno wrote:
>
>> The lower temperature thermostat would run the engine cooler by 15
>> degrees and that would increase intake air *density* resulting in more
>> power. For a performance application, the 160 thermostat might even gain
>> a little more power - for the same reason. Note too, running the engine
>> cooler means you have more leeway in the risk of auto-ignition of the
>> end gas meaning less risk of detonation. You can get away with either
>> more spark advance and a higher compression ratio.
>
> Hi Xeno,
>
> I do NOT profess to be an expert in this topic, not in the least, so be
> patient with me if I state what seems obvious & logical to me but which
> might not be the case in reality (for today's engines).
>
> The thermostat, as I was taught way back in the early sixties, opens up
> _once_ (in general), and stays open for the duration (until the engine
> shuts down).

You need to appreciate the two (2) primary functions of the thermostat;
it gives a faster warmup and maintains a *minimum* operating
temperature. What the thermostat does, therefore, is totally dependent
upon the capacity (efficiency) of the cooling system. That means, if the
cooling system capacity is greater than the needs of the engine, even
under maximum power, maximum load situations, the thermostat will
continue to *restrict* coolant flow. That means it will have to either
*cycle* or, alternatively, maintain an *intermediate flow restriction*
position.
>
> In fact, once an engine is "warmed up", I was taught you could completely
> remove the thermostat, and you couldn't tell, from the outside or from any
> measurement parameter, that the thermostat wasn't even there anymore.

Nope, remove the thermostat and you have *no control* over the minimum
operating temperature. All cooling systems are (or should be) designed
to provide *excess* cooling capacity. That provides some leeway as the
cooling system progressively degrades through blockage and buildup over
time.
>
> At least that was way back when...

Beg to differ, it never was like that. The engine would run *cooler*. In
fact, even a working and fully open thermostat provides some *extra*
restriction over an absent thermostat. What's more, some thermostats
provide a facility to block off a bypass passage once the engine has
warmed up. Removal of the thermostat on engines so designed will cause
*overheating* with the thermostat removal since the bypass flow is not
being blocked off as it should be thereby preventing a percentage of the
coolant circulating through the radiator.

https://www.are.com.au/feat/techt/thermostat.htm
>
> Fast forward to today and emissions controls, I understand that today's
> thermostats may be much more finely mapped such that they might open up a
> few times during a typical drive; but do they?

Yes they do. It is for the purposes of emissions control that we have
high temp cooling systems. For pure power without regard to emissions,
cooler is better (160-170F)
>
> If they do, then my comments below are moot, as the "lower temperature
> mapped thermostat" could perhaps maybe affect the engine temperature (if
> it's constantly in the never ending process of opening and closing and
> restricting coolant flow).

It could well remain, for example, in a half open position during normal
running if the temperature of the engine remains consistent.
>
> But if the thermostat opens only once (given an engine runs hotter than the
> thermostat set temperature), then wouldn't a lower temperature thermostat
> simply mean that it opens once, but at a cooler temperature than before?
>
Will affect the engine *minimum* operating temperature. In effect, this
should be the *normal operating temperature* of the engine. If the
engine runs hotter than this, then the cooling system capacity is either
insufficient or has been compromised by buildup of sediment, corrosion
or insulating layers on the radiator internals.

On the topic of why you might run a cooler thermostat than OEM for
racing, this link might provide the answer.

https://www.reischeperformance.com/WhyLowTemp.html

Supports points made in my original response.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

low-temperature thermostats
 

On Fri, 8 Jan 2021 11:42:12 +1100, Xeno wrote:

> You need to appreciate the two (2) primary functions of the thermostat;
> it gives a faster warmup and maintains a *minimum* operating
> temperature. What the thermostat does, therefore, is totally dependent
> upon the capacity (efficiency) of the cooling system. That means, if the
> cooling system capacity is greater than the needs of the engine, even
> under maximum power, maximum load situations, the thermostat will
> continue to *restrict* coolant flow. That means it will have to either
> *cycle* or, alternatively, maintain an *intermediate flow restriction*
> position.

Hi Xeno,
Thanks for explaining that the thermostat is, in some cases, _restricting_
flow most of the time, even when, from the outside looking inward, we'd
consider the engine well warmed up (e.g., after five or ten minutes).

> remove the thermostat and you have *no control* over the minimum
> operating temperature. All cooling systems are (or should be) designed
> to provide *excess* cooling capacity. That provides some leeway as the
> cooling system progressively degrades through blockage and buildup over
> time.

OK. It makes sense that if the thermostat can be fully open, but if it
usually isn't fully open, that it can regulate the _minimum_ engine temp.


>> At least that was way back when...
>
> Beg to differ, it never was like that. The engine would run *cooler*. In
> fact, even a working and fully open thermostat provides some *extra*
> restriction over an absent thermostat.

Understood and agreed.
o The thermostat itself, is a restriction, even when fully open.

> What's more, some thermostats
> provide a facility to block off a bypass passage once the engine has
> warmed up. Removal of the thermostat on engines so designed will cause
> *overheating* with the thermostat removal since the bypass flow is not
> being blocked off as it should be thereby preventing a percentage of the
> coolant circulating through the radiator.
> https://www.are.com.au/feat/techt/thermostat.htm

Ah. I remotely remember learning something about a "bypass" long long ago.

Thanks for your patient explanation of my misconceptions.

low-temperature thermostats
 

> Pedro Valdez wrote:
> I spotted a listing on eBay what claimed:
> Available for all new style LS series engine that have a separate
thermostat and water neck. These thermostats are available in 160, 180
and 195°F temperatures to suit any application. Mr. Gasket's 2005
Pontiac GTO test car gained 5 hp with the 180° unit.
>
> Surely if you were testing maximum power on a dyno, the engine
would warm up beyond the standard 195 degrees. How can it make a
difference?
> More likely the extra HP came from somebody turning off the
aircon.

Engines perform much worse with modifications of this
nature without tuning.

Stick to stock unless you're going to follow through with tuning.
Asking the factory ecu on most engines to cope with this is a way to
kill your cats quicker or have it run worse.


This is a response to the post seen at:
http://www.jlaforums.com/viewtopic.p...5443#584335443