ECI has two different cylinder barrel bores on their cylinders. When talking about ECI cylinders, most people think of the Nickel+Carbide? Bore Coating. ECI also makes a THRU HARDENED steel cylinder. The Nickel+Carbide cylinder bore also comes in both a CERTIFIDED and EXPERIMENTAL version. When asking about temperatures on ECI cylinders, it is a good idea to report on the barrel that you are using.
I am presently flying ECI STEEL cylinders. I previously had SUPERIOR Investment Cast head cylinders. The Superior cylinders flew over 2,000 hours on my RV-6. CHT are just about the same between the Superior and ECI steel cylinders. The big difference was that #2 was my coldest CHT with Superior cylinders with optional temperature riser. With the temperature riser, it was my hottest cylinder. After removing the temperature riser, the ECI cylinder #2 is within 10 degrees of my other 3 cylinders. One other RV pilot has reported to me that his #2 CHT went up with the ECI Nickel+Carbite cylinder but removing the temperature riser brought the temperature in line with all the other cylinders.
One data point (from 2 different aircraft) that I have is that ECI steel cylinder #2 on a 320 RV-6 and a Nickel+Carbite cylinder on a 360 RV-6A ran hotter than the Superior cylinder that was on the 320 RV-6 and the Lycoming cylinder that was on the 360 RV-6A. Removing the OPTIONAL temperature riser that was installed on both aircraft to get the #2 cylinder head temp up to where the other cylinders were brought the #2 CHT down to the temperature of the other cylinders.
Yes it gets confusing and difficult to compare.
ECI may have three diffent cylinders for your engine.
Titan Nickel+Carbite cylinder
Titan Nickel+Carbite taper fin EXPERIMENTAL cylinder
Titan Steel cylinder barrel
The SUPERIOR thru hardned cylinder was advertised by Lycoming as being a SOFTER wall than the Lycoming Nitrited barrel. I ran my SUPERIOR cylinders over 2,000 hours. (1,700 of those were with 10:1 pistons) When the cylinders were removed, you could still see the cross-hatch pattern in the barrel. The shop I sent them to said the barrel was still new stock spec including the taper / choke. My question is: "How hard do the barrels need to be?" I had excellent service from the thru hardened steel barrel. IF I lived where there is humidity or did not fly a lot, I would want the Titan Nickel+Carbite cylinder that has the BEST corrosion resitance in the industry.