As a rough estimate,(not that it helps in your case), I think the 1.8L DOHC, and having the duel runner intake, my guess is 85% efficient.
For your Gen1 GT...I´m not sure at all, but here´s a rough estimate.
SOHC motors are generally 45%-65% efficient. I think it would be safe to assume a HO anything would be close to 65% if not more.
Here´s another interesting fact. It is actually possible to get more then 100% VE efficiency out of a head. I´ve actually seen a 350 chevy with 110% efficient VE, running naturally aspirated.
For your Gen1 GT...I´m not sure at all, but here´s a rough estimate.
SOHC motors are generally 45%-65% efficient. I think it would be safe to assume a HO anything would be close to 65% if not more.
Here´s another interesting fact. It is actually possible to get more then 100% VE efficiency out of a head. I´ve actually seen a 350 chevy with 110% efficient VE, running naturally aspirated.