Corvee

I am considering installing a EGT probe for a data logger on my C6Z. I found general installation recommendations to place the EGT probe 1.0 to 1.5" from the targeted exhaust valve. I want to monitor #7 cylinder (since it failed before). But this would mean drilling into the header.

It would seem easier to install the sensor in the tube before the cats just past the header collector - I am running Kooks with integrated cats. Granted this will provide a general reading of that side, but is this location too far from the exhaust valves for acceptable accuracy? One probe manufaturer maintains the probe will read the highest temp from the exhaust valves located on that side, which is acceptable, but again I am unsure how far down-pipe is accurate.

Thanks,

Jim

fatbillybob

I have installed egt to monitor a weird ferrari system of kluges. most egt are 8mm x1 pitch that I have found. If you drill the header you also effect flow so you better have a good reason to monitor #7 and you really need to weld a bung. Do you really know why it failed here? I seem to remember #7 was an issue for some reason. If the source of the first problem on 7 is not fixed then monitoring egt could give you an early warning to a point but if you are track battling you will probably miss the warning and cook the motor and just see the damage on the data. If you get abnormal egt on data but not to the point of failures then you might be able to use the data to make changes for the better. Is that what you are trying to do? If you are just curious about egt then I would just plug the egt into the 2nd o2 sensor position and just simulate the 2nd 02 sensor. That data will not be as good as upstream data but it is data.

Corvee

No. 7 seems to be the most common failure point on the LS7. I am told it gets the hottest. Unsure of the cause of the failure but it cracked the piston and sleeve. The ring was also gone but don't know which failed first. I suspect detonation and hence the reason for the EGT probe. The entire engine has been rebuilt with forged internals, solid valves and the tune completely re-mapped. I do not know what else I can do to aovid a re-occurrence other than hopefully catch it if it leans out or the temperature spikes.

As you surmised - I have my hands full in the car and can't monitor gauges hence the datalogger and sensors. I also installed widebands on both sides. Idea is to check highs and lows when I come off track and the sensor data when I review my track runs. Both second O2 sensors are open because I eliminated them to create room for the wide bands.

Thanks for your reply.

fatbillybob

I don't know anything about LS7's but race and LS6 and know mechanics.
Are you running cats?
Is there any significant valve overlap on the LS7's?
What did the tuner tune for?
Can tuners specifically add or subtract fuel at specific injectors with the LS7 set-up?

Corvee

I am running cats integrated into the pipes behind the headers (Kooks).

In general I do not think overlap is significant with the stock LS7 cam I was running at the time of failure. Its specs are 0.591/0.591 lift with 211/230 intake/exhaust on a 220 LSA. During the rebuild I switched to a cam with similar lift and slightly longer duration 224/234 on a 112 LSA to increase my torque. Overlap probably increased some but is not significant due to modest lift.

The car was given a "track tune" by LG in Dallas. They spent a good deal of time on my fuel trims and the timing tables. I do not think you can add or subtract fuel via the tune. But I had my fuel injectors flowed and calibrated during the rebuild and they were all within spec. was suggested to place a richer injector on #7 to compensate for any lean condition but they were all pretty close.

Thanks,

Jim

RX-Ben

From my research, they should be 2-2.5" from the head. Farther than that and accuracy and response time diminish a bit. Use and open-tip style. You will also need an amplier since K-type thermocouples output between 4-20ma.
You will need a bung welded in. With stock manifolds, it is easy to drill into the iron and put in a compression fitting (http://www.widebando2sensor.com/EGT-Measurement).
I would imagine flow is not measurably affected.

You might want another egt so you have something to compare your cyl 7 temps.