I hurt the engine so as I rebuild it I want to loose the hand ported 241 heads I am currently running for an aftermarket casting for the thicker decks. However, I am in a quandary if the CNC versions from PRC, TFS or AFR are worth the $800+ premium over their as-cast beginnings. As for strictly looking at advertised flow numbers, the TFS 225 CNC outflows the as cast 220 version by quite a bit where as the PRC 227 CNC and 225 as-cast don't differ much at all in cfm.

Here is a snapshot from excel comparing the flow data of the TFS and PRC offerings...


I am just wondering on an as-cast version, when they cnc the combustion chambers and do the valve seats, are the bowls blended as well? Would an as-cast runner be more or less consistent between all runners as a CNC'ed runner? (This is an issue I think I am currently having with my hand ports is #2 is getting significantly more air that the others.) These are the biggest concerns I have with an as-cast in a force induction setup.
Thoughts??

 

Pony up for aftermarket castings for thicker deck. Good to see you think like me. Any set back is a set up for a comeback! Good luck man!

 

prc 225 as cast looks like an easy decision for F/I. that graph makes me love my CNC TFS225 heads

some of the FI guys on tech are doing awesome with ls3/vic jr setups. not sure i'm ready to jump on the LS3/L92 N/A bandwagon but it's hard to argue their FI results.

 

Just food for though.. its not always about cfm but rather port design and velocity.

 

What did you do to your motor?

 

I am not as concerned about intake flow numbers as I am exhaust which is where the CNC TFS really shines above the others.
I have to stick with a cathedral port to keep the KB otherwise I would be looking at some rectangular port heads too.


Which is exactly the reason for the question at hand and why I am wanting to stay with a head in the 220ish cc range.

Not exactly sure yet. I have a knock on the passenger side lots of metal in the oil and filter. Thinking either a bearing or cam/lifter issue considering all the metal is silver, some iron, some aluminum. I will be pulling it this weekend to start going thru it.

 

No other opinions on AS CAST vs CNC for forced induction?

 

It looks like the CNC version has a slight flow advantage so why not go with them? I would also think that runner volume is more consistent as well.

 

CNC version is a lot more expensive.

 

Cnc...