Re: Why not just remove thermostat?
 

FYI, Marc Haibeck's chip typically turns on both fans at 205 degrees. I don't recall my car showing anything higher than about 208 on a hot day, maybe 210. -- Bob

Re: Why not just remove thermostat?
 

Is that reading HVAC or analog (dash) gauge?

Re: Why not just remove thermostat?
 

There is 2 CTS, 1 for the gauge located in the waterneck, and 1 for the PCM in the drivers side cylinder head.

OBD2 vehicle with clutch fan. The temp gauge is constantly moving in a steady state cruise, I', assuming the stat is opening and closing? The stock stat deos not show any cycling on the gauge.
Further evidence of a temp change is the lower heater output when the lower temp stat is installed.

Closed Loop Fueling enable has a stock setting of 56.25ºC or 133.25ºF. Much lower than the LT5's. In Tunercat's OBD2 I can adjust the Closed Loop Enable temp to whatever I wish.

There is a point where running an engine too cool increases cylinder wall and other wear.

Re: Why not just remove thermostat?
 

I would ASSume that EPA testing for the ZR-1 is a bit more involved when testing a vehicle platform for EPA certification for manufacturer such as GM.
My point is that just because an OEM cant get a car to pass emmisions testing with lower temps, doesnt necessarily mean that a car with lower operating temps wont be able to pass a garden variety emissions test at the individual owners/driver level.
However, if a car had top be "sniffer tested" and the car was struggling to enter Closed Loop because the engine was running too cool, I can certainly see that causing issues in passing.

Graham Behan would have extensive experience with OEM and aftermarket emmisions testing as Lingenfelter PE had a couple LT5 emmissions compliant packages, and they even had an emissions compliant 550hp SAE net, 705 lb/ft torque from 605 cubes BBC engine package for their Suburban packages.
http://i1202.photobucket.com/albums/...pe605hp780.jpg
http://i1202.photobucket.com/albums/...erhorn/605.jpg
http://i1202.photobucket.com/albums/...felterburb.jpg

If they can get a dirty BBC to comply with emmissions laws, and "tuned" LT5 shouldnt be too hard.



When we had the chassis dyno testing similar to California spec testing, I had 160º thermostat, longtube headers, aftermarket cats, EGR disconnected(but present to pass the visual) and the truck blew very clean.

Re: Why not just remove thermostat?
 

I don't know that this will add anything useful to this interesting conversation. But, reading along, what gets written and what folks meant to say are not always the same. So, if that is the reason I got the impression that there was some confusion regarding some basic physics principals, I don't mean to be "speaking to the choir". :blahblah: But, for some perhaps majoring in sociology instead of science :p they might find something below worth using...maybe?

Anyway... It's easy. What it "boils" down to is simple physics:

1. HEAT (temperature, to be specific) generated in the engine/coolant will rise until heat escaping is equal to heat generated. (Temperature will stabilize at that level sans changes in the engine load, etc, for example)
2. HEAT transfer efficiency increases-

-with the relative difference in temperature between the heated medium, and the medium receiving that heat
-the amount of radiating surface area between the heated medium (aluminum in this case) and (air - also in this case).

Everything - the whole discussion about cooler or hotter thermostats circles around these two physical facts (1&2). Putting a 160º thermostat in for summer won't make any difference to the equilibrium temperature if conditions dictate that point to be closer to 230º. No matter if you have a 160 or a 200º stat, if the conditions dictate 230º, THAT is where temp will stabilize, regardless of the stat design.

Heat transfer efficiency for any given ambient air temperature can be increased by-

• increasing the surface area between the radiator and the air, i.e., BIGGER radiator
• increasing the differential temp between the (radiator) and (specifically) the air e.g, removing the heat-saturated air from the heated radiator surface.
• proper coolant level and additive (e.g., antifreeze or whatever).

So, the facts are -

• heat transfer gets better as (coolant) temps increase.
• The lower the engineered equilibrium temp is to the ambient temp (of the air, in this case) the greater the need for increased radiant transfer area and exchange of heat soaked recipient medium (air) to maintain the highest differential temp difference between the source and the receiving medium).

The thermostat rating will prevent heat transfer until the designed temp is reached. At that point, the thermostat opens and physics takes over. There is either enough surface area in combination with the differential between the radiator and the (air) temp surrounding the core to result in the temperature stabilizing when the thermostat opens, or NOT. If, for example, ambient air temps are such that equilibrium will be 230º, then temps will rise w/o regard to the thermostat setting (beit a 160º* or a 200º or whatever), rising quickly at first, and stabilize at 230º (in this example) until and unless there are changes in engine load resulting in a change in the amount of heat being given off.

*The only difference in temperature rise on the way to say a 230º equilibrium between using a 160º stat and a 200º stat is the rate of temp rise in that window between 160º to 200º. That will be useful and desirable on a drag strip. But, on the street...not so much. A more practical temp, in terms of radiator size and cooling fan metrics, closed loop and fuel efficiencies, might be closer to 200º. AND, instead of bigger fans, having BOTH come on instead of the factory staggering arrangement is a better solution, I say from practical experience with that (Marc's calibration) arrangement.

Just sayin...

Paul.

Re: Why not just remove thermostat?
 

:thumbsup:

What Paul Said :D

Re: Why not just remove thermostat?
 

Good post Paul^^
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I just wanted to add a tidbit about possible thermostats and the modern EFI vehcile. On the LT1 cars and L31 trucks, in the 90's there were ECM recalibration devices sold for these vehicles. Acommpanying these devices were 160º thermostats in order to help the engines and their 10.5:1 c/r produce full power with leaner WOT a/f ratios and advanced WOT timing curves these devices instilled into the ECM calibration.
If a lower temp thermostat only helped slow down rate of engine coolant temp increases(which they do after a cold startup) the lower temp thermostats these kits included, really would NOT help to prevent detonation/knock sensor counts by keeping engine coolant temps lower.

JET Performance and Hypertech were to companies that provided products in which they woudl suggest or include lower temp thermostats as part of their Level 2 (more agressive) ECM/PCM calibrations.

Re: Why not just remove thermostat?
 

I think you're better off cleaning your radiator, in and out, to gain maximum cooling efficiency.

Re: Why not just remove thermostat?
 

And................installing a radiator Debris Screen :p

Radiator Debris Screens

Re: Why not just remove thermostat?
 

True, but there's lots of tiny dirt particles that over time clog the areas between the coils. For a vehicle, coming from the Southwest for example, that kind of dirt restricts airflow. Before swapping T-stats, I'd blow out the rad.
Look at what Chevy found by doing the "flo-tie" on the Z28. Increase airflow by 3%. just from that amount of increased area.