From the Stink Thread: Run Hot or Not - Wrist Twisters
 
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post #1 of 16 Old 06-07-2015, 11:40 PM Thread Starter
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From the Stink Thread: Run Hot or Not

I didn't want to derail the "stink" thread, so I thought I'd start a new thread.
Marylandmike's use of a hotter thermostat caught my attention.
He is running his bike around 15F hotter (about 10 C hotter for those of us using the correct unit of measurement )

I wondered what the effects of this might be power wise. There's a few forums I found debating this and seems it enevitably degenerates into a shit fight between keyboard warriors. I'm sure we can refrain from doing so.

Initailly my thoughts were that you are warming up not only the combustion chamber (which is a good thing), but enevitably the entire engine would warm up effecting intake ducts/manifolds, etc. which is a bad thing, IMO.

Theoretically, I reckon you would want to have minimal heat loss from your combustion chamber. The only reason combustion chambers are cooled, is because we don't have the materials to make engines that will sustain that amount of heat and pressure at the same time, without deforming.
BUT, you would want to have your intake air (thus all your mainfolds, etc.) as cold as possible.

So MM's running a hotter thermostat is a sound one (IMO), provided you don't heat up the rest of your engine compents too much and you don't effect the design parameters/tolorences of your engine in a harmfull manner.

I found an interesting test:

Do Cooler Engines Make More Power? - Fact Or Fiction - Import Tuner Magazine

Anyone agree with this? Any other view points?

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post #2 of 16 Old 06-08-2015, 12:07 AM
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For this specific engine, and the connection to the stink, I wonder whether the higher temp thermostat finally creates a coolant temp that trips a yes/no switch in the ECU that says the coolant is up to temp, the engine is running as it should, and no further fuel enrichment is reqd.

But I don't have the stink...

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post #3 of 16 Old 06-08-2015, 01:09 AM Thread Starter
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Good point.

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post #4 of 16 Old 06-08-2015, 04:07 AM
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Quote:
Originally Posted by K1w1Boy View Post
For this specific engine, and the connection to the stink, I wonder whether the higher temp thermostat finally creates a coolant temp that trips a yes/no switch in the ECU that says the coolant is up to temp, the engine is running as it should, and no further fuel enrichment is reqd.

But I don't have the stink...
That was the theory with running a bit hotter. My 919 would hardly ever get above the "C" mark on the coolant gage and I wondered if that was connected to the 919 running rich (mine had the stink pretty bad). This book said that there was a map in the ECU that would add fuel before the engine was at normal operating temp.

Seems to have worked for me. I don't smell it at all any more. As far as more or less power, I didn't notice anything, but it's been ~40K miles since I swapped it. I thought I might have seen an increase in gas mileage but that was negligible too.

Not too worried about engine damage as the temp runs at about 1/4 on the gage.

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post #5 of 16 Old 06-08-2015, 08:50 AM
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Any chance you'd have a link for the thermostat you used, Mike? Mine rarely ever gets above C except when sitting in traffic at high ambient temps, and I'd like to remedy that situation.

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post #6 of 16 Old 06-08-2015, 09:45 AM
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Quote:
Originally Posted by BockHawk View Post
Any chance you'd have a link for the thermostat you used, Mike? Mine rarely ever gets above C except when sitting in traffic at high ambient temps, and I'd like to remedy that situation.
I can find the link when I get home. It's a common automotive one. If you look in the "Last word on stink" thread I think there is a link. It takes a small amount of dremeling on the thermostat flange to make it fit, but pretty easy.

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post #7 of 16 Old 06-08-2015, 11:01 AM
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Found it! Thanks for the pointer.

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post #8 of 16 Old 06-08-2015, 11:27 AM
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Quote:
Originally Posted by BockHawk View Post
Any chance you'd have a link for the thermostat you used, Mike? Mine rarely ever gets above C except when sitting in traffic at high ambient temps, and I'd like to remedy that situation.
Just for this thread's sake of reference, the thermostat is a Stant Superstat 45849


Stock the left side and Stant to the right. Now a little photoshop magic/diagram of what needs to be cut for this to go in then we're talking.

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post #9 of 16 Old 06-08-2015, 06:16 PM Thread Starter
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Does anyone have any further theories on running engines hotter? I concur with MM running his bike hotter. Looking at all the evidence and remembering that my bike also barely got off the Cold mark, it all makes sense, imo anyway.

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post #10 of 16 Old 06-08-2015, 06:54 PM
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Quote:
Originally Posted by Farab View Post
Does anyone have any further theories on running engines hotter?
In looking into whether my 2008 Hemi Ram would benefit from a cooler thermostat, I found some articles (don't recall where) that pointed to hotter temps being better for multiple reasons, one being better able to evaporate moisture, fuel, and other contaminants from the engine oil.

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post #11 of 16 Old 06-08-2015, 07:10 PM
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Quote:
Originally Posted by Farab View Post
Does anyone have any further theories on running engines hotter? I concur with MM running his bike hotter. Looking at all the evidence and remembering that my bike also barely got off the Cold mark, it all makes sense, imo anyway.
What it doesn't explain is why some engines don't have stink. Surely their thermostat can't be too far off? Or do thermostat have a wide margin of error?

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post #12 of 16 Old 06-09-2015, 02:48 AM
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This could be an interesting observation.

My survey on the exhaust stink issue produced somewhat inconsistent results - there didn't seem any one thing that stuck out as the cause and/or fix.

See: https://www.wristtwisters.com/forums/...ide-59561.html

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post #13 of 16 Old 06-09-2015, 06:40 PM
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It should be noted that it's is a well known fact that hotter temps will increase wear and if too hot also induce knock due to the fuel combusting before the spark.

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post #14 of 16 Old 06-10-2015, 01:41 AM
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My 2011 Ram Hemi is set at 197f from the factory.

My 2013 Mustang is right at 200.

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post #15 of 16 Old 06-10-2015, 08:27 AM
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Quote:
Originally Posted by SilverS4sAreFaster View Post
It should be noted that it's is a well known fact that hotter temps will increase wear and if too hot also induce knock due to the fuel combusting before the spark.
Not as much with modern materials and lubricants, proper maintenance, and quality fuel with the proper octane rating.

Quote:
Originally Posted by Sniper View Post
My 2011 Ram Hemi is set at 197f from the factory.
I wonder if they changed the t-stat location from the earlier Hemi motors. Mine came with a 203F (maybe 205) from the factory. I know the '09 and later versions had variable cams and some other stuff tweaked.

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post #16 of 16 Old 06-10-2015, 05:24 PM
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Quote:
Originally Posted by jrj View Post
Not as much with modern materials and lubricants, proper maintenance, and quality fuel with the proper octane rating.



I wonder if they changed the t-stat location from the earlier Hemi motors. Mine came with a 203F (maybe 205) from the factory. I know the '09 and later versions had variable cams and some other stuff tweaked.
Remember the metal expands when it's hot, the tolerances were all designed for stock running temperature. Raising it decreases the tolerance gaps and does increase wear even with modern materials.

Emissions is why they run engines hotter, it is not better for power as you have to decrease ignition timing to avoid detonation. Cooler temps, higher compression ratio, and more advanced ignition timing is the way to make power.

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