i have done loads 2.1s only done 1 1800 conversion as budget was tight,i rebuilt bottom end,skimmed 30thow of pistons,ported head,it made 187@wheels on 12psi,that was its limt as slight detonation was heard on 13,14psi,the car in question is still as i built it 4 years ago,cost was just under £1000 pounds.job done,inc buying lump.