Thermostats... Which one is really right... and why?

[97AutoXVette]

I have seen some conflicting arguments about thermostats, and am hoping to start a discussion on which is best and why. I know stock is 195, and obviously increasing the temp of the motor can increase efficiency (in some cases), reduce viscosity in the oil and other fluids, etc..

However, with increased heat comes increased opportunity for detonation, and higher thermal stresses, etc.

why do aftermarket manufacturers like ZZP recommend lower temp thermostats, such as a 160, even for mildly built motors?

What drawbacks are there from running lower temp thermostats on stock/mildly built motors other than maybe a slight reduction in efficiency? I would think that lower temps (within reasonable limits) would help keep the air/fuel mixture denser as well as prevent detonation? I guess the counter argument to that would be the combustion process that results may not get as hot which does not allow as much opportunity for thermal energy extraction from the fuel (possibly the loss in efficiency mentioned earlier??)

Let me know what you guys think. Open to suggestions and thoughts.

[coolone]

Don't need to examine all the particulars in a platform such as ours that's been around for more than a decade, just go with the flow. 180* drilled Tstat is where's its at!

Adjust the PCM for it and your done.
: )

[97AutoXVette]

Don't need to examine all the particulars in a platform such as ours that's been around for more than a decade, just go with the flow. 180* drilled Tstat is where's its at!

Adjust the PCM for it and your done.
: )

Don't worry, I am already drinking that coolade! 180* T-stat is in the car now and tune is programmed for it. Just trying to learn as much as I can. I am a mechanical engineer by profession so this stuff always peaks my interest

[Bio248]

in most cases where outside temperatures don't stay very high (arizona, texas, etc.) you really shouldn't ever need a lower thermostat. having lower coolant temperatures is just keeping the motor from legitimate running temperatures and you're just wasting gas then. wear and tear on the motor is also accelerated, although it's probably not very noticeable for a really long time.

i don't recommend thermostats to people anymore. it was something they had to do in 1997 and early years because they had no tuning software. it's very old school logic and it doesn't really apply.

[coolone]

I'm totally OLD school and seriously, in Arizona, a colder Tstat in 114* weather isn't going to help all that much, lol.


I've seen plenty of posts about the engine running at the correct temp, but have yet to see anything backing it up (dyno). Personally, I think the IAT is going to effect your gas usage more than the engine (coolant) temp. Furthermore, running a smaller pulley will further distance the combined effect of coolant vs air temp with regard to fueling. Once modded and spinning that SC faster (pulley), is going to negate any effect of a cooler Tstat, or what a cooler Tstat can do. But like I said, I am totally old school, I like keeping my engine cooler. For the record, has been done way before 97'... My 73' Grand Am had a drilled colder Tstat which was totally removed in the summer.


Just looking for an expansion on your logic Bio, I'm always learning and these are all just my opinion of course : )

[Bio248]

you explained exactly my thought process.

it ain't broke, don't fix it.