The long awaited SpeedCircuit Heads for the 4B11 Evo X are now available! All SpeedCircuit heads are completely stripped down and rebuilt, including new parts where necessary. There are 3 stages of heads available.
Stage 1 includes:
Special five-angle valve job
Bowl work to blend the stock machine cuts into a larger bowl
Resurface (if needed)
Valve lash set
Pressure tested to ensure no leaks
Stage 2 includes all of the above, as well as:
Completely ported and knife-edged intake ports
Completely ported and knife-edged exhaust ports
The extra porting and knife edging results in a larger port that is more consistent than the stock port, resulting in smoother power and better airflow.
Stage 3 adds deshrouding, but is only available on 88mm bores and larger (stock bore is 86mm).
Order will not be shipped until shipping is paid in full. This item is custom made to order, and therefore is not returnable. Please allow 3-7 weeks for delivery.