What are the main differences/advantages in the DOHC head vs. SOHC head?
While the exhaust ports are the same size on all of the heads in question (1g and 2g DOHC and 4G64 SOHC), the intake ports vary wildly between them. The largest intake ports are found on the 1G DOHC head, followed by the 2G DOHC head, and finally our 4G64 SOHC head. For comparison, the 2G DOHC head intake port is 27mm x 55mm in size, while our 4G64 SOHC intake port is 27mm x 43.5mm in size. That’s about a 20% reduction in size. For NA applications, the extra size won’t gain you a ton, but in turbo applications, the better flow will be very noticable.
