Yes, I'd agree about the better cooling system, but to get most of the
benefit you've got to put the whole thing in and not just the long
block. And to get full advantage of the 21's better breathing, you neet
to bring the injection and ignition system along too. (I know Dennis
knows this! Others have advocated changing just the long block.)
Al Brase

Dennis Haynes wrote:

>The 2.1L engine is the same head and gasket design but the cooling
>system has some design differences that make it superior. Much more
>tolerant of air or gases in the system and mostly self bleeding if there
>are no leaks.
>
>
>