Resurrection.....

So today I did some testing using a recently installed Mocal high-temp (202*F) thermostat. This type of thermostat, as David mentions above, is a bypass type. It never totally closes off either passage. Instead, the increased resistance to flow created by the cooler, and the longer flow runs, makes the oil bypass through the thermostat. As the oil temperature gets near the thermostatic temperature, the bypass starts to close and force more oil to the cooler. Even with the thermostat fully deployed there is still some internal bypass.

Two tests were performed. First, the car was run for about 1/2-hour in various street and highway conditions with the cooler plugged and oil temperatures noted. This allowed no oil to get to the cooler, hence, zero external cooling. The next test was to re-connect the oil cooler and do the same driving loop. Ambient temperatures were within 2* for both tests.

The total increase in the hose length of cooler connected vs. dis-connected is approximately 24". -10 lines are used. The cooler is located after the first pass of the dual-pass radiator. On most days the car can easily run with a block-off plate covering the entire first pass and still run cool without the fan coming on excessively, i.e., the car has excessive cooling capacity. The temperature sensor is placed at the bottom of the the oil pan sump. New Torco 5W-30 oil is used.

Results? No significant difference in overall oil temperatures. But here's the kicker. The oil temperatures never went over 155* in either test even when some "spirited" canyon driving was done. The ambient temperature is only 55*F so it is pretty cold. The coolant thermostat in the car is 160*F.

Warmer/summer ambient temperatures will hopefully bring up the temperatures.

So, the Mocal bypass thermostat is doing what it is supposed to do. It would be very nice if an aftermarket LS-series pan was available that utilized the stock LS small-body filter mount and location, an internal thermostat bypass, and the current ATS trap-door design. I'd gladly have paid additional money to clean up the installation and reduce the number of external hoses.

interesting... I've previously heard that oil temps usually can run similar to engine temps, and this seems to back that up in this application. This also concearns me a little. Would it not be better to run a hotter engine coolant thermostat ? (i did not read the enitre thread, so I do not know your complete set up)

I agree with that. I'd run a 195 in that LS motor in the winter time.

Going to a higher coolant thermostat is a mixed bag for me. Pros: Higher oil temperatures and some increase in engine longevity. Cons: Higher engine temperatures mean higher induction temperatures for forced induction. It also means having to change the fan on/off temperatures if a coolant thermostat swap was done at the beginning/end of summer.

If I pop for HPTuners so that I can easily change the fan on/off temps then I'll switch to a higher temperature coolant thermostat and retest. For now, with a fan preset of 170on/165off the switch to a 180+ thermostat means the fans will not shut off once they turn on. It would also allow real-time logging of intake vs. engine temperatures on cooler winter days to see if there is a significant difference.

There is always a compromise huh Carl. I've found my car runs way to cool in the winter as well. Mine went down to 125-130 on the way to the Optima challenge and it wasn't that chilly. I'm ditching the high flo t stat for a stock GM 180. I've read teh high flo stats don't like to close after they open until they cool off. My fans don't come on until 185 which would be reasonable for you. You're running alot thinner oil than I am so it probably not as big a deal. I just don't like not burning off the condensation in the oil.

A new 2010 ZO6 would cure a lot of the compromises Todd!

In general, the oil temperatures for this engine are far lower than the previous GEN1 SBC's the car has had. At the last track day the oil never exceeded 185* with an ambient around 85*F. With the previous 406 SBC it would have been 220+. The current supercharged LS makes more power, turns at higher engine speeds, and has less oil capacity, yet runs significantly cooler.

I see no need for whoop-de-do thermostats for these engines unless the build is pretty wild. These engines already have the good stuff built in.

I need to pony up for HPTuners so that I can change fan temps. I'm just a cheap SOB for some things.

Ha ha....that would be to cheap and easy. :rolleyes:

Are you pulling cold air into the intake system ? If so, (this is all theory) then will an increase in the engine temps make the same difference in intake charge temp at the intake port, after the supercharger ? if so, by how much ? You may be able to negate the some of that gain, if there is any, by insulating the intake duct work before the SC ?

Carl,

HPTuners can change fan temps, but on the newer Gen 4 ECU's it will take upgrading to the 2bar system, this allows you to put a lower temp value in the table.

If you are using a GMPP Gen 4 ECU then your Sh*t out of luck.

A cold-air intake system is definately as much, if not more, of an important function. It is not uncommon during the summer months for under-hood air intake temperatures to reach 140*F+. This is a killer for forced induction systems. The 160* coolant thermostat is worth 15-20 ft-lb across the board vs. 195* as a stand-alone modification for my build.

Heat soak of the entire intake system affects intake charge temperatures. So, the lower the intake track temperature, the lower the intake charge temperature. The OE plastic and dry intake manifold helps keep intake charge temperatures low. Mine in all aluminum, so there is more heat soak.

I'm still old-school GENIII so ECM programming is easy. Given the performance of this ancient (in the electronics world) system, and the later model GENIV, it's really hard for me to justify using an aftermarket (GMPP) system with minimal/difficult systems changes available. The aftemarket support for the stock PCM's is fantastic.

The guys at Canton made a good point when I spoke with them today. Thier oil t-stat is set at 215-degrees. Why? So that any water (ie moisture) in the oil will burn off.

They said that this is especially true of cars that sit alot (like our cars) and they aren't fond of the lower temp t-stats.

The hard part is getting the oil to 215*. Unless the coolant thermostat is 195+ and the engine is run hard, it may not get there very often. If the thermostat is a bypass design (MOCAL, CV, etc.) then some oil will always go through the cooler.

Funny.. mine gets there all the time the way I drive.. lol

Around town my oil temp is fine.. it's only when really flogging that it goes up and I need a cooler.

heck, at Optima I think it hit 260-270 with Dave.. the year before (no cooler) it almost hit 300.

To be honest, if you're running synthetic, 215 is a good temp..

How many quarts are you running in Penny?

That pan is around 6... plus the lines, remote filter and cooler.. so maybe a bit less than 8