180 Thermostat Results (With Towing Data)

[Higgs Boson]

So why does GM install a larger capacity radiator in the MAX TOW package instead of a cooler t-stat? It would be a helluva lot cheaper going with the t-stat....and we all know how cheap GM bean counters are!

 

RT

 

you may need both depending on the situation. you can install a lower temp thermostat and it will indeed keep temps colder overall unless you push so hard that it increases coolant temps above the point where it matters, like getting it up to 220-230. a lower thermostat will allow your ECT to drop back down to a cooler temp more quickly as well.

 

a radiator will maintain an overall lower average ECT in relation to your thermostat rating (floor). if you have a 160 thermostat a radiator will help you maintain 175 better, longer. if you have a stock 194 then the radiator will help you maintain 205 or 210. either stock or colder thermostat by itself could still allow the engine to get hot under extreme circumstances.

 

for example, cruising down the highway or a drag race, all you might need is a thermostat to maintain a lower average temp. but road racing or heavy towing, it is possible but not guaranteed, that you might need a radiator.

 

the factory builds all incorporate a hot thermostat for emissions purposes. bad for power.

[.justin.]

 

the factory builds all incorporate a hot thermostat for emissions purposes. bad for power.

 

On a gen-I sbc with an aluminum, water jacketed intake manifold, that would be correct. On Gen-III through Gen-IV SBCs, the higher coolant temperature is not a hindrance to performance in any vehicle that I've had on the dyno. Most have their HIGHEST power output at significantly higher coolant temps than standard operating temperature. The common-held belief that a colder combustion chamber makes more power is simply not true... The intake charge is the only "fluid" that needs to be cool to ensure appropriate oxygen density.

 

Regarding high IATs and timing reduction... the timing reduction is not the cause of the power loss. The timing reduction is a necessity due to the faster flame propagation with the increased mixture temp. The power reduction is due to the decrease in air density. For example, an increase in air temperature from 70*F to 120*F has an approximate decrease in density of 8%. That is where the power loss comes from, not the 2* decrease in ignition timing.

[Jon A]

 

On a gen-I sbc with an aluminum, water jacketed intake manifold, that would be correct. On Gen-III through Gen-IV SBCs, the higher coolant temperature is not a hindrance to performance in any vehicle that I've had on the dyno. Most have their HIGHEST power output at significantly higher coolant temps than standard operating temperature. The common-held belief that a colder combustion chamber makes more power is simply not true... The intake charge is the only "fluid" that needs to be cool to ensure appropriate oxygen density.

 

Please post some dynos. This is the exact opposite of every dyno comparison I’ve ever seen. In fact, many tuner shops/internet posters get in trouble for posting “hero run” dynos that they run after letting the car cool down to boost the numbers. No other tuner/dyno shop in the industry that I know of has ever made this claim. But virtually all of them do say the opposite.

 

I see lots of bags of ice at the drag strip, not heat blankets. Drag racers with electric water pumps consider it an advantage to be able to cool the entire engine down between runs. Any car that runs faster when it gets hot is a rare example indeed.

 

Yes, if your OIL is actually COLD (as in you just started it up for the first time all day and the oil is nowhere near normal operating temp—as is often the case with your first run on a dyno) it will cost a few HP. That is well known and really isn’t relevant to this discussion.

 

I’m sorry, but when your claim is the exact opposite of every other tuners’…and these other tuners have customers that run at the track and actually time their vehicles (which very few truck owners do) it’s going to require some compelling data if you want them to believe it. Most all of us who have ever gone to a drag strip have actual track data to prove we’re faster after a little cool off time between runs.

 

 

Regarding high IATs and timing reduction... the timing reduction is not the cause of the power loss. The timing reduction is a necessity due to the faster flame propagation with the increased mixture temp. The power reduction is due to the decrease in air density. For example, an increase in air temperature from 70*F to 120*F has an approximate decrease in density of 8%. That is where the power loss comes from, not the 2* decrease in ignition timing.

 

The reason the timing is retarded—to prevent detonation—does not remove it from the list of factors that reduce power. Yes, some power reduction comes from the reduced air density. It also comes from the timing loss. You can run more timing at the same air density but a lower temperature (lower pressure) and make more power. Think about it—why do you need to reduce timing with lower air density? You don’t if it’s the same temp—you can actually increase it. It’s the temp that’s the issue.

 

How do you keep IAT's cold on the dyno with a really hot engine? Most vehicles' intake tract will heat soak to some degree, the air around the vehicle gets heated up by the radiator, etc.

 

Anyway as I said earlier, when hundreds of miles from home with the whole family along, the last thing in the world you’re going to care about when warning lights start going off as you tow up a long hill is whether you may or may not have had an extra 5 HP at the time. Tuning an engine for a truck meant to tow in the summertime to run hot for a couple more HP (even if that was true) is a really dumb thing to do.

[Jon A]

A thermostat doesn't make the cooling system more efficient, it just allows the cooling system to start working sooner to keep temps at bay. A thermostat basically sets the floor for cooling not the ceiling so if radiator is too small for the load applied, thermostat size won't matter.

 

 

Correct, as said the larger radiator only makes for more consistent cooling temps while under load. Also the 180° stat will not keep you from seeing high temps, it will just allow the radiator to start cooling the coolant sooner since it will allow the coolant to circulate sooner in the system.

 

Yes guys, but don’t forget the size of the radiator does not determine the cooling system capacity by itself. It is only one component. The airflow across it is just as important. By having your fans blasting at 100% at a reasonable temp you have increased the total capacity of the cooling system even with the same radiator. You have lowered the temp ceiling the system will see steady state (infinitely long hill) under a certain load.

 

A lower temp thermostat means you can have the fans blasting 100% by 212 degrees; try that with the stock thermostat and you'll have an unecessarily noisy fan blasting away, even in the winter time. So the two go together nicely.

Edited August 10, 2015 by Jon A

[iCryWheniGoPoop]

I think we are starting to post in circles

[.justin.]

 

 

 

Yes guys, but don’t forget the size of the radiator does not determine the cooling system capacity by itself. It is only one component. The airflow across it is just as important. By having your fans blasting at 100% at a reasonable temp you have increased the total capacity of the cooling system even with the same radiator. You have lowered the temp ceiling the system will see steady state (infinitely long hill) under a certain load.

 

A lower temp thermostat means you can have the fans blasting 100% by 212 degrees; try that with the stock thermostat and you'll have an necessarily noisy fan blasting away, even in the winter time. So the two go together nicely.

 

Once the vehicle reaches a certain speed (determined by radiator size, grille openings and fan output), there is no benefit to having the fans on, as more air is pushed through the radiator by the vehicle than the fans can pull through. Most calibrations will turn the fans off automatically once that speed is reached and the fan settings will have no impact at that point.

[Jon A]

 

Once the vehicle reaches a certain speed (determined by radiator size, grille openings and fan output), there is no benefit to having the fans on, as more air is pushed through the radiator by the vehicle than the fans can pull through. Most calibrations will turn the fans off automatically once that speed is reached and the fan settings will have no impact at that point.

 

The calibrations for these vehicles do not turn off the fans at highway speeds. What vehicles are you talking about? Please read post #21. Nobody in the auto industry thinks the fans have no impact at highway speed. They know better.

[.justin.]

 

Please post some dynos. This is the exact opposite of every dyno comparison I’ve ever seen. In fact, many tuner shops/internet posters get in trouble for posting “hero run” dynos that they run after letting the car cool down to boost the numbers. No other tuner/dyno shop in the industry that I know of has ever made this claim. But virtually all of them do say the opposite.

 

I see lots of bags of ice at the drag strip, not heat blankets. Drag racers with electric water pumps consider it an advantage to be able to cool the entire engine down between runs. Any car that runs faster when it gets hot is a rare example indeed.

 

Yes, if your OIL is actually COLD (as in you just started it up for the first time all day and the oil is nowhere near normal operating temp—as is often the case with your first run on a dyno) it will cost a few HP. That is well known and really isn’t relevant to this discussion.

 

I’m sorry, but when your claim is the exact opposite of every other tuners’…and these other tuners have customers that run at the track and actually time their vehicles (which very few truck owners do) it’s going to require some compelling data if you want them to believe it. Most all of us who have ever gone to a drag strip have actual track data to prove we’re faster after a little cool off time between runs.

 

 

Show me one of those that serves as an example of a colder engine making more power. Everything you've described pertains to intake air temperatures being colder. Ice bags are very often used on metal intake manifolds, as they have a much greater tendency to negatively impact air density. There are still a large number of tuners/shops out there that hack injector settings to alter fuel trims. There are still a large number of shops/tuners that say that you should run as much timing as possible until there is knock and then back it off a degree. Both of those are proven time and time again to be the incorrect way of doing things, but people still do them. What is your point?

 

We did a dyno test comparing motor oil a couple of years back, with results on our facebook page as well as a few forums, that show higher power output at higher coolant and oil temperatures. It was an incidental result of the test with ACTUAL oil temperatures via probe in the dipstick, rather than a calculated value by an ECM which may or may not be accurate. Unfortunately it was in 2013 and I can't find the dyno graph at the moment... we've over 50,000 files in our tuning repository and several laptops that have been used for tuning over the years and they're buried in there somewhere. The post from that day was as follows:

 

 

 

Coolant, intake air and oil temperature were all monitored and normalized for testing purposes. Test vehicle was a 2013 6.2L with timing dialed back 2-3* from stock to ensure that there were no external factors affecting results.

 

As expected, Amsoil showed a 1.5% reduction in power output compared to the Mobil 1. Extended wear protection is not without cost somewhere. In our opinion though, an unnoticable 4-5hp difference is worth the longevity achieved with the Amsoil.

 

For all those interested in lower temperature thermostats as well, this test also proved that higher metal temperatures make more power. On both sets of runs, those with the highest coolant temps (approximately 216* average) made the most power. Those at 190* made the least power. Additional convective heating of cylinder walls = lost cylinder pressure!

 

What temperature does the average nascar engine run? I suppose that an organization that is so interested in squeezing every last hp out of an engine, to the point that cam lobes and compression ratio varies from cylinder to cylinder, would know a bit about power production, wouldn't they? Nascar engines tend to run in the 230-240 degree range with 260 being their absolute limit.

 

 

The reason the timing is retarded—to prevent detonation—does not remove it from the list of factors that reduce power. Yes, some power reduction comes from the reduced air density. It also comes from the timing loss. You can run more timing at the same air density but a lower temperature (lower pressure) and make more power. Think about it—why do you need to reduce timing with lower air density? You don’t if it’s the same temp—you can actually increase it. It’s the temp that’s the issue.

 

How do you keep IAT's cold on the dyno with a really hot engine? Most vehicles' intake tract will heat soak to some degree, the air around the vehicle gets heated up by the radiator, etc.

 

Anyway as I said earlier, when hundreds of miles from home with the whole family along, the last thing in the world you’re going to care about when warning lights start going off as you tow up a long hill is whether you may or may not have had an extra 5 HP at the time. Tuning an engine for a truck meant to tow in the summertime to run hot for a couple more HP (even if that was true) is a really dumb thing to do.

 

Refer above to the point about more timing being better. It is not always the case. When you had your truck on the dyno (assuming you tuned yours on one) performing your ignition timing tuning, what timing did you see the most power at at full throttle? What timing did it start to knock at? The two are NOT the same point and are often 3-4 degrees separated. Heck, the 4.8L can see 5-6 degrees of additional timing with not a single hp increase before any knock occurs. Why would you run it at the higher timing point in that situation?

 

Intake air temperatures are EASY to control on a dyno as well as any vehicle that is moving, as air moving over and through the fender sweeps away heat soaked air. Direct a fan towards the intake and IATs are stable.

I will reiterate. Timing is cut back with temperature increase due to the faster flame propagation speed. More timing WOULD cause detonation at that point because more timing is too much timing. Retarded timing by a few degrees is the CORRECT thing to do when intake air temperature increases. It is not the cause of the power drop with increased temperatures though, that is the role of the air density decrease. With temperatures being equal, a lower air density requires MORE ignition advance. Look at your spark table and you'll see this evident at every point on the table.

 

I've never said anything at all about your minute or two of extra headroom before overheating when towing uphill. If that makes you happy, by all means, go for it. My comments have been regarding the other discussions that have arisen here.

[.justin.]

 

The calibrations for these vehicles do not turn off the fans at highway speeds. What vehicles are you talking about? Please read post #21. Nobody in the auto industry thinks the fans have no impact at highway speed. They know better.

 

Just because you do not have access to those tables does not mean that they do not exist. For years HPTuners didn't allow anybody access to the majority of LS1 based fan settings, including A/C pressure and vehicle speed. Did that mean that those tables didn't exist? The previous generation fan control settings DO have speed enable and disable speeds and DO shut off at highway speeds. I would bet that if you calculated the CFM output of your fans and divided it by the cross sectional area of those fans, you could pretty easily determine the speed of air through them and thus, the point that vehicle speed ends up pushing the air faster through the radiator than the fans can draw.

[iCryWheniGoPoop]

Justin,

You said that higher temps making more power was an incidental finding. Could it be that timing was ideal for that temperature or have you actually tried tuning for different temperature ranges on the same vehicle so that you have some ground to stand on? I know I have heard LSx's like heat but I was just curious how extensive the testing was for this.

[.justin.]

Valid question. With various vehicles that I have had on the dyno, I have seen little to no difference in ignition timing needs based on coolant temperature differences and typically expand the zero modification range of the ect spark table to not negatively impact timing. Above 226, I do allow timing to begin to fall to reduce power output to allow more heat to escape out the exhaust, since that temperature is obviously not a "normal" operating temperature and the vehicle is being worked hard. That heat reduction via ect spark table is there to serve similar purpose as jon a's thermostat change.

[redwngr]

So why does GM install a larger capacity radiator in the MAX TOW package instead of a cooler t-stat? It would be a helluva lot cheaper going with the t-stat....and we all know how cheap GM bean counters are!

 

RT

+1

 

Once both thermostats are wide open, it the cooling system has the same capacity.

[.justin.]

+1

 

Once both thermostats are wide open, it the cooling system has the same capacity.

Exactly. The only difference is the colder stat offers a ~20° cushion in real world operating conditions when not pushing the truck hard. Probably 1-2 minutes to get from 175 to 198 when pushing it real hard.

[Jon A]

 

We did a dyno test comparing motor oil a couple of years back, with results on our facebook page as well as a few forums, that show higher power output at higher coolant and oil temperatures.

 

Thank you. That explains it. Try testing at the same oil temp and get back to us. You know, the scientific method and all.

 

I don't know if you've ever towed something heavy up a long hill, but when you do the oil heats right up even when the coolant remains cool. Try roadracing in cold weather--the coolant temp can remain very cold and you can still hit 300 degree oil temps. Most of the heat put into the oil is caused by the oil shearing against itself and has a very direct relationship with the engine output at the time--not the engine's coolant temp. These vehicles will only have more of a relationship between the two because the oil cooler is in the radiator.

 

 

 

What temperature does the average nascar engine run?

 

Why would somebody tuning a truck care? Apples and oranges. A million competing interests are all compromised when you have only one set of conditions in which you need to run and one goal. Here are a couple good ones: Every square inch of grill opening causes drag which slows down the car. The hotter the radiator is, the more efficient it is (Delta T between the coolant and air). A tiny gain of efficiency means a smaller radiator can be used.

 

Such a tiny gain would never be noticed by a truck on the highway but when you're on the razor's edge at that level tiny, tiny, differences can make all the difference. Again apples and oranges.

 

My Camaro runs that hot on the roadcourse because that's as cool as I can get it. Does that mean I should heat it up to 230 before drag racing it?

 

 

Nascar engines tend to run in the 230-240 degree range with 260 being their absolute limit.

 

Are you really recommending people use a 20 degree operating window between normal operating temps and total engine meltdown? Like I said, not smart.

 

 

Just because you do not have access to those tables does not mean that they do not exist.

 

It also has tables for running electric water pumps and thermostats. Do we have those as well? The fact is the fans don't turn off. Stop changing the subject.

Edited August 11, 2015 by Jon A

[iCryWheniGoPoop]

Valid question. With various vehicles that I have had on the dyno, I have seen little to no difference in ignition timing needs based on coolant temperature differences and typically expand the zero modification range of the ect spark table to not negatively impact timing. Above 226, I do allow timing to begin to fall to reduce power output to allow more heat to escape out the exhaust, since that temperature is obviously not a "normal" operating temperature and the vehicle is being worked hard. That heat reduction via ect spark table is there to serve similar purpose as jon a's thermostat change.

Yeah, I don't adjust ECT adders either except as you do, in the event of overheat conditions. You were also logging EOT's as well which you know typically don't run parallel to ECT's but it sounds like more testing could be done to validate this finding or theory, but I can't imagine it hasn't been done by now. I guess I can fire up google because since I sold the Dyno it gets expensive for me to play with this shit now...

I didn't consider it before but if 30* ECT variance is actually effecting cylinder temperature enough to effect horsepower then you may see positive effect by adjusting the spark plugs heat range as well. Just a thought.

Edited August 11, 2015 by TDT