I can't give you exact numbers but I'm bless to have access to some guys that have tested both aluminum and iron blocks in heads up in a limited tire class with both aluminum blocks and iron blocks filled and unfilled. They ended up going quicker and faster with the filled iron block after a lot of testing and racing both combinations up
What type of blocks do NHRA pro stock use today work
This debate will be ongoing until further notice stirthepot grin
I have a Koleno high nickel block in my shop and a new KB aluminum Wedge block on its way, I want to build a wedge B1-MC headed motor for running in NHRA Top Sportsman class in my 1965 Dart, I'll build the Koleno block first luck

Last edited by Cab_Burge; 08/14/20 12:55 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)