a cam (238/242 .608/.610 115LSA) only C5Z06 with full boltons, alum. flywheel, U/D pulley, FAST 90/ported LS2 90 making 438rwhp 397rwtq, how much more would it gain from switching from the stock ls6 heads to AFR 205s??? AFR 225s?

will a AFR 225 head make more power than a AFR 205 head??
what's the difference between the heads?

 

Gains depend somewhat on your final compression ratio. Since compression is your friend, especially with a cam of that size, I'd recommend a 59cc combustion chamber size and a .040" Cometic gasket. This will put your compression in the 11.5:1 range.

If you do this, you should expect 35-40 rwhp gain over LS6 heads with either the AFR 205s or small bore 225s. I've swapped from AFR 205s to AFR small bore 225s and I'm here to tell you that the gains would be very small if you're running a 3.900" bore. The 225s shine on 4.0" bore sizes and larger. My recommendation? Run the AFR 205s in the 59cc size and look for a nice jump in power AND torque...plus you'll get better throttle response and fuel economy over your stock LS6 heads.

 

with 59cc and 2.02/1.6 valves, won't flycutting be necessary with that cam?

 

Yes, you will need to flycut but if you're going to let fly-cutting stand in the way of getting an ideal combination, you're not that serious about doing what it takes to get there. Fly-cutting is necessary if you want to keep that huge cam. You could always run a smaller cam with better DCR and avoid fly-cutting.

 

I 100% agree...AFR 205s will make that car hard to beat on the street with that cam combo.

 

But he can also mill less...say till 62cc no?

I would imagine with that liftand duration hes not going to give up much hp with less CR.

 

More compression and with less duration makes equal horsepower, but more torque than less compression and more duration. As I stated earlier, get all the compression you can stand and get the tightest quench you can achieve. This will go miles further in giving you the ideal balance of power over a broader rpm range.

 

Louis @ LG mentioned in another thread, that even their G5X4 will work with 59cc AFR's and the .040 cometics and still not need flycutting.

The X4 is "bigger" in every respect than the cam posted here, on a much tighter LSA too.

I don't know who's right or wrong...but since I have an X4, I'd like to know myself. Supposedly the AFR's have more p/v clearance than stock heads, but I'm still skeptical.

 

There's no way I would run an X4 with 59cc AFRs without flycutting. If you did, I'm sure you'll get some valve reliefs automatically the first time you start it up