If you have bought or are thinking of buying an
aftermarket camshaft (anything not made by smart) you may like to
consider the pro's and con's of ownership and what you want from
your car with the new camshaft fitted.
First off depending on how the cam is designed
the engine will be rather lumpy, Generally you will
have to sacrifice some bottom end torque in favour of mid/top end
power.
A full race cam on the road is an absolute
nightmare if its your only car, not only will your fuel bills be the
same as a Skyline in traffic but its terribly uncomfortable.
A fast road cam (depending on manufacturer) can
be much more manageable, although if its your only car its probably
best to stick with something in the smart range as they are more
suited to the everyday driver wanting something slightly extra.
On our project car we went for a fast road cam
as we wanted something more aggressive than anything smart had to
offer yet still drivable. After fitting we experienced several
problems such as:
Stalling when stopping.
Problems starting.
Engine warning light coming on.
Car falling into safe mode (limp home).
Fault codes.
These problems usually arise as a result of the
management system being too far out of its range and not being able
to control idle speed efficiently for the lumpy cam.
To solve this we simply drilled a 2mm hole
through the throttle body butterfly, (see picture below) this quite
simply allowed more air to pass into the inlet manifold regardless
of the throttle position. This method is a little crude but is very
effective and solved all of the above problems in one hit.
The only noticeable change to the cars behavior
using the method is the engine will idle slightly higher (approx
1,000 rpm) but if you've made the decision to buy one of these
camshafts then I doubt its really going to be an issue.