Racing Thermostats:

[McRat]

During our LSR buildup we checked various things out that might keep the engine cooler at sustained high output.

What I found (with the help of Jason - LBZRcks) is our factory thermostats open very slow, and are quite a bit restrictive.
The bypass blocker opens in 20 seconds, and the second one opens in 43 seconds. Neither have very large openings.

So I bought a dozen different models of thermostats, and we tested their performance. We found a set of thermostats that open nearly 3 times faster, and flow about 1/3 more water when they open. They also open 25 deg sooner. Your water temp gauge will read ~175 instead of ~210 (gauge on trucks isn't too good).

Starting line water temp at Bonneville was 158 deg, and at the end of the track, the water never exceeded 180 deg. Dyno testing showed a maximum of 175 deg. A few beta testers have been running these with no issues so far.

If anyone is interested in running these, I'm selling them for $69 a set to help defray the cost of testing. Email [email protected] or call us at 951 270 0808 to order. Leave detailed message when calling if the machine kicks on.

These are intended for racing, especially sled pulling or LSR, to avoid hot spots from forming while awaiting the thermostats to open. Whether they would help an overheater or not, I have no idea, so no fights about overheating please.

 

[KEVINL]

What would be the disadavtage of these my truck doesn't overheat but I am tired of hearing my fan. It is worth a shot if there are no ill effects

 

[McRat]

They aren't too hard to change, and are fairly cheap, so it wouldn't be too bad if they didn't help the fan issue. Other than summer months, my trucks normally run about 175-180 anyhow when driving unladen.

Both thermostats are in a single housing at the front top of the engine. Both are different. One is a "bypass shutoff" and the other is a normal thermostat. You will reuse your existing rubber ring from your OEM thermostat, otherwise they are drop-in replacements.

 

[dmaxfireman]

would we need to modify our ect multiplier tables for these t-stats to still achieve full power?

 

[McRat]

Good question. I don't think so, since our trucks seem to have full power at 160, but that's something I'd have to look into. I do know Casper made 900+ hp running them on the dyno.

 

[TrentNell]

would we need to modify our ect multiplier tables for these t-stats to still achieve full power?

I have been running them for about a week and i havent seen the need for modding any tables , it wouldnt hurt though just to be safe so if your racing the fuel would be there either way .

so far i have really liked them , they rank pretty high on my list because for what you pay there are alot of benifits , 1 big one is lower underhood temps just while crusing around in the summer time , plus like Pat said it should help keep the oil cooler , which in turn is good for everything , pistons, turbo's and anything else oil cooled . I am towing my 5th wheel this weekend i will let you guys know how they do towing .

 

[MMLMM]

After my cooling issues I have been doing a lot of reading online, and have played with a few thermostats as well. Anyway, This pdf talks about how the dual thermostats work. I dont see it showing any secrets Pat learned in his testing so I though I would share here.

http://www.votechusa.com/DuramaxThermostatOperation.pdf

 

[dmaxlover]

Years ago on my big block I was always having cooling issues. One thing I tried was to completely block the bypass hose so that all the coolant had to go through the radiator. I can't remember the exact improvement, but it was significant.
Is this something that could be done with the Dmax?

 

[McRat]

Years ago on my big block I was always having cooling issues. One thing I tried was to completely block the bypass hose so that all the coolant had to go through the radiator. I can't remember the exact improvement, but it was significant.
Is this something that could be done with the Dmax?

On the Dmax, the bypass tube is blocked when the second thermostat opens fully.

 

[FMOS]

One thing to watch out for on a daily driver or a unit that is going to be run for a longer period of time is overheating. With a lower temp thermostat, it will open earlier, and over a given period of time the coolant will circulate more.

Not sure about the duramax, but I know in lots of other vehicle that will cause them to over heat if the cooling capacity is on the low side. Actually having the coolant sit in the radiator while the thermostat is closed will get it cooler, and when it opens will cool the motor more. Having the lower temp and it being open more often may just circulate warmer coolant, more often, until is slowly starts heating up and can't be cooled fast enough.

I'm just commenting on daily driver use.

 

[TrentNell]

One thing to watch out for on a daily driver or a unit that is going to be run for a longer period of time is overheating. With a lower temp thermostat, it will open earlier, and over a given period of time the coolant will circulate more.

Not sure about the duramax, but I know in lots of other vehicle that will cause them to over heat if the cooling capacity is on the low side. Actually having the coolant sit in the radiator while the thermostat is closed will get it cooler, and when it opens will cool the motor more. Having the lower temp and it being open more often may just circulate warmer coolant, more often, until is slowly starts heating up and can't be cooled fast enough.

I'm just commenting on daily driver use.

This isnt rocket sience guys , they only drop temp by 15 deg and i have put 100 + miles on my truck so far D/D with these stats in and there is no ill effect so far , and if it was to do it this weekend will show it , i tow 14k , it will be 95 deg and we will be hitting plenty of 8% grades @ 10k elevation and i tow with a heavy foot and big power .

 

[Turbotug]

It's not rocket science, but it has been taught that although a cooler t-stat may give the impression of a cooler engine by lower coolant temps, it may not actually be getting the engine any cooler. The theory is that the coolant passes through the engine at a rate too quick to transfer as much heat, therefore a cooler gauge reading initially. Also, in sustained high load situations, it may not be in the radiator long enough to unload it to the atmosphere. Causing an overheat situation.

Just sayin'... regurgitated from Auto tech school teachings...

 

[SteveFord]

Let us know Trent how it works pulling your 5th wheel in the heat. I do alot of pulling during the day and my truck seems to never go below what I would guess is the 200 degree hash mark?

 

[SteveFord]

It's not rocket science, but it has been taught that although a cooler t-stat may give the impression of a cooler engine by lower coolant temps, it may not actually be getting the engine any cooler. The theory is that the coolant passes through the engine at a rate too quick to transfer as much heat, therefore a cooler gauge reading initially. Also, in sustained high load situations, it may not be in the radiator long enough to unload it to the atmosphere. Causing an overheat situation.

Just sayin'... regurgitated from Auto tech school teachings...

I think you'd know by your oil pressure guage or oil temp if you have a guage if it's working or not.

 

[JoshH]

So you tried a bunch of different brands of thermostats with the same opening temp, and these that you are selling opened faster than any other thermostat out there?

 

[Turbotug]

Most OE gauges are dumbed down enough that a minute change would probably go unnoticed.

If someone were monitoring thier oil temps before and after t-stat change, IMO, that would give an honest assessment of temp change.

I know a guy that has 60k+ miles of watching an oil temp gauge who would be willing to do some testing if some t-stats were donated..


Also, IMO, the greatest benefit from these would be the speed they open. If you're putting large amounts of heat into the system, and the t-stats lazily open you are start the fight from a chasing position.

 

[TrentNell]

It's not rocket science, but it has been taught that although a cooler t-stat may give the impression of a cooler engine by lower coolant temps, it may not actually be getting the engine any cooler. The theory is that the coolant passes through the engine at a rate too quick to transfer as much heat, therefore a cooler gauge reading initially. Also, in sustained high load situations, it may not be in the radiator long enough to unload it to the atmosphere. Causing an overheat situation.

Just sayin'... regurgitated from Auto tech school teachings...

I agree and am aware of the theroy , I just hate when people start picking apart something before its tested , if it fails this weekends test then i will be the first to say not to use them , it it passes this test i cant imagine it causing a issue under any other circumstances then holding max power with a load for long periods of time , not to mention these were intended for race aplication , i am just hoping i can still tow with them as well

 

[Turbotug]

Be sure to bring cool drinks for the Ol' lady just in case you have to take an unplanned rest stop along side the road....

 

[TrentNell]

Be sure to bring cool drinks for the Ol' lady just in case you have to take an unplanned rest stop along side the road....

after what i have seen so far they wont be needed

 

[JoshH]

I agree and am aware of the theroy , I just hate when people start picking apart something before its tested , if it fails this weekends test then i will be the first to say not to use them , it it passes this test i cant imagine it causing a issue under any other circumstances then holding max power with a load for long periods of time , not to mention these were intended for race aplication , i am just hoping i can still tow with them as well

I thought the testing was done?