While my 1999 C5 is in having the shocks/sways/etc. put on, I'm having the mech throw an "econo" tune on it also. He's replacing the stock thermostat with a 160 degree thermostat. Being new to this, what the heck is that going to do for me besides cost????????

Padrino

 

It makes your car go faster because your wallet is lighter.

Waste of money.

 

From Zulatr in 2007 on the Z06 pages...

"Seems like something was missed here.
The thermostat regulates the water temperature to the temp listed on the thermostat. It is not a switch that opens up fully when the temp is reached.

So, with sufficent air crossing the radiator, either by fan or ram effect due to the car moving, the temperature stays at the set point plus or minus a few degrees. More load on the engine, more HP, equals more heat and the thermostat will open more to maintain the set temp. All this assumes that the radiator is correctly sized for the engine HP (heat).

The temp will only climb (if we still have sufficent air to remove heat and a right sized radiator) if the heat that needs to be rejected by the radiator is greater than what the radiator can reject. The biggest factor for that is the outside air temperature. The formula for calculating heat transfer is a function of the LMDT (log mean temp difference). Said simply, it's a lot easier to reject 190 degree heat from the radiator to 60 degree air than 110 degree air. The temp diff goes from 130 to 90, and in a log table, that's a lot.

What coolant temp does for HP is another story.

Internal Combustion (IC) engines don't make power from the explosions happening in the cyl. The power is from the expansion of the gas in the cyl increasing due to the heat of combustion. The expanding gas forces the piston away from the head. The LMDT formula comes into play here too, but the difference between 160 degree and 190 degree coolant is not much compared to the temp of combustion (+/- 1800 degree), so has minimal effect on HP generated. What is does affect is charge temperature, which if it's too high can cause detonation (intercoolers on FI engines) or too cold, can cause poor atomization of the fuel mix and degraded combustion efficency. It also may not allow the oil to come to full operating temperature and cause formation of acids due to the water not getting cooked out of the oil.

So do you get more power at 160 degree? Theoretically, not enough to measure. Can you advance the timing a little more and move away from the detonation point, yes, and you, or the ecu, can work the various parameters in the tune to get a HP increase. That's why so many tuners want the colder thermostats in the car - to prevent detonation at the faster timing advance curves that they use to increase power over stock."

Any of that make sense??? Padrino

 

Ask yourself the following questions .....

1) When sitting in traffic, what controls the engine temperature ... the thermostat, or the fans ??

2) If a "cold" engine is good for power, then how come every race engine in the world (F1, NASCAR, IRL, ALMS, ....) is run at 200 degrees, and higher, temperatures ??

3) Ask anyone who has a 160 degree thermo what temp their engine runs at on the highway .... unless the ambient temp is extremely cold the answer will be around 185 ..... what did the 160 unit do for them ??

4) If a 160 degree thermostat was "good" for your engine, why did after millions of dollars of researching the cooling system did GM Powertrain choose a higher opening thermostat ???

160 degree thermostats are an urban legend left over from the 1960's, and even then they were controversial ..... modern engine designers recognize them for what they are ... a way to lighten your wallet.

 

The 160 stat itself will not gain you any power but if tuning like more timing was to be added then you would need a little cooler engine. Hot engines will create spark knock easier than a cooler engine. I was just doing some tuning on a camaro today and had a little spark knock, after I installed a 160 stat most of the spark knock was gone. As why GM runs the hotter stat I believe it's all because of emissions. A hot engine will in fact burn cleaner than a cooler engine thus having cleaner exhaust. Anyway if you are doing any timing changes I would go with a 160. Don't forget to change the fan settings also.

 

I try to keep my motor around 190-195 and my oil between 200-210 (minimum). I think you will find that setup a little too cool, which according to one of the forums C5 experts who worked for GM, will cause premature wear of many of the internal components. Not trying to criticize your installation, but you should be aware there is a trade-off in every decision and running too cool can lead to problems down the road.

 

First ..... answer question #2 above in my post...... ?????

URBAN LEGEND that engines run hotter for "emissions" ..... you think an engineer in F1 or NASCAR or ALMS gives a rat's azz about emissions ????? They run the engines hot for POWER .....

And think about it, if one engine is "clean burning", consuming ALL the fuel fed to it, and a second engine is not burning all the fuel ... which one is more powerful (Hint for dummies - burning fuel creates power) ?????

And please explain how installing a 160 thermostat caused "most of the spark knock is gone" when you are sitting still working on an engine where the FAN turn-on temperatures are what control coolant temperatures ... not the thermostat. The PCM looks at coolant temperature as input to calculating spark timing. The PCM has NO CLUE what thermostat is in the engine ... you could remove the thermostat and if the coolant temperature is 180 degrees THAT is what the PCM takes into account, not the "missing" thermostat.

 

I have no idea on the race car thing but on the camaro I was getting around 2.4 of kr at 198 degrees. I ran several logs with EFI Live just to make sure. I then put the 160 stat in and changed the fans. After that the kr dropped to 1.2 at around 178 degrees. Nothing was changed in the pcm other than the fan settings so explain what happened. I would assume that there is a reason that companys like superchips and hypertech both require a 160 stat to use with even their tune in their handhelds. I know there is some people that say the 160 stat has bad effects like hurt gas milage but since my vette will get right at 30mpg on a 200 mile trip I'm not going to worry about it. If I want more than 30 then I will buy a Geo.

 

1) Both

2) Assuming this is true, these are full out race cars racing for hundreds of miles. This bears little resemblance to a street car racing a ¼ mile.

3) I have a 160 thermostat and my car runs 176 on the highway (down from 192 stock)

4) Define “good”. For some more power is “good”. For others reduced emissions is “good”.

A 160 thermostat may not be the correct choice for everyone, but it can provide increased performance, and is this certainly not an urban legend.

 

My car makes more power when it's hotter, rather than colder - proven that time and time again on different dyno's. For that reason I like to see coolant temps at 220+ and oil temps 220+ before I expect to be nearing peak HP output...

I could be an odd duck, but really doubt it - wonder how many people have actually made dyno pulls at different temps and seen the power differences?

 

I haven’t dyno tested, but at the track my car always runs quicker/faster when the coolant temperature is between 165 and 180. Above 190 the mph tanks big time (2-3 mph).

 

Take a look at this post (or search on Evil-Twin and "sweet spot") .....

http://forums.corvetteforum.com/show...post1557142528

Bill (Evil-Twin) was an engineer on the C5 design team. After the car was launched he spent several years in the field working on "product issues" before he retired from GM ... I think he knows what he's talking about.

MGorman ... you may be seeing a difference in intake AIR temperatures affecting you ET, rather than engine coolant. The "ideal" is a "hot" engine with "cold" air .... look at the airbox on an F1 car, pulling "cold" air directly to the "hot" engine.

 

Mine runs at 175-178 on the highway.

What the Tstat did for me was allow me to run the fans down to 185 without the Tstat closing, preventing the fans from running all the time when not moving.

Same logic can be applied to anything.
No need to ever change the heads, cam profile, clutch or any other part - the engineers obviously put a lot of effort into designing those parts, they are perfect and the pinnacle of performance - why on earth would anyone want to change them?

Seriously, the stock Tstat is as with many things, a piece of compromise. GM builds the car to survive in all weather extremes, including -40* f. I would guess that few owners here operate their cars in those conditions, and as such, can more closely tailor their own car for the climate they run it in, as well as how they personally use their cars. I would not run a 160 stat in the winter...but I don't drive mine in the winter, so it works out fine for me.

Between fan setpoints and the Tstat rating, I have my car setup to always run in a window of 175-200* coolant temps, and my far-from-stock high compression engine is very happy running in that narrow, controlled temperature window.

 

And Ironically, he runs a 160 stat in the summer on his car too - go figure.

http://forums.corvetteforum.com/show...91&postcount=4

 

The trap speed increases people see from any of the intakes that pull from outside of the hood are likely due to the decrease in air temp being delivered to the engine, rather than any supposed ram air effect...

 

 

I give some credence to this theory. I have thought about this issue. When I had a Camaro I data logged the IAT’s during ¼ mile passes. The IAT’s were increased during the burnout and while staging. After launching the IAT’s immediately dropped. Just past 60’ the IAT’s stabilized. It seems as soon as the car gets moving all the accumulated hot air is blown out of the engine compartment and the IAT’s drop to ambient or very close. It seems to me that yes, for the first second or two of a pass higher IAT’s may well reduce power. I am not really sure however how much a 15-20 degree reduction in coolant temperature is going to reduce under hood air temperature. The main benefit of the lower coolant temperature is the fact that it allows for more timing and more compression with less knock retard utilizing a given octane fuel.

 

ahh yes..the thermostat debate..one of the hot topics that has forced some members into corvette forum retirement.

 

Just a quick note here... keeping the car in the sweet spot, is very tricky, with a 190 stat on a hot 95+ day a black top road can reach 140 F. your not going to get much heat transfer with these types of temps, engine coolant can see 230/240 F. oil temps can reach 260F. So by running a 160 stat in the summer you can lower your fan setting to get a jump on the heat. The problem is no where as critical on the hot end as it is on the cold end... you have to be careful running a 160 stat when ambient gets so low that your oil never sees 200/210... you do not want to run your oil cold... so its a trade off... If I'M running my car and we get a 50 degree night, I turn off my fan controller and allow the PCM to use the stock settings to control fan on and off temps. I'M not as dumb as I look , and I have tried over the years here that you can "Tune your car" for specific road condidtion..we build this car to run in the Nevada desert at 110 Ambient, and we build the very same car to run in North Dakota when its -20 F... you can put your car in the sweet spot and get a little more out of it, and keep it in a much safer zone by trying to control the engine temps with direct control over oil temps... again this is not for the race car, this is for the 98% that use their car for the street... you can also do the same thing with your tires by trying to keep them in the sweet spot 30/31 HOT....... running a cold 30psi can quickly turn into a 36/38 psi when your running those tires on a hot Georgia black top road at 140/150 F. Ive said this many times setting cold temps do nothing for performance or longevity. Its what the tires sees on the road, under driving conditions. not sitting on a cold floor in your garage. this is the reason so many members sees center tire wear. they dont pay attention to the Hot driving conditions.. You want a 100 % contact patch, for traction and for handling... when your tire is too hard 37/38 psi. you lose 20% of the contact patch, thats why a hard tire wears in the center, and you lose traction and easily spin the tires, you think your car is powerful because with hard tires they are much easier to spin.. this wears the tire in the center but you look cool ( joke ).,...you also lose lateral steering control with less than 100% contact
the 30 psi sticker was put there for product liability reasons because people were putting max tire pressure found on the sidewall. The End.. the skeptical can have the floor I am done here... any questions, PM me.
Sorry this was not a quick note, but the reason I run a 160 stat in the summer..it should seem very logical , but of course the skeptics just need an opportunity. For those who understand this logic, please have pity on the skeptics that take every opportunity with their limited automotive knowledge, to cloud and dissect.

ON a side note ! Some one was saying they could achieve 30 hp with cold air... let me just add this... you get 1.7 hp gain for every 10 degrees of temp. the difference between summer and winter driving can be felt in the seat of the pants because in some cases you are going to see 80 degrees difference between summer and winter that will yield 13/14 hp... without any corrections.. the PCM trims the fuel mixture to accommodate this automatically no need for a tune The car is capable of adjusting the mixture for any driving conditions automatically, when its -20F in Bismark North Dakota..or 120F in the Nevada desert. Driving the car in Bismark is going to be noticeably more fun, than driving the car in the Nevada desert. BTW the 1.7 formula is what is used in "corrected" dyno numbers., as oppose to "uncorrected" dyno numbers.. this insures you see a real gain with out ambient temperatures adding or subtracting hp.... in order to gain 30 Hp by adding denser air mix there would have to be a temperature deviation of 180 degrees F. So much for the all knowing folks.... So much poor information here.

 

Interesting and informative thoughts. Thanks....