Great site Vader.
Basic thermostat question
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
Elite Torch Red Member
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
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Racer
Joined: Jan 2006
Posts: 393
Likes: 0
From: Palm Springs CA
Ideally, in terms of longevity you want the engine coolant to run somewhere around 180*F. Slightly cooler is fine, slightly warmer is fine. I prefer to keep mine cool. I use a 160* thermostat in my LT1, but only because it allowed me to set my fan-on/off temps lower without forcing the fans to run constantly at idle and low-speed after warm-up. Changing to a 160* 'stat without making any fan setting changes will accomplish nothing toward lowering low-speed and idling coolant temps.
You'll likely notice little HP difference with lowered coolant temps -- perhaps a bit, but not much if any. There's a bit of a tradeoff to be made there: Lowering the engine temp allows a more dense air/fuel charge into the cylinders, but more heat will be lost into the coolant, so the thermal efficiency goes down a bit.
IMHO, the benefits of lowering coolant temps are:
1. Much more headroom in the cooling system before really bad things begin to happen if something goes wrong. If you lose system pressure when running at, say, 230*F, the coolant will immediately boil and vacate the premises, leading quickly to meltdown of engine parts. If you lose system pressure while running at, say, 180*F, the coolant will not boil away. If you suffer a major coolant loss (blown hose, etc), you'll have more time to react and get the car shut down before meltdown occurs if running at 180*F vs 230*F.
2. Less stress on soft parts under the hood (belts, hoses, seals, gaskets, etc).
Lowering the fan-on/off settings, in combination with a 160*F thermostat also will tend to stabilize coolant temps within a narrower operating range. Mine runs typically no lower than 171*F on the coldest days, and no higher than 200*F on the hottest days, and it tends to remain fairly stable. The stock system allows temps to run anywhere from 190*F to 230*F or more, with a lot of cycling up and down within this range - sloppy engineering, IMHO.
My car's heater works just fine when ECT is at 170*F.
As I see it, the benefits of running at the higher temps generated by a stock C4 cooling system are:
None.
Be well,
SJW
You'll likely notice little HP difference with lowered coolant temps -- perhaps a bit, but not much if any. There's a bit of a tradeoff to be made there: Lowering the engine temp allows a more dense air/fuel charge into the cylinders, but more heat will be lost into the coolant, so the thermal efficiency goes down a bit.
IMHO, the benefits of lowering coolant temps are:
1. Much more headroom in the cooling system before really bad things begin to happen if something goes wrong. If you lose system pressure when running at, say, 230*F, the coolant will immediately boil and vacate the premises, leading quickly to meltdown of engine parts. If you lose system pressure while running at, say, 180*F, the coolant will not boil away. If you suffer a major coolant loss (blown hose, etc), you'll have more time to react and get the car shut down before meltdown occurs if running at 180*F vs 230*F.
2. Less stress on soft parts under the hood (belts, hoses, seals, gaskets, etc).
Lowering the fan-on/off settings, in combination with a 160*F thermostat also will tend to stabilize coolant temps within a narrower operating range. Mine runs typically no lower than 171*F on the coldest days, and no higher than 200*F on the hottest days, and it tends to remain fairly stable. The stock system allows temps to run anywhere from 190*F to 230*F or more, with a lot of cycling up and down within this range - sloppy engineering, IMHO.
My car's heater works just fine when ECT is at 170*F.
As I see it, the benefits of running at the higher temps generated by a stock C4 cooling system are:
None.
Be well,
SJW
Thanks
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Racer
Joined: Sep 2004
Posts: 495
Likes: 1
From: Spokane Washington
Do I need a special chip with a 160
OK, I have a problem I live in the Majave Desert. Also my 1990 (stock) runs hot. Everthing works. Tried all the normal stuff. Last thing is to go to a 160 tstat. I have heard I need to get a performance chip made for the 160 ts. Like the one from Mid A 9I think) Is this tru.
thanks
cal
thanks
cal
Le Mans Master
Joined: May 2005
Posts: 7,359
Likes: 2,281
From: Central Maryland
Primary fan on/off: 190/180
Secondary fan on/off: 195/185
Again for clarity, I'll restate this: The ONLY reason I installed the 160*F thermostat is that it allowed me to set the fan-on/off temps as noted above without having the fans run constantly at low speed and idle. Were it not for that, I'd have left the 180* 'stat in there.
I've been running this set-up for two years and 30k miles now, and I'm very pleased with it in every respect. The next time I have the cooling system drained down in my LT4, I'll duplicate the changes on it, too.
Be well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,359
Likes: 2,281
From: Central Maryland
I installed a HyperTech 160*F thermostat in my LT1. It has worked flawlessely for me so far. I bought it at a local speed shop. There is no OEM replacement 160*F 'stat for the LTx engines.
I've never used the HyperTech power programmer, but if I understand correctly, it can be used to alter the fan-on/off settings.
Be well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,359
Likes: 2,281
From: Central Maryland
OK, I have a problem I live in the Majave Desert. Also my 1990 (stock) runs hot. Everthing works. Tried all the normal stuff. Last thing is to go to a 160 tstat. I have heard I need to get a performance chip made for the 160 ts. Like the one from Mid A 9I think) Is this tru.
thanks
cal
thanks
cal
I suggest you consider an upgraded radiator such as the DeWitt unit. A radiator that can shed more heat is the only thing that's likely to make a lot of difference with your highway ECTs when ambient temps are well north of 100*F.
Be well,
SJW
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by cal camara
OK, I have a problem I live in the Majave Desert. Also my 1990 (stock) runs hot. Everthing works. Tried all the normal stuff. Last thing is to go to a 160 tstat.
thanks
cal
thanks
cal
Maintenance is the key to C4 cooling system success. Keep it flushed and full of a 50/50 water antifreeze mix. Pull the radiator and clean out between the radiator and condenser. If the desert heat causes your car to run hot at idle and low speeds, an earlier fan on temp may help. If it runs hot on the highway, you have either an air flow or a water flow problem, maybe both.
The 160° stat is fine for the LT engines that use a stock 180° thermostat on their reverse flow cooling systems. But 180° is the lowest that is prudent in the L98.
RACE ON!!!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
I wonder where people get the erronious idea that engines develop more HP when their coolant is run at a lower temperature. A lot of posters point out that the runners are at a lower temp so the fuel/air mixture is more dense. While there is some truth to this, other factors far more effect engine HP than inlet air temp. The largest effect is thermal efficiency. Heat is HP, [2545 Btu/Hr = 1 HP] and lower coolant temps remove heat from the combustion chamber, therefore you also lose HP, and much more loss than the gain caused by lower inlet air.
Continental Motors ran a test with a number of identical engines and controlled each engine water temp and ran them at max HP for a long time. They measured the cylinder bores and other parts before the test. Temps ran from 160 to over 200 F. What they found was that the cylinder bores increased in diameter for decreased operating temp. They also found that the higher the op temp, the higher the HP output and the lower the specific fuel consumption (more HP/gal/Hr, or higher fuel economy). So to answer you question, YES, there is some harm from running your engine at a lower coolant temp, namely, lower HP, lower fuel economy, and higher wear.
Continental Motors ran a test with a number of identical engines and controlled each engine water temp and ran them at max HP for a long time. They measured the cylinder bores and other parts before the test. Temps ran from 160 to over 200 F. What they found was that the cylinder bores increased in diameter for decreased operating temp. They also found that the higher the op temp, the higher the HP output and the lower the specific fuel consumption (more HP/gal/Hr, or higher fuel economy). So to answer you question, YES, there is some harm from running your engine at a lower coolant temp, namely, lower HP, lower fuel economy, and higher wear.
Last edited by jfb; Aug 23, 2007 at 12:51 PM.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
I got the idea from time slips. Bottom line as stated by me in the past as well as a host of other drag racers, such as Mr Mojo, John Mackey, etc. When getting the tempature as low as possible before staging makes for a quicker and faster run.
With my car, I loose at least a tenth going from 160 to 190-200 degrees.
I have been able to consistantly test this, as I have an electric waterpump and have both fans and pump set up so I can run them without the motor running and cool it down quickly
I dont argue wear on motor, as I just dont know. The car only gets 2,000-3,000 miles a year on it, and probably 300 or so passes at the track every year. But I can tell you I have 107,000 miles on the car now,the motor is fine, and the 160 stat (LT1) has been in there for over 3 years now.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
We have had two CFers pay for some dyno time and changed their thermostats in C4's from the OEM stat to a 160 stat and reran the dyno. Both reported that the measured HP was identical with either thermostat. Please note that I am not saying your experience at the drag strip is incorrect!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Le Mans Master
Joined: May 2000
Posts: 7,033
Likes: 12
Your thermostat is stuck closed. Thats why you have a leak at the water pump ( it's pumping and it has no where to go, so it goes out the gasket). Also explains why your overflow fills up after turning off the engine ( all the pressure is in the engine and non in the radiator, when the engine turns off, it back flows past the water pump thru the rad and into your overflow tank to even the pressure). I recomend replacing the thermostat with a safety valve type thermostat ( the ones that fail open, they cost a little more than the regular thermostats but you'll have peace of mind knowing there is flow regardles). Also flush the coolant system ( to get rid of any possibility that there is that orange sludge from a possible mixture of Dexcool and regular antifreeze). Thats it. All the best.
I did say trackman's post should be quoted in all stat threads so I will quote it.
As we all know a closed stat builds up too much pressure thus blowing out gaskets. Since I run a 160 my stat opens faster in the heat cycle thus saving various gaskets from their demise.
You should've made this thread a poll.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
We have had two CFers pay for some dyno time and changed their thermostats in C4's from the OEM stat to a 160 stat and reran the dyno. Both reported that the measured HP was identical with either thermostat. Please note that I am not saying your experience at the drag strip is incorrect!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Agreed, but if someone post this in the drag racing section, I believe you will see many more who have had positive results with the cooler motor. I just named two, who most will agree are 2 of the more seasoned, experienced racers on here.
Personally, I cant believe how upset some people get over this issue anyways. I think the gains are small, but also, I believe that any additional wear, if any is minimal. You may well disagree and we can leave it at that. I just dont understand why people cant just disagree quite like you and I but not make it into a personal battle.
Oh, and by the way, we dont race dyno's!!
Ill bet you aint heard that before!!
