I've had my duplicolor engine enamel stand up to plenty of fuel, exhaust from blown gaskets and couplers, and just about everything else. I was cleaning the grease and grime off it with regular soap and water and it was working well but I got impatient and decided that the purple power stuff would work better. The purple power dulled the paint real bad. Oh well...
Roo, not arguing that powder coating is much better and your engine really does look awesome but I spent $5-$10 painting my engine and you spent $330. One thing I did learn was that after 3-4 rides when it's covered in grease, grime, soot, and water spots, it all looks dull and nasty anyway.
For reference, right before Daytona I painted my engine bay with a super slick/high gloss white like in the picture I posted earlier. This picture was taken after 6-7 gallons at Daytona with a freshwater rinse at the end of both days and maybe 1 gallon on the lake when I got back. So 8 gallons later and here is what my engine bay looked like. Pretty sweet huh...