Forced induction and ported heads?
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 948
Likes: 0
From: orlando, florida
Forced induction and ported heads? There have been a few posts that have touched on the subject but never really got to indepth. How much HP are ported heads worth on a FI car? Most of the guys here running turbos or superchargers have ported heads but in a lot of the tech articles i`ve read they say that having your heads ported is usually money that could be better spent elsewhere, Is this true? If you have a good intercooler or alky injection would you be better off just uping the boost 1-2psi? I understand that if you turbo or charger is maxed out then you`d want to work on improving flow, but if you have plenty left is it worth it? 
Anyone that has before and after dynos of head installs let me know what you came up with. Thanks. 
Anyone that has before and after dynos of head installs let me know what you came up with. Thanks. 
Stock heads are probably fine for a good street turbo (450-550 HP)
Beyond that I think full prep is necessary. Chamfer all holes, tap all threads, deburr it completely, Remove excess spark plu threads to prevent pre-ignition etc.
As far as flow , airflow will be much higher through a turbo moter than NA obviously so any imperfection is expodential...so clean hand porting is definately a good idea...however is hogging them or worries about velocity as important as NA...I dont think so...but just incase I went with Stage 3 cnc/hand finished heads. There is some talk about porting procedured that can deter the reverse flow of the exhaust (sucking from the manifold back into the head). Most importantly is having excellent valve seating.
Beyond that I think full prep is necessary. Chamfer all holes, tap all threads, deburr it completely, Remove excess spark plu threads to prevent pre-ignition etc.
As far as flow , airflow will be much higher through a turbo moter than NA obviously so any imperfection is expodential...so clean hand porting is definately a good idea...however is hogging them or worries about velocity as important as NA...I dont think so...but just incase I went with Stage 3 cnc/hand finished heads. There is some talk about porting procedured that can deter the reverse flow of the exhaust (sucking from the manifold back into the head). Most importantly is having excellent valve seating.
I personally used stock heads from an Escalade. I hand blended the valve seats into the bowls, polished the exhausts to reduce carbon buildup.and polished the combustion chamber to reduce the chance of knock. I swapped in stock size Ferrea stainless valves for their durability, 918 springs for the baby B1 cam I'm running, and had TEA O ring the heads so I can run a shitload of boost. But the runners themselves are unported, if I dont get the power I want I'll switch to a set of ported TEAs later.
But for now we'll find out if it works when I hit the dyno on Friday.
But for now we'll find out if it works when I hit the dyno on Friday.
