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Discussion Starter #1
Hey everyone what is the optimum temp of the egt's? If its is higher does that mean it is running rich or lean (at idle)? thanks

Robert B
89T
:scratch:
 

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LEADED FUEL ONLY
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Higher temps mean that the timing is being retarded. A sign retarded timing could be a lean mixture, but not always.

If you want to monitor a/f ratios, then buy an air fuel ratio monitor from FJO or the like. A wideband sensor is what you need to do this job.

EGT is really dictated by timing. On an AEM, you can influence EGTs a lot by playing with the timing.
 

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Discussion Starter #4
So just what does knowing my EGT's help me with on a day to day basis or for tuning purposes? (dont laugh)

And am I also wrong in thinking that retarding the timing richens (more fuel) the mixture and advancing leans (less fuel) the mixture?
:dunce:

Robert B
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A Happy Dad
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mainly just to let you know if you have a problem coming on, such as injector failure, etc. or getting too hot near redline. It'll let you catch it in time and take corrective action before you have a nice hole in the piston or something.

Oh, and timing has nothing to do with mixture other than more or less efficient use of fuel air combination. It's just not that simple, there are so many factors.
 

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Discussion Starter #6
Ok but just for info purposes at this point, where should the egt's be at idle & then at say 3000 rpm's? A friend advised me that at idle it should be at about 900 degrees while mine is at about 700 so is that correct and if so why would mine be 200 degrees less than standard temp?

Robert B
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An egt for tuning is useless, unless you're tuning your ignition timing. Otherwise, its not going to do a whole lot for you.

For fuel tuning, you MUST go with a wideband oxygen sensor and controler module from FJO or whoever.

As mrd40z stated, timing is independ of fuel mixture.

Here's how this works.

Lean mixtures will produce knock. The knock sensors pick this up, and retard the timing to save the motor from burning holes in pistons, or cracking rings lands or what not. When this timing is pulled, the point at which energy (heat) is released is changed.

It still takes 5 milliseconds (just an arbitrary time i have no idea of this actual time) for complete combustion to happen. The only thing you can change is when you ignite it. We'll say that at 3ms into combustion, the maximium amount of energy (heat) is released. Idealy, we'd want this to happen just as the crank throw is about 15° ATDC (from memory) which would exert the most amount of force upon the crank.

When we retard (or pull) the timing, we release this energy later and later in the cycle. So late that some of this heat gets out of the combustion chamber and into the manifold. When this happens, EGT's go up.
 

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Discussion Starter #10
alright so ideally where should the EGT's at idle be at or does that just vary from each different setup people may be using?
 

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robbro89t said:
alright so ideally where should the EGT's at idle be at or does that just vary from each different setup people may be using?
at idle you could be anywhere from 500-900 once the car warms up...

temp shouldnt go higher then 1550 at full throttle...and thats pushing it as 1600 is when shit starts melting...
 
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