Just doing a bit more study. I know people bad mouth wiki all the time but I cant help that its such a user friendly source.
The link goes on to say the of the A series engines the 4age is the most race bred being over square bore/stroke. And the 7afe loses this to it economy style set up keeping the 81mm bore seen in the 4 series but increasing the stroke from 77mm to 85.5mm making it very much under square.
It doesnt say this but by my mind a heavily under square bore/stroke ratio means that the piston has to travel further than its over square 4age counterpart? Im not sure if im right or not. This would mean the what the 4a lacks in displacement make up for in top end power due to a high rpm favoured set up leading to it screaming passed the 7 series with ITBs wide open .
I know the 7age set up is mainly for torque but in doing that is the top end scarficed?
Anyone out there who has driven a decent 4age and or a decent 7 series please share your thoughts.
Cheers,
-Jamehij