Are there limitations to performance of the new high-flow FE heads regarding

[Qikbbstang]

mild to moderate FEs?
    If a guy builds a mild to moderate street motor that will not see over 5,500- 5,800, has 9-10:1CR and is limited to 390-435 cu in. - in short we're not talking big breathing.  I'm just thinking all these new heads that can comfortably handle a 450+ cu in stroker, 6500-7,000+rpm and 550-600+HP might not exactly perform all that well on a mild/moderate motor or will they?......
  Can heads be overkill?....................Be lazy at 1,000-2,000rpm vs production CJ heads/ stock Edelbrocks?
 

[jayb]

I think that depends mostly on the port size, BB.  If the port cross sectional area is the same as stock, but the heads flow better, you are probably going to pick up everywhere, regardless of the engine combination.  On the other hand, if the port is made larger in order to flow more air, you may lose port velocity, which would make the engine feel more lazy at the lower speed ranges (but stronger at the upper speed ranges).  As a general rule of thumb, for any given flow value you want the smallest port possible.  The smaller the port, the smaller the mass of the air/fuel mixture in the runner; this will lead to the air/fuel column moving more quickly into the cylinder when the intake valve opens, and the high velocity will help continue to fill the cylinder as the intake valve is closing and the piston is moving back up the bore.  To make the best power you need good flow, but ports are not just about flow; you need to maintain good velocity of the air/fuel column, along with good flow, to get the best performance.

[Barry_R]

From measurements here.
Take it for what its worth and consider the source, etc.

Intake port volumes:

Edelbrock is 170cc
Survival is    180cc
BBM is         190cc

[BBMTech]

BBM is 182cc. Don't know where the 190cc measurement came from. Both in house and Blair Patrick's independent and unbiased  measurements came up to 182cc.

[Barry_R]

The 190cc came from the exact same setup that provided the other data.
Measured your head with the same valves and valve job I use on mine.
About as comparable as can be done.
Edelbrock heads as assembled by them - not as comparable since they use smaller valves and larger stem diameters.

No negative or positive attached to the measurement.
No bias intended or implied - it simply "is" as measured.

My personal and obvious bias as to cylinder head selection does not have a significant impact upon the fluid.  And the graduated cylinder does not seem to have an opinion either.

Your port entry has a noticeably lower floor entry than mine, with a pronounced rise upward until it goes into the short turn radius. 
Mine has a higher port floor with a comparatively straight run to the short side radius.  That lower floor entry is likely where at least a portion of the added volume resides.  The bowl appears reasonably comparable and your head flows very well when I prepped it identically to mine.  Actually right in line with expectations - a 5% increase in port volume should show a reasonably close percentage increase in flow - and it gave us just that.  A bigger "hole" moves more air - that's why we all want tunnel ports...

I can and have fit Blue Thunder heads into a shock tower car - including my own Torino.  It is not much fun but it will work.  Blue Thunder heads will fit a factory type rocker system as well, but you need to use high riser height rocker stands.  We have modified both Harland Sharp, T&D and Erson medium riser stands to fit.  Its not that difficult a task since all of them have a recess in the mounting for head bolt clearance you simply mill the stand flush to that point and they will work without sacrificing strength.

I sell almost everybody's heads, and each has their place in the market.  Choices are good to have.  I am a little bit of an FE guy myself - I own them, race them, compete with them, build them, sell parts for them, and make parts for them.  I am a beginner compared to some of the folks on these forums, but got my first FE around 1973 or 74, and have had one or more ever since.

[BBMTech]

Your experience as an engine builder is known to everyone on here, and we can certainly respect that. However, we have had numerous very competent individuals whose credentials match yours, who neither manufacture heads nor have any bias whatsoever, and each and every one of them come up with a 180 to 182 cc port volume on our heads. Why yours doesn't match is a question to which we have no answer. Blair Patrick, Jim Kuntz, Jeff Colvert, Rob McQuarie all agree on the 180 number. They do not sell competing products. We confidently go with their numbers, as it matches ours (and some others) and comes from very highly experienced and respected builders with no axe whatsoever to grind. We'll just have to agree to disagree. We wish you the best with your product.  Good luck to you.