Mate, if you want to go supercharged, the 1.7 8V is easier to build.
But if you are planning on doing this with little expenses, its not going to work very well.
Have in mind that our boxer engines only have 3 mounds for the crank - so they arent very strong to begin with. Piston rods are fine if you are stock but they are probably the weakest point on our engines.
Pistons themselves might or might not take the extra pressure - depending if you have a good management ecu.
In other words, supercharging the 8v will need :
- Steel crank
- piston rods
- low compression forged pistons
- if you are getting wet you might as well go for ported heads, bigger valves, solid tappets.
Then of course you need:
- standalone managed ECU
- the supercharger
- relieve valve
- various sensors, tps, coil pack, crank sensor etc.
If you want to boost up your engine, it doesnt matter if you want to go 30 bhp up or 70 bhp up, if you are planning on doing a proper job, have a good 10 grand aside to play with :/
Other option - 16V engine with carbs.
you will need:
- 16v engine
- old broken 1.5 ti carb engine
- 16v front crossmember section
- 16v exhaust manifolds
- carb adaptors
- gasket set.
you will get rid of coil packs, ecu's, crank sensor and tps, air flow meter and all that junk that just slows the car down.
I would expect you could find both engines for 500 - 600 pounds, with all the things needed afterwards to make it work, you'll need less than 2 grand to finish it, plus you will still have your 8v engine stock and untouched
its up to you how frustrated you would like to be