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  #13  
Old 08-06-2012, 09:15 PM
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Re: Jeep produces lots of heat

So run cooler, less heat, more efficient. Right ?
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  #14  
Old 08-06-2012, 10:26 PM
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Re: Jeep produces lots of heat

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Originally Posted by padgett View Post
So run cooler, less heat, more efficient. Right ?
Negative.

Hot air = less dense = less gas injected = less fuel to cruise

You really only want colder air for higher performance.

Now if you were able to convert more of the energy in gasoline into power instead of heat, you'd be on to something. But running an engine cooler doesn't do that (and in fact in many cases does the exact opposite).
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  #15  
Old 08-07-2012, 07:22 AM
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Re: Jeep produces lots of heat

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OK please explain how starting further down the PV curve and reducing the likelihood of detonation causes lost HP. .

You think too much. The engine is making heat with the gasoline I feed it rather than turning the wheels.
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  #16  
Old 08-07-2012, 11:11 AM
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Re: Jeep produces lots of heat

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So run cooler, less heat, more efficient. Right ?
Technically, yes. If an engine was 100% efficient, it wouldn't give off any waste heat. An electric motor is typically 85% efficient, and therefore has considerably less heat than an internal combustion engine which is typically 30% efficient.
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Old 08-07-2012, 11:17 AM
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Re: Jeep produces lots of heat

Can we agree to disagree ? I live in a hot sea-level climate so my needs are different. My long term experience is that running a gasoline engine on the cool side (180-190F) and keeping the IAT under 100F, mimimises detonation on 87 PON & allows a slightly leaner mixture which maximises MPG.

A side benefit is that rubber and electrical components under the hood last longer (Florida is very hard on rubber).

The key is to run on the low side while staying within specifications. For example a 170F thermostat may set malfunction codes, a fast acting 180F or 185F should not.

If anyone is really interested in combustion theory may I suggest going to the library and look for texts by Ricardo or Obert.
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Old 08-07-2012, 11:46 AM
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Re: Jeep produces lots of heat




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  #19  
Old 08-07-2012, 11:53 AM
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Re: Jeep produces lots of heat

Quote:
Originally Posted by padgett View Post
Can we agree to disagree ? I live in a hot sea-level climate so my needs are different. My long term experience is that running a gasoline engine on the cool side (180-190F) and keeping the IAT under 100F, mimimises detonation on 87 PON & allows a slightly leaner mixture which maximises MPG.

A side benefit is that rubber and electrical components under the hood last longer (Florida is very hard on rubber).

The key is to run on the low side while staying within specifications. For example a 170F thermostat may set malfunction codes, a fast acting 180F or 185F should not.

If anyone is really interested in combustion theory may I suggest going to the library and look for texts by Ricardo or Obert.
Look up the second law of thermodynamics, specifically, Carnot's theorm. The general equation for thermal efficiency is 1- (Tc/Th), where Tc is the ambient temperature and Th is the temperature of the burning fuel mixture. Temperatures are in an absolute scale, such as Kelvin.

For a given engine, The hotter the fuel/ air mixture and the colder it is outside, the more efficient it will run.
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Old 08-07-2012, 01:20 PM
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Re: Jeep produces lots of heat

There are alot of factors that contribute to the heat a vehicle produces.

If I drive away from the wind I find the car to be hotter than when I drive into it.

Also the load you put on the engine before you park it will leave some residual heat.


I am with Padgett on Living in a hot climate. getting a thermostat 5 degress does help the overall performance and longevity of compontents underhood.


If you look through certain service manuals for older car you see different oil weight and thermostat ranges depending on climate.

Our cars try to cover both cold and warm climates but we could always optimize them for on climate.
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