High Performance Thermostats

[AM.MSCL]

I am getting ready to change my thermostat in my Pontiac 400 from a 195 degree to a 160 degree. I have the march Serp kit with the reverse high flow Edlebrock water pump that comes with the kit.
I was looking on Summit Racing and they show some High Flow water pump thermostats. The reasons they give for using one over a normal stat with a high flow water pump is that 1. a normal thermostat could be prevented from opening due to the higher pressure of flow of water and rad fluid. 2. have a bigger opening to allow more flow to pass due to the high flow pump.

This make sense but I have no real knowledge of this is true.
Does anyone know if this is proven or just marketing hype?
thanks
Ray

[John Wright]

... if the T'Stat doesn't have any bleed holes, add them. Usually two 1/8"-3/16" diameter holes will be sufficient to help bleed any trapped air out of the system....otherwise you have to wait until the engine gets up to temp before you can bleed the air out....and that can be troublesome and can take several attempts to remove all of the trapped air.




Another thing...many of the Hi-flo designs are built so that if they fail, they fail in the open position.

[AM.MSCL]

... if the T'Stat doesn't have any bleed holes, add them. Usually two 1/8"-3/16" diameter holes will be sufficient to help bleed any trapped air out of the system....otherwise you have to wait until the engine gets up to temp before you can bleed the air out....and that can be troublesome and can take several attempts to remove all of the trapped air.




Another thing...many of the Hi-flo designs are built so that if they fail, they fail in the open position.

John
Thanks I was planning to drill the holes in the new basic 160 got from Oreilly's that defaults open if it fails. I am just curious if the other ones I saw on summit truly allow more flow through?

[John Wright]

Your Oreilly's t'stat is probably just fine.

The opening might be just a bit larger on the Summit design, but probably not by much.

I like Stewart/Robert Shaw's stuff personally...but that is just my preference.

[paul67]

You mention you have a reverse flow pump does that not mean the water is flowing the other way to the stat,should there be a special stat for that ?.

[Mingus]

I think he means reverse rotation because of the serpentine system. The water should still flow through the engine the same direction.

[AM.MSCL]

Correct reverse rotation. I talked with the local performance shop and got a stewart/shaw high flow tstat w 3 holes built in. Car ran at 160 till I turn the a/c on then gets to about 190! A lot better

[MonzaRacer]

Why does everyone give up power by over cooling the engines? Everyone tries to run ice cubes rather than buy the products that make engines more efficient.
If you think your having cooling issues at 210-215, heck as long as the system will cool down when fans kick on then let the engine run a little warmer.
As for me I will get good water pumps, proper radiators and get some NPG+ from www.evanscooling.com. 375*F boiling point with no pressure. Add in only 2 or 4 lb cap and its over 400*F. It actually will add horsepower and economy.
Its amazing after having found, on the dyno, 24hp and 38lb. ft. of torque by a simply upping the running temp of the thermostat.
We went from a fresh engine and 160* and went right up with 180*F power up, 195*F power up and 205*F with decent change.
It was simply a 355 race engine, we brought our own rad and fan hooked to engine, NPG+ and the cooling fan only ran like 5 times. Only the air movement through the dyno cell just completely blew me away. Trying to get a video link up but converting the video is time consuming.
I figured some increase but this was very substantial and it could take much more timing, ran smoother, and just was so much easier to tune in honest real world time.
So think about HOW you put the cooling system together, what parts you use and how they work together.

[1969CamaroRS]

All a 160* thermostat is going to do is put extra wear on your engine, since it will take so much longer for your engine to come up to temp.

[garner67]

... and get some NPG+ from www.evanscooling.com. 375*F boiling point with no pressure. Add in only 2 or 4 lb cap and its over 400*F.

I thought about adding the Evan's Coolant, but I decided against it after hearing some negative stories from a road racer. It's not the coolant's performance that's the issue, because he said it works great for cooling. However, the problem he found was when the coolant leaked into the oil system (like from a blown head gasket). On 2 separate occasions he completely trashed the engine when the Evan's mixed with the engine oil. He said that he believes if he had blown a head gasket when running a simple water/water-wetter mixture, the engine would have been fine.

Of course take this as just hearsay, because I'm NOT an engine builder, nor do I have any first hand experience with Evans coolant or the "possible issue" stated above. I just found the story interesting enough to not use Evans, not to mention the issue of never being able to add water to the Evans (i.e. if you were to have any problems on a road trip).

Anyone else out there have real world experience with Evans coolant?

[MonzaRacer]

I thought about adding the Evan's Coolant, but I decided against it after hearing some negative stories from a road racer. It's not the coolant's performance that's the issue, because he said it works great for cooling. However, the problem he found was when the coolant leaked into the oil system (like from a blown head gasket). On 2 separate occasions he completely trashed the engine when the Evan's mixed with the engine oil. He said that he believes if he had blown a head gasket when running a simple water/water-wetter mixture, the engine would have been fine.

Of course take this as just hearsay, because I'm NOT an engine builder, nor do I have any first hand experience with Evans coolant or the "possible issue" stated above. I just found the story interesting enough to not use Evans, not to mention the issue of never being able to add water to the Evans (i.e. if you were to have any problems on a road trip).

Anyone else out there have real world experience with Evans coolant?

OK as for a head gasket leaking, ANY type of coolant will do damage if ran long enough.
EVEN WATER WITH WATER WETTER.
I find the fact that just because of ONE person destroying(supposedly) engines because of the coolant, you wont use a product that has millions of miles of use with no major issues thrown about.
How about he find out why his head gaskets blow and a system that NEEDS NO PRESSURE ingesting coolant?
I actually find that the Evan coolant has little need for a high pressure cap yet many of the converts wont quit using regualr pressure caps.
Heck I had a circle tracker running water/water wetter on a 400, 060 over and it ran hot no matter what, heck it had a custom built 6 row rad core to no avail. I put in a simple 2 row aluminum S10 rad, and flushed it after inspecting for cracks for the third time.
We installed NPG+ and he had 3 holes that were put in by rocks, but with a 2 lb cap he barely lost any coolant.
You dont need pressure to make it work.
Here we go:

Water: 212*F boiling point 1 psi raises this approx 3 degrees,,,,standard 15lb cap adds 45 degrees to this so 212+45= boiling point 257*F
Water plus EG (ethylene glycol): same as water basically 257*F boiling point
Water plus Water Wetter: boiling point 212*F 15lb cap = boiling point 257*F
NPG+: 375*F boiling point, not pressure cap required, but actually found 4lb was as low as could find so 4x3=12*+375= 387*F

Now all of the above will have corrosion issues EXCEPT the NPG+
All of the above will destroy an engine even water plus Water Wetter
Now lets see benefits, 375*F + boiling point, environmentally safe, no nucleate boiling, no need for a pressure cap, will mix down road if you need to add water but it basically ruins its properties.
Oh and its freeze point, -40*F but it never freezes completely it simply becomes slush and with engine running it will turn right back into liquid.
So becasue ONE racer has had 2 COMPETITION ENGINES damaged because they BLEW UP, NOT because of the coolant.
Come on if 50 people used it you wouldnt think twice.
Yeah its expensive,but how much does an engine run?
Oh and I would never trust my street car to water wetter and water. And I build engines for fun and profit.

[funcars]

I know folks that have run Evans to solve corrosion and electrolysis issues, but I don't know of anyone personally that run Evans so they can run higher temps. I understand that there is higher thermodynamic efficiency the higher the temp of the motor compared to the environment, but there are other limiting factors too. I don't really know what the operating temperature limits are with current design V8's but I know there has been a lot of research into alternate materials that can withstand higher temps and get greater efficiency.

I was curious what your experiences have been since it sounds like you have used Evans to run hotter operating temps.

A couple of questions: How much hotter do you let your motors get? Do you do set valve clearances differently for the higher temps? Is Evans extremely slippery like regular coolant - if it leaks on a tire is it easy to spin? Have you ever had conerns regarding warping heads, getting on the ragged edge of detonation from extra heat or losing head gasket seal or do you do something different during assembly if you intend on using Evans and running higher temps?

Thanks

[Tony_SS]

All a 160* thermostat is going to do is put extra wear on your engine, since it will take so much longer for your engine to come up to temp.

Agreed... I would run a standard 180* with 2 small bleed holes drilled.

[1969CamaroRS]

Robert Shaw also makes a nice high flowing T-Stat with the holes already drilled for you. Stewart Components carries em:
http://www.stewartcomponents.net/Mer...ory_Code=Therm

[aronhk_md]

I agree that people go overboard lowering operating temps. Aluminum heads actually are at a disadvantage in efficient combustion compared to stock cast iron at times due to their tendency to lower chamber temps. My understanding is you really need to be close to 200 degrees water temp to get into the better efficiency range on any V-8 from detroit. How high you go is also influenced by other factors like ignition timing, combustion chamber shape, air/fuel ratio, etc.

Having a cooling system sized properly will KEEP you at or near your T-stat opening temp if you use a good fan/shroud with it.

I plan to run a 195 T-stat once I switch to aluminum heads. You can actually run hotter. I'm guessing with the aluminum 4 core radiator, large intercooler, and A/C condenser I may end up running around 205. I'll be adding the Mk VIII 2 spd fan I just bought to help keep things under control. One other thing to consider when running hotter is engine oil and trans fluid temps. I have an extra cooler for each.....my turbo makes extra heat the oil has to absorb even with 10 quarts in my system.

The ability of a coolant to not boil off once above 250 degrees is to me a moot point. If my engine is that hot chances are something else is getting damaged. Also, I've never really had any corrosion issues with a good mix of antifreeze.....though maybe it has happened to others. Makes me wonder why I havent, but others have?

[The WidowMaker]

The ability of a coolant to not boil off once above 250 degrees is to me a moot point.

i agree with you, but your temp gauge shows the temp where the sender is at. the water that is up against the cylinder wall will be above 250, even if your temp is reading 250.

[aronhk_md]

I agree, but most modern engines run in the 220 water temp range. Agreed that they have more advanced combustion chamber designs. Still, all the older engines ran beautifully when they came from the factory with 195 degree thermostats. We have obviously upped the ante on performance of these engines, but in most cases we have added huge cooling systems as well to handle it. I think most well set up cars have no problems with water/antifreeze combos. My case for example: stock iron heads, large stock type 4 core radiator, twin fans.....1000+ hp with turbo. No problems.

I am putting in a 4 core monster aluminum radiator with a MKVIII fan, but mostly because I am adding A/C, not because of past problems.

[Skip Fix]

If you flip that HP Shaw thermostat over you will see only three small ovals on the bottom for the water to flow through. Looks like a smaller surface area than the area around the standard thermostat to me.



I'll take a 180 AC Delco for mine.

[aronhk_md]

Is anyone else wondering, what the hell...................?

[JRouche]

I have a cooling problem. And after reading this post Im thinking I have a bad stat. I was kinda over looking the entire picture.

There are over heating problems, and there are over cooling problems. I have an over cooling problem. My engine will come up to 185 at idle. And on a warm day stay around 185 if I dont push too much air through the radiator. But up to speed the temps slowly lower to around 160. NOT GOOD!! I have efi and aluminum heads. Id rather see 195-210 temps.

So I never thought to look at the stat as the problem. Because if its stuck open it wouldnt be a consistent 185 at idle. It would jump around as the fan kicked in to cool the fluid. I think I would see the temps move around as the fan cycled on and off, and it does cycle when stopped and idling.

But once there is a decent amount of air going through the radiator I get some major cool down. And I thought it was because the massive radiator was cooling it down too much.

But after reading these posts I started thinking. The stat should hold the coolant in the block until it got to say 185 or so. No matter how cold the radiator got due to the increased air flow. The stat should hold the coolant in the block, stay closed, and I should see the higher temps of the coolant with either of my two sensors. So if Im seeing a drop it means the stat is not closing right? Not good..

So now Im thinking the engine stayed around 185 at idle due to the fan thermostat kicking in when the temps got high enough. So the temp regulator was the fan stat and not the engine stat at idle.

Now when Im driving and getting even more cooling effect with the air passing through the radiator, the fan prolly isnt even turning on, but the radiator is getting cooled down enough and if the engine stat is stuck open its not giving the coolant time to heat soak in the block, its not cooling the block?

Worst case is the coolant is at 160 but not drawing enough heat from the block. So the coolant is reading 160 but the block is MUCH higher because the coolant isnt staying put in the block long enough to get a proper reading. Now that would really SUCK. Block is actually over heating but the coolant isnt carrying the temps like it should.

Ive read some thoughts on this. Usually with over heating engines. The thought was if the stat was open all the time, or if you didnt even have one in place the engine would over heat because the coolant didnt have enough time in the block to soak up the engine heat. Like it needs to have some "stopped or dwell time" time in the block to soak some heat off then flow through (when the stat opens) to allow cooler coolant to enter the passages. And that theory makes sense. But there was always a high coolant temp for those stories. That was the indication of a hot engine.

Never thought about it with an over cold engine though, but it might work the same way if the radiator was very large and all the other parts of the cooling system were working in overdrive. Just a thought.

But yes, I get the typical stat opening. Start the car cold, radiator cap off, idle it till I see the stat open, major turbulence in the radiator coolant when it opens. It does close and open.

I dont get it. I may end up popping the stat housing and putting in a warmer stat AFTER I pull some fuel out with the efi controller. Gonna try to lean her out first.

But more importantly, I learned something from this thread and all the posts. Thanks Ray for starting a great thread, hope you got as much as I did. JR