Extrememech
1. lighten & balanced - About RM600.00 excluding labout to remove the block + fllywheel and
to reinstall it. Add this and alot more...... as firstly when you do this, better add new pistons (+1size), rings, conrods, conrod bearings and get a lightweight aluminium pulley to be balanced also. Cost should be around 2,000.00 for all these parts plus labour. So should be 2,500.00+- for this whole lighten and balanced thingy.
2. 1.8 stroke.
The 1.6 cannot use a 1.8 crankshaft. Most it can go is 50-70cc more from a machined offset crank and slightly bigger pistons.(if your mechanic is smart that is). 1.6 is short stroke compared to 1.8. i.e it's more rev happy but less torquey than the 1.8.
Of course changin the engine is cheaper. But remember when you do this, its like having a completely rebuilt engine that could last longer than a half-cut which has 60k mileage. Power wise...you'd need to add a 1.8 dohc head (nicely ported and skimmed to around 11:1 cr) and some nice fastroad cams, proper fueling to make the 1.6 be really extreme. With all that, you could have a very balanced 7,500rpm 1.6 that's as fast as any 1.6 mivec. cost? add 1k plus for the head and the head job, nearly 2k for cams, 350.00 fuel regulator, better fuel pump (or run it through a relay for better pressure), exhaust system , piggyback ecu for fueling, cold air intake, etc...you'd be making about 160bhp or more if done properly.
I'd honestly not go down this road...i'd get a 1.8 and then start moddin that if i wanted to tweak the bottom end. My 1.6 is almost complete as far as i'm concerned, i'll just go 1.8 (4g93) for more torque. For the road, torque is more important than horses.
regards