Tuning off EGT's

Hey guys, i finally got to make a couple hits using my new datalogger setup and am loving the data. Now I can start tuning. does anyone have a good target EGT range for Alcohol?
My down track average for the 8 cylinders is 1212 degrees with 30 degrees timing.

Thanks,
Alan

There are way too many variables with EGT. You'll have to tune the engine, and then use the EGT for baseline tuning afterwards.

With alcohol, be certain that it is on the rich side ... being even a little bit to lean is carnage waiting to happen.

rmcomprandy wrote:With alcohol, be certain that it is on the rich side ... being even a little bit to lean is carnage waiting to happen.

I've been running alcohol for 30 years. We look for a lean condition on the water or oil temperature on no data cars.

Curt,
It was the oil and water temps that gave away the lean condition. My 514 never got hot and I never ran water. Went to the 533 and have been trying to figure out the combination ever since. I knew it was lean because it got hot too quick, and I started running water because of it. Now with the data logger and time slips, I can really see the effects of each change I make. The last visit to the track, I dropped timing to 28 deg and went to an 82 pill (from 86) and my egt's dropped in half. My ET dropped 3 hundreths, but my mph stayed about the same. I was going to run today going back to 32deg timing and an 84 pill, but the track canceled the race due to a very high chance for rain this afternoon.

Alan

We watch EGT on the dyno and it can be really helpful, but it can also be super misleading. If everything else stays the same, EGT will give you a read on rich or lean, but EGT will also change when timing changes so you can get confused unless you have a rock solid baseline to work from.
EGT will also change if the position of the sensor changes in the pipe. We see the probes vibrate loose on the dyno all the time and when the probe starts to change position inside the header tube the temp will change significantly. Just a small change in position will change the temp by several hundred degrees.
I love data, the more channels the better, but EGT information has to be cross checked against other data. If you have the channels I'd add a pair of wide band sensors to the mix. Wide band sensors can also be fooled into giving you bad data, but if you have both EGT and wide band data you can usually figure out what is really going on.

AndyF wrote:
I love data, the more channels the better, but EGT information has to be cross checked against other data. If you have the channels I'd add a pair of wide band sensors to the mix. Wide band sensors can also be fooled into giving you bad data, but if you have both EGT and wide band data you can usually figure out what is really going on.

Funny you should say that. When I placed my first order with RPM, We talked about getting O2's first then adding the EGT's and he talked me into going with EGT's saying if I run open headers and dump at the end of the collector, the O2's sensors won't provide accurate readings.
Before the logger, I had a Fast O2 meter, and the reading danced all over the place so I went with RPm's recommendation. Both headers are set up for O2 sensors, so it would be pretty easy to add them to my logger. I'd also like to add a couple shock travel sensors as well.

Wideband sensors will read okay with open headers once the exhaust gas is moving fast enough to keep the outside air out. Usually somewhere around 2500 RPM the sensors start to read properly. They'll read super lean at idle since the outside air confuses them but as the RPM goes up they'll start to read correctly. If you have a data logger that is triggered by RPM or throttle position then you should get a good reading as the car goes down the track.

AndyF wrote:Wideband sensors will read okay with open headers once the exhaust gas is moving fast enough to keep the outside air out. Usually somewhere around 2500 RPM the sensors start to read properly. They'll read super lean at idle since the outside air confuses them but as the RPM goes up they'll start to read correctly. If you have a data logger that is triggered by RPM or throttle position then you should get a good reading as the car goes down the track.

Nice, I will definitely add them then. I have my logger set to trigger off RPM.

For race cars we usually turn the data logger on when the two step is activated. Then the data logger turns off after 10 seconds or whatever it takes to capture the full run as well as some coast down time. I like to look at oil pressure during coast down as well as a few other things but you shouldn't need to capture more than 15 seconds from the time the two step goes on.
Some of the data will be weird during the two step operation since cylinders are being shut down. The AFR will be super lean and EGT will be all over the map. But you'll get used to seeing that after you look at a few logs.

Curt wrote:

rmcomprandy wrote:With alcohol, be certain that it is on the rich side ... being even a little bit to lean is carnage waiting to happen.

I've been running alcohol for 30 years. We look for a lean condition on the water or oil temperature on no data cars.

Then it was not "to lean".

AndyF wrote:Wideband sensors will read okay with open headers once the exhaust gas is moving fast enough to keep the outside air out. Usually somewhere around 2500 RPM the sensors start to read properly. They'll read super lean at idle since the outside air confuses them but as the RPM goes up they'll start to read correctly. If you have a data logger that is triggered by RPM or throttle position then you should get a good reading as the car goes down the track.

O2 sensors should be place about 6" from the header flange. I have one on each side in the header tube.