start with a ZT 1.8 engine, or a ZR120 or TF engine, or a vvc engine. Then you need ZT 1.8 rods (1mm shorter i.e. vvc mexico spec) and tap the block for the turbo oil return. 1.8T and 160vvc pistons are the same. Over 180ish you will need forgies and better liners. You will also need 1.8T ancilliaries. I would be hesitant to start with a ZT 1.8T as it could have had a hammering with the iffy thermostat position and large bulk to drag around. Either way its all swappable, all you really need is 1.8T rods and ancillaries. Instead of using 1.8T (mexico vvc) rods you could lower compression on a nasp 1.8 or vvc from 10.5:1 to 9.5:1 by excavating 5cc out each head chamber and/or using a shim. standard 1.8t is I think 9.2:1
for a great solution get any old k and add some top notch liners and forgies.
remap by Zand F
I reckon even a 1.8VVC Turbo would be as easy or even easier than a T series.
everyone is different and this is just my opinion but i wouldnt do the above at all, too much grief and overcomplicated and wont be good for over 200bhp. where as for £1500 i would
Buy a 1.8T engine - £600
Buy an emerald ecu - £600
Map it and have 220bhp
find an intercooler £50
use zt / 75 downpipe and weld to existing exhaust
For 3k and a k series i would, borrow a few grand more
Buy a 1.8T engine - £600
Buy forged crank £1500
Buy Forged pistons - £550
Buy Forged rods - £ 550
Buy turbo GT2860RS £800
Freelander Flywheel £25
Rover 220 Turbo Clutch 228mm £350
Custom exhaust to suit turbo £650
Custom Intercooler £350
Custom Rad £300
250bhp all day long with +250lbft torque
To get a bit more i would
VVC Head - £100
Port Polish - £450
Bigger Valves (for a giggle) - £1000
Piper 270H cams to suit head- £400
EVO4 Block scholar 1.9 - £850 irrc
This will see above 300bhp but you will start to see problems with the liner wall and with heat
Or forget the above and buy a T series, much simpler, cheaper, its been done lots before (only a few proper 300bhp k series in existance, one in a mini, one in a metro, one in an elise, one in poland in a metro)
VVC turbo would be a good idea due to the infinite cam timing, but the mapping would be a while longer and rev limit of 7500