Im looking at my auto meter catalog they have a pyrometer (Exhaust temp gauge) listed. It comes with the sensor. The gauge measures from 600-1600 degrees. Does that translate to 6:1 a/f to 16:1 a/f?? The thing is listed on summit racing for 85 dollars. Would it be very accurate? I'd be very tempted to get one.

heres a complete kit http://www.tognottisautoworld.com/se...UCT_ID=ATM4344


[Modified by nsimmons, 7:11 PM 1/11/2002]

 

Nope, there is no direct correlation between EGT and A/F ratio. Within a narrow spectrum hotter temperatures will equal a leaner mixture and cooler temperatures a richer mixture, but even here the relationship is not direct.

(note all numbers are approximations as the exact values depend on many other variables)
Here is kind of how the temp's go. Let's say we start around 13.5:1 or so.

As we go richer the temperatures will decrease, decrease, until we hit ~11.5:1 or so. As we start getting richer from there temps can actually increase because of fuel which continues to burn in the header.

Now back to 13.5:1 - as we go leaner EGT temps will increase - up to around 15.5-16:1 or so. From there the temps will start to back off simply because we aren't oxidizing enough fuel to maintain the heat content.

EGT's are awesome if you are working within a known context (you have already determined your general area and a general relationship), or if you are running a turbo setup and really need to directly monitor the value - but as a stand alone tool they are only marginally useful. Wideband dyno time would likely yield better results.

But if you just want a cool guage to stick in the car it's a much better choice than one of the generic stock o2 a/f guages.

 

I disagree with Chris on the benefits of an EGT gauge, but I don't have the experience on automotive applications. I believe an EGT gauge is better than O2 because you get instant air/fuel reading and more evident indication of problems. Ideally have a probe for each cylinder. I wouldn't buy the EGT gauge you listed, get a digital one.

 

its main use would be to look cool in the dash. I need a 4th gauge to fill the dead space and it either a cheapo rich/lean or the egt gauge. but i would also like to use it to fine tune my wot mixture. The chip will be pretty close, but since flooring the car invokes p/e mode, i cant monitor the mixture with the intergrator. What i am thinking..when i get the car idling well or at a stable cruise i can take note of the exhaust temp, and then some how make a educated guess on the wot ratio based on the fluxuation in the temp...basicly i'd like to monitor from stoich + or - 1.5-2 points

i'd appreciate suggestions on how to go about this

 

ttt