Supercharger Thermostat (1 Viewer)

[inkpot]

Howdy! So, after searching MUD for a while, I can't find any current discussions of this. There are old threads that refer to running a cooler than stock thermostat, but no part numbers or suppliers. The only hard number I could find was a reference to Bob Garner at TRD recommending a 160 degree unit. Any new info out there? What are you guys using? John

 

[cruiserdan]

The 160 was originally intended for the V8, it just happened to fit the 1FZ.

All it does is start the over-heating process from a lower threshold. If the motor has a tendency to run hot with the normal thermostat it will still get hot with the 160. There is no more peak flow available when it's wide open.

In addition the engine runs better when it's around 195-205 and is more efficent and there is less cylinder wall wear. I ran a 160 for a time several years ago and I took it out and tossed it into the bushes off to the side of the car port after I figured out the engine would still get hot under boost and a heavy load. The rest of my cooling system, specifically the radiator, was not in peak health.

 

[Corbet]

my SBC in my 40 actually ran hotter with a 180 degree thermostat than it did with a 195. The way my mechanic explained it was that the water spent less time in the radiator and could not cool off as much. Not sure if there was any merit to that theory but the engine temp was lower with the 195.

 

[LINUS]

my SBC in my 40 actually ran hotter with a 180 degree thermostat than it did with a 195. The way my mechanic explained it was that the water spent less time in the radiator and could not cool off as much. Not sure if there was any merit to that theory but the engine temp was lower with the 195.

Using what they teach us in the refinery, that seems off. Residencey time in the radiator would be controlled only by how well your water pump pushes coolant, or a change in path like using your heater core as a accessory radiator.

The only way this would work as your mechanic said is if the hole that opens when warm on the 180* was a larger port than your 195* one, and that's assuming that one hole was the only chokepoint in the entire system.

Refineries are just big, goofy piped version of motors, and the same science would make sense like how we use our fin-fan coolers & cooling towers to act just like a car radiator. That's why when refineries are under attack in the Middle East, they just take out the cooling towers - no radiator, no running refinery & you didn't set fire to anything that had hydrocarbons in it.

 

[Corbet]

ya, I don't know about his explanation but my 40 did run cooler with the 195 for what ever reason.

 

[inkpot]

The 160 was originally intended for the V8, it just happened to fit the 1FZ.

All it does is start the over-heating process from a lower threshold. If the motor has a tendency to run hot with the normal thermostat it will still get hot with the 160. There is no more peak flow available when it's wide open.

In addition the engine runs better when it's around 195-205 and is more efficent and there is less cylinder wall wear. I ran a 160 for a time several years ago and I took it out and tossed it into the bushes off to the side of the car port after I figured out the engine would still get hot under boost and a heavy load. The rest of my cooling system, specifically the radiator, was not in peak health.

This helps a lot. In the multitude of old S/C threads, there are several references to colder t-stats, but I never could find much detailed info. Last year, when I picked up my 80, I replaced the stock stuff with a 3fe fan and a OEM blue clutch running 24000CST fluid. Way better than stock, but maybe not perfect. Worst mountain pass in the summer was around 210 w A/C running, but I could not keep A/C on while crawling in the desert at 110 degrees. I reloaded my original Eaton clutch with 17000 CST, but never got it installed untill winter. It worked OK, but now when it was getting close to 90 degrees out, the coolant temps spike up around 205 for no obvious reason, and then go back to around 195, even while running down the freeway. Made me think of the old t-stat treads about colder one, and made me wonder if mine was sticking. Two weeks ago, I re-installed the blue clutch, and now the Scan Gauge reads a steady 184 going down the freeway with the A/C on, even when it was 100 degrees on April Fool's Day. Made me go back and think "Did they have a 185 t-stat for these things?" I'm not complaining, just trying to understand it better. Oh, and hoping, or course, that it runs that cool all summer long!! I should be so lucky. John

 

[skibob]

So what I'm hearing is that your s/c equipped l/c is running a bit hot.
Hang an oil cooler, (a big one), put on a big ass electric fan, make sure your radiator is clean.
The point about having a 160 t-stat is valid. Your rig is designed to run at the higher temp and it will run better that way. You want to get rid of heat. Lots of heat.
One cool thing that ford did (in and experimental way) was to add a refrigerated intercooler after the s/c.
The effect was massively increased volumetric efficiency with much lower exhaust gas temp and lower overall engine temperatures.
The only downside to this approach was that you couldn't stay at wide open throttle for more than a minute at a time without running out of cold. (When was the last time you needed a full minute of boost?)

 

[cruiserdan]

This helps a lot. In the multitude of old S/C threads, there are several references to colder t-stats, but I never could find much detailed info. Last year, when I picked up my 80, I replaced the stock stuff with a 3fe fan and a OEM blue clutch running 24000CST fluid. Way better than stock, but maybe not perfect. Worst mountain pass in the summer was around 210 w A/C running, but I could not keep A/C on while crawling in the desert at 110 degrees. I reloaded my original Eaton clutch with 17000 CST, but never got it installed untill winter. It worked OK, but now when it was getting close to 90 degrees out, the coolant temps spike up around 205 for no obvious reason, and then go back to around 195, even while running down the freeway. Made me think of the old t-stat treads about colder one, and made me wonder if mine was sticking. Two weeks ago, I re-installed the blue clutch, and now the Scan Gauge reads a steady 184 going down the freeway with the A/C on, even when it was 100 degrees on April Fool's Day. Made me go back and think "Did they have a 185 t-stat for these things?" I'm not complaining, just trying to understand it better. Oh, and hoping, or course, that it runs that cool all summer long!! I should be so lucky. John

Here is the intended operating temperature range, based on published specs although my conclusion is not spelled out in any factory literature I have been able to find.

The OEM thermostat begins to open at ~180 degrees and is fully open at ~190 degrees. I read this to mean they want the motor to be at least ~190.

The A/C thermal cutout takes the compressor off-line when the temp hits ~226 degrees and allows the compressor to come back on-line when the coolant comes down to ~217 degrees.
I read this to mean that they consider anything over 226 to be a threat and anything under 217 to be kosher as far as the upper limit goes.


So, I believe that the intended operating range is ~195 to ~217 degrees.




Interestingly enough the electric cooling fan trigger points on my SRT8 Challenger are almost identical to this plot.


Below is the text from my 2009 Challenger repair manual:

Theory of Operation
The Powertrain Control Module (PCM) sends a signal to the Totally Integrated Power Module (TIPM) to turn the cooling fan on or off depending upon the engine coolant temperature. The low speed cooling fan is commanded on when the temperature is at or above 103° C (217° F) and turned off at or below 101° C (214° F). The high speed cooling fan is commanded on when the temperature is at or above 108° C (226° F) and turned off at or below 105° C (221° F).




Based on the above Chrysler wants the 6.1 HEMI to run between ~214 and ~221.

 

[OGBeno]

anything under 217 to be kosher

I am rubbing off on you!



By the way, Dan's been researching this arcane knowledge for a long while now.

 

[Tools R Us]

... The OEM thermostat begins to open at ~180 degrees and is fully open at ~190 degrees. I read this to mean they want the motor to be at least ~190. ...

Agree, fully open spec is ~200F. But remember it is a lower/bypass thermostat design, the thermostat mixes/regulates the coolant intake temp. The temp sensor is in the output neck, so the motor will run and sensor will read higher than thermostat.

... So, I believe that the intended operating range is ~195 to ~217 degrees. ...

Agree, my take/observation is 190-205F normal range, with occasional spikes up to 220F ish when loaded, isn't a problem as long as it isn't sustained long term.

 

[cruiserdan]

The temp sensor is in the output neck

It's actually in the head, on the intake side, close to the block mounting surface, at about #2 cylinder.

 

[DRTDuck]

Quote:
Originally Posted by cruiserdan
... So, I believe that the intended operating range is ~195 to ~217 degrees. ...

Agree, my take/observation is 190-205F normal range, with occasional spikes up to 220F ish when loaded, isn't a problem as long as it isn't sustained long term.



Well, I certainly value your optinions, and treat them as FSM experet knowledge. So even with my supercharger, if I hit the 200-210 on warm days in the mountains, I am okay. I was always under the impressiont this was too hot. Perhaps, I'll wait to cut my hood for vents if I am not running any hotter than that.

 

[cruiserdan]

In my view 210 is not an issue.

 

[Kernal]

Here's a photo of a 10 year old Toyota T-stat (right) next to a new Toyota T-stat (left with green paint) in a pot of hot water. Both Tstat's are marked 82C.

The new T-stat has a different part number and the top center post looks slightly different (green paint and rubber gasket) compared to the older part. The new Tstat opened and closed faster than the old one; not sure if that was due to the new design or due to age of the used part??

The old T-stat after a few more minutes in boiling water did appear to open as much as the new Tstat. The photo was taken when the temp had reached ~200F. FWIW.

 

[inkpot]

Fantastic! This is the kind of thread that I've been looking for, but never found. It looks like my biggest problem is not my cooling system as much as it's getting my head to start thinking outside of the box. The box is full of too many years of hot rod, young punk, shade tree experience. That and the "head gasket fear" that is inherent in the 80's. The P O claimed that PowderPig did the SC install including the new head gasket on mine, so I should just shut up and drive. Tools has been trying to convince me of this, but I guess it has just taken a little extra reinforcement to get my brain over the hump. Now I can spend more time thinking about intake and exhaust temps. Thanks, John

 

[Tapage]

which it's the factory fan clutch oil weight . ?

 

[cruiserdan]

That information is not published.

 

[inkpot]

That information is not published.

I was thinking that someone had found that Toyota offered 4000 and 7000 as replacement options. Still doesn't tell us what the OEM stuff was from the factory. John

 

[cruiserdan]

I was thinking that someone had found that Toyota offered 4000 and 7000 as replacement options. Still doesn't tell us what the OEM stuff was from the factory. John

Toyota currently lists 3,000, 6,000 and 10,000 CST. All of which are intended for use in very early vehicles (1960s and early 1970s) that had clutches with fill plugs.

 

[guzzla]

Massive grave dig, but I thought it better to post here in a relevant thread than start a new one.

For various reasons, I would like to try this TRD thermostat that operates at slightly lower temps. After a bit of searching on eBay using the part# Cdan supplied above, I found this:
http://www.ebay.com.au/itm/TOYOTA-T...=AU_Car_Parts_Accessories&hash=item2c5f786de2

I understand this type of thermostat fitted the Toyota V8s but I do not know if the one in the link above will fit. Going off the engine numbers listed in the link, can anyone confirm if this thermostat will in fact fit a 1FZFE, please?