A set of 317's and head studs will work down into the 8's, your bottom end will murderized if you push it that hard. A set of aftermarket heads will make more power but is 30 or 40 hp gonna matter if you are running a stock bottom end LS.

317's come stock on 6.0 iron blocks the bore is not a problem. Just run the correct head gaskets..

I never had a set of AFR's but I hear good things about them. My last set of aftermarket heads were TFS 215's, was very happy with those. I ran a set of AllPro's in the past too. I ran a set of 317's on top of a low budget 8:1 348 LS6 and went 9.40@144 with 680rwhp with a blower @3500 raceweight back in 2006.

 

what is a good head gasket to run. i have been running stock gm 6.0 gaskets with the 317s. is there a stock gasket that is better?

 

1262-2033 7-Layer factory LS9 blower gaskets. These are the best for 4.080 bore or smaller on heads and block for MLS.

 

MLS sprayed both sides. Your 4 bolt head is the weak link under boost... not the gasket. Like John said... do studs.

 

sorry forgot to mention is already has arp studs torqued to 80. not really having an issue with what i got now just didnt know if aftermarket heads would be worth the money for the little extra. i figured the bottom would go first

 

A good aftermarket head is going to be 40-50 hp better than a stock casting. At 15 lbs of boost that gain is going to double.

The TFS Fast As Cast heads with a little hand work to blend the CNC bowl blend into the ports and profile the guide bosses is killer bang for the buck, especially if you can do the port work yourself.

I had a guy contact me that had some hand blended TFS Fast As Cast heads, pulled them off for the most expensive aftermarket 215 heads made and didn't pickup any power.

I hope this helps.

 

The TFS Fast As Cast heads with a little hand work to blend the CNC bowl blend into the ports and profile the guide bosses is killer bang for the buck, especially if you can do the port work yourself.

I can't believe my eyes Brian! Hand port a CNC head? :smt118


Wait until I tell Casey about this.

 

how thick are those LS9 gaskets compressed? I didn't know at the time but I used 5-layer LS3 gaskets on my nitrous 403 motor.

 

They are also about .052 or so compressed like the 5 layers 1261-0046 which are also very good.

 

Thats good info. I had alway's seen everyone claim the LS9 gaskets were awesome but I didn't know they were that much different from the LS3 gaskets. Any good 4.125"+ bore gaskets out there?

 

we use cometics in that range and they are usually LSX blocks too at that bore so the work great.