160 T-Stat to low?
08-04-2008, 08:15 PM
#41
As I said.... I run a 160* with coolant operating temps running between 185 to 190ish. So I guess I am running in what everyone is calling "the sweet spot". As for driving in the winter... heck I run ET streets so I don't even drive in the rain!! I'll drive my car from May to Oct and then it goes away for the winter. If you are driving your car during the summer months, then a 160 is the way to go. IMO. Also, I change oil every 2500 miles and oil contamination has never been a problem and I DID the oil analysis to know that for a fact.
08-04-2008, 08:22 PM
#42
The thing I haven't seen covered yet is the mechanism of oil contamination and resultant engine damage due to lower combustion chamber temps.
The engine books I've studied, and the instruction I've received, discuss incomplete combusion as a cause of oil contamination. As the oil is loaded up with gasoline, a solvent, it underlubricates the engine components and accelerates wear. Doesn't matter how good the oil is, it can't do its job if its being washed off the surface it's supposed to lubricate.
The engineering thinking is that combustion chamber heat is A Good Thing(tm) as pertains to combustion efficiency. The guys who made serious power with aluminum heads did so by moving the water jackets away from the chambers, thus retaining more heat in the chambers where it could be used to increase combustion efficiency.
If I was going to twiddle with my engine operating temps, I'd sample the engine oil and have a lab (Blackstone, for example) scope it. If I saw out-of-range quantities of fuel in the results, I'd either go hotter on my chamber temp or I'd lean down the fuel:air mix. And then I'd re-sample after a few hundred miles. Only after I nailed down this issue would I bother dyno testing to see if I made more power...because giving up engine longevity isn't my priority.
Thinking on this issue may vary, but there you have a snippet of conventional wisdom.
The engine books I've studied, and the instruction I've received, discuss incomplete combusion as a cause of oil contamination. As the oil is loaded up with gasoline, a solvent, it underlubricates the engine components and accelerates wear. Doesn't matter how good the oil is, it can't do its job if its being washed off the surface it's supposed to lubricate.
The engineering thinking is that combustion chamber heat is A Good Thing(tm) as pertains to combustion efficiency. The guys who made serious power with aluminum heads did so by moving the water jackets away from the chambers, thus retaining more heat in the chambers where it could be used to increase combustion efficiency.
If I was going to twiddle with my engine operating temps, I'd sample the engine oil and have a lab (Blackstone, for example) scope it. If I saw out-of-range quantities of fuel in the results, I'd either go hotter on my chamber temp or I'd lean down the fuel:air mix. And then I'd re-sample after a few hundred miles. Only after I nailed down this issue would I bother dyno testing to see if I made more power...because giving up engine longevity isn't my priority.
Thinking on this issue may vary, but there you have a snippet of conventional wisdom.
08-04-2008, 08:35 PM
#43
ALSO... if we are talking about incomplete combustion and oil contamination from gasoline then let's talk about how much unspent fuel is the result of a large cam at idle and low RPMs. There is at least 5 times the amount of unspent fuel with a large cam than there will be with a slightly lower operating temp. Just smell the exhaust for proof. That is why I am an advocat of frequent oil changes on a HI-PO motor.
If the total system of valve overlap, induction flow, and exhaust backpressure aren't properly designed you'll end up with (among several possible outcomes) incompletely reacted fuel discharged out the exhaust valve...no matter how hot or cold the chamber.
The problem in engine design is that everything's a compromise. If you want to fill cylinders and make power at high revs, you have to give up some amount of cylinder charging efficiency at lower revs.
08-04-2008, 08:38 PM
#44
You're now jumping into cylinder charging inefficiency, totally different science and very little relationship with combustion efficiency as pertains to the presence of unburned fuel in the exhaust.
If the total system of valve overlap, induction flow, and exhaust backpressure aren't properly designed you'll end up with (among several possible outcomes) incompletely reacted fuel discharged out the exhaust valve...no matter how hot or cold the chamber.
The problem in engine design is that everything's a compromise. If you want to fill cylinders and make power at high revs, you have to give up some amount of cylinder charging efficiency at lower revs.
If the total system of valve overlap, induction flow, and exhaust backpressure aren't properly designed you'll end up with (among several possible outcomes) incompletely reacted fuel discharged out the exhaust valve...no matter how hot or cold the chamber.
The problem in engine design is that everything's a compromise. If you want to fill cylinders and make power at high revs, you have to give up some amount of cylinder charging efficiency at lower revs.
08-04-2008, 10:07 PM
#45
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Wow, there's a bunch of misinformation on this thread! 
The stock T-stat is about 195ish degrees. The coolant fans are designed to modulate the temp around 220 degrees F. Yes, 220 degrees....and as high as 235 degrees
This is for emissions. Period. If you're reading the "stock" temp gauge on a 99-02 Camaro.....then you're reading an idiot light. The 98 and earlier Camaros (both LS1 and LT1) have a "true working" temp gauge that displays actual temp. Possibly GM though people would get scared seeing the true temp (or more likely an "idiot gauge" was cheaper). Result, from 150-230 your stock gauge will read 210.
I did a 3 part test in 2004:
Part 1: Installed an AutoMeter H2O gauge on the stock T-stat to see what the real temps were. Was horrified to see the 220-235 degree temps.
Part 2: Went to the track in Hawaii where I lived at the time and ran the car. Baselined 13.9 at 105.
Part 3: Installed 160 T-stat and reprogrammed fans for a 175on temp and 186 off temp. Temps averaged 180 degrees. Car then ran 13.7@106 like clockwork.
I've backed this up w/ HP Tuners scan data as well. Temps between my AutoMeter gauge and PCM coincide.. The thermistor in the cylinder head does read and send actual coolant temp data to the PCM.
In short, a 160 T-stat DOES improve performance. A cooler running engine is less prone to detonate. Fuel economy was unchanged. Emissions...... I had a turbo and now an aggressive HC setup.......so emissions went out the window a long time ago.
Have the car torn apart to the shortblock as we speak. 3rd time now in 6 years. Have yet to notice excess wear, etc. Ran the 160 T-stat for 4 years now. Also run synthetic oil....and run 10W30 NOT 5W30. So.... guess I'm breaking a couple manufacturer rules, but the car seems to like it
Conclusion...if you like a bone stock car....run a stock T-stat. Like more power for not much $$....run a 160. Just my $0.02
The stock T-stat is about 195ish degrees. The coolant fans are designed to modulate the temp around 220 degrees F. Yes, 220 degrees....and as high as 235 degrees
This is for emissions. Period. If you're reading the "stock" temp gauge on a 99-02 Camaro.....then you're reading an idiot light. The 98 and earlier Camaros (both LS1 and LT1) have a "true working" temp gauge that displays actual temp. Possibly GM though people would get scared seeing the true temp (or more likely an "idiot gauge" was cheaper). Result, from 150-230 your stock gauge will read 210.I did a 3 part test in 2004:
Part 1: Installed an AutoMeter H2O gauge on the stock T-stat to see what the real temps were. Was horrified to see the 220-235 degree temps.
Part 2: Went to the track in Hawaii where I lived at the time and ran the car. Baselined 13.9 at 105.
Part 3: Installed 160 T-stat and reprogrammed fans for a 175on temp and 186 off temp. Temps averaged 180 degrees. Car then ran 13.7@106 like clockwork.
I've backed this up w/ HP Tuners scan data as well. Temps between my AutoMeter gauge and PCM coincide.. The thermistor in the cylinder head does read and send actual coolant temp data to the PCM.
In short, a 160 T-stat DOES improve performance. A cooler running engine is less prone to detonate. Fuel economy was unchanged. Emissions...... I had a turbo and now an aggressive HC setup.......so emissions went out the window a long time ago.
Have the car torn apart to the shortblock as we speak. 3rd time now in 6 years. Have yet to notice excess wear, etc. Ran the 160 T-stat for 4 years now. Also run synthetic oil....and run 10W30 NOT 5W30. So.... guess I'm breaking a couple manufacturer rules, but the car seems to like it
Conclusion...if you like a bone stock car....run a stock T-stat. Like more power for not much $$....run a 160. Just my $0.02
08-04-2008, 10:18 PM
#46
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ok so from what im reading it might be better to just tune my stock fan temp. a lil lower and that wo,uld be all i would need for a night at the track instead of a 160 tstat, i live in texas so the temp. gets pretty hot here but the winter i could see 32 degrees so i dont not belive a 160 would be right for me all year around, so now my question is: is there a easy way to tune the stock fans?
08-04-2008, 10:41 PM
#47
+1
I haven't read through all of the replies, but, can attest that a 160* t-stat is fine. I have oil temp & coolant temp gauges. While using a 160* stat & an oil cooler, coolant temps were from 160*-190* depending on ambient temps & whether or not the car was moving or fan cooled. The oil temps were from 180*-210* under the same conditions. Most non-racing oils are designed for optimum operating viscocity @ 210* & viscocity is a bit thicker when the temp is lower. So, unless someone can prove that oil @ 180* is damaging, then ............
I have had no issues. Further, WOT engine dyno pulls are typically started once the engine oil reaches 180*.
My car now runs w/ no t-stat & the engine operates @ exactly the same temps as it did previously. Car is not Winter driven.
08-05-2008, 04:30 AM
#50
I thought I posted this earlier, but the stock thermostat is easily modified to open at any temp you want for under $1. This was a cheap mod when the LS1 first came out but now everyone seems to want to spend $60 on a thermostat. Also, if you ever have to change the water pump, kiss your $60 thermostat goodbye because the GM replacement pump uses the newer thermostat design.
08-05-2008, 05:43 AM
#51
08-05-2008, 07:32 AM
#52
Actually I have done lots of reading but these days I spend much more time driving my car after just rebuilding my stroker motor ( MYSELF!!) I spend more time doing.... not reading about it.
Or to put it in another perpective....you, with all your "knowledge" about cylinder charging inefficiency and overlap etc.... are running a stock motor with a little Thunder Racing 224 cam, an oil pump and a new chain and I (with my lack of knowledge from not reading as much as you) am into my 5th year with a 500+ HP stroker motor that I built myself aside from machining , that runs low 11's all day at the track without breaking a sweat. With all the books that you have read, can you completely take down a LS1, rebuild and put it back together in 35 hrs by yourself? I CAN
Last edited by StevieZ; 08-05-2008 at 11:14 AM.
08-05-2008, 10:12 AM
#54
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ok so from what im reading it might be better to just tune my stock fan temp. a lil lower and that wo,uld be all i would need for a night at the track instead of a 160 tstat, i live in texas so the temp. gets pretty hot here but the winter i could see 32 degrees so i dont not belive a 160 would be right for me all year around, so now my question is: is there a easy way to tune the stock fans?
08-05-2008, 11:30 AM
#56
Or to put it in another perpective....you, with all your "knowledge" about cylinder charging inefficiency and overlap etc.... are running a stock motor with a little Thunder Racing 224 cam, an oil pump and a new chain and I (with my lack of knowledge from not reading as much as you) am into my 5th year with a 500+ HP stroker motor that I built myself aside from machining , that runs low 11's all day at the track without breaking a sweat. With all the books that you have read, can you completely take down a LS1, rebuild and put it back together in 35 hrs by yourself? I CAN
While I haven't blown up enough engines to attain your level of practice at rebuilding them, I had built 14 SBCs before I graduated from college while working at a marina...boat engines that turn 5000+ RPM continuously for a lot longer than 11 seconds. And another 3 since then that are used in road course events where they run 30 minutes or more continuously.
I'd have built more, but mine don't blow up.
You assembled parts that can run fast for 11 seconds. Congrats.
edit to add: now standing by for his obligatory sarcastic "wow you're smart" comeback, complete with more grade school spelling errors. It's all he's got left.
Last edited by crainholio; 08-05-2008 at 11:35 AM.
08-05-2008, 11:38 AM
#58
Swapping the LS1 into my '82 Camaro back before there were step-by-step instructions on how to go about making it work was enough fun at the time. I figured I'd save the big engine project for later. The engine had great leakdown test numbers and very low mileage, so no need for a buildup.
While I haven't blown up enough engines to attain your level of practice at rebuilding them, I had built 14 SBCs before I graduated from college while working at a marina...boat engines that turn 5000+ RPM continuously for a lot longer than 11 seconds. And another 3 since then that are used in road course events where they run 30 minutes or more continuously.
I'd have built more, but mine don't blow up.
You assembled parts that can run fast for 11 seconds. Congrats.
While I haven't blown up enough engines to attain your level of practice at rebuilding them, I had built 14 SBCs before I graduated from college while working at a marina...boat engines that turn 5000+ RPM continuously for a lot longer than 11 seconds. And another 3 since then that are used in road course events where they run 30 minutes or more continuously.
I'd have built more, but mine don't blow up.
You assembled parts that can run fast for 11 seconds. Congrats.
08-05-2008, 11:45 AM
#59
You did say this:
can you completely take down a LS1, rebuild and put it back together in 35 hrs by yourself? I CAN