Benchtop building - maybe stupid, maybe not

[philminotti]

I'm so curious about these new head improvements, especially the CNC BBM product.  Let's say we took my 10.5:1 482 that currently has KCR
Stage II E-broks on it with a 248/252 .633 hydraulic roller cam and a nicely ported JDC Victor intake on it and just swapped in the BBM CNC heads (or Survival CNC heads, for that matter)...any educated guesses about that?  Or would one only realize major improvements with a max effort .700 solid roller cam spinning to 7K+ rpm?

As someone who is always impressed with new, shiny gizmos...just wondering out loud.

[Joe-JDC]

Look at your KC II flow sheet for .650"-.700" lift figures, and compare them with the figures posted for the BBM.  What is the difference?  That will tell you if it is worth the cost of changing everything out.  Take the average flow by taking the numbers at .200-.700 for both sets of heads.  The difference in cfm x .257 will tell you approximately how much you will gain or lose.  I bet there is not 20 hp difference between the two sets of heads at that lift.  Joe-JDC

[philminotti]

Thanks Joe.  Not having the experience or knowledge to make such comparisons, I was just curious.  BTW, the EFI Victor you ported for me is a gem.

[blykins]

Barry's head flows almost 370 cfm @ .750" lift and at your camshaft's lift, they move about 355 cfm.   All of that with just a 196cc port volume.   I'm pointing out the port volume because other heads that move that much air usually have a much larger port and much less velocity.

IMO, I think you'd gain a nice little bump with a head change.  If I'm not mistaken, Keith's Stage 2 heads move about 315-320 at your camshaft's lift. 

Here's the numbers from where I flowed one of Barry's heads....

*4.155" Bore Plate, Intake Flow

.1 102
.2 163
.3 229
.4 294
.5 324
.6 349
.7 364
.8 369

[blykins]

BTW,

Here's some flow numbers I have on Keith's Stage 2 Edelbrocks that I have here:

.300    220/162
.400    271/191
.500    304/214
.600    312/231
.700    322/246

This is a 180cc port.

[philminotti]

Thanks Brent.  When I get tired of my rear main seal doing an Exxon Valdez impression, maybe that's something to consider.  Right now, I'm losing a bunch of power through my inch and a half tailpipes on the Cobra.   The real estate under there is just so tight...

[Joe-JDC]

I have a set of KC IIs that flow 338/226 @ .700" with a 2.150/1.710 valve.  I have tested a couple of other sets for folks that flowed very similar results with same size valves.  My hand ported Survival heads flow 352/252 cfm @ .750" with a 2.150/1.710 valve,  and the port volume is 196 ccs.   Joe-JDC

[BigBlockFE]

sweet, I need those heads