[Robb]

I want to rum my RV7 lean of peak but I have a few issues. When in run LOP I have about 90 degrees difference between my highest and lowest EGT's. My cylinder temperatures are all around 280 degrees. The issue I have is no 2 and 3 are 90 degrees cooler than the other two. Has anyone else has experienced the same issues? I need to see if I can richen them up a little to match the others

 

[scsmith]

the absolute temp doesn't matter

Remember that you are not interested in the actual values of your EGTs. They are variable due to specific probe location and possibly other factors.
What you care about is how far past peak EGT each cylinder is.

Now, it may well be that your colder cylinders are more LOP, and you need to adjust your injector nozzles. But that is not automatically the case just because they are cooler. Do the GAMI-spread test.

 

[DanH]

Like this:

http://www.vansairforce.com/community/showpost.php?p=514214&postcount=8

...or lean very slowly while recording with an EIS system, which allows this sort of tabular data. This is after restrictor tuning. All four cylinders are peaking at about 9 GPH, but the EGT values are all different, just as Steve and Don have said.

BTW, I don't think Precision sells the necessary restrictor sizes to do this, but Airflow does.

 

[Robb]

The strange part is the highest egt I can get is 1284 degrees. The plane is new to me and when I do the annual I will see what is going on and why it is so low compared to what I am used to seeing

 

[scsmith]

EGT probe location

The strange part is the highest egt I can get is 1284 degrees. The plane is new to me and when I do the annual I will see what is going on and why it is so low compared to what I am used to seeing

It is very likely associated with the location of the probes. Its a trade-off: If you locate the probes closer to the exhaust port, you get higher temps and faster response time. If you locate the probes farther down the exhaust pipe away from the cylinder, you get slower response and lower temperature, but the benefit is much longer probe life.

Your temps probably indicate the probes are more than 3" from the cylinder mount flange.

Again, the actual values don't matter. Dan's data that he posted shows EGT's in the 1400's, whereas I see 1370 peak, and typically cruise at 1310 or less, sometimes as low as 1280.

 

[airguy]

My probes are right at the flange opening, and I see temps in the mid-1500 range commonly. I know that means I'll have shorter probe life, it is what it is.