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  #1  
Old October 14th, 2011, 11:07 AM
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barry f
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Thernostat

I noticed rovers north sells two different thermostats. One is 179 and one is 190. I ordered from will and he sent me a 190. Why would you want a 179?
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Old October 14th, 2011, 11:09 AM
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Im guessing if you live in tropical area?
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Old October 14th, 2011, 11:17 AM
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Keep it cool I use a 180 in both of my trucks.
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Old October 14th, 2011, 02:09 PM
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Quote:
Originally Posted by bjf View Post
I noticed rovers north sells two different thermostats. One is 179 and one is 190. I ordered from will and he sent me a 190. Why would you want a 179?
You want to go with a 180 one if you want to improve reliability. You will also pickup a few HP from it as well. In my Rover power tuning book it mentions that 195 was for OEM emissions and the engine prefers the 180 temp. Rpi web site also recommends this. I went with the Robertshaw stat modified by EMP. It has holes for air bubbles to exact and can flow much better then other stats.
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Old October 14th, 2011, 03:13 PM
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barry f
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Never heard this before. Radiator shop I went to said the cooler ones usually rob mpg
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Old October 14th, 2011, 05:28 PM
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Modern engines run hotter for emissions to be cleaner. They are designed to heat components as fast as possible. Most are designed to run lean, less unburnt fuel= cleaner exhaust. If you restrict heat to motor usually there will be a slight loss in performance, and a dirtier tail pipe emissions.
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Old October 16th, 2011, 09:39 PM
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In terms of thermal efficiency yes the MPG goes up when the engine is hotter but also wear will increase in regards to this engine due to the fact that the basic architecture was designed in the 60s and made to operate at 180F which many cars that the time did up until the later 70s when they turned up the heat to reduce HC. Rover engines started having cylinder cracking issues due to the high heat especially on the Range Rovers due to the cooling system. When the stock stat opens it will at 195F so comment running temps are 200F-205F as I have verified them on my laser thermometer gun. Aluminum Rover engines do not take to the heat well due to its design. They have high expansion rates and when they run hot or to hot the main caps can frett. This is more of an issue with the older blocks though since they went to larger main caps from 1994 Jan on but went to larger crack journal 4 bolt mains in the 4.0l as oppose to the 3.9l.

Keep in mind fuel enrichment is turned off on any EFI Defender after 172F so your still going to get the best MPG at 180F which I have also tested with no penalty using the 180F stat. MPG were accurate down to 1/10th of a MPG. This is also talked about in the book "How To Power Tune Rover V8 Engines" By Des Hammill. This book is like a bible when it comes to Rover engines and its not just about making power out of them but also making them run there best under and power level. RPi also has information on running cooler as well. These engines were being using for 40 years so they are not the same as modern aluminum engines that are deigned to run hot. I really recommend every one get and read the book. It's the best and last book you will ever have for our Rover engines.

Don't let New MFG truck emission standers that were stricter on imports stop you from doing what the factory could not do. I love the better response and power from running a bit cooler and you will too.
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Old October 17th, 2011, 08:04 AM
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Tom Rowe
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Land Rover specifies an 88c thermostat for both the 300Tdi and the V8. 88C = 190F
The 300Tdi manual says the the thermostat should be fully open at 88, the V8 manual is a bit more vague. However, I don't see having some that are fully open at 88 and others that are only partly open at 88, it would be hard to be sure you have the correct thermostat.

From testing various US domestic thermostats I've found that the temp specified on them is the temp at which they start to open. They weren't fully open until the mid to high 190's.
To get one that is fully open at 88C I had to go with a 180F.

Apparently in the UK the temp of a thermostat is when it's fully open, in US it's when they start to open.
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