What is the purpose of EGT(Engine Gas Temp) gage? I have an Idea but wanted to know what others know.


[Modified by Built_For_Boost, 2:51 AM 12/4/2002]

 

When you run lean on boost, the lean condition creates excess heat. The heat is what actually damages parts. The EGT guage measures heat directly whereas a a/f meter is measuring the lean condition. Both can help identify a problem, but they do it in different ways. The EGT is not as fast acting as an a/f meter would be, but you are getting a DIRECT reading on the part killer. Its like 60-120$ for an EGT setup compared with 250+++$ for a wideband a/f setup. Hooking up a a/f meter to a narrowband O2 doesn't really tell you much at all.

 

EGT = exhaust gas temp

 

very good response, mos ... also one other thing to add, the typical honda b-series racer puts the EGT probe about 3 inches off the primary from the #3 cylinder.

Greg

 

For sake of conversation, WHY is this done? And why not on the #1 primary? Or even on the downpipe?

 

I believe it's generally accepted te third cylinder runs the hottest. I put mine in the downpipe right after the turbo. This just in case something happens to the probe and shoots a piece into the turbo. Very unlikely but I try not to take any chances.

 

Would an EGT gauge also give one a rough idea as to ignition timing?

 

it can indicate changes in ignition timing. if your timing is retarded enough, the EGT will indicate higher temps as the exhaust gases will still be burning as they pass the sensor, but there is no way to say this temp = this much timing without a reference and all other variables are unchanged.

 

I do understand that I would not be able to directly correlate EGT with timing. I was just curious what an EGT gauge could tell me about the affects of the timing changes that I make. Thanks.

 

I know this is a well known fact....but for those who dont know, when you open the hood, the cylinders are labled:

|4| |3| |2| |1|

 

I think you get the highest egt's at 14.7 a/f ratio. Any leaner than that and there isn't enough fuel in the mixture to create a very hot flame and any richer and the excess fuel begins to cool the exhaust.

 

it can tell you if your running lean. As boost climb cylinder pressure increases, on a turbo cars etg will be as high as 1500-1600 at full boost, on n/a cars they are 1300- 1400 degrees. mine hits 1500 degress, etg is in the exhaust manifold. If you put it in the downpipe the temps will be off about 200-400 degrees.

 

Would any of you reccommend a EGT over an Air/Fuel gauge? I'm going GReddy turbo soon and I have to decide....

 

http://www.sdsefi.com/techegt.htm

All you need to know listed within.