160* Vs 187* Thermostat

[JennaBear]

I am almost certain that if you tune on the 160* with max timing and then switch to the OEM (195* I think) you lose power due to the heat causing some KR.

When engine temps are too cool (ie. below 195 or 200) more of the heat energy from the burn is actually absorbed from the block than transferred into kinetic energy. Yes, you might be able to get away with more timing without KR, but that does not mean more power (I am sure you already know this from the dyno ). Justin's truck made more power at 225 than 205.

 

[viximaging]

These engines love to be warm lol

 

[HMFDZ28]

I am 100% with Jenna on this. If ya dont believe then take some time reading below

Proper Coolant Temperature and Camshaft Life!

Have you ever tried to find what proper coolant temperature is for most automotive engines? There are a lot of people who think they know, but it is difficult to find specifics, even in textbooks. We know we want the intake air to be as cold as possible (for best power) because cold air is denser (there are more oxygen atoms per cubic foot). The coolant temperature, however, is a different matter. The internal combustion engine changes chemical energy stored in gasoline into heat energy that is focused on the piston tops. If the cylinder heads and engine block are too cold, they will absorb much of the combustion heat before it can be used to push the piston down the cylinder. If the engine gets too hot, engine lubricants can break down, as well as overheating of the intake charge can lead to detonation, etc.

It turns out that coolant (usually a 50/50 mixture of coolant and water) has some fantastic properties that are ideal for use in engines. With a properly pressurized cooling system, coolant will not freeze until –30°F, and it won’t boil until +270°F (new oils don’t start to break down until well over 270°F). With these characteristics, engine designers have decided that engines should operate at approximately 210-215°F. Why, you ask? Well, it has to do with operating the engine at a high enough temperature to boil water out of the oil after the engine is cold started. If you have dew on the grass, it is certain that you have water in your oil, as the crankcase is open to atmospheric pressure! You can either remove the water by draining it out the bottom of the oil pan (remember the oil floats on water) or run the engine long enough and hot enough to boil the water out of the lubrication system. Years ago, coolants weren’t as sophisticated and engines were run at 165-180F, but the oil was changed every 1000 miles or so. That’s why many old timers think engines should run at 165-180F. Have you ever noticed that Ford doesn’t put temperature marks on their gauges? They just mark C for cold and H for hot and write “normal” through the center. If you hook up a scan tool to a GM, you will often find that the gauge reads much lower than the coolant temp sensor. That is because they know most drivers don’t understand how hot an engine should run.

So what does this have to do with camshafts? Many enthusiasts erroneously think that the colder their engine runs the better! If they are not running the engine hot enough to boil the water out of the oil, the oil becomes contaminated and the lifter/cam lobe interface is the highest load point in the engine. Engines running too cool can contribute significantly to camshaft and lifter failure. Think about it: What good does it do to use the most expensive synthetic oil and then run the engine so cold that it is contaminated by water vapor??!! Another point, piston manufacturers’ piston-to-wall clearance recommendations assume you will be running the fully warmed engine at 200°+F. Run the engine too cold, and you could see some scuffed pistons because the cylinders had not expanded enough to provide clearance.

If your engine will only run its best at the drag strip with the engine at 165°F, you probably have too cold of a spark plug heat range and you are probably jetted way too rich! If you keep the engine hot (not the intake charge), you will be using more of the heat energy in the gasoline to make power instead of just heating up your block. It does take “tuning know-how” to run an engine at 200-210°F, but you might be surprised how well and how long it runs when you do!! One final point - running a computer managed engine at 165°F compared to the factory 210°F will often cost you as much as 4 MPG. The reason for this is that the computer thinks that the engine is not off the “choke cycle” and it is still putting out a rich mixture! Check the science on this and don’t pay attention to the “old wives tales” of the past. Materials and lubricants are much better and different today than they were in the past!!

Original site:
http://www.vincihiperformance.com/LS1 TECH AND TUNE PAGE .HTML#Proper Coolant Temperature and Camshaft Life!

 

[Eagle]

Depending on your location and mods depends on the T stat to use. The main purpose of the lower T stat is to have cooler engine coolant temps and increase spark advance (more power) with out KR.

---------- Post added at 05:31 PM ---------- Previous post was at 05:30 PM ----------



My 160* works fine in ALL seasons. My heater works great in the winter too and my truck still gets to normal operating temps.

How does it get to and stay at 205-215 at 70 mph on the freeway on a 32 degree day with a 160 in there? I bet it drops to around 160... so it does NOT STAY at normal operating temps.


1: The job of a T-stat is to keep temperatures UP... to keep them at the bottom end of the threshold for efficient operation. A t-stat is NOT FOR 'COOLING'.
2: FANS and RADIATORS are for cooling, their job is to prevent exceeding the upper end of the threshold for efficient operation, usually around 210-215 on modern cars. FANS ARE FOR COOLING

We used to run Lower T-stats on Small blocks because the carbs and intakes would get heat soaked on drag cars... it also helped band aid excessive timing and barely adequate cooling systems in hot weather, particularly in the days when cars were designed without A/C in mind.

This is not an issue anymore with port injection and composite manifolds, and other changes to modern vehicles.. As a matter of fact it can be very detrimental to Horsepower, emissions, and engine longevity simultaneously.

Down sides to low temp T-stats:

If you allow your coolant temps to become excessively low, you will fall out of closed loop engine operation and revert to a warm up map.

IN this map the timing is too early for best power, and would result in pre-detonation if not for excessive fuel being injected.
IE While you might gain more timing, you also gain significantly more fuel for a LOSS in power

I have seen numbers tossed around that are as high as 8:1 or 9:1 A/F ratios during warm up.

If the best 'safe' power is about 12.5-13.2:1 (the ragged edge BTW), best emissions is ~ 14.7 :1 and best economy v. drivability is usually about 15:1

then

you can

quickly conclude

that:

MORE FUEL DOES NOT EQUAL MORE POWER.
that is such an innovative idea that it bears repeating...

MORE FUEL DOES NOT EQUAL MORE POWER.

one more time

MORE FUEL DOES NOT EQUAL MORE POWER.


More fuel equals cooler combustion temps, which equals less power. If it wouldn't slag the pistons or blow the HG, running around LEANER and HOTTER would yield better results, not being richer and colder. Kinda like with women.



Did i mention combustion chamber deposits from incomplete combustion can led to hot spots and pre-ignition, necessitating reduction in timing and using conservative maps which reduce power and efficiency even when the vehicle is at operating temp?

How about that the excess fuel is bad for your cats and 02 sensors and will reduce their life span?

How about the fact that it washes down the cylinder walls, contaminating the oil and with a resultant increase in cylinder bore wear, reducing the life and performance of the engine?

How about the reduction in MPG?

How about the increased difficulty in passing emissions if the vehicle will not 'warm up' into closed loop mode?

It is amazing how much we have learned in the last 15 -20 years, and even in the last 5 years since A/F ratio monitoring and dyno tuning became affordable and proliferate.



What whiteout was talking about regarding coolant speed about is what happens on flathead fords and the like... it has never been an issue on any relatively modern (post 50s) cooling system. I think those old systems lacked turbulence to induce heat transfer since they were only the next step up from passive cooling and open non-pressurized systems. On those the restriction of the Tstat housing was the only thing that would bring coolant velocity down slow enough to transfer heat to the non turbulator equipped radiators.

 

[Mr.Martin]

When I had my stock thermostat in the gauge would always be straight up or a little higher if I played around. Ever since I installed the motorad 160 thermostat it never rises above the 1/4 mark no matter how hot it is or how hard I drive it. I have 05 silverado fans installed, but I think I had them on there when I still had the stock thermostat as well.

 

[Eagle]

Exactly Mr. Martin, and that is very very bad. When are you going to go back to the proper heat range?

 

[Mr.Martin]

I need it broke down for me because I thought the lower you keep engine temps the better...without going crazy with temps. It always seemed to run better with the 160. When I first bought the Tahoe it felt peppy-ish for a few miles then died down a hair after it got warmed up. After I installed the 160 the pep stayed there the whole time.

 

[Eagle]

Nope it is the opposite, the hotter the better.
Sounds like you are running around in warm up mode, and while it might feel more peppy in part throttle, you are losing power at cruise and under WOT, in addition to slowly harming the engine. See post above.

I'm sure Jenna could tell use exactly what the ECU would revert to at 160f compared to the regular map.

 

[WICKEDOWESIX]

How does it get to and stay at 205-215 at 70 mph on the freeway on a 32 degree day with a 160 in there? I bet it drops to around 160... so it does NOT STAY at normal operating temps.


1: The job of a T-stat is to keep temperatures UP... to keep them at the bottom end of the threshold for efficient operation. A t-stat is NOT FOR 'COOLING'.
2: FANS and RADIATORS are for cooling, their job is to prevent exceeding the upper end of the threshold for efficient operation, usually around 210-215 on modern cars. FANS ARE FOR COOLING

We used to run Lower T-stats on Small blocks because the carbs and intakes would get heat soaked on drag cars... it also helped band aid excessive timing and barely adequate cooling systems in hot weather, particularly in the days when cars were designed without A/C in mind.

This is not an issue anymore with port injection and composite manifolds, and other changes to modern vehicles.. As a matter of fact it can be very detrimental to Horsepower, emissions, and engine longevity simultaneously.

Down sides to low temp T-stats:

If you allow your coolant temps to become excessively low, you will fall out of closed loop engine operation and revert to a warm up map.

IN this map the timing is too early for best power, and would result in pre-detonation if not for excessive fuel being injected.
IE While you might gain more timing, you also gain significantly more fuel for a LOSS in power

I have seen numbers tossed around that are as high as 8:1 or 9:1 A/F ratios during warm up.

If the best 'safe' power is about 12.5-13.2:1 (the ragged edge BTW), best emissions is ~ 14.7 :1 and best economy v. drivability is usually about 15:1

then

you can

quickly conclude

that:

MORE FUEL DOES NOT EQUAL MORE POWER.
that is such an innovative idea that it bears repeating...

MORE FUEL DOES NOT EQUAL MORE POWER.

one more time

MORE FUEL DOES NOT EQUAL MORE POWER.


More fuel equals cooler combustion temps, which equals less power. If it wouldn't slag the pistons or blow the HG, running around LEANER and HOTTER would yield better results, not being richer and colder. Kinda like with women.



Did i mention combustion chamber deposits from incomplete combustion can led to hot spots and pre-ignition, necessitating reduction in timing and using conservative maps which reduce power and efficiency even when the vehicle is at operating temp?

How about that the excess fuel is bad for your cats and 02 sensors and will reduce their life span?

How about the fact that it washes down the cylinder walls, contaminating the oil and with a resultant increase in cylinder bore wear, reducing the life and performance of the engine?

How about the reduction in MPG?

How about the increased difficulty in passing emissions if the vehicle will not 'warm up' into closed loop mode?
QUOTE]

My operating temp is NOT 205-215. It is more like 175-185 on my truck with my current mods. As far as going into closed loop, what do you think because someone has a 160 stat that they do not go into closed loop? Wrong. I know that AFR doesnt do anything as far as power because I was there when Justin did all those AFR test on MY truck on the dyno to prove this AFR hype.

---------- Post added at 09:01 PM ---------- Previous post was at 08:58 PM ----------

Nope it is the opposite, the hotter the better.
Sounds like you are running around in warm up mode, and while it might feel more peppy in part throttle, you are losing power at cruise and under WOT, in addition to slowly harming the engine. See post above.

I'm sure Jenna could tell use exactly what the ECU would revert to at 160f compared to the regular map.

So I see you do not have Data Logging capabilities. I have EFI LIve to log/tune the truck. IIRC these engine go into closed loop at 140, therefore 160 coolant temps would still be closed loop operations. I can even say my truck has ran that cold (160) ever since I have owned it.

 

[JoeOmerta]

I used to run a 180* t-stat in my 2000 gtp b/c of the modifications(supercharger, smaller pulley, cam, and colder spark plugs).

I was seeing 36mpg on the highway @ 65mph.
The supercharger was actually an m90 roots blower(aka a hot box). To sum it up, the engine ran around 185* or so(shown by scan gauge), and after an 1/8 mile pass the engine temp was closer to 215* or so due to the excessive heat created by the blower. So the colder t-stat benefited me very well and i also tuned the vehicle for it.

In reality, the hotter the combustion chamber the more efficient the burn the better the mpg's. If anyone has torn into the toyota 4 cyl vvt motors, they shrunk the coolant passages and leaned out the cruising a/f ratio to 22:1 which is how they get 30+mpg. On these V8's, i doubt you'll ever see 30+ mpg but i am curious what leaning out the a/f ratio would be. So if anyone has a spare motor or test car laying around and doesn't care about chipping pistons, care to test this out?

 

[Eagle]

My operating temp is NOT 205-215. It is more like 175-185 on my truck with my current mods. As far as going into closed loop, what do you think because someone has a 160 stat that they do not go into closed loop? Wrong. I know that AFR doesnt do anything as far as power because I was there when Justin did all those AFR test on MY truck on the dyno to prove this AFR hype.

---------- Post added at 09:01 PM ---------- Previous post was at 08:58 PM ----------



So I see you do not have Data Logging capabilities. I have EFI LIve to log/tune the truck. IIRC these engine go into closed loop at 140, therefore 160 coolant temps would still be closed loop operations. I can even say my truck has ran that cold (160) ever since I have owned it.

you are right... no datalogger anymore.

I agree, it was ambiguous of me not to have added "on some vehicles" to the end of 'falling out of closed loop'.
I assumed incorrectly that people could READ what I wrote, instead of jumping to conclusions. And I was sure that itfit was not the case on these LSx engines someone would let me know.


This engine is designed to operate between 190 and 210 judging by the the materials used and the tolerances spec'd, and supported by the OE choice of t-stat temp (185F).

08 5.3s run at ~200 for example, on a 185F Tstat. You state you are running about 185 on a 160 t-stat... see the pattern? I did exaggerate by 5-10 degrees to make a point, that you are not running the PHYSICALLY specified operating temp, rather you are running 15 degrees below it and <apparently> playing with electronics to band aid it.
There are two things to look at though, electronic requirements and the physical specifications of the piston to block interface. Lets just say if you rebuilt with hyperuetic pistons you would design the gap to be much tighter and operating temp would be far less of an issue.
Last time I checked, GM was using cast pistons in our blocks which means that proper operating temp IS A PART of controlling piston to wall gap, and thus increasing internal efficiency.

ONe thing everyone also forgets is that hotter helps burn off the contaminates that accumulate in oil when the vehicle doesn't reach the manufacturer's specified operating temps. It makes no difference whether that be because of a cooler T-stat or very short commute, it is bad for your engine.

I have no idea what you mean with the gibberish about 'AFR making no difference'... Feel free to expound on that, if you would, because as written it makes no sense.


Now on to asking non-rhetorical questions:
Are you stating that at 140F on a stock computer (not yours) it is both closed loop and on the power map?

what is the changeover temp for warm up maps and the temp required for super cruise (hopefully it exists on these fat SOBs) and optimal power maps?


On older trucks/cars it was NOT that low (hell Spirits ran an OPEN LOOP SYSTEM into the 90s!), and I can tell you on my DSM it was not that low either, ~ 170 IIRC. What are the conditions for supercruise/lean burn (if it exists)?



Cliffs:

I still do not understand why people don;t simply keep a proper t-stat, instead of changing everything just to use a $5 feel good part that does nothing to improve power, economy, or reliability and ultimately is only trouble or a bandaid.
You disagree, and that is fine.

Seems a lot of trouble to go thru to correct a problem that doesn't exist.
Now Joe above, he was doing the same thing with the lower t-stat we were doing back in the TBI and carb days for the same reason- he needs a bigger radiator, or better airflow thru the core.

 

[WICKEDOWESIX]

you are right... no datalogger anymore.

I agree, it was ambiguous of me not to have added "on some vehicles" to the end of 'falling out of closed loop'.
I assumed incorrectly that people could READ what I wrote, instead of jumping to conclusions. And I was sure that itfit was not the case on these LSx engines someone would let me know.


This engine is designed to operate between 190 and 210 judging by the the materials used and the tolerances spec'd, and supported by the OE choice of t-stat temp (185F).

08 5.3s run at ~200 for example, on a 185F Tstat. You state you are running about 185 on a 160 t-stat... see the pattern? I did exaggerate by 5-10 degrees to make a point, that you are not running the PHYSICALLY specified operating temp, rather you are running 15 degrees below it and <apparently> playing with electronics to band aid it.
There are two things to look at though, electronic requirements and the physical specifications of the piston to block interface. Lets just say if you rebuilt with hyperuetic pistons you would design the gap to be much tighter and operating temp would be far less of an issue.
Last time I checked, GM was using cast pistons in our blocks which means that proper operating temp IS A PART of controlling piston to wall gap, and thus increasing internal efficiency.

ONe thing everyone also forgets is that hotter helps burn off the contaminates that accumulate in oil when the vehicle doesn't reach the manufacturer's specified operating temps. It makes no difference whether that be because of a cooler T-stat or very short commute, it is bad for your engine.

I have no idea what you mean with the gibberish about 'AFR making no difference'... Feel free to expound on that, if you would, because as written it makes no sense.


Now on to asking non-rhetorical questions:
Are you stating that at 140F on a stock computer (not yours) it is both closed loop and on the power map?

what is the changeover temp for warm up maps and the temp required for super cruise (hopefully it exists on these fat SOBs) and optimal power maps?


On older trucks/cars it was NOT that low (hell Spirits ran an OPEN LOOP SYSTEM into the 90s!), and I can tell you on my DSM it was not that low either, ~ 170 IIRC. What are the conditions for supercruise/lean burn (if it exists)?



Cliffs:

I still do not understand why people don;t simply keep a proper t-stat, instead of changing everything just to use a $5 feel good part that does nothing to improve power, economy, or reliability and ultimately is only trouble or a bandaid.
You disagree, and that is fine.

Seems a lot of trouble to go thru to correct a problem that doesn't exist.
Now Joe above, he was doing the same thing with the lower t-stat we were doing back in the TBI and carb days for the same reason- he needs a bigger radiator, or better airflow thru the core.

GM uses hyperutectic pistons NOT cast. As for AFR I was refering to it is simply thermal protection and chaning (lean/rich) AFR will not yeild more power. Playing with electronics to bandaid? Please explain. Yes at 140* the computer goes into closed loop on stock computers.

 

[clean454]

i have a hypertech chip in my 95 and it came with a a new t-stat a lower one ive had it in for about 4 years
and love it truck runs cool and fine. i think its a 160

 

[Eagle]

GM uses hyperutectic pistons NOT cast. As for AFR I was refering to it is simply thermal protection and chaning (lean/rich) AFR will not yeild more power. Playing with electronics to bandaid? Please explain. Yes at 140* the computer goes into closed loop on stock computers.

thanks fo r the info. are these ECUs advanced enough yet to run closed loop under WOT or partial acceleration (or both)?

As to your assertion regarding AFR not having an effect on power.
It absolutely will and does man. I can;t say it any plainer, despite your 'experience'.
Anyone who has ever tuned a carb can tell you afr does affect power.

Either you guys were on the wrong map for what you were testing or you weren't changing the values enough to see it (overly conservative) or you jsut didn;t have the equipment and resolution to get valid results. To really see it you need a steady state dyno, not multiple runs on a mass acceleration dyno, where the error factor of 3-5 hp per run completely obscures the values you are looking for.


I've picked up 35 hp by merely leaning out WOT by the equivalent of a full point over stock on a 2.0 Turbo car, down to 12.5:1 from 11.5:1. I've picked up 30+ lb/ft of usable power in the midrange by leaning out partial throttle and partial load maps on the same car.
Timing is NOT the only thing to tweak, load maps and partial load maps can be made leaner and show significant improvements... though fuel quality and maintenance then becomes far more critical.

I agree with you that minor changes to AFR on these relatively low specific output engines will probably not be hugely noticeable




Sure changing AFR will... it absolutely will. Changing steady state target AFRs will not change power on an acceleration map... but leaning it out cell by cell on on an acceleration map WILL, and it is a change in AFR.


Do you have a link to where GM switched to Hyperuetic pistons in the LSx engines, especially in our Truck variants? Everything I have seen indicates they are cast aluminum pistons, including the cold piston slap issue.

 

[WICKEDOWESIX]

thanks fo r the info. are these ECUs advanced enough yet to run closed loop under WOT or partial acceleration (or both)?

Partial acceleration yes depending on the TPS. At WOT the PCM goes into open loop.

As to your assertion regarding AFR not having an effect on power.
It absolutely will and does man. I can;t say it any plainer, despite your 'experience'.
Anyone who has ever tuned a carb can tell you afr does affect power.

We are talking FI not carb which really doesnt matter though. PM Jenna and ask her about it. Justin from Black Bear Perforamnce did these AFR tests on my truck on a Dyno Dynamic Dyno (steady state tuning dyno), with a wideband oxygen sensor and EFI Live software to porve these AFR hypes. We actually lost power leaning it out. from about 11.8-12.8 AFR there is not any power difference worth changing thus leaving WOT AFR at 12.5:1.

Either you guys were on the wrong map for what you were testing or you weren't changing the values enough to see it (overly conservative) or you jsut didn;t have the equipment and resolution to get valid results. To really see it you need a steady state dyno, not multiple runs on a mass acceleration dyno, where the error factor of 3-5 hp per run completely obscures the values you are looking for.


I've picked up 35 hp by merely leaning out WOT by the equivalent of a full point over stock on a 2.0 Turbo car, down to 12.5:1 from 11.5:1. I've picked up 30+ lb/ft of usable power in the midrange by leaning out partial throttle and partial load maps on the same car.
Timing is NOT the only thing to tweak, load maps and partial load maps can be made leaner and show significant improvements... though fuel quality and maintenance then becomes far more critical.

I agree with you that minor changes to AFR on these relatively low specific output engines will probably not be hugely noticeable




Sure changing AFR will... it absolutely will. Changing steady state target AFRs will not change power on an acceleration map... but leaning it out cell by cell on on an acceleration map WILL, and it is a change in AFR.


Do you have a link to where GM switched to Hyperuetic pistons in the LSx engines, especially in our Truck variants? Everything I have seen indicates they are cast aluminum pistons, including the cold piston slap issue.

GM has been usuing hyperutectic pistons since the LT1 engine and has not run cast pistons ever since. Go on GM performance parts website and look under the info and you will see that they all use hyperutectic pistons.

 

[Eagle]

ok, you just stated it does have an effect... which is what i said.
You are stating that LEANING out AFRs ON THESE TRUCKS won't INCREASE power because they are already leaned out to best power. No surprise since they are so well tuned from the factory. But as you then indicate, AFR DOES have a result on power. You leaned it out more and lost power, proving my exact point. If you had fattened it up some more you would have lost power too.


Perhaps the way I phrased it is what threw you for a loop?


BTW I can;t find any OEM pistons for sale on GMPP.
What I have found is NUMEROUS references to the LM7 (and early LS1) having cast pistons...
and one reference that says that later ls1 switched to hypers because of piston slap issues.

http://www.smokemup.com/tech/ls1.php
http://www.maxchevy.com/tech/2008/iii_6-lm7-1.html
http://www.fbody.com/3gen/72431

I have not found anything ANYWHERE that says the LM7 uses hypers, Sorry. Not even something NON-authoritative.

 

[WICKEDOWESIX]

BTW I can;t find any OEM pistons for sale on GMPP.
What I have found is NUMEROUS references to the LM7 (and early LS1) having cast pistons...
and one reference that says that later ls1 switched to hypers because of piston slap issues.

http://www.smokemup.com/tech/ls1.php
http://www.maxchevy.com/tech/2008/iii_6-lm7-1.html
http://www.fbody.com/3gen/72431

I have not found anything ANYWHERE that says the LM7 uses hypers, Sorry. Not even something NON-authoritative.

Here ya go.

Pistons
The LS9 is the only production LS engine with forged aluminum pistons; all the
other engines use hypereutectic (cast) aluminum alloy pistons—varied mostly
by diameter to accommodate various bore sizes. LS cast pistons shouldn’t
be used on applications greater than approximately 550 horsepower. The LS7
piston’s inner bracing and larger pin diameter require the use of the matching
LS7 connecting rod. The same is true for LS9 pistons; they require the use of LS9
connecting rods.

Its on page 190 http://www.gmperformanceparts.com/_res/pdf/GMPP_2009_Catalog.pdf


http://www.gmperformanceparts.com/EngineShowcase/tech_specs.jsp?engId=LS1&engine=LS1&sku=25534322&engCat=ls

 

[Eagle]

thanks man, great info to learn.

 

[WICKEDOWESIX]

thanks man, great info to learn.

Your welcome. I am trying to find another link that I came across that tells you everything about the LS family engine.