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We all know that the 3.0 V-6 runs hot (roughly 200 degrees). Fans don't kick on till 208 and the computer begins retarding performance at 210 degrees. Obviously, a mod to make the cooling fans to come on at a lower temp (which is in the works for the v6) or 84FordMan's lower temp t-stat solution can bring down the operating temperature of the engine.

I want more consistent power from the engine, but am concerned about doing this mod. I think that Mazda wants the engine running this hot for some reason. If not, they could've made the engine run cooler stock.

Lower temps = more power & less wear. But do lower temps also mean worse gas mileage? What's the tradeoff to doing this mod?

thanks for any answers :)
 

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Well, if I remember my theory correctly :huh:

Higher temps will result in slightly better engine efficiency (to a certain degree) in an Otto cycle engine. ie: conventional 4-stroke. Higher compression will do this as well. This is of course, when all things are being equal, and remembering that there are limits to this (like materials that can handle a maxiumum temp range). But when Mazda retards timing, we don't really get the efficiency increases they talk about in textbooks.

Of course, there's a reason why I didn't get into thermodynamics for a career, you guys will just have to take my word for it. Until somebody proves me wrong. :p

...also, higher head temps will result in a more complete burn meaning lowering HC emissions. However, higher temps also means increases in NOx... so I'm sure that it's a compromise.
 

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The EPA loves you all!
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The EPA also hates catalytic converters for creating all these NOx emissions but force all new cars to have as many as four of them. I don't pretend to understand government agencies since nearly all double talk.

The lower temp thermostat does exactly what a thermostat does, lower the minimum operating temperature of the engine. The whole hullabaloo over it messing up engine controls is silly, since a car's mean coolant temperature is only the sum of it's cooling components, especially the radiator and fan system.
 

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Isn't the solution 2 part? A fan control module and then something else along with it?

I am wondering how often the engine gets that hot as i never hear my fans kick in while driving only while idle parked, and the only time ive "felt" the timing retarding was on a dyno.. and the numbers sure showed it... 5th run though...
 

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Isn't the solution 2 part? A fan control module and then something else along with it?

I am wondering how often the engine gets that hot as i never hear my fans kick in while driving only while idle parked, and the only time ive "felt" the timing retarding was on a dyno.. and the numbers sure showed it... 5th run though...
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If you ask around you will notice that all of the newer engines out there run much hotter than there predesscors. It has to do with what was mentioned above about emissions. hotter running engines burn there fuel more competely. The newer engines of today burn so hot that combustions continue even after the air/fuel mixture exits the cylinder. If you lowered the temps then the only ill effect I can think off is a little lower lifetime for your cats since they will see a little more un burnt fuel(which is the undoing of all cats)
 

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Yeah I dont think this is just a Mazda issue, if you browse around the WRX forums for example, you'll see threads discussing engine temp and lower performance. But I will admit, I can really feel the difference with the 6 when it gets hot so the degree to which timing is retarded is probably a lot different between manufacturers. With my older cars (all 4-bangers) I can never remember the performance difference being so great. Could our aluminum block and the fact that we have six cylinders have something to do with it? I'd think so considering how fast it gets up to temp.
 

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Yeah I dont think this is just a Mazda issue, if you browse around the WRX forums for example, you'll see threads discussing engine temp and lower performance. But I will admit, I can really feel the difference with the 6 when it gets hot so the degree to which timing is retarded is probably a lot different between manufacturers. With my older cars (all 4-bangers) I can never remember the performance difference being so great. Could our aluminum block and the fact that we have six cylinders have something to do with it? I'd think so considering how fast it gets up to temp.
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With your older cars LEV and ULEV were not an issue either. Aluminum is a much better conductor of heat than iron, copper is a better conductor of heat than aluminum and silver is nearly the best conductor of the common metals. Copper is heavy, thus we don't use it. Silver is expensive, thus we don't use it.

The problem is the need to lower emissions/smog (By raising even further deadlier emissions, ie NOx) has outgrown the pace of automotive technology. This is why we are taking shots in the dark with gasoline-electric hybrids and fuel cell vehicles that cost in the millions to make, because the technology is so new and so unrefined. To show you the insanity of the anti-pollution hippies, the government of California forced Toyota to build about 1,500 Toyota Rav4 Electric Vehicles at the cost to Toyota of about 14 million dollars (IIRC) and forced them to sell the vehicles for under $30,000. Toyota took a huge loss.
 

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Well Mazda does this with a few cars that i know of and maybe more. I just sold my 3rd Gen. Rx-7 and from the factory they ran hot i mean real hot, the fans didn't come on till well above 100*C. And if you know anything about rotarys running them real hot will blow coolant seals so there must be a damn good reason why they have them run hot.

Also a friend of mines mx-6 runs hot too so i imagine mazdas been doing this for awhile.

Many FD owners just used lower temp. stats which will work the best and less of a hassle then a fan switch mod. like this one

http://www.rx7.voodoobox.net/howto/fanswitch/fanswitch.html
 

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The FD fan came on at 100 with the second coming on at 105. With an electrical load or A/C it was 95.

As far as that goes, it WILL take more than that to warp the thing or blow a seal.

220 is not that hot by any means, granted it IS getting to the upper limit and leaves not much room for error.
 

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Your coolant seals can go pretty easily, certainly now they have age on them. Its just stupid that mazda lets something as heat sesitive as the rotary to get that hot!!
 

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And also a hotter engine more completely burns the fuel and gives lower emissions
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Bingo

The EPA also hates catalytic converters for creating all these NOx emissions but force all new cars to have as many as four of them. I don't pretend to understand government agencies since nearly all double talk.

The lower temp thermostat does exactly what a thermostat does, lower the minimum operating temperature of the engine. The whole hullabaloo over it messing up engine controls is silly, since a car's mean coolant temperature is only the sum of it's cooling components, especially the radiator and fan system.
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I don't think the catalyst creates NOx, it just can't do anything to lower it like it can HC. NOx is a by product of a lean mixture. Which may be why the 6 runs so rich.
 

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I happen to know a small bit about this from my work with Zetec engines as well as knowing a nascar engine builder;
The engine builder does something on his engines that most don't and he runs a reverse coolant flow which keeps the entire block hotter. Why? it is easier to MAINTAIN A CONSTANT hotter temp than raising and lowering a temp as standard engines do. In maintaining a constant temp you can run much tighter tolerances of metal to metal contact. i.e. 5w-20 oil. you can run a tighter compression and yes, the fuel will burn more effectively, but that is secondary. it's all about consistancy. Our engines are built to operate in a very narrow temperature window; did you know if they get too hot they will shut off cylinders while running to cool?
yay, we learned.
 

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I don't think the catalyst creates NOx, it just can't do anything to lower it like it can HC. NOx is a by product of a lean mixture. Which may be why the 6 runs so rich.
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The 1998 New York Times article doesn't go into much detail about the EPA's study, and trying to find any particular study on the EPA's search engine is a nightmare:

http://www.junkscience.com/news2/catalyt.htm
 
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