Curiously enough, Nissan didn’t incorporate variable valve carry or variable valve timing for the RB26. However, you could fix the lack of VVT and VVL with HKS’ “V CAM” program. The camshafts are driven by a timing belt while you’d anticipate. It commenced in 2017 with just some pieces like https://lanecavto.theisblog.com/28837257/nissan-rb-engine-for-sale-no-further-a-mystery