bigport to smallport install

[totta Crolla]

I have done this and I am using a cut 'n shut inlet manifold.
The cut 'n shut is straightforward for anyone who can accurately cut and weld aluminium just make sure they get the angle of the throttle body somewhere
close to the TVIS inlet otherwise the TB can foul the bonnet.
You will need somewhere for the air temperature sensor to screw into and
you will also need to get some bosses welded on to allow fitment of the throttle cable.
It is all worth the effort and the smallport inlet is half the reason why the
smallport makes the power it does.
I used big port injectors in the smallport fuel rail and a big port ecu, there
were no problems with this.
The smallport ecu is completely different to the bigport and requires
extensive rewiring.
A spigot bearing will need to be fitted into the crankshaft, an easy job
just tap it in using a suitable drift.
Expect a couple of clearance issues with the water pipes and the
oil return from the head, easily solved though.
Bigport cams with adjustable pulleys are a worthwhile upgrade especially if you already have the cams.