What would be the best heads for me?
Heads that I am thinking about (don't want to go over $2K):
Advanced Induction 223cc Dart/RHS
Advanced Induction 226cc GM LS6/LS2 + used 243/799 cores
Advanced Induction 232cc GM LS6/LS2 + used 243/799 cores
PRC As-Cast 225cc LS1/LS2 Cathedral Heads
Trick Flow® GenX® 220 Cylinder Heads for GM LS2
Also, the TFS 220s I'd seriously look at, but with the upgrades TEA, BTR, Tick, or VR does to them - installing PM guides (for stock rocker usage), new valve springs, and turned-down LS3 valves, and sometimes, hand porting. Price might creep over 2k with all those options, but they would beat down a lot of heads and offer no real downside.
Is there any downside to getting the Trick Flow ones over the machined AI Dart heads? Prices are just about identical, but the AI 223s have better hardware installed.
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Last edited by dr_whigham; Jan 31, 2015 at 12:34 PM.
I wish there was more info comparing the TrickFlow 220's to the PRC 225's. The PRC's look to be a really good deal and should really be advertised as semi CNC'd heads instead of as cast, the chambers and valve guides are CNC'd and any transitions for the CNC work to the as cast portion along with any casting defects are hand blended.
The PRC225 heads seem like quite a kick *** cylinder head but just don't seem to get the "check my dyno numbers" cred they deserve. I'd love to throw a set of those on a 4.8 crank/ 4.200" bore LSX block and an 80mm snail shaped muffler thingy....

What is the advantage to changing the valve angle, besides piston clearance?
What does relocating the spark plug accomplish?
Combustion chamber shape also plays two huge roles as well.
First you want it to be large and smooth enough to unshroud the valves which are actually in the way of flow. Second it needs to be shaped in a fashion to promote compression turbulence/efficient combustion. This is why engines respond to tightening the quench clearance, it reduces the Brake Specific Fuel Consumption.
Company A, 4” bore NO EXHAUST
Intake Exhaust
.100"___68_______56
.200"___145______113
.300"___210______164
.400"___257______200
.500"___300______214
.600"___318______229
Company B 4” bore 1 7/8 exhaust
Intake Exhaust
.100"___66.7____52.5
.200"___149.4___113.1
.300"___217.6___156.3
.400"___262.7___201
.500"___297.3___247.6
.600"___311.4___273.3
Company C 4” bore 1 7/8 exhaust
Intake Exhaust
.100”___67______47
.200”___133_____104
.300”___211_____167
.400”___263_____202
.500”___297_____222
.600"___314_____233
The PRCs are nice, but I prefer much lighter valvetrain components for both power and reliability. The PRC 2.06" intake valves are a bit heavy especially compared to the 2.04" turned down LS3s you can get for the TFS.
And as I said earlier, the TFS 205s are fully CNC ported, come with smaller chambers, and the PM guides. They flow as well as any of the others listed, but with more velocity due to their mid-lift numbers and cross-sectional area.
One word of advice: don't get caught up in flow numbers. It's a waste. The numbers vary so much bench to bench. Buy what actually makes power.
I went with the TEA Stage 2s... I have yet to find anything that puts out consistently higher power than these LS6 castings (including the TFS 215s). But when I bought these, they were a better deal. If I had to do it today, the TFS 220s is what I'd do.









