Hmm, did dig up an A-B comparison of TFS vs BBM CNC on the same bench. As the title states, results are surprising. The numbers don't seem to jive with other published numbers, but heads done on same bench are definitely the best comparison.
https://www.fordfe.com/bbm-cnc-vs-trick-flow-out-of-the-box-surprising-t162336.html
Also, I hear "flow isn't everything" parroted quite a bit. I agree. But if both are similarly prepped with proper valve and throat size, and valve job, and both are modern chambers with good quench....is the smaller cross section with better average flow not the preferred head for a majority of builds (not talking about an 8000rpm 510ci all out drag build)?
With those elements all known, are they talking about airspeed being too high in the small head where it's going to be turbulent on an actual running engine? Could it be a low floor/short turn showing good flow but causing fuel shear or turbulence on a running engine?
I had found that thread (again) & it's one reason I asked. In that thread the BBM intake seems more like a CNC number, but the exhaust looks too low to be CNC. The TFS exhaust looks higher than Brent's "no pipe" flow but is close to the TFS website's "with pipe" flow.
It now seem like their websites arent that far out of line, and if you compare BBM_CNC with NO pipe to TFS_CNC with NO pipe (subtract about 25 from their website numbers) they're pretty close. They are pretty close in burn efficiency too from the dyno data I've seen, BBM may even have a slight edge but too close to call. So it's down to price reliability, and availability.
As far as reliability, well of course header bolts aren't main caps, but that is part of the problem- they see a similar environment. They've got heavy headers with a long swing-arm hanging off them, with a cam shaking them every rev for 50,000 miles and 100,000 traffic lights. (We add as many traffic lights as we can here in CA for Safety, and sometimes just to Hate on Cars in general). With that kind of vibration environment I'd prefer inserts in aluminum- but not if THEY are going to strip out. I'm just over-cautious with aluminum - I know people use those carb plates to pull an engine/trans from an aluminum intake, which I would never do, but it seems to work.
On price I fully agree, if BBM is that far out on price - you do have to allow some bucks to get TFS stands cut, and I shudder to think what that would cost out here in CA, we have so many people to feed, so likely best to buy stands milled to order, but seems the BBM are still higher. Maybe TFS will update theirs to 2% inflation when they come back out & they'll be $2800/pair.
