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Pyrometer
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Author:  steponmebbbboom [ Tue Apr 13, 2004 8:48 pm ]
Post subject:  Pyrometer
I have a Super Six intake with EGR waiting to go on my rebuilt Slant. I also have a diesel engine exhaust temperature indicator kit at work. My plan is to use the pyrometer gauge to monitor the exhaust temperature and adjust the carb circuits as necessary to keep the car in optimum tune. Sound like a good idea? I havent examined my manifolds with the EGR off yet but Im hoping I can thread one of the ports for the thermocouple. I can always bung the header pipe if I have to.
Author:  mnecaise [ Wed Apr 14, 2004 5:06 am ]
Post subject: 
You might not get flow over the gauge if you use the EGR port. without the exhaust flowing over the gauge you might not get an accurate temperature reading.

Just drill & tap the manifold below the heat riser & just above the flange. It should work.
Author:  MitchB [ Wed Apr 14, 2004 2:13 pm ]
Post subject: 
Won't work. Here's why:

A pyrometer needs to be precisely positioned to be accurate. Most I have seen need to be located right off the exhaust port, otherwise your readings will be misleading. More significant is the inability to correlate EGT readings with air/fuel ratios (most common misconception) or any other single variable by itself. You need to tune A/F with a wide band O2 sensor and once you are sure of this, EGT can be then be used to determine what spark your engine needs. Let me give you an example - once you are sure of A/F, EGT is used primarily to determine combustion efficiency. In a large port, low swirl or quench deficient chamber (or any one or combination of these) which results in a slow flame front (low combustion efficiency) the mixture will continue to burn in the exhaust manifold(s) after the exhaust valve has opened. This will give you high EGTs. This tells you you need more spark advance so combustion will begin sooner. EGT is really a window into where your engine is making peak cylinder pressures. Taking this example further, by advancing the spark, you will lower your EGTs by starting the flame front earlier. More of the mixture will burn while the valves are closed and the engine will develop peak cylinder pressures earlier while the engine closer to it's maximum mechanical advantage. This is when the piston/rod angle enables the most efficient transfer of cylinder pressure to the crankshaft - typically 15-25 degrees after TDC. By reading EGT, an experienced tuner will be able to determine what spark your particular engine combination needs. This is the primary use of a pyrometer. EGT varies greatly with many factors and A/F is just one. More importantly, you cannot infer anything one factor by reading EGTs alone. It is another piece of the tuning puzzle that helps to clarify what is going inside an engine.

Hope this helps.

Mitch
Author:  steponmebbbboom [ Sun Apr 18, 2004 1:16 pm ]
Post subject: 
I see what you are saying.

Is there another more efficient way to monitor my mixture that doesnt involve pulling plugs on a daily basis or turning down the radio to listen for pinging that could really just be a rattle in the dash somewhere.

So to accomplish what I want to do, I need to interface an oxygen sensor to a gauge. How could I do this? What type of oxygen sensor should I look for?
Author:  MitchB [ Sun Apr 18, 2004 2:45 pm ]
Post subject: 
It is only feasible to use a wide band O2 sensor on a dyno. There are kits out there that allow you to monitor a standard O2 sensor, but all this allows you to do, really, is determine when your A/F is at 14.7:1. One tenth or two on either side (+/-0.1) and the accuracy of a standard O2 sensor degrades rapidly. In practical terms, you are left only with reading your plugs. You need to be careful because you want to get your cruise and WOT A/F correct. Tuning is a bit of an art form. Without sophisticated tuning equipment, you just need to take your time and make small changes.

Mitch


Quote:
I see what you are saying.

Is there another more efficient way to monitor my mixture that doesnt involve pulling plugs on a daily basis or turning down the radio to listen for pinging that could really just be a rattle in the dash somewhere.

So to accomplish what I want to do, I need to interface an oxygen sensor to a gauge. How could I do this? What type of oxygen sensor should I look for?
Author:  Guest [ Sun Apr 18, 2004 4:19 pm ]
Post subject: 
http://www.motorsportsinnovations.com/wide_band_o2.htm

Here is a link to a WBO2. A bit pricey - around $380 but logs the runs...etc.
Author:  steponmebbbboom [ Sun Apr 18, 2004 7:43 pm ]
Post subject: 
OMG!!! :shock:

WB758 AFR GAUGE!!!!

Guest you just answered my prayers!

Heh... now all I have to do is CNC machine a mixture screw with a gear drive on the end of it, and run a rotary cable with a handcrank under the dash, and I won't even have to leave the seat :twisted:
Author:  steponmebbbboom [ Sun Apr 18, 2004 8:01 pm ]
Post subject: 
*looks up*

:lol:

Man, it would be nice to have all this information on your dash though, ridiculous as it sounds. I am under my hood every day trying to keep it running smooth as glass. FYI guys, the gauge is not meant to directly interface with the O2 sensor. You either have to buy the analyser or burn your own board and ICs to interface the two. We'll see what the mfr says.
Author:  kens75duster [ Mon Apr 19, 2004 2:03 am ]
Post subject: 
Hey I think I might be able to help with finding a Wideband O2 setup. My friend has a turbo'd Miata, and just recently he got a WBO2 setup....I cannot remember the name of the manufacturer... I will ask him and post it tomorow... I think he paid less than $400 for everything, including the sensor itself.... I remember him commenting on the price being very good... It has worked well for him.... pretty easy to use with a fully programable ECU.

Ken
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