The V8 Owners Forum -

Killed some time tonight measuring some parts in the gararge.found some interesting results comparing the GEMS and Thor 4.6 intakes and the late 10 bolt head intake ports.
The ports in the head are 37mm-37.5mm in height and 23-24mm wide.The Gems intake is narrower at 21.8-22.5mm wide and 36.5-37.5mm high,so pretty close in height.
The thor intake however is a lot larger.The runners are 38.1mm as opposed to the Gems trumpets at 37.8 I.D,the ports are 24-25.5 width and 39.5-41mm high.
Quite a bit of mismatch there,the step would cause a lot of airflow disruption I would assume.Might explain the lack of top-end asociated with the thor manifold? None of these parts have been ported or recoed
Doug

ozrover wrote:.Might explain the lack of top-end asociated with the thor manifold?

THOR was designed specifically for low / mid range torque that a 4x4 needs.

Yeah the design has way longer tacts than the earlier stuff agreed.I am dumfounded by the mismatch though.With the stuff I also work on (Chrysker small block,fiat twin cams,Holden 6 & 8 cyl) it is always the other way around, i.e the ports in the heads larger than the intake requiring some port matching.The step produding into the inlet tract at the head face on the 4.6 is huge, I wish I had access to a flow bench.
Doug