[Barry_R]

OK
I've watched, read, listened, and even unknowingly provided a fair amount of the info in this thread. Some info I provided was referenced without crediting the source. Some is right, some is wrong, some is out of context. This is pretty long - but it should be helpful. I apologize in advance for the length.

I built the Engine Masters Challenge 505 FE. Development dyno work was done at Wheel to Wheel Powertrain in Michigan. That work was handicapped by dyno fixture interference that required the headers to be installed upside down and thus block a portion of the exhaust port. With that known limitation we left for the contest with expectations of about 725HP and maybe a bit more with the headers on properly.

It made 752HP at 6300-6400RPM at the contest on Bill Mitchell's dyno on 91 octane. Jon Kaase took that same engine, disassembled it for photography (for his upcoming big block Ford book), and then put the freshened piece on HIS dyno. On Kaase's dyno that same engine made 759HP at 6500RPM. That a reliable backup number in my book.

That motor has out of the box ET CNC ported Blue Thunder head castings, assembled in my shop. I am geographically very close to ET and have a developmental relationship with them on this product. These heads flow at 360 on the intake as tested at ET, with that number verified by both "Birdie" at Flow Technologies, and by Kaase himself. I have not flowed any B-Ts in "as shipped" condition. Since they are designed to be ported such testing is largely irrelevent. The low flowing set referenced in the FE Forum thread were said to have been "butchered" by the person who posted the data.

The development mule for the EMC project was my "other" 505 FE - - the
"675 Horsepower Dinosaur" featured in the July 2004 Hot Rod magazine. That engine is well documented, thoroughly flogged, and had a well developed set of Flow Technology Edelbrocks (around 330). We used it to A-B test parts instead of using up the contest engine. Other changes got us to repeated 689HP pulls. Swapping to CNC BT heads with an intake port match job gave us 30+ lbs/ft. more torque throughout much of the curve, and about 10HP at peak. It also got us 1.7" of vacuum in the intake - - the engine now wanted more air. A Dominator throttle body on an adapter gained us another 13 - ending up at 712HP for a cumulative peak power gain of +/-23HP.

Punchline:
In my opinion, based on my testing, the Blue Thunder heads will make more power than a similarly modified set of Edelbrocks. The Edelbrock assemblies, with 2.09 and single springs, are nice for a driver but not useful in this context. Edelbrock bare castings are around $1000 - - the B-Ts around $1400. The CNC program is around $1500 for the B-T vs. $1350 for Ebrocks. Valves, springs, etc. are the same. The B-T requires high riser stands - - we fabricated our own at a street cost of roughly $350. Standard rockers and shafts will work - - so total added cost to go B-T is $900 comparing apples to apples. Using the added B-T fastener locations and the available T&D setup will provide a far more robust max effort race valvetrain package than is possible with any Edelbrock based combination.

The intake manifold port mods req'd are within the skill range of an experienced hobbiest, port work and pushrod tubes are also common to highly modified Edelbrock heads. The added .400 in exhaust port height may be an issue for some - but I was able to install the BT equipped engine into my '69 Torino with minor denting on a set of shelf Hookers - - they required some denting with the Edelbrocks too. Your hammerring may differ. Detail data and images of the CNC B-T heads are readily available on my web site.