138Hp or 165Hp

Simple answer is that the quoted 138hp is a net figure and the 165hp is gross horsepower.
My dport supplement quotes the gross horsepower at 157hp.
Thats still a bit shorter of the 165hp which appears on the yellow sticker in the engine bay of the australian ford uprated Dport cars.
The 157 hp is gross DIN, which is euro metric and the 165 hp is gross SAE and when converted the 157 rounds up to about 160 gross SAE.
Possibilities for the 5 hp discrepancy.
Carby settings for europe a little conservative to allow for emissions control that we in aus didnt have.
In 1972 conversion figuring was done by hand and produced inaccurate results as evidenced in the workshop manuals.
Finally there was "rounding up". Why round down when rounding up produces a better looking number?
 
So for ballpark numbers, 
Oval port = 128 net din.
D port     = 138 net din.
D port RS3100 = 148 net din.
 
As far as i can tell, looking into the actual engine and the dport spec supplement its a standard dport 722F apart from any specific carby tuning for australia.

Very interesting  ........... 
is it possible we're not comparing apples with apples due to different RON in variable fuels used here in Oz compared to UK?
Also. I was led to believe our Dizzies had more Advance Curve in our 165 HP than ones in UK ?
And can anyone tell me if it was ONLY Oz V6 that got fitted with extractors, because if they didn't in UK, this would also influence HP figures ?

I think we are comparing apples with apples as both HP figures are quoted out of the UK.  So fuel, extractors, dizzy advance etc. would also apply to Aus oval ports so the relative difference in power would be about the same.
 
Part of the upgrade was a viscous fan coupling so that would have dealt with a reasonable amount of fan power consumption.
 
Jermey Waltons book also states that the D Port upgrades saw max torque drop from 193lb/ft  for oval port engine to 174, both at 3000rpm.

As far as I know. Dport had different pistons to raise compression to acheive more. The oval port flywheel doesn't fit? ( Never tried) and should be matched to motor. Others here know more but that's a start. The Dport block can be made to go much better than any Oval port block. Thicker walls so +60 is a start point not end point regards piston size.

I've been looking at some d-port heads for a few days and from what I can see there is little difference between them apart from the obvious port shape. They are still a high-swirl port. The port finish on the pair I have is poor/very daggy. I cannot see much to account for a loss of torque as per walton's book. Pistons are interchangeable - so no real issue there. Iron heron head will be likely to have greater heat issues for the amount of power produced. 

Gxlcapri1974
Hi beevee,all Essex v6 mk1 capris were fitted with extractors I believe.certainly my facelift in Nz was fitted either new.

Thanks GXLcapri .........  I can tick NZ as one that had them. Did NZ assemble their own or were they imported from Australia or UK?
............hoping someone can vouch for UK or other countries for Extractors question where the Essex V6 was used in Mk1 Capri
cheers

If all official Capri V6 were imported ex UK fully built and with Extractors,  chances are extractors was default equipment on ALL Mk1 Capri worldwide
 
As far as I can tell, the Capri Mk1 V6 was the ONLY mass produced vehicle in the world to be fitted with Extractors as standard equipment, albeit "flimsy" and barely outlasted the "12 months vehicle warranty" !
Lukey, Perry, Stevens, Walker, Can-Am, and the like, must have thought all their Xmasses came at once !
 
Imagine trying to sell a car today with ONLY 12 m warranty ! ........  I warrant very few to zero cars produced post 2000 will be around in anything like 50 YEARS like all our Fords, Valiants, Holdens, Toyotas, Datsuns, VW and the like from the 50's , 60's and 70's that have stood the test of time ! 
.....  plus many Chevs and my 1937 Oldsmobile Straight 8 as in pic !