Yellowbrother

iTrader: (2)

hi guys...i'm done with all the stuff with the engine in the car...waiting for body guy to come tow my car to finish up the car...i just installed the metric adapter on the passenger head...running full sweep autometer temp gauge...i let it run for bout 15-30 min...got a steady 200 degrees for the last 5 min or so...

i did some research...appears some guys are getting steady 190...205...210...and some as high as 235....there was someone mentioning gm documentation shows 235 as normal...so i just wanted to start this thread to see wat everyone is running for future reference...

my personal setup is

- stock 300zx (z32) radiator
- stock ls1 t-stat
- taurus dual speed fan
- autometer full sweep with sender adapter on passenger head

during my test i was manually powering the taurus hi speed fan...

another question of mine is at wat temperature would be considered "overheating"?

chevyboy91188

iTrader: (15)

I personally dont like anything over 220 but thats not what most say. I know the gm gages in the trucks and vans go to 260 and then its red so judging by their gages I'd say if you get to 260 better shut the thing down asap but i really don;t know what the threshold is for these motors

knievel

iTrader: (11)

It is probably a 190-195 thermostat so around 200 isn't extremely warm

try a 180 thermo and see what the car runs at

word sux

an oil cooler is also a great adition and should make about a 10 degree difference

gofastwclass

iTrader: (2)

Funny you ask that question... my TA was set from the factory for fan 1 (low) to come on at 226 and fan 2 (high) at 234. If the engine was off it would kick on the low fan at 235+ for 150 seconds. That seems to defy everything I learned in high school so I used HPT to modify the temps to a lower point and it never gets above 208 in heavy traffic. My Thunderbird swap runs all day at 197 with the factory 'bird V6 radiator and electric fan unless sitting or idling in heavy traffic which puts it around 205 as well. Both cars are using factory 190 or 195 degree (I can't remember) stats which may be changed out in the future for a lower temp in the 180 range. All my temp readings are straight from the VCM with either my hand held scan tool reading live data and logging or HP Tuners reading live data and reviewing my data logs.

Yellowbrother

iTrader: (2)

what makes u think/reason that a lower temp tstat will lower the operating temp of the car??? tstat is either open or closed...so at a lower temp tstat...it'll just open up sooner...but should still get up to normal operating tempt eventually but just at a slower pace no???

Pop N Wood

iTrader: (1)

Running a

- LS2 crate motor
- JTR radiator (Stock single core Astro Van aluminum radiator)
- 160° thermostat
- Taurus dual speed fan with only the low speed connected
- Fan controller with an external radiator fin probe

The stock Datsun sender sits right at mid scale, 185°, pretty much all the time.

gofastwclass

iTrader: (2)

In theory the lower stat will allow coolant to flow through the radiator sooner which will allow the engine to run cooler. In reality there are other factors that may limit your ability to get below a certain temperature. This is the point where it becomes impractical. The real benefit is I can set my fan temps to turn on at a lower point to take advantage of the earlier opening point.

If you try to run the engine cooler than the stat you have to either have a huge fan and radiator or run smaller fan(s) all the time to get or keep the engine temp below the stat opening point.

xvictimx26

i have a 5.3 in my 84 trans am with 190 tstat and 90 v6 rad and i let it run for about half an hour to break in a cam and it never got over 195 on a mech gauge also with the stock fan and aftermarket temp switch set at 190-200

chevyboy91188

iTrader: (15)

i just had to do temporary fix on a workvan with hairline cracked heads and the way you do the head sealant is you take out the thermostat and let it idle for an hour without it in. While doing this I had half of the fan shroud off because on an express van thats about the only way to get to the thermostat on a 4.8 from above. The van never even got to 170 after idling for an hour with only water and the head sealant running through it.

so by having the thermostat open sooner it will keep the engine cooler. The cooling capacity of your system is limited to a certain temperature drop rate just by your radiator and fan, so if you make it so that you cant start utilizing that till a higher temperature thats a higher starting point and it will limit how far down your cooling system will be able to reduce the temperature due to the rate the heat is generated by the engine compared to the rate at which your cooling system can remove it. It creates an equilibrium based on the heat flow and the higher you let the temp get before you start cooling the higher that equilibrium will be.


so yes a lower thermostat will help lower operating temperature. my thermodynamics book agrees

Pop N Wood

iTrader: (1)

If the cooling system is working right than the temp should stay around the thermostat setting. But I see Yellowbrother's point, if the cooling system can't keep up then it really doesn't matter what temp thermostat is in there. Eventually the T stat will fully open and the engine will just keep heating up till it overheats.

In other words, changing the thermostat doesn't change the cooling capacity of the system.

knievel

iTrader: (11)

Having a 195 thermo in the car and it will not run any less that 195 (99.9% of the time)

The water won't circulate until the thermo is open


Dropping the thermo to a 180 may allow the engine to run around 180 if the cooling ysstem is up to par.

On a system that doesn't have a good working radiator/fan the car may not run any cooler



Personally my LQ4 swap without a thermo didn't get over 150 without the fan on going down the road.
sitting in traffic it got upto about 170-175 still without the fan


Also as a side note:
a cooling system raises the boiling point of the coolant by about 3 degrees per lb of pressure it is under.

a system with a 15lb cap raises the boiling point by about 45 degrees
Taking about 257 degrees before it boils over

Yellowbrother

iTrader: (2)

I see wat u r talking bout now....thas given if ur cooling system is efficient enuff to maintain that low temp ......never thought of it that way before...my thinking was how pop n wood said...

chevyboy91188

iTrader: (15)

Yes efficiency is key, so if your system is lower efficiency the lower thermostat will help it function better because it will basically give it a little head start