Question about camshaft

[jondee86]

Camshafts are not as important for performance on forced induction
engines as they are for naturally aspirated engines. When air is being
pushed into the cylinder under pressure and there is a turbo in the
exhaust, intake tuning and exhaust scavenging play a reduced part in
overall performance. Of course, anything that helps the smooth flow of
air (reduces resistance) will be beneficial, so a properly designed intake
manifold, head work, decent exhaust manifold and correctly sized exhaust
will help extract the maximum from your setup.

Stock 4AGE cams work just fine for a lot of people. If you want to go
further look for cams with more lift but without a lot more duration.
Around 8.1-8.2mm of lift will work with stock springs, and duration in the
256-264deg (advertised) range. Kelford Cams make a set of 193-T turbo
cams for the 4AGE with specs 262/266 Degrees advertised duration.
8.25mm/8.25mm lift. However if you look around you may be able to pick
up a set of used HKS cams for less money.

There is a fair amount of voodoo involved in matching cams and cam
timing to a turbo. Your turbo needs to be matched to the engine to
ensure that it operates in the higher efficiency part of its performance
map. You will need adjustable cam gears and the makers of turbo cams
often recommend uprated valve springs to make sure the valves close
correctly at higher boost pressures.

Cheers... jondee86