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I have around 1000 flow tests in my flow bench data base.
Back in the 60's Ford cast special 'thick floor' heads for Cosworth. This is noted on the Cortina GT homologation, move the chamber floor down 4mm of so to increase compression without skimming, and also increases short side radius, which improves flow ( there's a bit more going on but its technical ;-) ). I have seen a few over the years. FJ ones, never a specific 1500 one though. The early Richardson head is almost identical. And it flows much better than a std 105 head. In fact they flow as well as the best 1500 heads, hence FJ's jumping from 105 to 120+ BHP. One I did for a Caravelle made 125 BHP @7800 . . . later rebuilt by a leading FJ engine Co. It made 123 BHP at 9000!!
105 heads . .the ports are too big, I've not seen a new one but I have been informed the ports are smaller. They look better than they flow. Sound better than they go, very Italian ;-)
Other new 'improved' heads I know of
Lotus TC (better casing for cam/follower/lift and 10mm plugs to enable bigger valves without cracks, probably more meat for bigger ports without breaking into the inlet cam bucket area ( seen a few with raldite under the spring seats
TR (2-4) New TR head missed a trick, big ports and no valve throat.
A series ( not seen one in detail, but the limits and weak spots are obvious even to the uninitiated)
289 Ford (I've seen some very expensive original heads with totally OTT porting which in some ways made them worse)
I've seen a lot of CNC heads, V8. V6 and xflow. all pretty crap really. Bling not science.
A good example was a very expensive pair of 289 heads. I spent a few days on them, got 10% flow gain in some places and the engine jumped from 390 to 425 BHP on the Dyno with no other physical changes. The V8 like x-flow suffers from turbulance if ported in a certain way . . .the v* howled, I stuck a screw driver in the port and moved it about . . . . until the noise stopped . . . the flow went up!
Ally CNC xflow head was a chunk of Sh!t . . ports weren't even the same, you could see it, didn't need a flow bench!
A lot of FF heads seem to have been ported for pub talk. good flow at a point the valve won't get to.
I'm no rocket scientist, but its pretty bloody obvious a lot of things have been developed for profit. Equally there are some great performing things out there, most of dubious legality.
I guess we all have our own threshold of acceptability. most claiming reliability, as do I . . . . but reliability at 6-7000, the natural limit of an original engine is one thing . . . . reliability at 8-9000 is something else.
If you were to strip and check most FiA engines and go to the letter of the law more than 90% would be illegal. At a guess half of them would be sensibly uprated and deemed acceptable, the other half . . . part of the ongoing debate, from pushing it a bit to 70's modsports!
Last FiA TC engine I built had Farndon crank and Rods, as per acceptable design, an original head, block and correct length valves, I think it made about 165 BHP at 7000, good torque from 3500. the gains over period will be better valve throats and low lift flow, better pistons/rings slightly higher CR and better cams.
Getting 180+ at 8-9000 is another engine entirely.
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