Cams and Tuning

With a well-matched set of camshafts and adjustable cam gears, a good tuner

should be able to smooth the transition to boost and to play with the power

delivery to allow some of the seamless acceleration to return.

Cams achieve this goal by regulating airflow through the cylinder head. The

big boost supercharger or turbocharger is trying to push an enormous volume

of air through the engine. Even if every restriction in the intake and exhaust

path has been eliminated, the bottleneck created by stock cams impacts the

power delivery and makes for a shorter and peakier powerband.

A set of performance camshafts (intake and exhaust, see Chapter 15 for

further discussion) adds more valve lift and duration to your cylinder head.

They allow you to run less boost with comparable results. The downsides

are that they

-

 Take more labor than simply upping the boost

-

 Reduce your low-end power

-

 Mess with your idle (cams with a high duration and lift have a distinctive

loping idle)

-

 May make your car’s emissions illegal. Since cams are altering the way

your car burns air and fuel, your tailpipe emissions may be affected.

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