I was beginning to wonder about this as I was reading this post, since a 180 degree Stant was installed in my L98 :thumbs:

 

Actually if you look at the "AboutUs" link on Motorad, I am pretty sure they make the GM stats as well as Hypertech. Sometimes it is a small world.

 

It is posible that Hypertech has the smaller opening by desing. I know running w/o a stat is not recomended because it is posible for the coolant to move to fast trough the block not disapating the heat and that is the reason many racers use restrictors instaed of T-Stats. So mabey Hypertechs desing works better (Mabey not probably). I doubt this is the case because I just dont trust Hypertech but just because the T-stat has a smaller opening doesn't mean it cools less eficiently.

 

Another data point.
As Alex mentioned the Hypertech does appear better made with better materials. That was my reason for choosing it. I use the 180 on my 88 in the Central Valley of California where we had 17 days over 100 in July. Main fan never came on as the car never reached 230. The auxiliary kicks in at about 200 on my car.

 

:iagree: I have been told the same thing by various sources. For an LT1, a coolant flush or water pump swap is a perfect time to change the thermo.

Somebody above asked why GM didn't use a 160F if it would benefit. There are a number of reasons but in short, they will optimize the car for emissions, fuel economy, etc, not just hp and max life of the cooling system (seen plenty of cracked plastic radiator tanks).

 

I have a book on small-block chevy engines that mentioned this as a misconception. I don't remember the author or publisher right now but I'll dig it out of my closet and find out if anybody wants to know. The book states that the real problem with removing the thermostat is that it moves the highest pressure reageon of the cooling system from the block to the radiator. This causes the radiator cap to vent the excess pressure. In some cases you can loose enough coolent to actually cause the engine to overheat. You see steam pouring out from under your hood, look at the temp guage and see 240+ and think OMG the engine overheated and I'm loosing coolent due to excess preasure caused by heat. In reality, you have too much pressure in the wrong place due to lack of restriction, this causes you to loose coolent and then overheat. Again, I have no personal experience with this, just theory from a book.


[Modified by rkessel, 9:51 PM 11/1/2003]

 

:iagree: More flow is not always better! If it doesn't sit in the radiator long enough it'll never cool off and if it doesn't stay in the engine long enough it'll never heat up. I've experienced both by removing the stat.

The reason they put in a hotter stat is strictly for emmisions.

Lowering the temp with a cooler stat will save you some ponies, but not after the engine is completely heat soaked, when the race gets down to the final few and it's round robin.

If you want optimal race temp, lower the stat, install an electric pump (LT1) and always race it at running temp.

Oh and water cools much better than coolant. During the summer months you could drain the coolant and put in water, but don't leave it or you could end up with a rusted system.


[Modified by MyX10sion, 11:02 PM 11/2/2003]

 

More flow IS always better IF you don't put too much pressure under the radiator cap. Think of it this way. The hottest part of the system is the inside of the block, the coolest part is the air going through the rad. the heat has to transfer from the block to the water to the rad to the air. None of these steps are going to be 100% efficient. The block will be hotter then the water. The water will be hotter then the radiator. The hotter the radiator is the faster it will transfer heat to the air. You want the radiator to be as close to engine temperature as possible and the way to do that is by moving the fluid back and forth as fast as possible. It is true that each ounce of water traveling through the system will cary away less heat but you are pumping more ounces and the net effect will be better cooling. The trick is to pump as much water as you can without creating so much pressure under the cap that you litterely pump water out the pressure reliefe valve.

Did this on my first car (88 Cavalier). Discovered the coolent also is supposed to lubricate the water pump. Oops. :banghead:

 

Pressure or not, if it doesn't stay in the radiator long enough it can't do it's job. I didn't make this up, the engineers put in a thermostat that restricts flow for a reason. I've removed the thermostat only to ride around in a freezer box during winter months. Likewise, I've had overheating problems that were resolved by putting the thermostat back in.

My point here is that if the temp of the coolant as it leaves the radiator isn't sufficiently cooled, the hot block will simply heat it higher and higher each time it passes through.


[Modified by MyX10sion, 12:46 PM 11/13/2003]

 

pressure is also needed, but its needed in the block and heads. pressure is needed to keep the coolant from boiling and to prevent air pockets from forming in the coolant passages from combustion( the explosion causes vibrations that cause this). the pressure differential from the engine to the radiator also helps your waterpump operate more efficiently.

 

Alex, good info & research. A couple of points others may use:

1. In summer (PHX has more than 100 days over 100) I run a Moroso restrictor plate with a 1/2" opening instead of a stat. Engines stay pretty close to 175 degrees.
2. In winter, I change to a 180 because with the restrictor plate I can't get my '89 over 147 degrees no matter how long & fast I drive when its 70 degrees or less outside.
3. Opening dimensions (thus, coolant flow rate capability) of a stat is not necessarily determined by the outside diameter of the moving close-off assembly. I.e., if the sliding portion that opens at designated temp only allows a narrow slit, even though its diameter is greater, it may not flow more than one like the HyperTech (or the s/s Stants) that have a small diameter, but very unrestricted opening.
4. Always place a stat (new or an old one going back in) in pan of water on stove & heat before using. Use oven thermometer to check when it actually starts to open & when it gets to full open. Then watch as it cools and see how fast it closes. I've bought bad ones and someone taught me this many years ago. A little time, but no money!
5. Those saying too much flow can be bad are right - too much flow & coolant can't pick up enough heat from engine or disipate enough in the radiator.
6. If you change stats for winter, consider getting the new FlePro thermostat housing gasket that is plastic with an o-ring (about $5). You can re-use them & no sealer req'd :) Clean bolt holes & threads. Remember not to tighten them too much. Tighten stat housing bolts evenly back & forth to no more than 20 ft lbs torque.

OOPS - I forgot. It's always a good idea to drill the edge of the stat so it will flow a little bit even when closed fully. This will make burping all air out of the system easier too. I use a small (3/32") bit and make 3 holes around the edge - making sure I don't bend anything or interfere with the seating in the recess of the intake. Tip comes from the old TPIS Performance Book.

On burping air from the system, L98s are harder than most cars because the radiator cap sits lower than the highest coolant passages in the intake/heads. We all know about holding revs @ 1,800 or so when stat is open to evacuate air, topping off, & sealing the cap before returning engine to idle. Another thing I did was to buy a Moroso in-line filler pipe. It's a cast aluminum "T" that goes into the highest point of the upper radiator hose & takes a regular radiator cap. No plastic. Anyway, it sure makes things easier.


[Modified by NavyVet, 12:25 PM 11/13/2003]

 

:bs More flow is ALWAYS better, as long as the coolant stays in the system. The coolant's mass flowrate is the SAME throughout the entire system. This is the case for all closed systems.

I have no doubts that this is the case, I'm just trying to think of the best way to explain to folks that this urban myth is false.

If the coolant spends less time in the radiator, it doesn't cool off as much, but flow is the same, so it also spends less time in the engine, and picks up less heat.

You don't even have to look at the engine side of things for this to make sense. At steady state, heat transfer from the engine to the coolant equals heat transfer from the coolant to the radiator equals heat transfer from the radiator to outside air.

Heat transfer is dependent on temperature difference. As a mass of heated coolant makes its way through the radiator, it decreases in temperature as it loses heat to the metal in the radiator fins. As it cools, the temperature difference between that coolant and the outside air decreases... therefore, less heat transfer occurs. The longer that coolant stays in the radiator, the cooler it gets, and the less effective the radiator is.

Now, if that water is flowing MUCH faster, it doesn't have as much time to cool, so it's hotter exiting the radiator, has a greater temperature difference, therfore MORE heat transfer occurs in the same amount of time.

Don't think of it in terms of temperatures, but in terms of heat transfer. And please, think about this before you start rebutting it. I don't want to argue for the sake of arguing and have nothing to gain by being condescending. It's never too late to learn something new. :)

 

These two statements are contradictory.

 

I would like to thank you for taking your time and sharing this knowledge with us. I didn't think when I started reading this article, that there would be so much controversy on this topic. But with that aside, I really do thank you for sharing this information. :thumbs:

 

The Delco OEM tstats are made by Stant also. Actually the manufacturing company is Standard-Thomson Corporation, which Stant bought in 1988. That is why a Stant tstat has the "STC" imprint on it, which the Delco OEM also has (mine did), and I suspect the NAPA one has also. I beleive that Stant is owned by Gates Rubber (as in Gates belts, etc), or maybe Stant also owns Gates in add'n to Standard-Thomson Corp.

Last week I bought a Stant 180F tstat at Advance Auto parts for $9.98. Pulled my Hypertech 160 out for winter.

 

I agree with central coaster, think of it this way:

liquids are for all intense and purposes conducting energy by means of conduction.

liquids in the closed system of the engine are ALWAYS in contact with the whole system.

(assuming that the radiator is/and always will be cooler then the system)

circulating coolant through a radiator will radiate heat off until the temp of the coolant coming back to the block is as hot as the block.

fastest means of cooling the block will be to lower the temp of returning water to the block.

fastest means of cooling the water returning is to keep the water conducting heat the fastest.

since water conducts heat based on temp gradient by time in contact and the water is always in contact with the block/radiator/system the fastest means of cooling the system off will be to circulate the water the fastest up until the temp of the water returning from the block is equal to the temp leaving to/or into the block, all assuming of course the temp of air is lower then radiator.


I do here note that pressure (psi) plays a role in the temp gradient (Kj/sec). I do not know however if it is linear, geometric, or for that matter the exact relation. hence, i can not derive if increasing pressure will increase overall temp fall because pressure increase is an effect of flow rate being resisted. I can find it I THINK in my old physics book, im to lazy though.

MY VOTE IS FOR FLOW RATE, FIRST!!

 

Sprained my brain trying to comprehend all that.


[Modified by Lone Ranger, 7:31 PM 11/13/2003]

 

my bad... :leaving: