the sr engine in a 180sx is 2689 lbs... almost exactly same as the ka
if you want weight reduction get a ca, that in a s13 silvia is 2469 lbs.
next time try typing sr20det weight in google...
google answers 90% of your questions peeps...
also of note, i managed to purchase the name
www.rb25det.com -- if anyone is interested in purchasing it contact me.