Static CR & Intake Cam Duration Relationship - Team Integra


more info from team-integra @ Engine Package : Swapping Parts For Power - Team Integra:
Camshaft Choice: With the piston geometry described in 1. , B18 engines like Long Duration, Big Overlap Cams because we need more scavenging and time to fill the chamber, especially at high rpms .

eg. of high overlap cams :

- for the B18A/B Crower 62403 or 62404.

- for B18C Toda Spec B, Jun Type 3, Skunk2 Stage 2, Crower 63403, Zex 57300.

The exception to this rule is when we add nitrous, a turbocharger, or a supercharger. Intermediate overlap, short duration cams are chosen to prevent the boost from shooting into the exhaust manifold with a long cam overlap.

eg. intermediate overlap short duration cams for forced induction:

for B18A/B - Crower 62402/62403, Crane 101-0014 turbo cams

for B18C - Toda Spec A, Jun Type 2, Crower 63402/63402A, Zex/Compcams 57100 or 57200, Crane roller 253-0510 cams with roller rockers.


However, with more intake cam duration there is a greater chance of cylinder pressure being lost out of the opening intake valve. We lose dynamic compression . Along with High Piston Speeds Away From TDC, big overlap cams will reduce cylinder pressures and prevent efficient burning or combustion of the air fuel mix.