,

... which is Leeper.

Anyway, disregarding EVERYTHING that Mr Stupid (Leeper) has to say, the OP probably has heard about old tech that running somewhat cooler would make for a cooler (i.e. denser) intake charge, and therefore slightly more power.
However, since that is no longer the case with all the happy fuel injection systems, it would only be a detriment. Granted, ten degrees isn't very much at all, but even so I don't see anything to gain either way.

 

Wow, I guess when you lack any substance or facial basis to support a different viewpoint you'll both resort to name calling!?!? Honestly I hoped and expected much much better from either of you. Very sorry it came to that but Lesson learned.

You do realize that both of your posted videos absolutely affirm everything I wrote right?

 

Taking your theory there is no need in having a thermostat as once the engine warms up it will maintain a temperature which cannot be modulated. It seems the videos explained that as it opens and closes it maintains a constant temperature. It does not open and stay open it varies its opening dependent on the bi-metal/paraffin function of the unit. If you were driving in the winter at -30* with a full open thermostat the engine would never warm up and if it opened at 195 it would have to modulate in order to keep the temp at 195. You can believe your theory or believe the principle of operation put out by the various manufactures like Stant or others. This is the end of this discussion for me.

 

O wow,, I come back and there is 2 pages

So to my original post, and as to why I wanted a lower temp:
I have a pulley and a tune and at a certain RPM there is slight pinging issue only when engine is fully warmed up, So I was just hoping to reduce the pinging by slightly lowering the running temperature, which probably means the fan must come on a little earlier as well.

 

The thermostat does not directly affect when the fan turns on. There is a separate temp sensor that controls when the fan turns on and that has a preset temp. You would need to find a lower temp sensor. What you should do is go back to the tune guy and have them fine tune the map to eliminate the ping. If it wasn't there before the mod and is now there , well you can guess the answer.

 

I am aware that thermostat has nothing to do with the fan, I was going to use the lower thermostat in combination with lower fan turn on switch.
If I turn the tune off, there is still some pinging, so it might also have to do with the pulley, whch im not planning to remove...

 

Did the pulley change and tune happen at the same time. Did the ping take place before any mods happened. If it is ping it is either a knock sensor issue or the timing not being adjusted from the ECM. I don't think a 10* cooler thermostat or fan control would correct the problem. I would still go back to the tuner and have him tweak it.

 

Ok, so how about a cooler range of spark plugs? I don't know a whole bunch of anything about heat ranges other than there are a bunch and how they are made.
Anyone out there (no trolls, please) know anything?

 

If your 'pinging' is actually detonation, forget fooling with coolant temps and instead ditch the tune- immediately. Get your money back if you can.

 

A colder plug may be worse and cause a misfire and a warmer plug might help but with a tune I believe the A/F ratio is adjusted through the rev range to get the optimum . The pinging could be due to an over lean mixture . I think adjusting the tune will solve the issue.

 

Spark plug heat ranges are neither the cause nor cure for detonation (pinging) issues. Detonation is not be confused with pre-ignition which can be caused by too hot a plug.

 

To answer your original question, the way to find a cooler thermostat is to use one of the
more comprehensive thermostat catalogs.

Start by looking up the original thermostat. Pick the more costly OEM version
from the thermostat manufacturer. Record the dimensions.

Look through the catalog again and find other thermostats that have the
exact same dimensions, but with the rating your want.

Thermostat manufacturers find life to be simpler if they do not offer listings
for alternative temperatures. But, the units exist. They are just listed under
other applications.

I am currently running a 71*C/160*F thermostat in a AJ27 SC. I ordered
a 76*C thermostat, and a 71*C thermostat came in the box. Oh, well.

Tested and it indeed starts to crack open at 71*C on the button.


What I know about this combination:

- at highway speed, the temperature gauge sits at 1 full mark
below the middle. i have that full mark space to notice that
the engine is running warmer than normal before the idiot
gauge stops and parks itself in the middle

- the engine runs closed loop

- the engine warms up no slower or faster up to the rated temperature

- in sub-zero temperatures there is as much cabin heat as with
the normal thermostat. this is due to the fact that in those
temperatures with the heater blasting, the coolant does not
reach the opening temperature of the thermostat anyways.

- around town, the temperature will still reach the middle mark
because the fan is programmed to come on at 195*F. i have
a programmable fan controller sitting in the parts bin that
cost all of $20 that can change that ... if i get around to
it

- i do not have a oil sludge problem. lots of engine parts punish
the oil at temperatures well above 212*F. Think bearings at
400*F and cylinder walls.

- i have less cooking of delicate plastic and wiring insulation
under the hood

- fuel economy is no worse or better than with the higher temp
thermostat

I can see no downside to having done this.

Seeing the temperature gauge sitting below the middle mark
puts me in a happy place on the highway. Just like knowing
I have checked the tire pressures just before departure.

oh yeah ... no warning lights, no mil, no DTC's and I have been
hooked up with IDS and other scanners multiple times since the
change.

 

The only thing that seems odd is the apparently unchanged fuel economy. Not that you're probably much interested in fuel economy but the Carnot cycle and related physics seems like it ought to apply...

What max temp does the ECT now report?

I'm wondering if fooling ECT so it appears hotter than it really is would help?

The idea being that instead of (say) being truly 195 it's 185 (or whatever) but reports as 195, then the fans will keep it there (or whatever the PCM aims for). (MPG will suffer somewhat, I reckon, and also max power, but so what.)

 

I have researched and have been unable to find a lower temp thermostat. The OEM thermostat is somewhat unique in dimensions which makes finding an interchange difficult. I have tried cross-referencing the NAPA catalog with no result.
Should you find a cooler thermostat please post your finding, etc.

 

If you were asking me ...

past experience shows the ECT to be reported at up to 205*F with the previous
thermostat.

in town temps probably still get up there because of the fan controller not being
synchronised with the change. it still has a turn on setting of 195*F. that's why
the change is mostly observable at highway speeds. in town, it takes longer to
get up to the usual middle mark because the thermostat has already cracked open
at 160*F and is at least attempting to keep the temperature at 160*F but is not
aided by the fan. air flow at 10 mph average is dismal.

on the highway, with the same ECT sensor, the steady temps dropped immediately upon
installation. the reason for the "immediately" is to put aside the argument of some
mysterious drift of the sensor. the drop has remained consistent.

physics may apply in a general way, but with a lot of variables theory goes out
the window in terms of observability.

the only true applicability is a steady state. as soon as drive cycles and ambient
changes steady state goes out the window.

anyhooo ... theory aside, the observed real life behaviour is no change in fuel
economy. at least i didn't say "MPG's" which is a horrible expression in that
context.

 

I was, thanks.

So how about fooling the ECT reading. Then the PCM should drive the fans sooner/faster than it otherwise would and your job is done, at least I can't see why not. No need for a different fan controller and anyway with that the PCM may be upset that ECT does not do as it expects.

 

To me, it all sounds like a lot of trickery and hard work/cash to do something that probably won't affect anything anyway.

 

Steady on, plums has been thinking this through, let's see where this leads...

 

The statement that the coolant temp rises to 'normal' levels when the car is stopped or in traffic says it all. There is not enough system capacity to run at sub-design levels without the assistance of the fans.

If the other recommendations to the OP to abandon his plans wasn't enough, the above should do it.

 

That was why I was thinking to fool ECT to make the fans run sooner & a bit faster as needed. Can't see why that would not work but someone say if you can.