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Discussion Starter · #1 ·
Well, I bit the bullet and installed the 180 thermo. I am hoping this doesn't lead to any difficulties in the long run. My reasoning was the canned fan settings in the tune are set for the lower temps so it was either reset the settings or change the thermo. I figure the lower temp might not be too much of an issue but I don't have a warm fuzzy changing what the engineers originally intended. Does anyone have a definite answer on why the 6.1 needs the higher temp thermo? Emissions? Clearances? Talk to me....
 

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Well...

I'm a 5.7 guy, but my info should apply equally to your motor.

The OEM 203o F Tstats are to help really cook off the fuel for clean emissions. Secondly, suitable engine heat is required for the pistons and related parts to achieve the correct expansion and fit.

The PCM cuts fuel slightly when your motor exceeds the 190o F range, this is due to the air hitting the hot combustion chamber and expanding, which equals less air inside, so less fuel is applied. The exact temp at which the fuel is trimmed and whether or not it is linear I cannot get a straight answer on - and I've looked!

Dropping to 180o Tstat and lowering your fan temps in the Predator will certainly help - I noticed a big difference. I spoke to Diablosport John on the phone and he said the canned tunes Do lower the fan temps, but you can Drop Them An Additional 5 Degrees safely to insure you do not exceed the 190o F threshold.

It is worth noting some users on LX Forums have done some great research on Tstats and some are running the 176o F as the "best choice" for fast times.

On the other hand, many say going lower than 180o F is flirting with a cold code being set, and the motor will not expand properly when on the too cold side.

Hope this was useful. :)
 

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Discussion Starter · #3 ·
That makes me feel much better. I don't mind the 190 threshold. I am not out to get the best time. I was just unhappy with the fans being on high all the time.
 

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Well, I bit the bullet and installed the 180 thermo. I am hoping this doesn't lead to any difficulties in the long run. My reasoning was the canned fan settings in the tune are set for the lower temps so it was either reset the settings or change the thermo. I figure the lower temp might not be too much of an issue but I don't have a warm fuzzy changing what the engineers originally intended. Does anyone have a definite answer on why the 6.1 needs the higher temp thermo? Emissions? Clearances? Talk to me....

I also had the bullet break my teeth today because of the constant fans and just installed the 180 #4128 therm just now!
I am very nervous about this mod and long term probs:(
 

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Discussion Starter · #5 ·
I am not as nervous now considering that other engines are just fine at that temperature. There are no exotic materials used in the 6.1 so I am OK with it. I was just thinking that if it was for reasons other than emissions then I would be nervous.
 

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I asked about this in the SRT chat session and the reason was Emissions.
 

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I had the same exact feelings as you kawasabi with the exact same result :)
4128 it is. I am waiting for a custom tune for my Diablo because of my PPP heads though.
 

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Maybe it's just me, but I swear since I have dropped to the 183 degree thermostat, I can smell my fuel burn more. I run 91-92 octane and sometimes I will get a wiff of it even in my car. It smells like racing fuel. I swear!
 

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We dyno tuned a Chrysler 300C SRT8 (Diablo CMR) ast night who had a thermostat and the car was running great around 163 degrees on every dyno pull...
 

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We dyno tuned a Chrysler 300C SRT8 (Diablo CMR) ast night who had a thermostat and the car was running great around 163 degrees on every dyno pull...
You think a car making constant back to back WOT dyno pulls at 163 degrees means it's "running great?" I see it as the opposite... At those temps, I'd be really concerned with improper lubrication due to the fluids not being nearly hot enough.
 

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You think a car making constant back to back WOT dyno pulls at 163 degrees means it's "running great?" I see it as the opposite... At those temps, I'd be really concerned with improper lubrication due to the fluids not being nearly hot enough.

Improper lubication would be your Oil Temps sir... We are talking Engine Coolant Temps :) The car was warmed up and the oil temps were fine...

Also no pulls are done on a car constantly back to back on a tuning session
 
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