EGT for 2nd Gen RX-7

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Weaver7

New member
Been reviewing the data from our AIM system and it appears that it is running anywhere from 50 to 150 degrees colder on the front bank. The max temp was 1940 degrees. Was curious to see what everyone else is getting as far EGT temps.
 
Sounds like you're lean. I used to run quite lean at high RPMs and had EG temps over 1900. Had a heck of a time keeping oil and water temps under control, too. I think optimal is somewhere south of 1700. A wideband O2 meter is your friend. Put two bungs in so you can check either rotor. The most important use of my EGT gauges these days is to easily spot a fouled plug.
 
To some degree, distance from the engine can affect readings as well. make sure you are comparing apples to apples.
 
EGT is dependent on air/fuel ratio, ignition timing, and sensor placement. Seeing abnormally low readings can also be caused by thermocouples with a great deal of insulation and the resulting slow responsiveness.

Short answer is that retarded ignition timing can cause the high egts just as easily as a lean mixture. Which do you have? Use a lambda meter to read a/f ratio. Period. An egt gauge involves too many variables to be trusted in and of itself to gauge mixture. An egt gauge has a place in tuning but in the modern day of fast response wideband o2 sensors it's place is not in gauging absolute mixture.
 
C. Ludwig said:
Use a lambda meter to read a/f ratio. Period. An egt gauge involves too many variables to be trusted in and of itself to gauge mixture. An egt gauge has a place in tuning but in the modern day of fast response wideband o2 sensors it's place is not in gauging absolute mixture.
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Chris, do you have a source that you recommend for a lambda (wide band?) meter for in-car use, or do you simply rely on regular trips to the dyno for that info?
 
Chris Wire said:
Chris, do you have a source that you recommend for a lambda (wide band?) meter for in-car use, or do you simply rely on regular trips to the dyno for that info?
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I've had good luck with the Innovate products. We sell the Haltech version which simply is a rebadged Innovate LC-1. A lot of dynos use the LM-1 (is my personal choice). Both have some nice logging options. I used a PLX Devices wideband for a few years and had pretty good luck with it too and really only got away from it because I wanted to step up to something that had more logging capability. PLX has since stepped up and has some pretty powerful hardware. If you run leaded fuel you'll want to spend the money and upgrade to something that supports the NTK sensor versus the standard Bosch sensor that just about everyone is using. The Bosch sensor is just not as good in many aspects as the NTK. Interestingly the NTK wideband controller ships with a Bosch sensor but it does support the NTK sensor. FJO also makes a nice unit with logging ability that supports the NTK sensor.

FWIW I had an interesting experience a couple weeks ago. The dyno I've been using for a while uses an Innovate LM-1 and logs through the dyno. The sample rate on the dyno is a lot less than what the LM-1 alone is capable of. On this particular day I was logging with my own LM-1 and we hooked their's up as well. The car we were working with had a horrible ignition mis-fire. On one run I recorded something like 20 mis-fire events with my LM-1 while the same controller logging through the dyno at a much slower sample rate showed none. It was just pretty eye opening for me.

One of the muscle car mags did a wideband shootout a while back. Think I might have even posted a link on here.
 
Chris, you bring up good points. I have a 1st gen, run premixed, and have an AIM MXL data aq system. off the top of your head, would I be wise to log of a wideband, (i think yes) and if so, which one would be smart?
 
Logging more information never hurts anything. I like to log a/f ratio and have an egt probe in each primary. When you're logging a/f past the collector you're getting a composite view of what's happening. You might be seeing 14:1 on one rotor and 12:1 on another so the wideband is showing you 13:1 and you think the engine is happy while it's really not. By running the wideband plus with the egt probes you can tell if the mixture is consistent between the two rotors. A fast response, non-shielded egt probe is a must.

Again, I like the Innovate stuff but there are a lot of good meters on the market.
 
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