QuadDriver, any material which rejects heat would be classed as an insulator. Aluminum is most assuredly NOT an insulator - it readily takes up heat, which by implication, the logical conclusion follows that aluminum is also an excellent heat transfer medium. That's why the metal is routinely used in heat exchangers. Your physics may be solid, but your basic definitions are bass-ackwards.
Replacing 192 thermostat with 180 for better oil life ?
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well, google up 'aluminum' and 'heat' and 'rejection'
I prefer my college physics texts...
If your physics texts say "any material which rejects heat would be classed as an insulator." then you should go back the book store and demand a refund.
The 94-96 b-body LT1s had 10:1 with iron heads and the base Caprice motor a 4.3L version of the LT1 had 9.8:1 again iron heads, the LT1 will routinely have a cranking compression of 200+psi even beyond 100K. To make this even more unbelievable all that on 87 octane
, reverse flow cooling and a stock 180stat plus good injection and ignition control with duel knock sensors. I can prove all that if you like. The aluminum head versions of this motor came with 10.4 and 10.8 depending on which set of aluminum heads the LT1 or LT4.
mechtech, I do understand your points on engine temp and heat, this is exactly the same reason why iron heads should be better than aluminum, because they hold in heat better, but there are other factors that have to be considered and every application is different. As to
) and the thing that brought me here.
Oil temps get warm because of an in rad. oil cooler right at the hot inlet, and my warmup is fine with adequate heat in sub-zero weather rarely even requiring the second speed on the fan and that only for defrosting.
I actually do have a new 180 I plan to try again, and have dynoed the car as is so maybe I should try again after the 180 goes back in wont be a very exact test given neither try will be dialed in perfectly. As another interesting note I yanked the 4.3L V8 from my car at 110K, had the stock original 180 and dexcool for the first 96K then the 160, I swapped it for a 5.7l not due to internal problems, there is crosshatch left in every cylinder, so the low temp can't be too bad for the motor, this is downright common for the LT1s, just today a guy on one of the forums found the same thing on his wagon LT1 with 130K he too is modifying not repairing. If anyone is in the area and wants to see that old block sits in my garage.
mechtech, I do understand your points on engine temp and heat, this is exactly the same reason why iron heads should be better than aluminum, because they hold in heat better, but there are other factors that have to be considered and every application is different. As to
This is why I do my own work, mechanics have to know about a huge variety or cars and because of that can miss important details if they become too sure they know everything. I say with absolute certainty that I know this application better than you and better than most of the people who built it, it is my one bad habit(at least the wife thinks it bad
Oil temps get warm because of an in rad. oil cooler right at the hot inlet, and my warmup is fine with adequate heat in sub-zero weather rarely even requiring the second speed on the fan and that only for defrosting.
I actually do have a new 180 I plan to try again, and have dynoed the car as is so maybe I should try again after the 180 goes back in wont be a very exact test given neither try will be dialed in perfectly. As another interesting note I yanked the 4.3L V8 from my car at 110K, had the stock original 180 and dexcool for the first 96K then the 160, I swapped it for a 5.7l not due to internal problems, there is crosshatch left in every cylinder, so the low temp can't be too bad for the motor, this is downright common for the LT1s, just today a guy on one of the forums found the same thing on his wagon LT1 with 130K he too is modifying not repairing. If anyone is in the area and wants to see that old block sits in my garage.
Ok, I stand corrected. So I'll say VIRTUALLY all Mfrs use 195 or higher therms.
I haven't seen a piston bore WITHOUT cross hatch left in it, even on abused POS vehicles, since the early '70s [doing head gaskets, rblds,etc..].
If the factory calls for a cooler thermostat in a vehicle , to address a particular problem, I'd contunue to use it, however.
I haven't seen a piston bore WITHOUT cross hatch left in it, even on abused POS vehicles, since the early '70s [doing head gaskets, rblds,etc..].
If the factory calls for a cooler thermostat in a vehicle , to address a particular problem, I'd contunue to use it, however.
Patman
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My 98 LS1 Formula's owner's manual lised it's stock thermo to be 177-184.
My 98 Corvette's owner's manual lists the stock thermo to be 184 (it's the same engine, so probably the same unit) My cooling temp runs at 187-190F on the highway, so I believe this unit opens up sooner than 180.
GM and ford make the 180s as regular 'in store stock' for every engine they sell. On motors produced to be shipped outside the USA into warmer climes (south america, middle east etc) the motors come with 180's or even 160's. Domestically, many severe duty packages include the cooler thermo. Like I said in my first post, a thermostat is something that should change with the seasons, especially if you tow (as I do). It is actually generally easier to change than snow tires, which people do without complaint. Go figure.
btw if you want to see polished bores simply tear down an olds Y-code 307. It is very common for my customers to complain of 300miles/qt consumption rates at highway speeds due to stuck rings and polished bores. Most of these are in large GM Bcar wagons which for those that still own them (I myself had until recently 4, 2 ycodes, 2 h codes) are the family truckster of choice.
Keep in mind that the 180 stat in an LT1 gives roughly the same cylinder wall temps as a 192 in a 1st gen SBC. This is because the water hits the heads first, rather than the cylinder jacket, with a reverse cooled engine.
VaderSS - Sounds like they are shooting for the same ultimate internal conditions, then.
Quad4 - I'm not sure why they'd spec 160-180 thermostats in foreign countries. It wouldn't prevent overheating, since by then the thermostat is fully opened anyway. I think it may be because they are considering that there may not be adequate anti-freeze kept/available in the vehicle in way out locations, and need to keep the temps below water's boiling point. I still don't think it is the best for engine's efficiency or economy to run a cooler than spec'd therm.
I've seen plenty of old V8s with very pretty, mirrored, bores - just nothing for quite a while.
Happy Motoring!
Quad4 - I'm not sure why they'd spec 160-180 thermostats in foreign countries. It wouldn't prevent overheating, since by then the thermostat is fully opened anyway. I think it may be because they are considering that there may not be adequate anti-freeze kept/available in the vehicle in way out locations, and need to keep the temps below water's boiling point. I still don't think it is the best for engine's efficiency or economy to run a cooler than spec'd therm.
I've seen plenty of old V8s with very pretty, mirrored, bores - just nothing for quite a while.
Happy Motoring!
My 96 LT4 also has a 180F thermostat from the factory.
Its been pointed out already but the temp rating of the thermostat is the opening temperature-when it starts to crack open. The thermostat doesn't just snap fully open, it gradually opens farther with increasing temp. It usually is fully open by 20F higher than rated temp. It is not unusual for a 195 degree thermostat to run coolant temps of 205 degrees. I run the stock thermostat temperature in my vehicles.
With stock programming I would run a stock stat but these things are amazingly easy to gain access to the computer of, well actually onece I switched to a 94-5 computer it was CHEAP and easy, the OBD2 stuff costs more but is readily available as well. Been years since I had stock programming in the car, once you begin modding a vehicle you try all sorts of stuff, some good some bad. The 160 stat I do believe makes some compromises but overall in this application does work well. On the crosshatch it is even 150K mile former cop cars finding this and imagine the idling hours on those.
A lower temp thermostat will keep the oil and ATF cooler, but will also delay warmup of the engine. This means it will take longer to burn off any fuel or water that gets into the oil, possibly shortening its life, especially in winter. With the ATF, you would almost certainly extend its life by doing this.
In some operating conditions the higher temperature thermostat would greatly extend oil life. Shorter trip operation in cold weather.
In the hottest weather scenarios when oil temperatures are most likely to skyrocket, thermostats of any temperature calibration may be wide open and have no effect on the actual temperature of the coolant.
Perhaps under the scenario of extended high speed travel where the thermostat is controlling the coolant temperature, a cooler thermostat setting could keep average oil temperatures lower (but not too low) and could extend oil life.
Like pretty much all the oil questions here, the way the vehicle is used is very relevant.
I don't understand the longer warmup thing, yes you are dropping the peak temp but the temp climb rate should remain about the same till the stat opens anyway.
A couple scenarios:
Oil temp ususally lags behind coolant temp during warmup. The additional run up in coolant temp may help burn off additional condensate on a short trip.
The engine will hold temp longer if it is warmer. Consider a vehicle which makes several shutdowns in a 3 hr. period. The additional retained heat will speed warmup past point of condensate in the oil.
An observation: When 190 degree plus thermostats became common in the late '60s I saw the beginning of much cleaner engine internals.
Oil temp ususally lags behind coolant temp during warmup. The additional run up in coolant temp may help burn off additional condensate on a short trip.
The engine will hold temp longer if it is warmer. Consider a vehicle which makes several shutdowns in a 3 hr. period. The additional retained heat will speed warmup past point of condensate in the oil.
An observation: When 190 degree plus thermostats became common in the late '60s I saw the beginning of much cleaner engine internals.
AND...
The 'road draft tube' was replaced by the PCV....
'color' of the inside of the motor means nothing to me. Its caused by oil and blowby vapor coming in contact with extremely hot surfaces. I have pulled apart 'amsoil since birth' engines that were just as carmel colored as 'changed the oil when I felt like it' engines.
The real arbiter(s) are stuff like cylinder taper, bearing wear, crank/cam/skirt scoring. I have taken off fairly clean valve covers on 3.1s that had the bearings crushed to the point of failure. See my point?
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