Hey guys, just like title states - I'm trying to figure out my best bang for the buck approach at more power. Truck right now has a 6.0 with TSP stage 4 truck cam and factory flat top pistons. Truck has prc heads with 62cc chambers. ls9 head gaskets atm. Engine has been together for roughly 2 years and about 8k miles. I haven't done the math in a bit but I thought it was right around 12:1 compression. Dynoed at lsfest at 450rwhp. I need more. Also, broke 3 10 bolts so far - upgraded to 14 bolt with truetrac and 4.10s recently.
I'm trying to figure out which way to go - procharger - lsa - whipple- or turbo/turbos. I'd like to have around 800rwhp. I'm not sure exactly which way to tackle this - which is going to be the most cost effective/safe for the combo I have? Or is it time to sell this engine and start over with forged internals? Each power added has pros and cons - I understand - but which makes the most sense? Also - this is my daily if that sways anyone in any particular direction. I'm very open to suggestions. As always - thanks for your time and advice.

 

With that compression your engine will not be very happy with forced induction even on e85. I would either throw in some lower compression pistons for boost unless your planning on running something really high octane in it.

 

I appreciate the advice. I know with any type of FI - I'm going to have to lower compression. I'd like to get by on 93 pump gas. I'm just trying to figure out which is the best way to go to make great power, be reliable, and daily driver friendly. I've been looking at prochargers website and the kit they sale says 55-65% more power then stock. I'm already pretty far from stock. How would one of their kits work out for me? Say the p1sc charger? How much boost am I looking at to get to 800 rwhp? Is that even possible with this charger or would I need a larger one? Do turbos have to be retuned for large weather swings? Would a turbo setup be better? Do I need forged internals? Whats the limit for a gen4 stock bottom end 6.0? Truck right now has a walbro255 in tank. How much larger of a pump am I looking at? Lots of questions - I know. I'm searching - just not finding what I'm looking for I guess. Thanks again for the help.

 

I’m still fairly new to ls Motors to be honest but I can lend you a little knowledge from my other forced induction backgrounds. As far as fuel supply a 450lph should support about 700whp give or take on pump fuel so you’ll probably wanna go with a dual pump setup if your stuck on 800whp. The super chargers are going to take power to run as the motor has to spin the charger where as a properly sized turbo uses exhaust gas to spin itself. Generally speaking turbos will make more hp per lb of boost and be a bit friendlier for pump gas when matched well with the engine, turbos will have lag as well as spool up time but if you have a well matched turbo system for your engine it can be very minimal. A pd style blower will have no lag and full boost right off the bat, a centrifugal blower will gradually make more boost as rpms go up. As far as having power later in the powerband it’s not always a bad thing, allot of times a gradually linear torque curve helps maintain traction allot better on the street to be able to put that kind of power down. Also with turbos boost control can be setup as boost by speed or boost by gear (not sure if hptuners can do this or not) but the wastegate can be controlled allot better then a blower can be to make it where your pretty much at the limit of traction each gear. From my experience superchargers can be prone to heat soak and hot intake temps on low octane don’t work well together. I would do forged internals probably around 9-9.5 to 1 comp to support that power on pump gas reliably. As far as I’ve seen the 6.0l iron blocks are pretty damn strong. I’ve seen people make 1000+whp with them.

 

reliability @ 800hp depends partially on how much torque you're making to produce 800hp. a PD or turbo setup running that hard is gonna make GOBS more torque in your normally-usable DD powerband, therefore it'll cause a lot more stress on your driveline than a centrifugal that drives fairly the same until the RPMs are climbing, therefore making less torque where you normally drive & ramping up on the top end to hit your desired peak HP.

as for compression, you can boost a high-CR motor - it's just gonna have less room for error or variation without dialing the tune back. the way i understand it, knock happens at a specific temperature for your fuel quality, and cylinder pressure is one of the biggest factors that gets it up to that temp. a high compression ratio will only allow a few pounds of boost prior to that point (but results in faster throttle response, better efficiency, & more off-boost power). lower compression allows more boost before getting to that same cylinder pressure, which results in more air to burn in the cylinder. full-throttle power potential goes up while DD driving feel goes the other direction, though. a happy medium for DDing boosted LS engines has been around 10:1ish (static). obviously your cam/valve selection will make a difference (dynamic compression ratio), but you'd have to talk to somebody smarter than me for specifics on that.

my car's ~10.6:1 SCR with a built top end, donkey-dick (for an LS1) blower cam, & a TVS. the DCR's actually just a little lower than the stock top end was, and it makes 13psi now but was dynoed at 10psi putting down 650h/630t. it's actually still pretty decent to drive around town, even with the touchy clutch.

with 4.10s, i'm guessing you're running the GTO gearing - and even then, that should still load it up enough for a decent turbo setup.

 

Factory flat lay top with 62cc head and ls9 HG works out to about 10.65:1 You can run FI.

 

not sure what numbers your using but, that’s a bit off. A 6.0 with those heads and gaskets and at .003 out of the hole since most are around there factory (some more) comes in at around 11.3-1

 

i was figure 3.0 for valve reliefs and .003 below deck 10.7 Think I used .055 vs .051 for ls9 head gasket as I’ve seen both. Any way 11 far cry from 12+