Well, everything is changing, I wouldn’t expect too much more w/ the current setup (right now the car has 1 3/4" Kooks on a 348 cui forged LS6, ~440RWHP w/ a small cam). But everything is changing… if you look back at some of my posts in this thread my builder sent his spare LS7 block off for sleeves for me, but it was damaged beyond use so I actually just ordered up one of these instead…
(LS7-based 427cui Shortblock)
…that showed up earlier this week. I’m doing a full, true dry sump, eliminating the in-motor oil pump and doing it “right” (as opposed to the LS7 style semi-dry sump which uses an in-motor pump for pressure and a sorta half-assed scavenge pump).
I’m looking at PRC’s 265cc LS7 heads, but since I haven’t actually ordered them I haven’t posted them in this thread. The cam will probably be in the high 240s intake, low 250s exhaust (split towards the exhaust to make up for the stock Ti mufflers/tips which I will retain). I’ll also do the FAST 102mm intake manifold/Nick Williams 102mm TB but again, not purchased yet so no pics in this thread.
All-in-all I’d expect about 580-600 RWHP without the Ti exhaust restriction I’m putting on it, so I’m looking at more like 560-570 maybe? My builder made 590 I believe on his C6Z w/ the same heads, smaller headers (1 7/8" all the way) but a true 3" exhaust and the 102/102. And that is with the C6Z semi-dry sump which does not actually pull vacuum. Builders are telling me they see 10-20 flywheel HP just from crankcase vacuum.
Only time will tell what it really does.
The headers are 1 7/8" at the flange, transitioning to 2" where you see the first weld in the primaries, then 3" collectors, yes. My X-pipe which I’ll keep is 3" necking down to 2.5" being that it mates to the factory Ti exhaust (which is slightly under 2.5" IIRC).
I will probably be giving up ~20 RWHP w/ the Ti but I love the sound, and I still want to be able to run some of the courses around here w/ sound restriction (Laguna Seca, Infineon aka Sears Point, even THill techincally has a restriction and its in bum-fuck nowhere).
We’ll probably make a few pulls w/ the Ti’s disconnected (still going through the 3" to 2.5" X) just to see what I’m giving up vs. aftermarket catbacks.
-TJ